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llvm-project/llvm/lib/Target/X86/X86ISelLoweringCall.cpp
Matt Arsenault ae56b6712d RuntimeLibcalls: Add entries for stackprotector globals 
Add entries for_stack_chk_guard, __ssp_canary_word, __security_cookie,
and __guard_local. As far as I can tell these are all just different
names for the same shaped functionality on different systems.

These aren't really functions, but special global variable names. They
should probably be treated the same way; all the same contexts that
need to know about emittable function names also need to know about
this. This avoids a special case check in IRSymtab.

This isn't a complete change, there's a lot more cleanup which
should be done. The stack protector configuration system is a
complete mess. There are multiple overlapping controls, used in
3 different places. Some of the target control implementations overlap
with conditions used in the emission points, and some use correlated
but not identical conditions in different contexts.

i.e. useLoadStackGuardNode, getIRStackGuard, getSSPStackGuardCheck and
insertSSPDeclarations are all used in inconsistent ways so I don't know
if I've tracked the intention of the system correctly.

The PowerPC test change is a bug fix on linux. Previously the manual
conditions were based around !isOSOpenBSD, which is not the condition
where __stack_chk_guard are used. Now getSDagStackGuard returns the
proper global reference, resulting in LOAD_STACK_GUARD getting a
MachineMemOperand which allows scheduling.
2025-08-22 20:18:30 +09:00

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//===- llvm/lib/Target/X86/X86ISelCallLowering.cpp - Call lowering --------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
/// \file
/// This file implements the lowering of LLVM calls to DAG nodes.
//
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/X86MCAsmInfo.h"
#include "X86.h"
#include "X86CallingConv.h"
#include "X86FrameLowering.h"
#include "X86ISelLowering.h"
#include "X86InstrBuilder.h"
#include "X86MachineFunctionInfo.h"
#include "X86TargetMachine.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/ObjCARCUtil.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/WinEHFuncInfo.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Module.h"
#define DEBUG_TYPE "x86-isel"
using namespace llvm;
STATISTIC(NumTailCalls, "Number of tail calls");
/// Call this when the user attempts to do something unsupported, like
/// returning a double without SSE2 enabled on x86_64. This is not fatal, unlike
/// report_fatal_error, so calling code should attempt to recover without
/// crashing.
static void errorUnsupported(SelectionDAG &DAG, const SDLoc &dl,
const char *Msg) {
MachineFunction &MF = DAG.getMachineFunction();
DAG.getContext()->diagnose(
DiagnosticInfoUnsupported(MF.getFunction(), Msg, dl.getDebugLoc()));
}
/// Returns true if a CC can dynamically exclude a register from the list of
/// callee-saved-registers (TargetRegistryInfo::getCalleeSavedRegs()) based on
/// the return registers.
static bool shouldDisableRetRegFromCSR(CallingConv::ID CC) {
switch (CC) {
default:
return false;
case CallingConv::X86_RegCall:
case CallingConv::PreserveMost:
case CallingConv::PreserveAll:
return true;
}
}
/// Returns true if a CC can dynamically exclude a register from the list of
/// callee-saved-registers (TargetRegistryInfo::getCalleeSavedRegs()) based on
/// the parameters.
static bool shouldDisableArgRegFromCSR(CallingConv::ID CC) {
return CC == CallingConv::X86_RegCall;
}
static std::pair<MVT, unsigned>
handleMaskRegisterForCallingConv(unsigned NumElts, CallingConv::ID CC,
const X86Subtarget &Subtarget) {
// v2i1/v4i1/v8i1/v16i1 all pass in xmm registers unless the calling
// convention is one that uses k registers.
if (NumElts == 2)
return {MVT::v2i64, 1};
if (NumElts == 4)
return {MVT::v4i32, 1};
if (NumElts == 8 && CC != CallingConv::X86_RegCall &&
CC != CallingConv::Intel_OCL_BI)
return {MVT::v8i16, 1};
if (NumElts == 16 && CC != CallingConv::X86_RegCall &&
CC != CallingConv::Intel_OCL_BI)
return {MVT::v16i8, 1};
// v32i1 passes in ymm unless we have BWI and the calling convention is
// regcall.
if (NumElts == 32 && (!Subtarget.hasBWI() || CC != CallingConv::X86_RegCall))
return {MVT::v32i8, 1};
// Split v64i1 vectors if we don't have v64i8 available.
if (NumElts == 64 && Subtarget.hasBWI() && CC != CallingConv::X86_RegCall) {
if (Subtarget.useAVX512Regs())
return {MVT::v64i8, 1};
return {MVT::v32i8, 2};
}
// Break wide or odd vXi1 vectors into scalars to match avx2 behavior.
if (!isPowerOf2_32(NumElts) || (NumElts == 64 && !Subtarget.hasBWI()) ||
NumElts > 64)
return {MVT::i8, NumElts};
return {MVT::INVALID_SIMPLE_VALUE_TYPE, 0};
}
MVT X86TargetLowering::getRegisterTypeForCallingConv(LLVMContext &Context,
CallingConv::ID CC,
EVT VT) const {
if (VT.isVector()) {
if (VT.getVectorElementType() == MVT::i1 && Subtarget.hasAVX512()) {
unsigned NumElts = VT.getVectorNumElements();
MVT RegisterVT;
unsigned NumRegisters;
std::tie(RegisterVT, NumRegisters) =
handleMaskRegisterForCallingConv(NumElts, CC, Subtarget);
if (RegisterVT != MVT::INVALID_SIMPLE_VALUE_TYPE)
return RegisterVT;
}
if (VT.getVectorElementType() == MVT::f16 && VT.getVectorNumElements() < 8)
return MVT::v8f16;
}
// We will use more GPRs for f64 and f80 on 32 bits when x87 is disabled.
if ((VT == MVT::f64 || VT == MVT::f80) && !Subtarget.is64Bit() &&
!Subtarget.hasX87())
return MVT::i32;
if (isTypeLegal(MVT::f16)) {
if (VT.isVector() && VT.getVectorElementType() == MVT::bf16)
return getRegisterTypeForCallingConv(
Context, CC, VT.changeVectorElementType(MVT::f16));
if (VT == MVT::bf16)
return MVT::f16;
}
return TargetLowering::getRegisterTypeForCallingConv(Context, CC, VT);
}
unsigned X86TargetLowering::getNumRegistersForCallingConv(LLVMContext &Context,
CallingConv::ID CC,
EVT VT) const {
if (VT.isVector()) {
if (VT.getVectorElementType() == MVT::i1 && Subtarget.hasAVX512()) {
unsigned NumElts = VT.getVectorNumElements();
MVT RegisterVT;
unsigned NumRegisters;
std::tie(RegisterVT, NumRegisters) =
handleMaskRegisterForCallingConv(NumElts, CC, Subtarget);
if (RegisterVT != MVT::INVALID_SIMPLE_VALUE_TYPE)
return NumRegisters;
}
if (VT.getVectorElementType() == MVT::f16 && VT.getVectorNumElements() < 8)
return 1;
}
// We have to split f64 to 2 registers and f80 to 3 registers on 32 bits if
// x87 is disabled.
if (!Subtarget.is64Bit() && !Subtarget.hasX87()) {
if (VT == MVT::f64)
return 2;
if (VT == MVT::f80)
return 3;
}
if (VT.isVector() && VT.getVectorElementType() == MVT::bf16 &&
isTypeLegal(MVT::f16))
return getNumRegistersForCallingConv(Context, CC,
VT.changeVectorElementType(MVT::f16));
return TargetLowering::getNumRegistersForCallingConv(Context, CC, VT);
}
unsigned X86TargetLowering::getVectorTypeBreakdownForCallingConv(
LLVMContext &Context, CallingConv::ID CC, EVT VT, EVT &IntermediateVT,
unsigned &NumIntermediates, MVT &RegisterVT) const {
// Break wide or odd vXi1 vectors into scalars to match avx2 behavior.
if (VT.isVector() && VT.getVectorElementType() == MVT::i1 &&
Subtarget.hasAVX512() &&
(!isPowerOf2_32(VT.getVectorNumElements()) ||
(VT.getVectorNumElements() == 64 && !Subtarget.hasBWI()) ||
VT.getVectorNumElements() > 64)) {
RegisterVT = MVT::i8;
IntermediateVT = MVT::i1;
NumIntermediates = VT.getVectorNumElements();
return NumIntermediates;
}
// Split v64i1 vectors if we don't have v64i8 available.
if (VT == MVT::v64i1 && Subtarget.hasBWI() && !Subtarget.useAVX512Regs() &&
CC != CallingConv::X86_RegCall) {
RegisterVT = MVT::v32i8;
IntermediateVT = MVT::v32i1;
NumIntermediates = 2;
return 2;
}
// Split vNbf16 vectors according to vNf16.
if (VT.isVector() && VT.getVectorElementType() == MVT::bf16 &&
isTypeLegal(MVT::f16))
VT = VT.changeVectorElementType(MVT::f16);
return TargetLowering::getVectorTypeBreakdownForCallingConv(Context, CC, VT, IntermediateVT,
NumIntermediates, RegisterVT);
}
EVT X86TargetLowering::getSetCCResultType(const DataLayout &DL,
LLVMContext& Context,
EVT VT) const {
if (!VT.isVector())
return MVT::i8;
if (Subtarget.hasAVX512()) {
// Figure out what this type will be legalized to.
EVT LegalVT = VT;
while (getTypeAction(Context, LegalVT) != TypeLegal)
LegalVT = getTypeToTransformTo(Context, LegalVT);
// If we got a 512-bit vector then we'll definitely have a vXi1 compare.
if (LegalVT.getSimpleVT().is512BitVector())
return EVT::getVectorVT(Context, MVT::i1, VT.getVectorElementCount());
if (LegalVT.getSimpleVT().isVector() && Subtarget.hasVLX()) {
// If we legalized to less than a 512-bit vector, then we will use a vXi1
// compare for vXi32/vXi64 for sure. If we have BWI we will also support
// vXi16/vXi8.
MVT EltVT = LegalVT.getSimpleVT().getVectorElementType();
if (Subtarget.hasBWI() || EltVT.getSizeInBits() >= 32)
return EVT::getVectorVT(Context, MVT::i1, VT.getVectorElementCount());
}
}
return VT.changeVectorElementTypeToInteger();
}
bool X86TargetLowering::functionArgumentNeedsConsecutiveRegisters(
Type *Ty, CallingConv::ID CallConv, bool isVarArg,
const DataLayout &DL) const {
// On x86-64 i128 is split into two i64s and needs to be allocated to two
// consecutive registers, or spilled to the stack as a whole. On x86-32 i128
// is split to four i32s and never actually passed in registers, but we use
// the consecutive register mark to match it in TableGen.
if (Ty->isIntegerTy(128))
return true;
// On x86-32, fp128 acts the same as i128.
if (Subtarget.is32Bit() && Ty->isFP128Ty())
return true;
return false;
}
/// Helper for getByValTypeAlignment to determine
/// the desired ByVal argument alignment.
static void getMaxByValAlign(Type *Ty, Align &MaxAlign) {
if (MaxAlign == 16)
return;
if (VectorType *VTy = dyn_cast<VectorType>(Ty)) {
if (VTy->getPrimitiveSizeInBits().getFixedValue() == 128)
MaxAlign = Align(16);
} else if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
Align EltAlign;
getMaxByValAlign(ATy->getElementType(), EltAlign);
if (EltAlign > MaxAlign)
MaxAlign = EltAlign;
} else if (StructType *STy = dyn_cast<StructType>(Ty)) {
for (auto *EltTy : STy->elements()) {
Align EltAlign;
getMaxByValAlign(EltTy, EltAlign);
if (EltAlign > MaxAlign)
MaxAlign = EltAlign;
if (MaxAlign == 16)
break;
}
}
}
/// Return the desired alignment for ByVal aggregate
/// function arguments in the caller parameter area. For X86, aggregates
/// that contain SSE vectors are placed at 16-byte boundaries while the rest
/// are at 4-byte boundaries.
Align X86TargetLowering::getByValTypeAlignment(Type *Ty,
const DataLayout &DL) const {
if (Subtarget.is64Bit())
return std::max(DL.getABITypeAlign(Ty), Align::Constant<8>());
Align Alignment(4);
if (Subtarget.hasSSE1())
getMaxByValAlign(Ty, Alignment);
return Alignment;
}
/// It returns EVT::Other if the type should be determined using generic
/// target-independent logic.
/// For vector ops we check that the overall size isn't larger than our
/// preferred vector width.
EVT X86TargetLowering::getOptimalMemOpType(
LLVMContext &Context, const MemOp &Op,
const AttributeList &FuncAttributes) const {
if (!FuncAttributes.hasFnAttr(Attribute::NoImplicitFloat)) {
if (Op.size() >= 16 &&
(!Subtarget.isUnalignedMem16Slow() || Op.isAligned(Align(16)))) {
// FIXME: Check if unaligned 64-byte accesses are slow.
if (Op.size() >= 64 && Subtarget.hasAVX512() && Subtarget.hasEVEX512() &&
(Subtarget.getPreferVectorWidth() >= 512)) {
return Subtarget.hasBWI() ? MVT::v64i8 : MVT::v16i32;
}
// FIXME: Check if unaligned 32-byte accesses are slow.
if (Op.size() >= 32 && Subtarget.hasAVX() &&
Subtarget.useLight256BitInstructions()) {
// Although this isn't a well-supported type for AVX1, we'll let
// legalization and shuffle lowering produce the optimal codegen. If we
// choose an optimal type with a vector element larger than a byte,
// getMemsetStores() may create an intermediate splat (using an integer
// multiply) before we splat as a vector.
return MVT::v32i8;
}
if (Subtarget.hasSSE2() && (Subtarget.getPreferVectorWidth() >= 128))
return MVT::v16i8;
// TODO: Can SSE1 handle a byte vector?
// If we have SSE1 registers we should be able to use them.
if (Subtarget.hasSSE1() && (Subtarget.is64Bit() || Subtarget.hasX87()) &&
(Subtarget.getPreferVectorWidth() >= 128))
return MVT::v4f32;
} else if (((Op.isMemcpy() && !Op.isMemcpyStrSrc()) || Op.isZeroMemset()) &&
Op.size() >= 8 && !Subtarget.is64Bit() && Subtarget.hasSSE2()) {
// Do not use f64 to lower memcpy if source is string constant. It's
// better to use i32 to avoid the loads.
// Also, do not use f64 to lower memset unless this is a memset of zeros.
// The gymnastics of splatting a byte value into an XMM register and then
// only using 8-byte stores (because this is a CPU with slow unaligned
// 16-byte accesses) makes that a loser.
return MVT::f64;
}
}
// This is a compromise. If we reach here, unaligned accesses may be slow on
// this target. However, creating smaller, aligned accesses could be even
// slower and would certainly be a lot more code.
if (Subtarget.is64Bit() && Op.size() >= 8)
return MVT::i64;
return MVT::i32;
}
bool X86TargetLowering::isSafeMemOpType(MVT VT) const {
if (VT == MVT::f32)
return Subtarget.hasSSE1();
if (VT == MVT::f64)
return Subtarget.hasSSE2();
return true;
}
static bool isBitAligned(Align Alignment, uint64_t SizeInBits) {
return (8 * Alignment.value()) % SizeInBits == 0;
}
bool X86TargetLowering::isMemoryAccessFast(EVT VT, Align Alignment) const {
if (isBitAligned(Alignment, VT.getSizeInBits()))
return true;
switch (VT.getSizeInBits()) {
default:
// 8-byte and under are always assumed to be fast.
return true;
case 128:
return !Subtarget.isUnalignedMem16Slow();
case 256:
return !Subtarget.isUnalignedMem32Slow();
// TODO: What about AVX-512 (512-bit) accesses?
}
}
bool X86TargetLowering::allowsMisalignedMemoryAccesses(
EVT VT, unsigned, Align Alignment, MachineMemOperand::Flags Flags,
unsigned *Fast) const {
if (Fast)
*Fast = isMemoryAccessFast(VT, Alignment);
// NonTemporal vector memory ops must be aligned.
if (!!(Flags & MachineMemOperand::MONonTemporal) && VT.isVector()) {
// NT loads can only be vector aligned, so if its less aligned than the
// minimum vector size (which we can split the vector down to), we might as
// well use a regular unaligned vector load.
