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llvm-project/llvm/lib/CodeGen/StackMaps.cpp
Matt Arsenault 5e727e8bed
[Statepoint] Treat undef operands less specially (#119682) 
This reverts commit f7443905af1e06eaacda1e437fff8d54dc89c487.

This is to avoid an assertion if an undef operand appears in a
stackmap. This is important to avoid hitting verifier errors
when register allocation starts adding undefs in error scenarios.

Rather than trying to treat undef operands as special, leave them
alone and avoid producing an invalid spill. It would a bit more
precise to produce a spill of an undef register here, but that's not
exposed through the storeRegToStackSlot API.

https://reviews.llvm.org/D122605

This was an alternative to https://reviews.llvm.org/D122582
2024-12-17 12:59:46 +07:00

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//===- StackMaps.cpp ------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/StackMaps.h"
#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/TargetOpcodes.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <iterator>
#include <utility>
using namespace llvm;
#define DEBUG_TYPE "stackmaps"
static cl::opt<int> StackMapVersion(
"stackmap-version", cl::init(3), cl::Hidden,
cl::desc("Specify the stackmap encoding version (default = 3)"));
const char *StackMaps::WSMP = "Stack Maps: ";
static uint64_t getConstMetaVal(const MachineInstr &MI, unsigned Idx) {
assert(MI.getOperand(Idx).isImm() &&
MI.getOperand(Idx).getImm() == StackMaps::ConstantOp);
const auto &MO = MI.getOperand(Idx + 1);
assert(MO.isImm());
return MO.getImm();
}
StackMapOpers::StackMapOpers(const MachineInstr *MI)
: MI(MI) {
assert(getVarIdx() <= MI->getNumOperands() &&
"invalid stackmap definition");
}
PatchPointOpers::PatchPointOpers(const MachineInstr *MI)
: MI(MI), HasDef(MI->getOperand(0).isReg() && MI->getOperand(0).isDef() &&
!MI->getOperand(0).isImplicit()) {
#ifndef NDEBUG
unsigned CheckStartIdx = 0, e = MI->getNumOperands();
while (CheckStartIdx < e && MI->getOperand(CheckStartIdx).isReg() &&
MI->getOperand(CheckStartIdx).isDef() &&
!MI->getOperand(CheckStartIdx).isImplicit())
++CheckStartIdx;
assert(getMetaIdx() == CheckStartIdx &&
"Unexpected additional definition in Patchpoint intrinsic.");
#endif
}
unsigned PatchPointOpers::getNextScratchIdx(unsigned StartIdx) const {
if (!StartIdx)
StartIdx = getVarIdx();
// Find the next scratch register (implicit def and early clobber)
unsigned ScratchIdx = StartIdx, e = MI->getNumOperands();
while (ScratchIdx < e &&
!(MI->getOperand(ScratchIdx).isReg() &&
MI->getOperand(ScratchIdx).isDef() &&
MI->getOperand(ScratchIdx).isImplicit() &&
MI->getOperand(ScratchIdx).isEarlyClobber()))
++ScratchIdx;
assert(ScratchIdx != e && "No scratch register available");
return ScratchIdx;
}
unsigned StatepointOpers::getNumGcMapEntriesIdx() {
// Take index of num of allocas and skip all allocas records.
unsigned CurIdx = getNumAllocaIdx();
unsigned NumAllocas = getConstMetaVal(*MI, CurIdx - 1);
CurIdx++;
while (NumAllocas--)
CurIdx = StackMaps::getNextMetaArgIdx(MI, CurIdx);
return CurIdx + 1; // skip <StackMaps::ConstantOp>
}
unsigned StatepointOpers::getNumAllocaIdx() {
// Take index of num of gc ptrs and skip all gc ptr records.
unsigned CurIdx = getNumGCPtrIdx();
unsigned NumGCPtrs = getConstMetaVal(*MI, CurIdx - 1);
CurIdx++;
while (NumGCPtrs--)
CurIdx = StackMaps::getNextMetaArgIdx(MI, CurIdx);
return CurIdx + 1; // skip <StackMaps::ConstantOp>
}
unsigned StatepointOpers::getNumGCPtrIdx() {
// Take index of num of deopt args and skip all deopt records.
unsigned CurIdx = getNumDeoptArgsIdx();
unsigned NumDeoptArgs = getConstMetaVal(*MI, CurIdx - 1);
CurIdx++;
while (NumDeoptArgs--) {
CurIdx = StackMaps::getNextMetaArgIdx(MI, CurIdx);
}
return CurIdx + 1; // skip <StackMaps::ConstantOp>
}
int StatepointOpers::getFirstGCPtrIdx() {
unsigned NumGCPtrsIdx = getNumGCPtrIdx();
unsigned NumGCPtrs = getConstMetaVal(*MI, NumGCPtrsIdx - 1);
if (NumGCPtrs == 0)
return -1;
++NumGCPtrsIdx; // skip <num gc ptrs>
assert(NumGCPtrsIdx < MI->getNumOperands());
return (int)NumGCPtrsIdx;
}
unsigned StatepointOpers::getGCPointerMap(
SmallVectorImpl<std::pair<unsigned, unsigned>> &GCMap) {
unsigned CurIdx = getNumGcMapEntriesIdx();
unsigned GCMapSize = getConstMetaVal(*MI, CurIdx - 1);
CurIdx++;
for (unsigned N = 0; N < GCMapSize; ++N) {
unsigned B = MI->getOperand(CurIdx++).getImm();
unsigned D = MI->getOperand(CurIdx++).getImm();
GCMap.push_back(std::make_pair(B, D));
}
return GCMapSize;
}
bool StatepointOpers::isFoldableReg(Register Reg) const {