// We don't have any NT loads pre-SSE41.
if (!!(Flags & MachineMemOperand::MOLoad))
return (Alignment < 16 || !Subtarget.hasSSE41());
return false;
}
// Misaligned accesses of any size are always allowed.
return true;
}
bool X86TargetLowering::allowsMemoryAccess(LLVMContext &Context,
const DataLayout &DL, EVT VT,
unsigned AddrSpace, Align Alignment,
MachineMemOperand::Flags Flags,
unsigned *Fast) const {
if (Fast)
*Fast = isMemoryAccessFast(VT, Alignment);
if (!!(Flags & MachineMemOperand::MONonTemporal) && VT.isVector()) {
if (allowsMisalignedMemoryAccesses(VT, AddrSpace, Alignment, Flags,
/*Fast=*/nullptr))
return true;
// NonTemporal vector memory ops are special, and must be aligned.
if (!isBitAligned(Alignment, VT.getSizeInBits()))
return false;
switch (VT.getSizeInBits()) {
case 128:
if (!!(Flags & MachineMemOperand::MOLoad) && Subtarget.hasSSE41())
return true;
if (!!(Flags & MachineMemOperand::MOStore) && Subtarget.hasSSE2())
return true;
return false;
case 256:
if (!!(Flags & MachineMemOperand::MOLoad) && Subtarget.hasAVX2())
return true;
if (!!(Flags & MachineMemOperand::MOStore) && Subtarget.hasAVX())
return true;
return false;
case 512:
if (Subtarget.hasAVX512() && Subtarget.hasEVEX512())
return true;
return false;
default:
return false; // Don't have NonTemporal vector memory ops of this size.
}
}
return true;
}
/// Return the entry encoding for a jump table in the
/// current function. The returned value is a member of the
/// MachineJumpTableInfo::JTEntryKind enum.
unsigned X86TargetLowering::getJumpTableEncoding() const {
// In GOT pic mode, each entry in the jump table is emitted as a @GOTOFF
// symbol.
if (isPositionIndependent() && Subtarget.isPICStyleGOT())
return MachineJumpTableInfo::EK_Custom32;
if (isPositionIndependent() &&
getTargetMachine().getCodeModel() == CodeModel::Large &&
!Subtarget.isTargetCOFF())
return MachineJumpTableInfo::EK_LabelDifference64;
// Otherwise, use the normal jump table encoding heuristics.
return TargetLowering::getJumpTableEncoding();
}
bool X86TargetLowering::useSoftFloat() const {
return Subtarget.useSoftFloat();
}
void X86TargetLowering::markLibCallAttributes(MachineFunction *MF, unsigned CC,
ArgListTy &Args) const {
// Only relabel X86-32 for C / Stdcall CCs.
if (Subtarget.is64Bit())
return;
if (CC != CallingConv::C && CC != CallingConv::X86_StdCall)
return;
unsigned ParamRegs = 0;
if (auto *M = MF->getFunction().getParent())
ParamRegs = M->getNumberRegisterParameters();
// Mark the first N int arguments as having reg
for (auto &Arg : Args) {
Type *T = Arg.Ty;
if (T->isIntOrPtrTy())
if (MF->getDataLayout().getTypeAllocSize(T) <= 8) {
unsigned numRegs = 1;
if (MF->getDataLayout().getTypeAllocSize(T) > 4)
numRegs = 2;
if (ParamRegs < numRegs)
return;
ParamRegs -= numRegs;
Arg.IsInReg = true;
}
}
}
const MCExpr *
X86TargetLowering::LowerCustomJumpTableEntry(const MachineJumpTableInfo *MJTI,
const MachineBasicBlock *MBB,
unsigned uid,MCContext &Ctx) const{
assert(isPositionIndependent() && Subtarget.isPICStyleGOT());
// In 32-bit ELF systems, our jump table entries are formed with @GOTOFF
// entries.
return MCSymbolRefExpr::create(MBB->getSymbol(), X86::S_GOTOFF, Ctx);
}
/// Returns relocation base for the given PIC jumptable.
SDValue X86TargetLowering::getPICJumpTableRelocBase(SDValue Table,
SelectionDAG &DAG) const {
if (!Subtarget.is64Bit())
// This doesn't have SDLoc associated with it, but is not really the
// same as a Register.
return DAG.getNode(X86ISD::GlobalBaseReg, SDLoc(),
getPointerTy(DAG.getDataLayout()));
return Table;
}
/// This returns the relocation base for the given PIC jumptable,
/// the same as getPICJumpTableRelocBase, but as an MCExpr.
const MCExpr *X86TargetLowering::
getPICJumpTableRelocBaseExpr(const MachineFunction *MF, unsigned JTI,
MCContext &Ctx) const {
// X86-64 uses RIP relative addressing based on the jump table label.
if (Subtarget.isPICStyleRIPRel() ||
(Subtarget.is64Bit() &&
getTargetMachine().getCodeModel() == CodeModel::Large))
return TargetLowering::getPICJumpTableRelocBaseExpr(MF, JTI, Ctx);
// Otherwise, the reference is relative to the PIC base.
return MCSymbolRefExpr::create(MF->getPICBaseSymbol(), Ctx);
}
std::pair<const TargetRegisterClass *, uint8_t>
X86TargetLowering::findRepresentativeClass(const TargetRegisterInfo *TRI,
MVT VT) const {
const TargetRegisterClass *RRC = nullptr;
uint8_t Cost = 1;
switch (VT.SimpleTy) {
default:
return TargetLowering::findRepresentativeClass(TRI, VT);
case MVT::i8: case MVT::i16: case MVT::i32: case MVT::i64:
RRC = Subtarget.is64Bit() ? &X86::GR64RegClass : &X86::GR32RegClass;
break;
case MVT::x86mmx:
RRC = &X86::VR64RegClass;
break;
case MVT::f32: case MVT::f64:
case MVT::v16i8: case MVT::v8i16: case MVT::v4i32: case MVT::v2i64:
case MVT::v4f32: case MVT::v2f64:
case MVT::v32i8: case MVT::v16i16: case MVT::v8i32: case MVT::v4i64:
case MVT::v8f32: case MVT::v4f64:
case MVT::v64i8: case MVT::v32i16: case MVT::v16i32: case MVT::v8i64:
case MVT::v16f32: case MVT::v8f64:
RRC = &X86::VR128XRegClass;
break;
}
return std::make_pair(RRC, Cost);
}
unsigned X86TargetLowering::getAddressSpace() const {
if (Subtarget.is64Bit())
return (getTargetMachine().getCodeModel() == CodeModel::Kernel) ? X86AS::GS
: X86AS::FS;
return X86AS::GS;
}
static bool hasStackGuardSlotTLS(const Triple &TargetTriple) {
return TargetTriple.isOSGlibc() || TargetTriple.isOSFuchsia() ||
(TargetTriple.isAndroid() && !TargetTriple.isAndroidVersionLT(17));
}
static Constant* SegmentOffset(IRBuilderBase &IRB,
int Offset, unsigned AddressSpace) {
return ConstantExpr::getIntToPtr(
ConstantInt::get(Type::getInt32Ty(IRB.getContext()), Offset),
IRB.getPtrTy(AddressSpace));
}
Value *X86TargetLowering::getIRStackGuard(IRBuilderBase &IRB) const {
// glibc, bionic, and Fuchsia have a special slot for the stack guard in
// tcbhead_t; use it instead of the usual global variable (see
// sysdeps/{i386,x86_64}/nptl/tls.h)
if (hasStackGuardSlotTLS(Subtarget.getTargetTriple())) {
unsigned AddressSpace = getAddressSpace();
// <zircon/tls.h> defines ZX_TLS_STACK_GUARD_OFFSET with this value.
if (Subtarget.isTargetFuchsia())
return SegmentOffset(IRB, 0x10, AddressSpace);
Module *M = IRB.GetInsertBlock()->getParent()->getParent();
// Specially, some users may customize the base reg and offset.
int Offset = M->getStackProtectorGuardOffset();
// If we don't set -stack-protector-guard-offset value:
// %fs:0x28, unless we're using a Kernel code model, in which case
// it's %gs:0x28. gs:0x14 on i386.
if (Offset == INT_MAX)
Offset = (Subtarget.is64Bit()) ? 0x28 : 0x14;
StringRef GuardReg = M->getStackProtectorGuardReg();
if (GuardReg == "fs")
AddressSpace = X86AS::FS;
else if (GuardReg == "gs")
AddressSpace = X86AS::GS;
// Use symbol guard if user specify.
StringRef GuardSymb = M->getStackProtectorGuardSymbol();
if (!GuardSymb.empty()) {
GlobalVariable *GV = M->getGlobalVariable(GuardSymb);
if (!GV) {
Type *Ty = Subtarget.is64Bit() ? Type::getInt64Ty(M->getContext())
: Type::getInt32Ty(M->getContext());
GV = new GlobalVariable(*M, Ty, false, GlobalValue::ExternalLinkage,
nullptr, GuardSymb, nullptr,
GlobalValue::NotThreadLocal, AddressSpace);
if (!Subtarget.isTargetDarwin())
GV->setDSOLocal(M->getDirectAccessExternalData());
}
return GV;
}
return SegmentOffset(IRB, Offset, AddressSpace);
}
return TargetLowering::getIRStackGuard(IRB);
}
void X86TargetLowering::insertSSPDeclarations(Module &M) const {
// MSVC CRT provides functionalities for stack protection.
if (Subtarget.getTargetTriple().isWindowsMSVCEnvironment() ||
Subtarget.getTargetTriple().isWindowsItaniumEnvironment()) {
// MSVC CRT has a global variable holding security cookie.
M.getOrInsertGlobal("__security_cookie",
PointerType::getUnqual(M.getContext()));
// MSVC CRT has a function to validate security cookie.
FunctionCallee SecurityCheckCookie = M.getOrInsertFunction(
"__security_check_cookie", Type::getVoidTy(M.getContext()),
PointerType::getUnqual(M.getContext()));
if (Function *F = dyn_cast<Function>(SecurityCheckCookie.getCallee())) {
F->setCallingConv(CallingConv::X86_FastCall);
F->addParamAttr(0, Attribute::AttrKind::InReg);
}
return;
}
StringRef GuardMode = M.getStackProtectorGuard();
// glibc, bionic, and Fuchsia have a special slot for the stack guard.
if ((GuardMode == "tls" || GuardMode.empty()) &&
hasStackGuardSlotTLS(Subtarget.getTargetTriple()))
return;
TargetLowering::insertSSPDeclarations(M);
}
Function *X86TargetLowering::getSSPStackGuardCheck(const Module &M) const {
// MSVC CRT has a function to validate security cookie.
if (Subtarget.getTargetTriple().isWindowsMSVCEnvironment() ||
Subtarget.getTargetTriple().isWindowsItaniumEnvironment()) {
return M.getFunction("__security_check_cookie");
}
return TargetLowering::getSSPStackGuardCheck(M);
}
Value *
X86TargetLowering::getSafeStackPointerLocation(IRBuilderBase &IRB) const {
// Android provides a fixed TLS slot for the SafeStack pointer. See the
// definition of TLS_SLOT_SAFESTACK in
// https://android.googlesource.com/platform/bionic/+/master/libc/private/bionic_tls.h
if (Subtarget.isTargetAndroid()) {
// %fs:0x48, unless we're using a Kernel code model, in which case it's %gs:
// %gs:0x24 on i386
int Offset = (Subtarget.is64Bit()) ? 0x48 : 0x24;
return SegmentOffset(IRB, Offset, getAddressSpace());
}
// Fuchsia is similar.
if (Subtarget.isTargetFuchsia()) {
// <zircon/tls.h> defines ZX_TLS_UNSAFE_SP_OFFSET with this value.
return SegmentOffset(IRB, 0x18, getAddressSpace());
}
return TargetLowering::getSafeStackPointerLocation(IRB);
}
//===----------------------------------------------------------------------===//
// Return Value Calling Convention Implementation
//===----------------------------------------------------------------------===//
bool X86TargetLowering::CanLowerReturn(
CallingConv::ID CallConv, MachineFunction &MF, bool isVarArg,
const SmallVectorImpl<ISD::OutputArg> &Outs, LLVMContext &Context,
const Type *RetTy) const {
SmallVector<CCValAssign, 16> RVLocs;
CCState CCInfo(CallConv, isVarArg, MF, RVLocs, Context);
return CCInfo.CheckReturn(Outs, RetCC_X86);
}
const MCPhysReg *X86TargetLowering::getScratchRegisters(CallingConv::ID) const {
static const MCPhysReg ScratchRegs[] = { X86::R11, 0 };
return ScratchRegs;
}
ArrayRef<MCPhysReg> X86TargetLowering::getRoundingControlRegisters() const {
static const MCPhysReg RCRegs[] = {X86::FPCW, X86::MXCSR};
return RCRegs;
}
/// Lowers masks values (v*i1) to the local register values
/// \returns DAG node after lowering to register type
static SDValue lowerMasksToReg(const SDValue &ValArg, const EVT &ValLoc,
const SDLoc &DL, SelectionDAG &DAG) {
EVT ValVT = ValArg.getValueType();
if (ValVT == MVT::v1i1)
return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, ValLoc, ValArg,
DAG.getIntPtrConstant(0, DL));
if ((ValVT == MVT::v8i1 && (ValLoc == MVT::i8 || ValLoc == MVT::i32)) ||
(ValVT == MVT::v16i1 && (ValLoc == MVT::i16 || ValLoc == MVT::i32))) {
// Two stage lowering might be required
// bitcast: v8i1 -> i8 / v16i1 -> i16
// anyextend: i8 -> i32 / i16 -> i32
EVT TempValLoc = ValVT == MVT::v8i1 ? MVT::i8 : MVT::i16;
SDValue ValToCopy = DAG.getBitcast(TempValLoc, ValArg);
if (ValLoc == MVT::i32)
ValToCopy = DAG.getNode(ISD::ANY_EXTEND, DL, ValLoc, ValToCopy);
return ValToCopy;
}
if ((ValVT == MVT::v32i1 && ValLoc == MVT::i32) ||
(ValVT == MVT::v64i1 && ValLoc == MVT::i64)) {
// One stage lowering is required
// bitcast: v32i1 -> i32 / v64i1 -> i64
return DAG.getBitcast(ValLoc, ValArg);
}
return DAG.getNode(ISD::ANY_EXTEND, DL, ValLoc, ValArg);
}
/// Breaks v64i1 value into two registers and adds the new node to the DAG
static void Passv64i1ArgInRegs(
const SDLoc &DL, SelectionDAG &DAG, SDValue &Arg,
SmallVectorImpl<std::pair<Register, SDValue>> &RegsToPass, CCValAssign &VA,
CCValAssign &NextVA, const X86Subtarget &Subtarget) {
assert(Subtarget.hasBWI() && "Expected AVX512BW target!");
assert(Subtarget.is32Bit() && "Expecting 32 bit target");
assert(Arg.getValueType() == MVT::i64 && "Expecting 64 bit value");
assert(VA.isRegLoc() && NextVA.isRegLoc() &&
"The value should reside in two registers");
// Before splitting the value we cast it to i64
Arg = DAG.getBitcast(MVT::i64, Arg);
// Splitting the value into two i32 types
SDValue Lo, Hi;
std::tie(Lo, Hi) = DAG.SplitScalar(Arg, DL, MVT::i32, MVT::i32);
// Attach the two i32 types into corresponding registers
RegsToPass.push_back(std::make_pair(VA.getLocReg(), Lo));
RegsToPass.push_back(std::make_pair(NextVA.getLocReg(), Hi));
}
SDValue
X86TargetLowering::LowerReturn(SDValue Chain, CallingConv::ID CallConv,
bool isVarArg,
const SmallVectorImpl<ISD::OutputArg> &Outs,
const SmallVectorImpl<SDValue> &OutVals,
const SDLoc &dl, SelectionDAG &DAG) const {
MachineFunction &MF = DAG.getMachineFunction();
X86MachineFunctionInfo *FuncInfo = MF.getInfo<X86MachineFunctionInfo>();
// In some cases we need to disable registers from the default CSR list.
// For example, when they are used as return registers (preserve_* and X86's
// regcall) or for argument passing (X86's regcall).
bool ShouldDisableCalleeSavedRegister =
shouldDisableRetRegFromCSR(CallConv) ||
MF.getFunction().hasFnAttribute("no_caller_saved_registers");
if (CallConv == CallingConv::X86_INTR && !Outs.empty())
report_fatal_error("X86 interrupts may not return any value");
SmallVector<CCValAssign, 16> RVLocs;
CCState CCInfo(CallConv, isVarArg, MF, RVLocs, *DAG.getContext());
CCInfo.AnalyzeReturn(Outs, RetCC_X86);
SmallVector<std::pair<Register, SDValue>, 4> RetVals;
for (unsigned I = 0, OutsIndex = 0, E = RVLocs.size(); I != E;
++I, ++OutsIndex) {
CCValAssign &VA = RVLocs[I];
assert(VA.isRegLoc() && "Can only return in registers!");
// Add the register to the CalleeSaveDisableRegs list.
if (ShouldDisableCalleeSavedRegister)
MF.getRegInfo().disableCalleeSavedRegister(VA.getLocReg());
SDValue ValToCopy = OutVals[OutsIndex];
EVT ValVT = ValToCopy.getValueType();
// Promote values to the appropriate types.
if (VA.getLocInfo() == CCValAssign::SExt)
ValToCopy = DAG.getNode(ISD::SIGN_EXTEND, dl, VA.getLocVT(), ValToCopy);
else if (VA.getLocInfo() == CCValAssign::ZExt)
ValToCopy = DAG.getNode(ISD::ZERO_EXTEND, dl, VA.getLocVT(), ValToCopy);
else if (VA.getLocInfo() == CCValAssign::AExt) {
if (ValVT.isVector() && ValVT.getVectorElementType() == MVT::i1)
ValToCopy = lowerMasksToReg(ValToCopy, VA.getLocVT(), dl, DAG);
else
ValToCopy = DAG.getNode(ISD::ANY_EXTEND, dl, VA.getLocVT(), ValToCopy);
}
else if (VA.getLocInfo() == CCValAssign::BCvt)
ValToCopy = DAG.getBitcast(VA.getLocVT(), ValToCopy);
assert(VA.getLocInfo() != CCValAssign::FPExt &&
"Unexpected FP-extend for return value.");
// Report an error if we have attempted to return a value via an XMM
// register and SSE was disabled.
if (!Subtarget.hasSSE1() && X86::FR32XRegClass.contains(VA.getLocReg())) {
errorUnsupported(DAG, dl, "SSE register return with SSE disabled");
VA.convertToReg(X86::FP0); // Set reg to FP0, avoid hitting asserts.
} else if (!Subtarget.hasSSE2() &&
X86::FR64XRegClass.contains(VA.getLocReg()) &&
ValVT == MVT::f64) {
// When returning a double via an XMM register, report an error if SSE2 is
// not enabled.
errorUnsupported(DAG, dl, "SSE2 register return with SSE2 disabled");
VA.convertToReg(X86::FP0); // Set reg to FP0, avoid hitting asserts.
}
// Returns in ST0/ST1 are handled specially: these are pushed as operands to
// the RET instruction and handled by the FP Stackifier.
if (VA.getLocReg() == X86::FP0 ||
VA.getLocReg() == X86::FP1) {
// If this is a copy from an xmm register to ST(0), use an FPExtend to
// change the value to the FP stack register class.
if (isScalarFPTypeInSSEReg(VA.getValVT()))
ValToCopy = DAG.getNode(ISD::FP_EXTEND, dl, MVT::f80, ValToCopy);
RetVals.push_back(std::make_pair(VA.getLocReg(), ValToCopy));
// Don't emit a copytoreg.
continue;
}
// 64-bit vector (MMX) values are returned in XMM0 / XMM1 except for v1i64
// which is returned in RAX / RDX.
if (Subtarget.is64Bit()) {
if (ValVT == MVT::x86mmx) {
if (VA.getLocReg() == X86::XMM0 || VA.getLocReg() == X86::XMM1) {
ValToCopy = DAG.getBitcast(MVT::i64, ValToCopy);
ValToCopy = DAG.getNode(ISD::SCALAR_TO_VECTOR, dl, MVT::v2i64,
ValToCopy);
// If we don't have SSE2 available, convert to v4f32 so the generated
// register is legal.
if (!Subtarget.hasSSE2())
ValToCopy = DAG.getBitcast(MVT::v4f32, ValToCopy);
}
}
}
if (VA.needsCustom()) {
assert(VA.getValVT() == MVT::v64i1 &&
"Currently the only custom case is when we split v64i1 to 2 regs");
Passv64i1ArgInRegs(dl, DAG, ValToCopy, RetVals, VA, RVLocs[++I],
Subtarget);
// Add the second register to the CalleeSaveDisableRegs list.
if (ShouldDisableCalleeSavedRegister)
MF.getRegInfo().disableCalleeSavedRegister(RVLocs[I].getLocReg());
} else {
RetVals.push_back(std::make_pair(VA.getLocReg(), ValToCopy));
}
}
SDValue Glue;
SmallVector<SDValue, 6> RetOps;
RetOps.push_back(Chain); // Operand #0 = Chain (updated below)
// Operand #1 = Bytes To Pop
RetOps.push_back(DAG.getTargetConstant(FuncInfo->getBytesToPopOnReturn(), dl,
MVT::i32));
// Copy the result values into the output registers.
for (auto &RetVal : RetVals) {
if (RetVal.first == X86::FP0 || RetVal.first == X86::FP1) {
RetOps.push_back(RetVal.second);
continue; // Don't emit a copytoreg.
}
Chain = DAG.getCopyToReg(Chain, dl, RetVal.first, RetVal.second, Glue);
Glue = Chain.getValue(1);
RetOps.push_back(
DAG.getRegister(RetVal.first, RetVal.second.getValueType()));
}
// Swift calling convention does not require we copy the sret argument
// into %rax/%eax for the return, and SRetReturnReg is not set for Swift.
// All x86 ABIs require that for returning structs by value we copy
// the sret argument into %rax/%eax (depending on ABI) for the return.
// We saved the argument into a virtual register in the entry block,
// so now we copy the value out and into %rax/%eax.
//
// Checking Function.hasStructRetAttr() here is insufficient because the IR
// may not have an explicit sret argument. If FuncInfo.CanLowerReturn is
// false, then an sret argument may be implicitly inserted in the SelDAG. In
// either case FuncInfo->setSRetReturnReg() will have been called.
if (Register SRetReg = FuncInfo->getSRetReturnReg()) {
// When we have both sret and another return value, we should use the
// original Chain stored in RetOps[0], instead of the current Chain updated
// in the above loop. If we only have sret, RetOps[0] equals to Chain.
// For the case of sret and another return value, we have
// Chain_0 at the function entry
// Chain_1 = getCopyToReg(Chain_0) in the above loop
// If we use Chain_1 in getCopyFromReg, we will have
// Val = getCopyFromReg(Chain_1)
// Chain_2 = getCopyToReg(Chain_1, Val) from below
// getCopyToReg(Chain_0) will be glued together with
// getCopyToReg(Chain_1, Val) into Unit A, getCopyFromReg(Chain_1) will be
// in Unit B, and we will have cyclic dependency between Unit A and Unit B:
// Data dependency from Unit B to Unit A due to usage of Val in
// getCopyToReg(Chain_1, Val)
// Chain dependency from Unit A to Unit B
// So here, we use RetOps[0] (i.e Chain_0) for getCopyFromReg.
SDValue Val = DAG.getCopyFromReg(RetOps[0], dl, SRetReg,
getPointerTy(MF.getDataLayout()));
Register RetValReg
= (Subtarget.is64Bit() && !Subtarget.isTarget64BitILP32()) ?
X86::RAX : X86::EAX;
Chain = DAG.getCopyToReg(Chain, dl, RetValReg, Val, Glue);
Glue = Chain.getValue(1);
// RAX/EAX now acts like a return value.
RetOps.push_back(
DAG.getRegister(RetValReg, getPointerTy(DAG.getDataLayout())));
// Add the returned register to the CalleeSaveDisableRegs list. Don't do
// this however for preserve_most/preserve_all to minimize the number of
// callee-saved registers for these CCs.
if (ShouldDisableCalleeSavedRegister &&
CallConv != CallingConv::PreserveAll &&
CallConv != CallingConv::PreserveMost)
MF.getRegInfo().disableCalleeSavedRegister(RetValReg);
}
const X86RegisterInfo *TRI = Subtarget.getRegisterInfo();
const MCPhysReg *I =
TRI->getCalleeSavedRegsViaCopy(&DAG.getMachineFunction());
if (I) {
for (; *I; ++I) {
if (X86::GR64RegClass.contains(*I))
RetOps.push_back(DAG.getRegister(*I, MVT::i64));
else
llvm_unreachable("Unexpected register class in CSRsViaCopy!");
}
}
RetOps[0] = Chain; // Update chain.
// Add the glue if we have it.
if (Glue.getNode())
RetOps.push_back(Glue);
X86ISD::NodeType opcode = X86ISD::RET_GLUE;
if (CallConv == CallingConv::X86_INTR)
opcode = X86ISD::IRET;
return DAG.getNode(opcode, dl, MVT::Other, RetOps);
}
bool X86TargetLowering::isUsedByReturnOnly(SDNode *N, SDValue &Chain) const {
if (N->getNumValues() != 1 || !N->hasNUsesOfValue(1, 0))
return false;
SDValue TCChain = Chain;
SDNode *Copy = *N->user_begin();
if (Copy->getOpcode() == ISD::CopyToReg) {
// If the copy has a glue operand, we conservatively assume it isn't safe to
// perform a tail call.
if (Copy->getOperand(Copy->getNumOperands()-1).getValueType() == MVT::Glue)
return false;
TCChain = Copy->getOperand(0);
} else if (Copy->getOpcode() != ISD::FP_EXTEND)
return false;
bool HasRet = false;
for (const SDNode *U : Copy->users()) {
if (U->getOpcode() != X86ISD::RET_GLUE)
return false;
// If we are returning more than one value, we can definitely
// not make a tail call see PR19530
if (U->getNumOperands() > 4)
return false;
if (U->getNumOperands() == 4 &&
U->getOperand(U->getNumOperands() - 1).getValueType() != MVT::Glue)
return false;
HasRet = true;
}
if (!HasRet)
return false;
Chain = TCChain;
return true;
}
EVT X86TargetLowering::getTypeForExtReturn(LLVMContext &Context, EVT VT,
ISD::NodeType ExtendKind) const {
MVT ReturnMVT = MVT::i32;
bool Darwin = Subtarget.getTargetTriple().isOSDarwin();
if (VT == MVT::i1 || (!Darwin && (VT == MVT::i8 || VT == MVT::i16))) {
// The ABI does not require i1, i8 or i16 to be extended.
//
// On Darwin, there is code in the wild relying on Clang's old behaviour of
// always extending i8/i16 return values, so keep doing that for now.
// (PR26665).
ReturnMVT = MVT::i8;
}
EVT MinVT = getRegisterType(Context, ReturnMVT);
return VT.bitsLT(MinVT) ? MinVT : VT;
}
/// Reads two 32 bit registers and creates a 64 bit mask value.
/// \param VA The current 32 bit value that need to be assigned.
/// \param NextVA The next 32 bit value that need to be assigned.
/// \param Root The parent DAG node.
/// \param [in,out] InGlue Represents SDvalue in the parent DAG node for
/// glue purposes. In the case the DAG is already using
/// physical register instead of virtual, we should glue
/// our new SDValue to InGlue SDvalue.
/// \return a new SDvalue of size 64bit.
static SDValue getv64i1Argument(CCValAssign &VA, CCValAssign &NextVA,
SDValue &Root, SelectionDAG &DAG,
const SDLoc &DL, const X86Subtarget &Subtarget,
SDValue *InGlue = nullptr) {
assert((Subtarget.hasBWI()) && "Expected AVX512BW target!");
assert(Subtarget.is32Bit() && "Expecting 32 bit target");
assert(VA.getValVT() == MVT::v64i1 &&
"Expecting first location of 64 bit width type");
assert(NextVA.getValVT() == VA.getValVT() &&
"The locations should have the same type");
assert(VA.isRegLoc() && NextVA.isRegLoc() &&
"The values should reside in two registers");
SDValue Lo, Hi;
SDValue ArgValueLo, ArgValueHi;
MachineFunction &MF = DAG.getMachineFunction();
const TargetRegisterClass *RC = &X86::GR32RegClass;
// Read a 32 bit value from the registers.
if (nullptr == InGlue) {
// When no physical register is present,
// create an intermediate virtual register.
Register Reg = MF.addLiveIn(VA.getLocReg(), RC);
ArgValueLo = DAG.getCopyFromReg(Root, DL, Reg, MVT::i32);
Reg = MF.addLiveIn(NextVA.getLocReg(), RC);
ArgValueHi = DAG.getCopyFromReg(Root, DL, Reg, MVT::i32);
} else {
// When a physical register is available read the value from it and glue
// the reads together.
ArgValueLo =
DAG.getCopyFromReg(Root, DL, VA.getLocReg(), MVT::i32, *InGlue);
*InGlue = ArgValueLo.getValue(2);
ArgValueHi =
DAG.getCopyFromReg(Root, DL, NextVA.getLocReg(), MVT::i32, *InGlue);
*InGlue = ArgValueHi.getValue(2);
}
// Convert the i32 type into v32i1 type.
Lo = DAG.getBitcast(MVT::v32i1, ArgValueLo);
// Convert the i32 type into v32i1 type.
Hi = DAG.getBitcast(MVT::v32i1, ArgValueHi);
// Concatenate the two values together.
return DAG.getNode(ISD::CONCAT_VECTORS, DL, MVT::v64i1, Lo, Hi);
}
/// The function will lower a register of various sizes (8/16/32/64)
/// to a mask value of the expected size (v8i1/v16i1/v32i1/v64i1)
/// \returns a DAG node contains the operand after lowering to mask type.
static SDValue lowerRegToMasks(const SDValue &ValArg, const EVT &ValVT,
const EVT &ValLoc, const SDLoc &DL,
SelectionDAG &DAG) {
SDValue ValReturned = ValArg;
if (ValVT == MVT::v1i1)
return DAG.getNode(ISD::SCALAR_TO_VECTOR, DL, MVT::v1i1, ValReturned);
if (ValVT == MVT::v64i1) {
// In 32 bit machine, this case is handled by getv64i1Argument
assert(ValLoc == MVT::i64 && "Expecting only i64 locations");
// In 64 bit machine, There is no need to truncate the value only bitcast
} else {
MVT MaskLenVT;
switch (ValVT.getSimpleVT().SimpleTy) {
case MVT::v8i1:
MaskLenVT = MVT::i8;
break;
case MVT::v16i1:
MaskLenVT = MVT::i16;
break;
case MVT::v32i1:
MaskLenVT = MVT::i32;
break;
default:
llvm_unreachable("Expecting a vector of i1 types");
}
ValReturned = DAG.getNode(ISD::TRUNCATE, DL, MaskLenVT, ValReturned);
}
return DAG.getBitcast(ValVT, ValReturned);
}
static SDValue getPopFromX87Reg(SelectionDAG &DAG, SDValue Chain,
const SDLoc &dl, Register Reg, EVT VT,
SDValue Glue) {
SDVTList VTs = DAG.getVTList(VT, MVT::Other, MVT::Glue);
SDValue Ops[] = {Chain, DAG.getRegister(Reg, VT), Glue};
return DAG.getNode(X86ISD::POP_FROM_X87_REG, dl, VTs,
ArrayRef(Ops, Glue.getNode() ? 3 : 2));
}
/// Lower the result values of a call into the
/// appropriate copies out of appropriate physical registers.
///
SDValue X86TargetLowering::LowerCallResult(
SDValue Chain, SDValue InGlue, CallingConv::ID CallConv, bool isVarArg,
const SmallVectorImpl<ISD::InputArg> &Ins, const SDLoc &dl,
SelectionDAG &DAG, SmallVectorImpl<SDValue> &InVals,
uint32_t *RegMask) const {
const TargetRegisterInfo *TRI = Subtarget.getRegisterInfo();
// Assign locations to each value returned by this call.
SmallVector<CCValAssign, 16> RVLocs;
CCState CCInfo(CallConv, isVarArg, DAG.getMachineFunction(), RVLocs,
*DAG.getContext());
CCInfo.AnalyzeCallResult(Ins, RetCC_X86);
// Copy all of the result registers out of their specified physreg.
for (unsigned I = 0, InsIndex = 0, E = RVLocs.size(); I != E;
++I, ++InsIndex) {
CCValAssign &VA = RVLocs[I];
EVT CopyVT = VA.getLocVT();
// In some calling conventions we need to remove the used registers
// from the register mask.
if (RegMask) {
for (MCPhysReg SubReg : TRI->subregs_inclusive(VA.getLocReg()))
RegMask[SubReg / 32] &= ~(1u << (SubReg % 32));
}
// Report an error if there was an attempt to return FP values via XMM
// registers.
if (!Subtarget.hasSSE1() && X86::FR32XRegClass.contains(VA.getLocReg())) {
errorUnsupported(DAG, dl, "SSE register return with SSE disabled");
if (VA.getLocReg() == X86::XMM1)
VA.convertToReg(X86::FP1); // Set reg to FP1, avoid hitting asserts.
else
VA.convertToReg(X86::FP0); // Set reg to FP0, avoid hitting asserts.
} else if (!Subtarget.hasSSE2() &&
X86::FR64XRegClass.contains(VA.getLocReg()) &&
CopyVT == MVT::f64) {
errorUnsupported(DAG, dl, "SSE2 register return with SSE2 disabled");
if (VA.getLocReg() == X86::XMM1)
VA.convertToReg(X86::FP1); // Set reg to FP1, avoid hitting asserts.
else
VA.convertToReg(X86::FP0); // Set reg to FP0, avoid hitting asserts.
}
// If we prefer to use the value in xmm registers, copy it out as f80 and
// use a truncate to move it from fp stack reg to xmm reg.
bool RoundAfterCopy = false;
bool X87Result = VA.getLocReg() == X86::FP0 || VA.getLocReg() == X86::FP1;
if (X87Result && isScalarFPTypeInSSEReg(VA.getValVT())) {
if (!Subtarget.hasX87())
report_fatal_error("X87 register return with X87 disabled");
CopyVT = MVT::f80;
RoundAfterCopy = (CopyVT != VA.getLocVT());
}
SDValue Val;
if (VA.needsCustom()) {
assert(VA.getValVT() == MVT::v64i1 &&
"Currently the only custom case is when we split v64i1 to 2 regs");
Val =
getv64i1Argument(VA, RVLocs[++I], Chain, DAG, dl, Subtarget, &InGlue);
} else {
Chain =
X87Result
? getPopFromX87Reg(DAG, Chain, dl, VA.getLocReg(), CopyVT, InGlue)
.getValue(1)
: DAG.getCopyFromReg(Chain, dl, VA.getLocReg(), CopyVT, InGlue)
.getValue(1);
Val = Chain.getValue(0);
InGlue = Chain.getValue(2);
}
if (RoundAfterCopy)
Val = DAG.getNode(ISD::FP_ROUND, dl, VA.getValVT(), Val,
// This truncation won't change the value.
DAG.getIntPtrConstant(1, dl, /*isTarget=*/true));
if (VA.isExtInLoc()) {
if (VA.getValVT().isVector() &&
VA.getValVT().getScalarType() == MVT::i1 &&
((VA.getLocVT() == MVT::i64) || (VA.getLocVT() == MVT::i32) ||
(VA.getLocVT() == MVT::i16) || (VA.getLocVT() == MVT::i8))) {
// promoting a mask type (v*i1) into a register of type i64/i32/i16/i8
Val = lowerRegToMasks(Val, VA.getValVT(), VA.getLocVT(), dl, DAG);
} else
Val = DAG.getNode(ISD::TRUNCATE, dl, VA.getValVT(), Val);
}
if (VA.getLocInfo() == CCValAssign::BCvt)
Val = DAG.getBitcast(VA.getValVT(), Val);
InVals.push_back(Val);
}
return Chain;
}
//===----------------------------------------------------------------------===//
// C & StdCall & Fast Calling Convention implementation
//===----------------------------------------------------------------------===//
// StdCall calling convention seems to be standard for many Windows' API
// routines and around. It differs from C calling convention just a little:
// callee should clean up the stack, not caller. Symbols should be also
// decorated in some fancy way :) It doesn't support any vector arguments.
// For info on fast calling convention see Fast Calling Convention (tail call)
// implementation LowerX86_32FastCCCallTo.
/// Determines whether Args, either a set of outgoing arguments to a call, or a
/// set of incoming args of a call, contains an sret pointer that the callee
/// pops
template <typename T>
static bool hasCalleePopSRet(const SmallVectorImpl<T> &Args,
const X86Subtarget &Subtarget) {
// Not C++20 (yet), so no concepts available.
static_assert(std::is_same_v<T, ISD::OutputArg> ||
std::is_same_v<T, ISD::InputArg>,
"requires ISD::OutputArg or ISD::InputArg");
// Only 32-bit pops the sret. It's a 64-bit world these days, so early-out
// for most compilations.
if (!Subtarget.is32Bit())
return false;
if (Args.empty())
return false;
// Most calls do not have an sret argument, check the arg next.
const ISD::ArgFlagsTy &Flags = Args[0].Flags;
if (!Flags.isSRet() || Flags.isInReg())
return false;
// The MSVCabi does not pop the sret.
if (Subtarget.getTargetTriple().isOSMSVCRT())
return false;
// MCUs don't pop the sret
if (Subtarget.isTargetMCU())
return false;
// Callee pops argument
return true;
}
/// Make a copy of an aggregate at address specified by "Src" to address
/// "Dst" with size and alignment information specified by the specific
/// parameter attribute. The copy will be passed as a byval function parameter.
static SDValue CreateCopyOfByValArgument(SDValue Src, SDValue Dst,
SDValue Chain, ISD::ArgFlagsTy Flags,
SelectionDAG &DAG, const SDLoc &dl) {
SDValue SizeNode = DAG.getIntPtrConstant(Flags.getByValSize(), dl);
return DAG.getMemcpy(
Chain, dl, Dst, Src, SizeNode, Flags.getNonZeroByValAlign(),
/*isVolatile*/ false, /*AlwaysInline=*/true,
/*CI=*/nullptr, std::nullopt, MachinePointerInfo(), MachinePointerInfo());
}
/// Return true if the calling convention is one that we can guarantee TCO for.
static bool canGuaranteeTCO(CallingConv::ID CC) {
return (CC == CallingConv::Fast || CC == CallingConv::GHC ||
CC == CallingConv::X86_RegCall || CC == CallingConv::HiPE ||
CC == CallingConv::Tail || CC == CallingConv::SwiftTail);
}
/// Return true if we might ever do TCO for calls with this calling convention.
static bool mayTailCallThisCC(CallingConv::ID CC) {
switch (CC) {
// C calling conventions:
case CallingConv::C:
case CallingConv::Win64:
case CallingConv::X86_64_SysV:
case CallingConv::PreserveNone:
// Callee pop conventions:
case CallingConv::X86_ThisCall:
case CallingConv::X86_StdCall:
case CallingConv::X86_VectorCall:
case CallingConv::X86_FastCall:
// Swift:
case CallingConv::Swift:
return true;
default:
return canGuaranteeTCO(CC);
}
}
/// Return true if the function is being made into a tailcall target by
/// changing its ABI.
static bool shouldGuaranteeTCO(CallingConv::ID CC, bool GuaranteedTailCallOpt) {
return (GuaranteedTailCallOpt && canGuaranteeTCO(CC)) ||
CC == CallingConv::Tail || CC == CallingConv::SwiftTail;
}
bool X86TargetLowering::mayBeEmittedAsTailCall(const CallInst *CI) const {
if (!CI->isTailCall())
return false;
CallingConv::ID CalleeCC = CI->getCallingConv();
if (!mayTailCallThisCC(CalleeCC))
return false;
return true;
}
SDValue
X86TargetLowering::LowerMemArgument(SDValue Chain, CallingConv::ID CallConv,
const SmallVectorImpl<ISD::InputArg> &Ins,
const SDLoc &dl, SelectionDAG &DAG,
const CCValAssign &VA,
MachineFrameInfo &MFI, unsigned i) const {
// Create the nodes corresponding to a load from this parameter slot.
ISD::ArgFlagsTy Flags = Ins[i].Flags;
bool AlwaysUseMutable = shouldGuaranteeTCO(
CallConv, DAG.getTarget().Options.GuaranteedTailCallOpt);
bool isImmutable = !AlwaysUseMutable && !Flags.isByVal();
EVT ValVT;
MVT PtrVT = getPointerTy(DAG.getDataLayout());
// If value is passed by pointer we have address passed instead of the value
// itself. No need to extend if the mask value and location share the same
// absolute size.
bool ExtendedInMem =
VA.isExtInLoc() && VA.getValVT().getScalarType() == MVT::i1 &&
VA.getValVT().getSizeInBits() != VA.getLocVT().getSizeInBits();
if (VA.getLocInfo() == CCValAssign::Indirect || ExtendedInMem)
ValVT = VA.getLocVT();
else
ValVT = VA.getValVT();
// FIXME: For now, all byval parameter objects are marked mutable. This can be
// changed with more analysis.
// In case of tail call optimization mark all arguments mutable. Since they
// could be overwritten by lowering of arguments in case of a tail call.
if (Flags.isByVal()) {
unsigned Bytes = Flags.getByValSize();
if (Bytes == 0) Bytes = 1; // Don't create zero-sized stack objects.
// FIXME: For now, all byval parameter objects are marked as aliasing. This
// can be improved with deeper analysis.
int FI = MFI.CreateFixedObject(Bytes, VA.getLocMemOffset(), isImmutable,
/*isAliased=*/true);
return DAG.getFrameIndex(FI, PtrVT);
}
EVT ArgVT = Ins[i].ArgVT;
// If this is a vector that has been split into multiple parts, don't elide
// the copy. The layout on the stack may not match the packed in-memory
// layout.
bool ScalarizedVector = ArgVT.isVector() && !VA.getLocVT().isVector();
// This is an argument in memory. We might be able to perform copy elision.
// If the argument is passed directly in memory without any extension, then we
// can perform copy elision. Large vector types, for example, may be passed
// indirectly by pointer.
if (Flags.isCopyElisionCandidate() &&
VA.getLocInfo() != CCValAssign::Indirect && !ExtendedInMem &&
!ScalarizedVector) {
SDValue PartAddr;
if (Ins[i].PartOffset == 0) {
// If this is a one-part value or the first part of a multi-part value,
// create a stack object for the entire argument value type and return a
// load from our portion of it. This assumes that if the first part of an
// argument is in memory, the rest will also be in memory.
int FI = MFI.CreateFixedObject(ArgVT.getStoreSize(), VA.getLocMemOffset(),
/*IsImmutable=*/false);
PartAddr = DAG.getFrameIndex(FI, PtrVT);
return DAG.getLoad(
ValVT, dl, Chain, PartAddr,
MachinePointerInfo::getFixedStack(DAG.getMachineFunction(), FI));
}
// This is not the first piece of an argument in memory. See if there is
// already a fixed stack object including this offset. If so, assume it
// was created by the PartOffset == 0 branch above and create a load from
// the appropriate offset into it.
int64_t PartBegin = VA.getLocMemOffset();
int64_t PartEnd = PartBegin + ValVT.getSizeInBits() / 8;
int FI = MFI.getObjectIndexBegin();
for (; MFI.isFixedObjectIndex(FI); ++FI) {
int64_t ObjBegin = MFI.getObjectOffset(FI);
int64_t ObjEnd = ObjBegin + MFI.getObjectSize(FI);
if (ObjBegin <= PartBegin && PartEnd <= ObjEnd)
break;
}
if (MFI.isFixedObjectIndex(FI)) {
SDValue Addr =
DAG.getNode(ISD::ADD, dl, PtrVT, DAG.getFrameIndex(FI, PtrVT),
DAG.getIntPtrConstant(Ins[i].PartOffset, dl));
return DAG.getLoad(ValVT, dl, Chain, Addr,
MachinePointerInfo::getFixedStack(
DAG.getMachineFunction(), FI, Ins[i].PartOffset));
}
}
int FI = MFI.CreateFixedObject(ValVT.getSizeInBits() / 8,
VA.getLocMemOffset(), isImmutable);
// Set SExt or ZExt flag.
if (VA.getLocInfo() == CCValAssign::ZExt) {
MFI.setObjectZExt(FI, true);
} else if (VA.getLocInfo() == CCValAssign::SExt) {
MFI.setObjectSExt(FI, true);
}
MaybeAlign Alignment;
if (Subtarget.isTargetWindowsMSVC() && !Subtarget.is64Bit() &&
ValVT != MVT::f80)
Alignment = MaybeAlign(4);
SDValue FIN = DAG.getFrameIndex(FI, PtrVT);
SDValue Val = DAG.getLoad(
ValVT, dl, Chain, FIN,
MachinePointerInfo::getFixedStack(DAG.getMachineFunction(), FI),
Alignment);
return ExtendedInMem
? (VA.getValVT().isVector()
? DAG.getNode(ISD::SCALAR_TO_VECTOR, dl, VA.getValVT(), Val)
: DAG.getNode(ISD::TRUNCATE, dl, VA.getValVT(), Val))
: Val;
}
// FIXME: Get this from tablegen.
static ArrayRef<MCPhysReg> get64BitArgumentGPRs(CallingConv::ID CallConv,
const X86Subtarget &Subtarget) {
assert(Subtarget.is64Bit());
if (Subtarget.isCallingConvWin64(CallConv)) {
static const MCPhysReg GPR64ArgRegsWin64[] = {
X86::RCX, X86::RDX, X86::R8, X86::R9
};
return GPR64ArgRegsWin64;
}
static const MCPhysReg GPR64ArgRegs64Bit[] = {
X86::RDI, X86::RSI, X86::RDX, X86::RCX, X86::R8, X86::R9
};
return GPR64ArgRegs64Bit;
}
// FIXME: Get this from tablegen.
static ArrayRef<MCPhysReg> get64BitArgumentXMMs(MachineFunction &MF,
CallingConv::ID CallConv,
const X86Subtarget &Subtarget) {
assert(Subtarget.is64Bit());
if (Subtarget.isCallingConvWin64(CallConv)) {
// The XMM registers which might contain var arg parameters are shadowed
// in their paired GPR. So we only need to save the GPR to their home
// slots.
// TODO: __vectorcall will change this.
return {};
}
bool isSoftFloat = Subtarget.useSoftFloat();
if (isSoftFloat || !Subtarget.hasSSE1())
// Kernel mode asks for SSE to be disabled, so there are no XMM argument
// registers.
return {};
static const MCPhysReg XMMArgRegs64Bit[] = {
X86::XMM0, X86::XMM1, X86::XMM2, X86::XMM3,
X86::XMM4, X86::XMM5, X86::XMM6, X86::XMM7
};
return XMMArgRegs64Bit;
}
#ifndef NDEBUG
static bool isSortedByValueNo(ArrayRef<CCValAssign> ArgLocs) {
return llvm::is_sorted(
ArgLocs, [](const CCValAssign &A, const CCValAssign &B) -> bool {
return A.getValNo() < B.getValNo();
});
}
#endif
namespace {
/// This is a helper class for lowering variable arguments parameters.
class VarArgsLoweringHelper {
public:
VarArgsLoweringHelper(X86MachineFunctionInfo *FuncInfo, const SDLoc &Loc,
SelectionDAG &DAG, const X86Subtarget &Subtarget,
CallingConv::ID CallConv, CCState &CCInfo)
: FuncInfo(FuncInfo), DL(Loc), DAG(DAG), Subtarget(Subtarget),
TheMachineFunction(DAG.getMachineFunction()),
TheFunction(TheMachineFunction.getFunction()),
FrameInfo(TheMachineFunction.getFrameInfo()),
FrameLowering(*Subtarget.getFrameLowering()),
TargLowering(DAG.getTargetLoweringInfo()), CallConv(CallConv),
CCInfo(CCInfo) {}
// Lower variable arguments parameters.
void lowerVarArgsParameters(SDValue &Chain, unsigned StackSize);
private:
void createVarArgAreaAndStoreRegisters(SDValue &Chain, unsigned StackSize);
void forwardMustTailParameters(SDValue &Chain);
bool is64Bit() const { return Subtarget.is64Bit(); }
bool isWin64() const { return Subtarget.isCallingConvWin64(CallConv); }
X86MachineFunctionInfo *FuncInfo;
const SDLoc &DL;
SelectionDAG &DAG;
const X86Subtarget &Subtarget;
MachineFunction &TheMachineFunction;
const Function &TheFunction;
MachineFrameInfo &FrameInfo;
const TargetFrameLowering &FrameLowering;
const TargetLowering &TargLowering;
CallingConv::ID CallConv;
CCState &CCInfo;
};
} // namespace
void VarArgsLoweringHelper::createVarArgAreaAndStoreRegisters(
SDValue &Chain, unsigned StackSize) {
// If the function takes variable number of arguments, make a frame index for
// the start of the first vararg value... for expansion of llvm.va_start. We
// can skip this if there are no va_start calls.
if (is64Bit() || (CallConv != CallingConv::X86_FastCall &&
CallConv != CallingConv::X86_ThisCall)) {
FuncInfo->setVarArgsFrameIndex(
FrameInfo.CreateFixedObject(1, StackSize, true));
}
// 64-bit calling conventions support varargs and register parameters, so we
// have to do extra work to spill them in the prologue.
if (is64Bit()) {
// Find the first unallocated argument registers.
ArrayRef<MCPhysReg> ArgGPRs = get64BitArgumentGPRs(CallConv, Subtarget);
ArrayRef<MCPhysReg> ArgXMMs =
get64BitArgumentXMMs(TheMachineFunction, CallConv, Subtarget);
unsigned NumIntRegs = CCInfo.getFirstUnallocated(ArgGPRs);
unsigned NumXMMRegs = CCInfo.getFirstUnallocated(ArgXMMs);
assert(!(NumXMMRegs && !Subtarget.hasSSE1()) &&
"SSE register cannot be used when SSE is disabled!");
if (isWin64()) {
// Get to the caller-allocated home save location. Add 8 to account
// for the return address.
int HomeOffset = FrameLowering.getOffsetOfLocalArea() + 8;
FuncInfo->setRegSaveFrameIndex(
FrameInfo.CreateFixedObject(1, NumIntRegs * 8 + HomeOffset, false));
// Fixup to set vararg frame on shadow area (4 x i64).
if (NumIntRegs < 4)
FuncInfo->setVarArgsFrameIndex(FuncInfo->getRegSaveFrameIndex());
} else {
// For X86-64, if there are vararg parameters that are passed via
// registers, then we must store them to their spots on the stack so
// they may be loaded by dereferencing the result of va_next.
FuncInfo->setVarArgsGPOffset(NumIntRegs * 8);
FuncInfo->setVarArgsFPOffset(ArgGPRs.size() * 8 + NumXMMRegs * 16);
FuncInfo->setRegSaveFrameIndex(FrameInfo.CreateStackObject(
ArgGPRs.size() * 8 + ArgXMMs.size() * 16, Align(16), false));
}
SmallVector<SDValue, 6>
LiveGPRs; // list of SDValue for GPR registers keeping live input value
SmallVector<SDValue, 8> LiveXMMRegs; // list of SDValue for XMM registers
// keeping live input value
SDValue ALVal; // if applicable keeps SDValue for %al register
// Gather all the live in physical registers.
for (MCPhysReg Reg : ArgGPRs.slice(NumIntRegs)) {
Register GPR = TheMachineFunction.addLiveIn(Reg, &X86::GR64RegClass);
LiveGPRs.push_back(DAG.getCopyFromReg(Chain, DL, GPR, MVT::i64));
}
const auto &AvailableXmms = ArgXMMs.slice(NumXMMRegs);
if (!AvailableXmms.empty()) {
Register AL = TheMachineFunction.addLiveIn(X86::AL, &X86::GR8RegClass);
ALVal = DAG.getCopyFromReg(Chain, DL, AL, MVT::i8);
for (MCPhysReg Reg : AvailableXmms) {
// FastRegisterAllocator spills virtual registers at basic
// block boundary. That leads to usages of xmm registers
// outside of check for %al. Pass physical registers to
// VASTART_SAVE_XMM_REGS to avoid unneccessary spilling.
TheMachineFunction.getRegInfo().addLiveIn(Reg);
LiveXMMRegs.push_back(DAG.getRegister(Reg, MVT::v4f32));
}
}
// Store the integer parameter registers.
SmallVector<SDValue, 8> MemOps;
SDValue RSFIN =
DAG.getFrameIndex(FuncInfo->getRegSaveFrameIndex(),
TargLowering.getPointerTy(DAG.getDataLayout()));
unsigned Offset = FuncInfo->getVarArgsGPOffset();
for (SDValue Val : LiveGPRs) {
SDValue FIN = DAG.getNode(ISD::ADD, DL,
TargLowering.getPointerTy(DAG.getDataLayout()),
RSFIN, DAG.getIntPtrConstant(Offset, DL));
SDValue Store =
DAG.getStore(Val.getValue(1), DL, Val, FIN,
MachinePointerInfo::getFixedStack(
DAG.getMachineFunction(),
FuncInfo->getRegSaveFrameIndex(), Offset));
MemOps.push_back(Store);
Offset += 8;
}
// Now store the XMM (fp + vector) parameter registers.
if (!LiveXMMRegs.empty()) {
SmallVector<SDValue, 12> SaveXMMOps;
SaveXMMOps.push_back(Chain);
SaveXMMOps.push_back(ALVal);
SaveXMMOps.push_back(RSFIN);
SaveXMMOps.push_back(
DAG.getTargetConstant(FuncInfo->getVarArgsFPOffset(), DL, MVT::i32));
llvm::append_range(SaveXMMOps, LiveXMMRegs);
MachineMemOperand *StoreMMO =
DAG.getMachineFunction().getMachineMemOperand(
MachinePointerInfo::getFixedStack(
DAG.getMachineFunction(), FuncInfo->getRegSaveFrameIndex(),
Offset),
MachineMemOperand::MOStore, 128, Align(16));
MemOps.push_back(DAG.getMemIntrinsicNode(X86ISD::VASTART_SAVE_XMM_REGS,
DL, DAG.getVTList(MVT::Other),
SaveXMMOps, MVT::i8, StoreMMO));
}
if (!MemOps.empty())
Chain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, MemOps);
}
}
void VarArgsLoweringHelper::forwardMustTailParameters(SDValue &Chain) {
// Find the largest legal vector type.
MVT VecVT = MVT::Other;
// FIXME: Only some x86_32 calling conventions support AVX512.
if (Subtarget.useAVX512Regs() &&
(is64Bit() || (CallConv == CallingConv::X86_VectorCall ||
CallConv == CallingConv::Intel_OCL_BI)))
VecVT = MVT::v16f32;
else if (Subtarget.hasAVX())
VecVT = MVT::v8f32;
else if (Subtarget.hasSSE2())
VecVT = MVT::v4f32;
// We forward some GPRs and some vector types.
SmallVector<MVT, 2> RegParmTypes;
MVT IntVT = is64Bit() ? MVT::i64 : MVT::i32;
RegParmTypes.push_back(IntVT);
if (VecVT != MVT::Other)
RegParmTypes.push_back(VecVT);
// Compute the set of forwarded registers. The rest are scratch.
SmallVectorImpl<ForwardedRegister> &Forwards =
FuncInfo->getForwardedMustTailRegParms();
CCInfo.analyzeMustTailForwardedRegisters(Forwards, RegParmTypes, CC_X86);
// Forward AL for SysV x86_64 targets, since it is used for varargs.
if (is64Bit() && !isWin64() && !CCInfo.isAllocated(X86::AL)) {
Register ALVReg = TheMachineFunction.addLiveIn(X86::AL, &X86::GR8RegClass);
Forwards.push_back(ForwardedRegister(ALVReg, X86::AL, MVT::i8));
}
// Copy all forwards from physical to virtual registers.
for (ForwardedRegister &FR : Forwards) {
// FIXME: Can we use a less constrained schedule?
SDValue RegVal = DAG.getCopyFromReg(Chain, DL, FR.VReg, FR.VT);
FR.VReg = TheMachineFunction.getRegInfo().createVirtualRegister(
TargLowering.getRegClassFor(FR.VT));
Chain = DAG.getCopyToReg(Chain, DL, FR.VReg, RegVal);
}
}
void VarArgsLoweringHelper::lowerVarArgsParameters(SDValue &Chain,
unsigned StackSize) {
// Set FrameIndex to the 0xAAAAAAA value to mark unset state.
// If necessary, it would be set into the correct value later.
FuncInfo->setVarArgsFrameIndex(0xAAAAAAA);
FuncInfo->setRegSaveFrameIndex(0xAAAAAAA);
if (FrameInfo.hasVAStart())
createVarArgAreaAndStoreRegisters(Chain, StackSize);
if (FrameInfo.hasMustTailInVarArgFunc())
forwardMustTailParameters(Chain);
}
SDValue X86TargetLowering::LowerFormalArguments(
SDValue Chain, CallingConv::ID CallConv, bool IsVarArg,
const SmallVectorImpl<ISD::InputArg> &Ins, const SDLoc &dl,
SelectionDAG &DAG, SmallVectorImpl<SDValue> &InVals) const {
MachineFunction &MF = DAG.getMachineFunction();
X86MachineFunctionInfo *FuncInfo = MF.getInfo<X86MachineFunctionInfo>();
const Function &F = MF.getFunction();
if (F.hasExternalLinkage() && Subtarget.isTargetCygMing() &&
F.getName() == "main")
FuncInfo->setForceFramePointer(true);
MachineFrameInfo &MFI = MF.getFrameInfo();
bool Is64Bit = Subtarget.is64Bit();
bool IsWin64 = Subtarget.isCallingConvWin64(CallConv);
assert(
!(IsVarArg && canGuaranteeTCO(CallConv)) &&
"Var args not supported with calling conv' regcall, fastcc, ghc or hipe");
// Assign locations to all of the incoming arguments.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CallConv, IsVarArg, MF, ArgLocs, *DAG.getContext());
// Allocate shadow area for Win64.
if (IsWin64)
CCInfo.AllocateStack(32, Align(8));
CCInfo.AnalyzeArguments(Ins, CC_X86);
// In vectorcall calling convention a second pass is required for the HVA
// types.
if (CallingConv::X86_VectorCall == CallConv) {
CCInfo.AnalyzeArgumentsSecondPass(Ins, CC_X86);
}
// The next loop assumes that the locations are in the same order of the
// input arguments.
assert(isSortedByValueNo(ArgLocs) &&
"Argument Location list must be sorted before lowering");
SDValue ArgValue;
for (unsigned I = 0, InsIndex = 0, E = ArgLocs.size(); I != E;
++I, ++InsIndex) {
assert(InsIndex < Ins.size() && "Invalid Ins index");
CCValAssign &VA = ArgLocs[I];
if (VA.isRegLoc()) {
EVT RegVT = VA.getLocVT();
if (VA.needsCustom()) {
assert(
VA.getValVT() == MVT::v64i1 &&
"Currently the only custom case is when we split v64i1 to 2 regs");
// v64i1 values, in regcall calling convention, that are
// compiled to 32 bit arch, are split up into two registers.
ArgValue =
getv64i1Argument(VA, ArgLocs[++I], Chain, DAG, dl, Subtarget);
} else {
const TargetRegisterClass *RC;
if (RegVT == MVT::i8)
RC = &X86::GR8RegClass;
else if (RegVT == MVT::i16)
RC = &X86::GR16RegClass;
else if (RegVT == MVT::i32)
RC = &X86::GR32RegClass;
else if (Is64Bit && RegVT == MVT::i64)
RC = &X86::GR64RegClass;
else if (RegVT == MVT::f16)
RC = Subtarget.hasAVX512() ? &X86::FR16XRegClass : &X86::FR16RegClass;
else if (RegVT == MVT::f32)
RC = Subtarget.hasAVX512() ? &X86::FR32XRegClass : &X86::FR32RegClass;
else if (RegVT == MVT::f64)
RC = Subtarget.hasAVX512() ? &X86::FR64XRegClass : &X86::FR64RegClass;
else if (RegVT == MVT::f80)
RC = &X86::RFP80RegClass;
else if (RegVT == MVT::f128)
RC = &X86::VR128RegClass;
else if (RegVT.is512BitVector())
RC = &X86::VR512RegClass;
else if (RegVT.is256BitVector())
RC = Subtarget.hasVLX() ? &X86::VR256XRegClass : &X86::VR256RegClass;
else if (RegVT.is128BitVector())
RC = Subtarget.hasVLX() ? &X86::VR128XRegClass : &X86::VR128RegClass;
else if (RegVT == MVT::x86mmx)
RC = &X86::VR64RegClass;
else if (RegVT == MVT::v1i1)
RC = &X86::VK1RegClass;
else if (RegVT == MVT::v8i1)
RC = &X86::VK8RegClass;
else if (RegVT == MVT::v16i1)
RC = &X86::VK16RegClass;
else if (RegVT == MVT::v32i1)
RC = &X86::VK32RegClass;
else if (RegVT == MVT::v64i1)
RC = &X86::VK64RegClass;
else
llvm_unreachable("Unknown argument type!");
Register Reg = MF.addLiveIn(VA.getLocReg(), RC);
ArgValue = DAG.getCopyFromReg(Chain, dl, Reg, RegVT);
}
// If this is an 8 or 16-bit value, it is really passed promoted to 32
// bits. Insert an assert[sz]ext to capture this, then truncate to the
// right size.
if (VA.getLocInfo() == CCValAssign::SExt)
ArgValue = DAG.getNode(ISD::AssertSext, dl, RegVT, ArgValue,
DAG.getValueType(VA.getValVT()));
else if (VA.getLocInfo() == CCValAssign::ZExt)
ArgValue = DAG.getNode(ISD::AssertZext, dl, RegVT, ArgValue,
DAG.getValueType(VA.getValVT()));
else if (VA.getLocInfo() == CCValAssign::BCvt)
ArgValue = DAG.getBitcast(VA.getValVT(), ArgValue);
if (VA.isExtInLoc()) {
// Handle MMX values passed in XMM regs.
if (RegVT.isVector() && VA.getValVT().getScalarType() != MVT::i1)
ArgValue = DAG.getNode(X86ISD::MOVDQ2Q, dl, VA.getValVT(), ArgValue);
else if (VA.getValVT().isVector() &&
VA.getValVT().getScalarType() == MVT::i1 &&
((VA.getLocVT() == MVT::i64) || (VA.getLocVT() == MVT::i32) ||
(VA.getLocVT() == MVT::i16) || (VA.getLocVT() == MVT::i8))) {
// Promoting a mask type (v*i1) into a register of type i64/i32/i16/i8
ArgValue = lowerRegToMasks(ArgValue, VA.getValVT(), RegVT, dl, DAG);
} else
ArgValue = DAG.getNode(ISD::TRUNCATE, dl, VA.getValVT(), ArgValue);
}
} else {
assert(VA.isMemLoc());
ArgValue =
LowerMemArgument(Chain, CallConv, Ins, dl, DAG, VA, MFI, InsIndex);
}
// If value is passed via pointer - do a load.
if (VA.getLocInfo() == CCValAssign::Indirect &&
!(Ins[I].Flags.isByVal() && VA.isRegLoc())) {
ArgValue =
DAG.getLoad(VA.getValVT(), dl, Chain, ArgValue, MachinePointerInfo());
}
InVals.push_back(ArgValue);
}
for (unsigned I = 0, E = Ins.size(); I != E; ++I) {
if (Ins[I].Flags.isSwiftAsync()) {
auto X86FI = MF.getInfo<X86MachineFunctionInfo>();
if (X86::isExtendedSwiftAsyncFrameSupported(Subtarget, MF))
X86FI->setHasSwiftAsyncContext(true);
else {
int PtrSize = Subtarget.is64Bit() ? 8 : 4;
int FI =
MF.getFrameInfo().CreateStackObject(PtrSize, Align(PtrSize), false);
X86FI->setSwiftAsyncContextFrameIdx(FI);
SDValue St = DAG.getStore(
DAG.getEntryNode(), dl, InVals[I],
DAG.getFrameIndex(FI, PtrSize == 8 ? MVT::i64 : MVT::i32),
MachinePointerInfo::getFixedStack(MF, FI));
Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, St, Chain);
}
}
// Swift calling convention does not require we copy the sret argument
// into %rax/%eax for the return. We don't set SRetReturnReg for Swift.
if (CallConv == CallingConv::Swift || CallConv == CallingConv::SwiftTail)
continue;
// All x86 ABIs require that for returning structs by value we copy the
// sret argument into %rax/%eax (depending on ABI) for the return. Save
// the argument into a virtual register so that we can access it from the
// return points.
if (Ins[I].Flags.isSRet()) {
assert(!FuncInfo->getSRetReturnReg() &&
"SRet return has already been set");
MVT PtrTy = getPointerTy(DAG.getDataLayout());
Register Reg =
MF.getRegInfo().createVirtualRegister(getRegClassFor(PtrTy));
FuncInfo->setSRetReturnReg(Reg);
SDValue Copy = DAG.getCopyToReg(DAG.getEntryNode(), dl, Reg, InVals[I]);
Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Copy, Chain);
break;
}
}
unsigned StackSize = CCInfo.getStackSize();
// Align stack specially for tail calls.
if (shouldGuaranteeTCO(CallConv,
MF.getTarget().Options.GuaranteedTailCallOpt))
StackSize = GetAlignedArgumentStackSize(StackSize, DAG);
if (IsVarArg)
VarArgsLoweringHelper(FuncInfo, dl, DAG, Subtarget, CallConv, CCInfo)
.lowerVarArgsParameters(Chain, StackSize);
// Some CCs need callee pop.
if (X86::isCalleePop(CallConv, Is64Bit, IsVarArg,
MF.getTarget().Options.GuaranteedTailCallOpt)) {
FuncInfo->setBytesToPopOnReturn(StackSize); // Callee pops everything.
} else if (CallConv == CallingConv::X86_INTR && Ins.size() == 2) {
// X86 interrupts must pop the error code (and the alignment padding) if
// present.
FuncInfo->setBytesToPopOnReturn(Is64Bit ? 16 : 4);
} else {
FuncInfo->setBytesToPopOnReturn(0); // Callee pops nothing.
// If this is an sret function, the return should pop the hidden pointer.
if (!canGuaranteeTCO(CallConv) && hasCalleePopSRet(Ins, Subtarget))
FuncInfo->setBytesToPopOnReturn(4);
}
if (!Is64Bit) {
// RegSaveFrameIndex is X86-64 only.
FuncInfo->setRegSaveFrameIndex(0xAAAAAAA);
}
FuncInfo->setArgumentStackSize(StackSize);
if (WinEHFuncInfo *EHInfo = MF.getWinEHFuncInfo()) {
EHPersonality Personality = classifyEHPersonality(F.getPersonalityFn());
if (Personality == EHPersonality::CoreCLR) {
assert(Is64Bit);
// TODO: Add a mechanism to frame lowering that will allow us to indicate
// that we'd prefer this slot be allocated towards the bottom of the frame
// (i.e. near the stack pointer after allocating the frame). Every
// funclet needs a copy of this slot in its (mostly empty) frame, and the
// offset from the bottom of this and each funclet's frame must be the
// same, so the size of funclets' (mostly empty) frames is dictated by
// how far this slot is from the bottom (since they allocate just enough
// space to accommodate holding this slot at the correct offset).
int PSPSymFI = MFI.CreateStackObject(8, Align(8), /*isSpillSlot=*/false);
EHInfo->PSPSymFrameIdx = PSPSymFI;
}
}
if (shouldDisableArgRegFromCSR(CallConv) ||
F.hasFnAttribute("no_caller_saved_registers")) {
MachineRegisterInfo &MRI = MF.getRegInfo();
for (std::pair<MCRegister, Register> Pair : MRI.liveins())
MRI.disableCalleeSavedRegister(Pair.first);
}
if (CallingConv::PreserveNone == CallConv)
for (const ISD::InputArg &In : Ins) {
if (In.Flags.isSwiftSelf() || In.Flags.isSwiftAsync() ||
In.Flags.isSwiftError()) {
errorUnsupported(DAG, dl,
"Swift attributes can't be used with preserve_none");
break;
}
}
return Chain;
}
SDValue X86TargetLowering::LowerMemOpCallTo(SDValue Chain, SDValue StackPtr,
SDValue Arg, const SDLoc &dl,
SelectionDAG &DAG,
const CCValAssign &VA,
ISD::ArgFlagsTy Flags,
bool isByVal) const {
unsigned LocMemOffset = VA.getLocMemOffset();
SDValue PtrOff = DAG.getIntPtrConstant(LocMemOffset, dl);
PtrOff = DAG.getNode(ISD::ADD, dl, getPointerTy(DAG.getDataLayout()),
StackPtr, PtrOff);
if (isByVal)
return CreateCopyOfByValArgument(Arg, PtrOff, Chain, Flags, DAG, dl);
MaybeAlign Alignment;
if (Subtarget.isTargetWindowsMSVC() && !Subtarget.is64Bit() &&
Arg.getSimpleValueType() != MVT::f80)
Alignment = MaybeAlign(4);
return DAG.getStore(
Chain, dl, Arg, PtrOff,
MachinePointerInfo::getStack(DAG.getMachineFunction(), LocMemOffset),
Alignment);
}
/// Emit a load of return address if tail call
/// optimization is performed and it is required.
SDValue X86TargetLowering::EmitTailCallLoadRetAddr(
SelectionDAG &DAG, SDValue &OutRetAddr, SDValue Chain, bool IsTailCall,
bool Is64Bit, int FPDiff, const SDLoc &dl) const {
// Adjust the Return address stack slot.
EVT VT = getPointerTy(DAG.getDataLayout());
OutRetAddr = getReturnAddressFrameIndex(DAG);
// Load the "old" Return address.
OutRetAddr = DAG.getLoad(VT, dl, Chain, OutRetAddr, MachinePointerInfo());
return SDValue(OutRetAddr.getNode(), 1);
}
/// Emit a store of the return address if tail call
/// optimization is performed and it is required (FPDiff!=0).
static SDValue EmitTailCallStoreRetAddr(SelectionDAG &DAG, MachineFunction &MF,
SDValue Chain, SDValue RetAddrFrIdx,
EVT PtrVT, unsigned SlotSize,
int FPDiff, const SDLoc &dl) {
// Store the return address to the appropriate stack slot.
if (!FPDiff) return Chain;
// Calculate the new stack slot for the return address.
int NewReturnAddrFI =
MF.getFrameInfo().CreateFixedObject(SlotSize, (int64_t)FPDiff - SlotSize,
false);
SDValue NewRetAddrFrIdx = DAG.getFrameIndex(NewReturnAddrFI, PtrVT);
Chain = DAG.getStore(Chain, dl, RetAddrFrIdx, NewRetAddrFrIdx,
MachinePointerInfo::getFixedStack(
DAG.getMachineFunction(), NewReturnAddrFI));
return Chain;
}
/// Returns a vector_shuffle mask for an movs{s|d}, movd
/// operation of specified width.
SDValue X86TargetLowering::getMOVL(SelectionDAG &DAG, const SDLoc &dl, MVT VT,
SDValue V1, SDValue V2) const {
unsigned NumElems = VT.getVectorNumElements();
SmallVector<int, 8> Mask;
Mask.push_back(NumElems);
for (unsigned i = 1; i != NumElems; ++i)
Mask.push_back(i);
return DAG.getVectorShuffle(VT, dl, V1, V2, Mask);
}
SDValue
X86TargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
SmallVectorImpl<SDValue> &InVals) const {
SelectionDAG &DAG = CLI.DAG;
SDLoc &dl = CLI.DL;
SmallVectorImpl<ISD::OutputArg> &Outs = CLI.Outs;
SmallVectorImpl<SDValue> &OutVals = CLI.OutVals;
SmallVectorImpl<ISD::InputArg> &Ins = CLI.Ins;
SDValue Chain = CLI.Chain;
SDValue Callee = CLI.Callee;
CallingConv::ID CallConv = CLI.CallConv;
bool &isTailCall = CLI.IsTailCall;
bool isVarArg = CLI.IsVarArg;
const auto *CB = CLI.CB;
MachineFunction &MF = DAG.getMachineFunction();
bool Is64Bit = Subtarget.is64Bit();
bool IsWin64 = Subtarget.isCallingConvWin64(CallConv);
bool IsSibcall = false;
bool IsGuaranteeTCO = MF.getTarget().Options.GuaranteedTailCallOpt ||
CallConv == CallingConv::Tail || CallConv == CallingConv::SwiftTail;
bool IsCalleePopSRet = !IsGuaranteeTCO && hasCalleePopSRet(Outs, Subtarget);
X86MachineFunctionInfo *X86Info = MF.getInfo<X86MachineFunctionInfo>();
bool HasNCSR = (CB && isa<CallInst>(CB) &&
CB->hasFnAttr("no_caller_saved_registers"));
bool IsIndirectCall = (CB && isa<CallInst>(CB) && CB->isIndirectCall());
bool IsCFICall = IsIndirectCall && CLI.CFIType;
const Module *M = MF.getFunction().getParent();
// If the indirect call target has the nocf_check attribute, the call needs
// the NOTRACK prefix. For simplicity just disable tail calls as there are
// so many variants.
bool IsNoTrackIndirectCall = IsIndirectCall && CB->doesNoCfCheck() &&
M->getModuleFlag("cf-protection-branch");
if (IsNoTrackIndirectCall)
isTailCall = false;
MachineFunction::CallSiteInfo CSInfo;
if (CallConv == CallingConv::X86_INTR)
report_fatal_error("X86 interrupts may not be called directly");
// Set type id for call site info.
if (MF.getTarget().Options.EmitCallGraphSection && CB && CB->isIndirectCall())
CSInfo = MachineFunction::CallSiteInfo(*CB);
if (IsIndirectCall && !IsWin64 &&
M->getModuleFlag("import-call-optimization"))
errorUnsupported(DAG, dl,
"Indirect calls must have a normal calling convention if "
"Import Call Optimization is enabled");
// Analyze operands of the call, assigning locations to each operand.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CallConv, isVarArg, MF, ArgLocs, *DAG.getContext());
// Allocate shadow area for Win64.
if (IsWin64)
CCInfo.AllocateStack(32, Align(8));
CCInfo.AnalyzeArguments(Outs, CC_X86);
// In vectorcall calling convention a second pass is required for the HVA
// types.
if (CallingConv::X86_VectorCall == CallConv) {
CCInfo.AnalyzeArgumentsSecondPass(Outs, CC_X86);
}
bool IsMustTail = CLI.CB && CLI.CB->isMustTailCall();
if (Subtarget.isPICStyleGOT() && !IsGuaranteeTCO && !IsMustTail) {
// If we are using a GOT, disable tail calls to external symbols with
// default visibility. Tail calling such a symbol requires using a GOT
// relocation, which forces early binding of the symbol. This breaks code
// that require lazy function symbol resolution. Using musttail or
// GuaranteedTailCallOpt will override this.
GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee);
if (!G || (!G->getGlobal()->hasLocalLinkage() &&
G->getGlobal()->hasDefaultVisibility()))
isTailCall = false;
}
if (isTailCall && !IsMustTail) {
// Check if it's really possible to do a tail call.
isTailCall = IsEligibleForTailCallOptimization(CLI, CCInfo, ArgLocs,
IsCalleePopSRet);
// Sibcalls are automatically detected tailcalls which do not require
// ABI changes.
if (!IsGuaranteeTCO && isTailCall)
IsSibcall = true;
if (isTailCall)
++NumTailCalls;
}
if (IsMustTail && !isTailCall)
report_fatal_error("failed to perform tail call elimination on a call "
"site marked musttail");
assert(!(isVarArg && canGuaranteeTCO(CallConv)) &&
"Var args not supported with calling convention fastcc, ghc or hipe");
// Get a count of how many bytes are to be pushed on the stack.
unsigned NumBytes = CCInfo.getAlignedCallFrameSize();
if (IsSibcall)
// This is a sibcall. The memory operands are available in caller's
// own caller's stack.
NumBytes = 0;
else if (IsGuaranteeTCO && canGuaranteeTCO(CallConv))
NumBytes = GetAlignedArgumentStackSize(NumBytes, DAG);
int FPDiff = 0;
if (isTailCall &&
shouldGuaranteeTCO(CallConv,
MF.getTarget().Options.GuaranteedTailCallOpt)) {
// Lower arguments at fp - stackoffset + fpdiff.
unsigned NumBytesCallerPushed = X86Info->getBytesToPopOnReturn();
FPDiff = NumBytesCallerPushed - NumBytes;
// Set the delta of movement of the returnaddr stackslot.
// But only set if delta is greater than previous delta.
if (FPDiff < X86Info->getTCReturnAddrDelta())
X86Info->setTCReturnAddrDelta(FPDiff);
}
unsigned NumBytesToPush = NumBytes;
unsigned NumBytesToPop = NumBytes;
// If we have an inalloca argument, all stack space has already been allocated
// for us and be right at the top of the stack. We don't support multiple
// arguments passed in memory when using inalloca.
if (!Outs.empty() && Outs.back().Flags.isInAlloca()) {
NumBytesToPush = 0;
if (!ArgLocs.back().isMemLoc())
report_fatal_error("cannot use inalloca attribute on a register "
"parameter");
if (ArgLocs.back().getLocMemOffset() != 0)
report_fatal_error("any parameter with the inalloca attribute must be "
"the only memory argument");
} else if (CLI.IsPreallocated) {
assert(ArgLocs.back().isMemLoc() &&
"cannot use preallocated attribute on a register "
"parameter");
SmallVector<size_t, 4> PreallocatedOffsets;
for (size_t i = 0; i < CLI.OutVals.size(); ++i) {
if (CLI.CB->paramHasAttr(i, Attribute::Preallocated)) {
PreallocatedOffsets.push_back(ArgLocs[i].getLocMemOffset());
}
}
auto *MFI = DAG.getMachineFunction().getInfo<X86MachineFunctionInfo>();
size_t PreallocatedId = MFI->getPreallocatedIdForCallSite(CLI.CB);
MFI->setPreallocatedStackSize(PreallocatedId, NumBytes);
MFI->setPreallocatedArgOffsets(PreallocatedId, PreallocatedOffsets);
NumBytesToPush = 0;
}
if (!IsSibcall && !IsMustTail)
Chain = DAG.getCALLSEQ_START(Chain, NumBytesToPush,
NumBytes - NumBytesToPush, dl);
SDValue RetAddrFrIdx;
// Load return address for tail calls.
if (isTailCall && FPDiff)
Chain = EmitTailCallLoadRetAddr(DAG, RetAddrFrIdx, Chain, isTailCall,
Is64Bit, FPDiff, dl);
SmallVector<std::pair<Register, SDValue>, 8> RegsToPass;
SmallVector<SDValue, 8> MemOpChains;
SDValue StackPtr;
// The next loop assumes that the locations are in the same order of the
// input arguments.
assert(isSortedByValueNo(ArgLocs) &&
"Argument Location list must be sorted before lowering");
// Walk the register/memloc assignments, inserting copies/loads. In the case
// of tail call optimization arguments are handle later.
const X86RegisterInfo *RegInfo = Subtarget.getRegisterInfo();
for (unsigned I = 0, OutIndex = 0, E = ArgLocs.size(); I != E;
++I, ++OutIndex) {
assert(OutIndex < Outs.size() && "Invalid Out index");
// Skip inalloca/preallocated arguments, they have already been written.
ISD::ArgFlagsTy Flags = Outs[OutIndex].Flags;
if (Flags.isInAlloca() || Flags.isPreallocated())
continue;
CCValAssign &VA = ArgLocs[I];
EVT RegVT = VA.getLocVT();
SDValue Arg = OutVals[OutIndex];
bool isByVal = Flags.isByVal();
// Promote the value if needed.
switch (VA.getLocInfo()) {
default: llvm_unreachable("Unknown loc info!");
case CCValAssign::Full: break;
case CCValAssign::SExt:
Arg = DAG.getNode(ISD::SIGN_EXTEND, dl, RegVT, Arg);
break;
case CCValAssign::ZExt:
Arg = DAG.getNode(ISD::ZERO_EXTEND, dl, RegVT, Arg);
break;
case CCValAssign::AExt:
if (Arg.getValueType().isVector() &&
Arg.getValueType().getVectorElementType() == MVT::i1)
Arg = lowerMasksToReg(Arg, RegVT, dl, DAG);
else if (RegVT.is128BitVector()) {
// Special case: passing MMX values in XMM registers.
Arg = DAG.getBitcast(MVT::i64, Arg);
Arg = DAG.getNode(ISD::SCALAR_TO_VECTOR, dl, MVT::v2i64, Arg);
Arg = getMOVL(DAG, dl, MVT::v2i64, DAG.getUNDEF(MVT::v2i64), Arg);
} else
Arg = DAG.getNode(ISD::ANY_EXTEND, dl, RegVT, Arg);
break;
case CCValAssign::BCvt:
Arg = DAG.getBitcast(RegVT, Arg);
break;
case CCValAssign::Indirect: {
if (isByVal) {
// Memcpy the argument to a temporary stack slot to prevent
// the caller from seeing any modifications the callee may make
// as guaranteed by the `byval` attribute.
int FrameIdx = MF.getFrameInfo().CreateStackObject(
Flags.getByValSize(),
std::max(Align(16), Flags.getNonZeroByValAlign()), false);
SDValue StackSlot =
DAG.getFrameIndex(FrameIdx, getPointerTy(DAG.getDataLayout()));
Chain =
CreateCopyOfByValArgument(Arg, StackSlot, Chain, Flags, DAG, dl);
// From now on treat this as a regular pointer
Arg = StackSlot;
isByVal = false;
} else {
// Store the argument.
SDValue SpillSlot = DAG.CreateStackTemporary(VA.getValVT());
int FI = cast<FrameIndexSDNode>(SpillSlot)->getIndex();
Chain = DAG.getStore(
Chain, dl, Arg, SpillSlot,
MachinePointerInfo::getFixedStack(DAG.getMachineFunction(), FI));
Arg = SpillSlot;
}
break;
}
}
if (VA.needsCustom()) {
assert(VA.getValVT() == MVT::v64i1 &&
"Currently the only custom case is when we split v64i1 to 2 regs");
// Split v64i1 value into two registers
Passv64i1ArgInRegs(dl, DAG, Arg, RegsToPass, VA, ArgLocs[++I], Subtarget);
} else if (VA.isRegLoc()) {
RegsToPass.push_back(std::make_pair(VA.getLocReg(), Arg));
const TargetOptions &Options = DAG.getTarget().Options;
if (Options.EmitCallSiteInfo)
CSInfo.ArgRegPairs.emplace_back(VA.getLocReg(), I);
if (isVarArg && IsWin64) {
// Win64 ABI requires argument XMM reg to be copied to the corresponding
// shadow reg if callee is a varargs function.
Register ShadowReg;
switch (VA.getLocReg()) {
case X86::XMM0: ShadowReg = X86::RCX; break;
case X86::XMM1: ShadowReg = X86::RDX; break;
case X86::XMM2: ShadowReg = X86::R8; break;
case X86::XMM3: ShadowReg = X86::R9; break;
}
if (ShadowReg)
RegsToPass.push_back(std::make_pair(ShadowReg, Arg));
}
} else if (!IsSibcall && (!isTailCall || isByVal)) {
assert(VA.isMemLoc());
if (!StackPtr.getNode())
StackPtr = DAG.getCopyFromReg(Chain, dl, RegInfo->getStackRegister(),
getPointerTy(DAG.getDataLayout()));
MemOpChains.push_back(LowerMemOpCallTo(Chain, StackPtr, Arg,
dl, DAG, VA, Flags, isByVal));
}
}
if (!MemOpChains.empty())
Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, MemOpChains);
if (Subtarget.isPICStyleGOT()) {
// ELF / PIC requires GOT in the EBX register before function calls via PLT
// GOT pointer (except regcall).
if (!isTailCall) {
// Indirect call with RegCall calling convertion may use up all the
// general registers, so it is not suitable to bind EBX reister for
// GOT address, just let register allocator handle it.
if (CallConv != CallingConv::X86_RegCall)
RegsToPass.push_back(std::make_pair(
Register(X86::EBX), DAG.getNode(X86ISD::GlobalBaseReg, SDLoc(),
getPointerTy(DAG.getDataLayout()))));
} else {
// If we are tail calling and generating PIC/GOT style code load the
// address of the callee into ECX. The value in ecx is used as target of
// the tail jump. This is done to circumvent the ebx/callee-saved problem
// for tail calls on PIC/GOT architectures. Normally we would just put the
// address of GOT into ebx and then call target@PLT. But for tail calls
// ebx would be restored (since ebx is callee saved) before jumping to the
// target@PLT.
// Note: The actual moving to ECX is done further down.
GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee);
if (G && !G->getGlobal()->hasLocalLinkage() &&
G->getGlobal()->hasDefaultVisibility())
Callee = LowerGlobalAddress(Callee, DAG);
else if (isa<ExternalSymbolSDNode>(Callee))
Callee = LowerExternalSymbol(Callee, DAG);
}
}
if (Is64Bit && isVarArg && !IsWin64 && !IsMustTail &&
(Subtarget.hasSSE1() || !M->getModuleFlag("SkipRaxSetup"))) {
// From AMD64 ABI document:
// For calls that may call functions that use varargs or stdargs
// (prototype-less calls or calls to functions containing ellipsis (...) in
// the declaration) %al is used as hidden argument to specify the number
// of SSE registers used. The contents of %al do not need to match exactly
// the number of registers, but must be an ubound on the number of SSE
// registers used and is in the range 0 - 8 inclusive.
// Count the number of XMM registers allocated.
static const MCPhysReg XMMArgRegs[] = {
X86::XMM0, X86::XMM1, X86::XMM2, X86::XMM3,
X86::XMM4, X86::XMM5, X86::XMM6, X86::XMM7
};
unsigned NumXMMRegs = CCInfo.getFirstUnallocated(XMMArgRegs);
assert((Subtarget.hasSSE1() || !NumXMMRegs)
&& "SSE registers cannot be used when SSE is disabled");
RegsToPass.push_back(std::make_pair(Register(X86::AL),
DAG.getConstant(NumXMMRegs, dl,
MVT::i8)));
}
if (isVarArg && IsMustTail) {
const auto &Forwards = X86Info->getForwardedMustTailRegParms();
for (const auto &F : Forwards) {
SDValue Val = DAG.getCopyFromReg(Chain, dl, F.VReg, F.VT);
RegsToPass.push_back(std::make_pair(F.PReg, Val));
}
}
// For tail calls lower the arguments to the 'real' stack slots. Sibcalls
// don't need this because the eligibility check rejects calls that require
// shuffling arguments passed in memory.
if (!IsSibcall && isTailCall) {
// Force all the incoming stack arguments to be loaded from the stack
// before any new outgoing arguments or the return address are stored to the
// stack, because the outgoing stack slots may alias the incoming argument
// stack slots, and the alias isn't otherwise explicit. This is slightly
// more conservative than necessary, because it means that each store
// effectively depends on every argument instead of just those arguments it
// would clobber.
Chain = DAG.getStackArgumentTokenFactor(Chain);
SmallVector<SDValue, 8> MemOpChains2;
SDValue FIN;
int FI = 0;
for (unsigned I = 0, OutsIndex = 0, E = ArgLocs.size(); I != E;
++I, ++OutsIndex) {
CCValAssign &VA = ArgLocs[I];
if (VA.isRegLoc()) {
if (VA.needsCustom()) {
assert((CallConv == CallingConv::X86_RegCall) &&
"Expecting custom case only in regcall calling convention");
// This means that we are in special case where one argument was
// passed through two register locations - Skip the next location
++I;
}
continue;
}
assert(VA.isMemLoc());
SDValue Arg = OutVals[OutsIndex];
ISD::ArgFlagsTy Flags = Outs[OutsIndex].Flags;
// Skip inalloca/preallocated arguments. They don't require any work.
if (Flags.isInAlloca() || Flags.isPreallocated())
continue;
// Create frame index.
int32_t Offset = VA.getLocMemOffset()+FPDiff;
uint32_t OpSize = (VA.getLocVT().getSizeInBits()+7)/8;
FI = MF.getFrameInfo().CreateFixedObject(OpSize, Offset, true);
FIN = DAG.getFrameIndex(FI, getPointerTy(DAG.getDataLayout()));
if (Flags.isByVal()) {
// Copy relative to framepointer.
SDValue Source = DAG.getIntPtrConstant(VA.getLocMemOffset(), dl);
if (!StackPtr.getNode())
StackPtr = DAG.getCopyFromReg(Chain, dl, RegInfo->getStackRegister(),
getPointerTy(DAG.getDataLayout()));
Source = DAG.getNode(ISD::ADD, dl, getPointerTy(DAG.getDataLayout()),
StackPtr, Source);
MemOpChains2.push_back(
CreateCopyOfByValArgument(Source, FIN, Chain, Flags, DAG, dl));
} else {
// Store relative to framepointer.
MemOpChains2.push_back(DAG.getStore(
Chain, dl, Arg, FIN,
MachinePointerInfo::getFixedStack(DAG.getMachineFunction(), FI)));
}
}
if (!MemOpChains2.empty())
Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, MemOpChains2);
// Store the return address to the appropriate stack slot.
Chain = EmitTailCallStoreRetAddr(DAG, MF, Chain, RetAddrFrIdx,
getPointerTy(DAG.getDataLayout()),
RegInfo->getSlotSize(), FPDiff, dl);
}
// Build a sequence of copy-to-reg nodes chained together with token chain
// and glue operands which copy the outgoing args into registers.
SDValue InGlue;
for (const auto &[Reg, N] : RegsToPass) {
Chain = DAG.getCopyToReg(Chain, dl, Reg, N, InGlue);
InGlue = Chain.getValue(1);
}
bool IsImpCall = false;
if (DAG.getTarget().getCodeModel() == CodeModel::Large) {
assert(Is64Bit && "Large code model is only legal in 64-bit mode.");
// In the 64-bit large code model, we have to make all calls
// through a register, since the call instruction's 32-bit
// pc-relative offset may not be large enough to hold the whole
// address.
} else if (Callee->getOpcode() == ISD::GlobalAddress ||
Callee->getOpcode() == ISD::ExternalSymbol) {
// Lower direct calls to global addresses and external symbols. Setting
// ForCall to true here has the effect of removing WrapperRIP when possible
// to allow direct calls to be selected without first materializing the
// address into a register.
Callee = LowerGlobalOrExternal(Callee, DAG, /*ForCall=*/true, &IsImpCall);
} else if (Subtarget.isTarget64BitILP32() &&
Callee.getValueType() == MVT::i32) {
// Zero-extend the 32-bit Callee address into a 64-bit according to x32 ABI
Callee = DAG.getNode(ISD::ZERO_EXTEND, dl, MVT::i64, Callee);
}
SmallVector<SDValue, 8> Ops;
if (!IsSibcall && isTailCall && !IsMustTail) {
Chain = DAG.getCALLSEQ_END(Chain, NumBytesToPop, 0, InGlue, dl);
InGlue = Chain.getValue(1);
}
Ops.push_back(Chain);
Ops.push_back(Callee);
if (isTailCall)
Ops.push_back(DAG.getSignedTargetConstant(FPDiff, dl, MVT::i32));
// Add argument registers to the end of the list so that they are known live
// into the call.
for (const auto &[Reg, N] : RegsToPass)
Ops.push_back(DAG.getRegister(Reg, N.getValueType()));
// Add a register mask operand representing the call-preserved registers.
const uint32_t *Mask = [&]() {
auto AdaptedCC = CallConv;
// If HasNCSR is asserted (attribute NoCallerSavedRegisters exists),
// use X86_INTR calling convention because it has the same CSR mask
// (same preserved registers).
if (HasNCSR)
AdaptedCC = (CallingConv::ID)CallingConv::X86_INTR;
// If NoCalleeSavedRegisters is requested, than use GHC since it happens
// to use the CSR_NoRegs_RegMask.
if (CB && CB->hasFnAttr("no_callee_saved_registers"))
AdaptedCC = (CallingConv::ID)CallingConv::GHC;
return RegInfo->getCallPreservedMask(MF, AdaptedCC);
}();
assert(Mask && "Missing call preserved mask for calling convention");
if (MachineOperand::clobbersPhysReg(Mask, RegInfo->getFramePtr())) {
X86Info->setFPClobberedByCall(true);
if (CLI.CB && isa<InvokeInst>(CLI.CB))
X86Info->setFPClobberedByInvoke(true);
}
if (MachineOperand::clobbersPhysReg(Mask, RegInfo->getBaseRegister())) {
X86Info->setBPClobberedByCall(true);
if (CLI.CB && isa<InvokeInst>(CLI.CB))
X86Info->setBPClobberedByInvoke(true);
}
// If this is an invoke in a 32-bit function using a funclet-based
// personality, assume the function clobbers all registers. If an exception
// is thrown, the runtime will not restore CSRs.
// FIXME: Model this more precisely so that we can register allocate across
// the normal edge and spill and fill across the exceptional edge.
if (!Is64Bit && CLI.CB && isa<InvokeInst>(CLI.CB)) {
const Function &CallerFn = MF.getFunction();
EHPersonality Pers =
CallerFn.hasPersonalityFn()
? classifyEHPersonality(CallerFn.getPersonalityFn())
: EHPersonality::Unknown;
if (isFuncletEHPersonality(Pers))
Mask = RegInfo->getNoPreservedMask();
}
// Define a new register mask from the existing mask.
uint32_t *RegMask = nullptr;
// In some calling conventions we need to remove the used physical registers
// from the reg mask. Create a new RegMask for such calling conventions.
// RegMask for calling conventions that disable only return registers (e.g.
// preserve_most) will be modified later in LowerCallResult.
bool ShouldDisableArgRegs = shouldDisableArgRegFromCSR(CallConv) || HasNCSR;
if (ShouldDisableArgRegs || shouldDisableRetRegFromCSR(CallConv)) {
const TargetRegisterInfo *TRI = Subtarget.getRegisterInfo();
// Allocate a new Reg Mask and copy Mask.
RegMask = MF.allocateRegMask();
unsigned RegMaskSize = MachineOperand::getRegMaskSize(TRI->getNumRegs());
memcpy(RegMask, Mask, sizeof(RegMask[0]) * RegMaskSize);
// Make sure all sub registers of the argument registers are reset
// in the RegMask.
if (ShouldDisableArgRegs) {
for (auto const &RegPair : RegsToPass)
for (MCPhysReg SubReg : TRI->subregs_inclusive(RegPair.first))
RegMask[SubReg / 32] &= ~(1u << (SubReg % 32));
}
// Create the RegMask Operand according to our updated mask.
Ops.push_back(DAG.getRegisterMask(RegMask));
} else {
// Create the RegMask Operand according to the static mask.
Ops.push_back(DAG.getRegisterMask(Mask));
}
if (InGlue.getNode())
Ops.push_back(InGlue);
if (isTailCall) {
// We used to do:
//// If this is the first return lowered for this function, add the regs
//// to the liveout set for the function.
// This isn't right, although it's probably harmless on x86; liveouts
// should be computed from returns not tail calls. Consider a void
// function making a tail call to a function returning int.
MF.getFrameInfo().setHasTailCall();
SDValue Ret = DAG.getNode(X86ISD::TC_RETURN, dl, MVT::Other, Ops);
if (IsCFICall)
Ret.getNode()->setCFIType(CLI.CFIType->getZExtValue());
DAG.addNoMergeSiteInfo(Ret.getNode(), CLI.NoMerge);
DAG.addCallSiteInfo(Ret.getNode(), std::move(CSInfo));
return Ret;
}
// Returns a chain & a glue for retval copy to use.
SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);
if (IsImpCall) {
Chain = DAG.getNode(X86ISD::IMP_CALL, dl, NodeTys, Ops);
} else if (IsNoTrackIndirectCall) {
Chain = DAG.getNode(X86ISD::NT_CALL, dl, NodeTys, Ops);
} else if (CLI.CB && objcarc::hasAttachedCallOpBundle(CLI.CB)) {
// Calls with a "clang.arc.attachedcall" bundle are special. They should be
// expanded to the call, directly followed by a special marker sequence and
// a call to a ObjC library function. Use the CALL_RVMARKER to do that.
assert(!isTailCall &&
"tail calls cannot be marked with clang.arc.attachedcall");
assert(Is64Bit && "clang.arc.attachedcall is only supported in 64bit mode");
// Add a target global address for the retainRV/claimRV runtime function
// just before the call target.
Function *ARCFn = *objcarc::getAttachedARCFunction(CLI.CB);
auto PtrVT = getPointerTy(DAG.getDataLayout());
auto GA = DAG.getTargetGlobalAddress(ARCFn, dl, PtrVT);
Ops.insert(Ops.begin() + 1, GA);
Chain = DAG.getNode(X86ISD::CALL_RVMARKER, dl, NodeTys, Ops);
} else {
Chain = DAG.getNode(X86ISD::CALL, dl, NodeTys, Ops);
}
if (IsCFICall)
Chain.getNode()->setCFIType(CLI.CFIType->getZExtValue());
InGlue = Chain.getValue(1);
DAG.addNoMergeSiteInfo(Chain.getNode(), CLI.NoMerge);
DAG.addCallSiteInfo(Chain.getNode(), std::move(CSInfo));
// Save heapallocsite metadata.
if (CLI.CB)
if (MDNode *HeapAlloc = CLI.CB->getMetadata("heapallocsite"))
DAG.addHeapAllocSite(Chain.getNode(), HeapAlloc);
// Create the CALLSEQ_END node.
unsigned NumBytesForCalleeToPop = 0; // Callee pops nothing.
if (X86::isCalleePop(CallConv, Is64Bit, isVarArg,
DAG.getTarget().Options.GuaranteedTailCallOpt))
NumBytesForCalleeToPop = NumBytes; // Callee pops everything
else if (!canGuaranteeTCO(CallConv) && IsCalleePopSRet)
// If this call passes a struct-return pointer, the callee
// pops that struct pointer.
NumBytesForCalleeToPop = 4;
// Returns a glue for retval copy to use.
if (!IsSibcall) {
Chain = DAG.getCALLSEQ_END(Chain, NumBytesToPop, NumBytesForCalleeToPop,
InGlue, dl);
InGlue = Chain.getValue(1);
}
if (CallingConv::PreserveNone == CallConv)
for (const ISD::OutputArg &Out : Outs) {
if (Out.Flags.isSwiftSelf() || Out.Flags.isSwiftAsync() ||
Out.Flags.isSwiftError()) {
errorUnsupported(DAG, dl,
"Swift attributes can't be used with preserve_none");
break;
}
}
// Handle result values, copying them out of physregs into vregs that we
// return.
return LowerCallResult(Chain, InGlue, CallConv, isVarArg, Ins, dl, DAG,
InVals, RegMask);
}
//===----------------------------------------------------------------------===//
// Fast Calling Convention (tail call) implementation
//===----------------------------------------------------------------------===//
// Like std call, callee cleans arguments, convention except that ECX is
// reserved for storing the tail called function address. Only 2 registers are
// free for argument passing (inreg). Tail call optimization is performed
// provided:
// * tailcallopt is enabled
// * caller/callee are fastcc
// On X86_64 architecture with GOT-style position independent code only local
// (within module) calls are supported at the moment.
// To keep the stack aligned according to platform abi the function
// GetAlignedArgumentStackSize ensures that argument delta is always multiples
// of stack alignment. (Dynamic linkers need this - Darwin's dyld for example)
// If a tail called function callee has more arguments than the caller the
// caller needs to make sure that there is room to move the RETADDR to. This is
// achieved by reserving an area the size of the argument delta right after the
// original RETADDR, but before the saved framepointer or the spilled registers
// e.g. caller(arg1, arg2) calls callee(arg1, arg2,arg3,arg4)
// stack layout:
// arg1
// arg2
// RETADDR
// [ new RETADDR
// move area ]
// (possible EBP)
// ESI
// EDI
// local1 ..
/// Make the stack size align e.g 16n + 12 aligned for a 16-byte align
/// requirement.
unsigned
X86TargetLowering::GetAlignedArgumentStackSize(const unsigned StackSize,
SelectionDAG &DAG) const {
const Align StackAlignment = Subtarget.getFrameLowering()->getStackAlign();
const uint64_t SlotSize = Subtarget.getRegisterInfo()->getSlotSize();
assert(StackSize % SlotSize == 0 &&
"StackSize must be a multiple of SlotSize");
return alignTo(StackSize + SlotSize, StackAlignment) - SlotSize;
}
/// Return true if the given stack call argument is already available in the
/// same position (relatively) of the caller's incoming argument stack.
static
bool MatchingStackOffset(SDValue Arg, unsigned Offset, ISD::ArgFlagsTy Flags,
MachineFrameInfo &MFI, const MachineRegisterInfo *MRI,
const X86InstrInfo *TII, const CCValAssign &VA) {
unsigned Bytes = Arg.getValueSizeInBits() / 8;
for (;;) {
// Look through nodes that don't alter the bits of the incoming value.
unsigned Op = Arg.getOpcode();
if (Op == ISD::ZERO_EXTEND || Op == ISD::ANY_EXTEND || Op == ISD::BITCAST ||
Op == ISD::AssertZext) {
Arg = Arg.getOperand(0);
continue;
}
if (Op == ISD::TRUNCATE) {
const SDValue &TruncInput = Arg.getOperand(0);
if (TruncInput.getOpcode() == ISD::AssertZext &&
cast<VTSDNode>(TruncInput.getOperand(1))->getVT() ==
Arg.getValueType()) {
Arg = TruncInput.getOperand(0);
continue;
}
}
break;
}
int FI = INT_MAX;
if (Arg.getOpcode() == ISD::CopyFromReg) {
Register VR = cast<RegisterSDNode>(Arg.getOperand(1))->getReg();
if (!VR.isVirtual())
return false;
MachineInstr *Def = MRI->getVRegDef(VR);
if (!Def)
return false;
if (!Flags.isByVal()) {
if (!TII->isLoadFromStackSlot(*Def, FI))
return false;
} else {
unsigned Opcode = Def->getOpcode();
if ((Opcode == X86::LEA32r || Opcode == X86::LEA64r ||
Opcode == X86::LEA64_32r) &&
Def->getOperand(1).isFI()) {
FI = Def->getOperand(1).getIndex();
Bytes = Flags.getByValSize();
} else
return false;
}
} else if (LoadSDNode *Ld = dyn_cast<LoadSDNode>(Arg)) {
if (Flags.isByVal())
// ByVal argument is passed in as a pointer but it's now being
// dereferenced. e.g.
// define @foo(%struct.X* %A) {
// tail call @bar(%struct.X* byval %A)
// }
return false;
SDValue Ptr = Ld->getBasePtr();
FrameIndexSDNode *FINode = dyn_cast<FrameIndexSDNode>(Ptr);
if (!FINode)
return false;
FI = FINode->getIndex();
} else if (Arg.getOpcode() == ISD::FrameIndex && Flags.isByVal()) {
FrameIndexSDNode *FINode = cast<FrameIndexSDNode>(Arg);
FI = FINode->getIndex();
Bytes = Flags.getByValSize();
} else
return false;
assert(FI != INT_MAX);
if (!MFI.isFixedObjectIndex(FI))
return false;
if (Offset != MFI.getObjectOffset(FI))
return false;
// If this is not byval, check that the argument stack object is immutable.
// inalloca and argument copy elision can create mutable argument stack
// objects. Byval objects can be mutated, but a byval call intends to pass the
// mutated memory.
if (!Flags.isByVal() && !MFI.isImmutableObjectIndex(FI))
return false;
if (VA.getLocVT().getFixedSizeInBits() >
Arg.getValueSizeInBits().getFixedValue()) {
// If the argument location is wider than the argument type, check that any
// extension flags match.
if (Flags.isZExt() != MFI.isObjectZExt(FI) ||
Flags.isSExt() != MFI.isObjectSExt(FI)) {
return false;
}
}
return Bytes == MFI.getObjectSize(FI);
}
static bool
mayBeSRetTailCallCompatible(const TargetLowering::CallLoweringInfo &CLI,
Register CallerSRetReg) {
const auto &Outs = CLI.Outs;
const auto &OutVals = CLI.OutVals;
// We know the caller has a sret pointer argument (CallerSRetReg). Locate the
// operand index within the callee that may have a sret pointer too.
unsigned Pos = 0;
for (unsigned E = Outs.size(); Pos != E; ++Pos)
if (Outs[Pos].Flags.isSRet())
break;
// Bail out if the callee has not any sret argument.
if (Pos == Outs.size())
return false;
// At this point, either the caller is forwarding its sret argument to the
// callee, or the callee is being passed a different sret pointer. We now look
// for a CopyToReg, where the callee sret argument is written into a new vreg
// (which should later be %rax/%eax, if this is returned).
SDValue SRetArgVal = OutVals[Pos];
for (SDNode *User : SRetArgVal->users()) {
if (User->getOpcode() != ISD::CopyToReg)
continue;
Register Reg = cast<RegisterSDNode>(User->getOperand(1))->getReg();
if (Reg == CallerSRetReg && User->getOperand(2) == SRetArgVal)
return true;
}
return false;
}
/// Check whether the call is eligible for tail call optimization. Targets
/// that want to do tail call optimization should implement this function.
/// Note that the x86 backend does not check musttail calls for eligibility! The
/// rest of x86 tail call lowering must be prepared to forward arguments of any
/// type.
bool X86TargetLowering::IsEligibleForTailCallOptimization(
TargetLowering::CallLoweringInfo &CLI, CCState &CCInfo,
SmallVectorImpl<CCValAssign> &ArgLocs, bool IsCalleePopSRet) const {
SelectionDAG &DAG = CLI.DAG;
const SmallVectorImpl<ISD::OutputArg> &Outs = CLI.Outs;
const SmallVectorImpl<SDValue> &OutVals = CLI.OutVals;
const SmallVectorImpl<ISD::InputArg> &Ins = CLI.Ins;
SDValue Callee = CLI.Callee;
CallingConv::ID CalleeCC = CLI.CallConv;
bool isVarArg = CLI.IsVarArg;
if (!mayTailCallThisCC(CalleeCC))
return false;
// If -tailcallopt is specified, make fastcc functions tail-callable.
MachineFunction &MF = DAG.getMachineFunction();
X86MachineFunctionInfo *FuncInfo = MF.getInfo<X86MachineFunctionInfo>();
const Function &CallerF = MF.getFunction();
// If the function return type is x86_fp80 and the callee return type is not,
// then the FP_EXTEND of the call result is not a nop. It's not safe to
// perform a tailcall optimization here.
if (CallerF.getReturnType()->isX86_FP80Ty() && !CLI.RetTy->isX86_FP80Ty())
return false;
CallingConv::ID CallerCC = CallerF.getCallingConv();
bool CCMatch = CallerCC == CalleeCC;
bool IsCalleeWin64 = Subtarget.isCallingConvWin64(CalleeCC);
bool IsCallerWin64 = Subtarget.isCallingConvWin64(CallerCC);
bool IsGuaranteeTCO = DAG.getTarget().Options.GuaranteedTailCallOpt ||
CalleeCC == CallingConv::Tail || CalleeCC == CallingConv::SwiftTail;
// Win64 functions have extra shadow space for argument homing. Don't do the
// sibcall if the caller and callee have mismatched expectations for this
// space.
if (IsCalleeWin64 != IsCallerWin64)
return false;
if (IsGuaranteeTCO) {
if (canGuaranteeTCO(CalleeCC) && CCMatch)
return true;
return false;
}
// Look for obvious safe cases to perform tail call optimization that do not
// require ABI changes. This is what gcc calls sibcall.
// Can't do sibcall if stack needs to be dynamically re-aligned. PEI needs to
// emit a special epilogue.
const X86RegisterInfo *RegInfo = Subtarget.getRegisterInfo();
if (RegInfo->hasStackRealignment(MF))
return false;
// Avoid sibcall optimization if we are an sret return function and the callee
// is incompatible, unless such premises are proven wrong. See comment in
// LowerReturn about why hasStructRetAttr is insufficient.
if (Register SRetReg = FuncInfo->getSRetReturnReg()) {
// For a compatible tail call the callee must return our sret pointer. So it
// needs to be (a) an sret function itself and (b) we pass our sret as its
// sret. Condition #b is harder to determine.
if (!mayBeSRetTailCallCompatible(CLI, SRetReg))
return false;
} else if (IsCalleePopSRet)
// The callee pops an sret, so we cannot tail-call, as our caller doesn't
// expect that.
return false;
// Do not sibcall optimize vararg calls unless all arguments are passed via
// registers.
LLVMContext &C = *DAG.getContext();
if (isVarArg && !Outs.empty()) {
// Optimizing for varargs on Win64 is unlikely to be safe without
// additional testing.
if (IsCalleeWin64 || IsCallerWin64)
return false;
for (const auto &VA : ArgLocs)
if (!VA.isRegLoc())
return false;
}
// If the call result is in ST0 / ST1, it needs to be popped off the x87
// stack. Therefore, if it's not used by the call it is not safe to optimize
// this into a sibcall.
bool Unused = false;
for (const auto &In : Ins) {
if (!In.Used) {
Unused = true;
break;
}
}
if (Unused) {
SmallVector<CCValAssign, 16> RVLocs;
CCState RVCCInfo(CalleeCC, false, MF, RVLocs, C);
RVCCInfo.AnalyzeCallResult(Ins, RetCC_X86);
for (const auto &VA : RVLocs) {
if (VA.getLocReg() == X86::FP0 || VA.getLocReg() == X86::FP1)
return false;
}
}
// Check that the call results are passed in the same way.
if (!CCState::resultsCompatible(CalleeCC, CallerCC, MF, C, Ins,
RetCC_X86, RetCC_X86))
return false;
// The callee has to preserve all registers the caller needs to preserve.
const X86RegisterInfo *TRI = Subtarget.getRegisterInfo();
const uint32_t *CallerPreserved = TRI->getCallPreservedMask(MF, CallerCC);
if (!CCMatch) {
const uint32_t *CalleePreserved = TRI->getCallPreservedMask(MF, CalleeCC);
if (!TRI->regmaskSubsetEqual(CallerPreserved, CalleePreserved))
return false;
}
// The stack frame of the caller cannot be replaced by the tail-callee one's
// if the function is required to preserve all the registers. Conservatively
// prevent tail optimization even if hypothetically all the registers are used
// for passing formal parameters or returning values.
if (CallerF.hasFnAttribute("no_caller_saved_registers"))
return false;
unsigned StackArgsSize = CCInfo.getStackSize();
// If the callee takes no arguments then go on to check the results of the
// call.
if (!Outs.empty()) {
if (StackArgsSize > 0) {
// Check if the arguments are already laid out in the right way as
// the caller's fixed stack objects.
MachineFrameInfo &MFI = MF.getFrameInfo();
const MachineRegisterInfo *MRI = &MF.getRegInfo();
const X86InstrInfo *TII = Subtarget.getInstrInfo();
for (unsigned I = 0, E = ArgLocs.size(); I != E; ++I) {
const CCValAssign &VA = ArgLocs[I];
SDValue Arg = OutVals[I];
ISD::ArgFlagsTy Flags = Outs[I].Flags;
if (VA.getLocInfo() == CCValAssign::Indirect)
return false;
if (!VA.isRegLoc()) {
if (!MatchingStackOffset(Arg, VA.getLocMemOffset(), Flags, MFI, MRI,
TII, VA))
return false;
}
}
}
bool PositionIndependent = isPositionIndependent();
// If the tailcall address may be in a register, then make sure it's
// possible to register allocate for it. In 32-bit, the call address can
// only target EAX, EDX, or ECX since the tail call must be scheduled after
// callee-saved registers are restored. These happen to be the same
// registers used to pass 'inreg' arguments so watch out for those.
if (!Subtarget.is64Bit() && ((!isa<GlobalAddressSDNode>(Callee) &&
!isa<ExternalSymbolSDNode>(Callee)) ||
PositionIndependent)) {
unsigned NumInRegs = 0;
// In PIC we need an extra register to formulate the address computation
// for the callee.
unsigned MaxInRegs = PositionIndependent ? 2 : 3;
for (const auto &VA : ArgLocs) {
if (!VA.isRegLoc())
continue;
Register Reg = VA.getLocReg();
switch (Reg) {
default: break;
case X86::EAX: case X86::EDX: case X86::ECX:
if (++NumInRegs == MaxInRegs)
return false;
break;
}
}
}
const MachineRegisterInfo &MRI = MF.getRegInfo();
if (!parametersInCSRMatch(MRI, CallerPreserved, ArgLocs, OutVals))
return false;
}
bool CalleeWillPop =
X86::isCalleePop(CalleeCC, Subtarget.is64Bit(), isVarArg,
MF.getTarget().Options.GuaranteedTailCallOpt);
if (unsigned BytesToPop = FuncInfo->getBytesToPopOnReturn()) {
// If we have bytes to pop, the callee must pop them.
bool CalleePopMatches = CalleeWillPop && BytesToPop == StackArgsSize;
if (!CalleePopMatches)
return false;
} else if (CalleeWillPop && StackArgsSize > 0) {
// If we don't have bytes to pop, make sure the callee doesn't pop any.
return false;
}
return true;
}
/// Determines whether the callee is required to pop its own arguments.
/// Callee pop is necessary to support tail calls.
bool X86::isCalleePop(CallingConv::ID CallingConv,
bool is64Bit, bool IsVarArg, bool GuaranteeTCO) {
// If GuaranteeTCO is true, we force some calls to be callee pop so that we
// can guarantee TCO.
if (!IsVarArg && shouldGuaranteeTCO(CallingConv, GuaranteeTCO))
return true;
switch (CallingConv) {
default:
return false;
case CallingConv::X86_StdCall:
case CallingConv::X86_FastCall:
case CallingConv::X86_ThisCall:
case CallingConv::X86_VectorCall:
return !is64Bit;
}
}
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