unsigned FoldableAreaStart = getVarIdx();
for (const MachineOperand &MO : MI->uses()) {
if (MO.getOperandNo() >= FoldableAreaStart)
break;
if (MO.isReg() && MO.getReg() == Reg)
return false;
}
return true;
}
bool StatepointOpers::isFoldableReg(const MachineInstr *MI, Register Reg) {
if (MI->getOpcode() != TargetOpcode::STATEPOINT)
return false;
return StatepointOpers(MI).isFoldableReg(Reg);
}
StackMaps::StackMaps(AsmPrinter &AP) : AP(AP) {
if (StackMapVersion != 3)
llvm_unreachable("Unsupported stackmap version!");
}
unsigned StackMaps::getNextMetaArgIdx(const MachineInstr *MI, unsigned CurIdx) {
assert(CurIdx < MI->getNumOperands() && "Bad meta arg index");
const auto &MO = MI->getOperand(CurIdx);
if (MO.isImm()) {
switch (MO.getImm()) {
default:
llvm_unreachable("Unrecognized operand type.");
case StackMaps::DirectMemRefOp:
CurIdx += 2;
break;
case StackMaps::IndirectMemRefOp:
CurIdx += 3;
break;
case StackMaps::ConstantOp:
++CurIdx;
break;
}
}
++CurIdx;
assert(CurIdx < MI->getNumOperands() && "points past operand list");
return CurIdx;
}
/// Go up the super-register chain until we hit a valid dwarf register number.
static unsigned getDwarfRegNum(unsigned Reg, const TargetRegisterInfo *TRI) {
int RegNum;
for (MCPhysReg SR : TRI->superregs_inclusive(Reg)) {
RegNum = TRI->getDwarfRegNum(SR, false);
if (RegNum >= 0)
break;
}
assert(RegNum >= 0 && isUInt<16>(RegNum) && "Invalid Dwarf register number.");
return (unsigned)RegNum;
}
MachineInstr::const_mop_iterator
StackMaps::parseOperand(MachineInstr::const_mop_iterator MOI,
MachineInstr::const_mop_iterator MOE, LocationVec &Locs,
LiveOutVec &LiveOuts) {
const TargetRegisterInfo *TRI = AP.MF->getSubtarget().getRegisterInfo();
if (MOI->isImm()) {
switch (MOI->getImm()) {
default:
llvm_unreachable("Unrecognized operand type.");
case StackMaps::DirectMemRefOp: {
auto &DL = AP.MF->getDataLayout();
unsigned Size = DL.getPointerSizeInBits();
assert((Size % 8) == 0 && "Need pointer size in bytes.");
Size /= 8;
Register Reg = (++MOI)->getReg();
int64_t Imm = (++MOI)->getImm();
Locs.emplace_back(StackMaps::Location::Direct, Size,
getDwarfRegNum(Reg, TRI), Imm);
break;
}
case StackMaps::IndirectMemRefOp: {
int64_t Size = (++MOI)->getImm();
assert(Size > 0 && "Need a valid size for indirect memory locations.");
Register Reg = (++MOI)->getReg();
int64_t Imm = (++MOI)->getImm();
Locs.emplace_back(StackMaps::Location::Indirect, Size,
getDwarfRegNum(Reg, TRI), Imm);
break;
}
case StackMaps::ConstantOp: {
++MOI;
assert(MOI->isImm() && "Expected constant operand.");
int64_t Imm = MOI->getImm();
if (isInt<32>(Imm)) {
Locs.emplace_back(Location::Constant, sizeof(int64_t), 0, Imm);
} else {
// ConstPool is intentionally a MapVector of 'uint64_t's (as
// opposed to 'int64_t's). We should never be in a situation
// where we have to insert either the tombstone or the empty
// keys into a map, and for a DenseMap<uint64_t, T> these are
// (uint64_t)0 and (uint64_t)-1. They can be and are
// represented using 32 bit integers.
assert((uint64_t)Imm != DenseMapInfo<uint64_t>::getEmptyKey() &&
(uint64_t)Imm != DenseMapInfo<uint64_t>::getTombstoneKey() &&
"empty and tombstone keys should fit in 32 bits!");
auto Result = ConstPool.insert(std::make_pair(Imm, Imm));
Locs.emplace_back(Location::ConstantIndex, sizeof(int64_t), 0,
Result.first - ConstPool.begin());
}
break;
}
}
return ++MOI;
}
// The physical register number will ultimately be encoded as a DWARF regno.
// The stack map also records the size of a spill slot that can hold the
// register content. (The runtime can track the actual size of the data type
// if it needs to.)
if (MOI->isReg()) {
// Skip implicit registers (this includes our scratch registers)
if (MOI->isImplicit())
return ++MOI;
assert(MOI->getReg().isPhysical() &&
"Virtreg operands should have been rewritten before now.");
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(MOI->getReg());
assert(!MOI->getSubReg() && "Physical subreg still around.");
unsigned Offset = 0;
unsigned DwarfRegNum = getDwarfRegNum(MOI->getReg(), TRI);
MCRegister LLVMRegNum = *TRI->getLLVMRegNum(DwarfRegNum, false);
unsigned SubRegIdx = TRI->getSubRegIndex(LLVMRegNum, MOI->getReg());
if (SubRegIdx)
Offset = TRI->getSubRegIdxOffset(SubRegIdx);
Locs.emplace_back(Location::Register, TRI->getSpillSize(*RC),
DwarfRegNum, Offset);
return ++MOI;
}
if (MOI->isRegLiveOut())
LiveOuts = parseRegisterLiveOutMask(MOI->getRegLiveOut());
return ++MOI;
}
void StackMaps::print(raw_ostream &OS) {
const TargetRegisterInfo *TRI =
AP.MF ? AP.MF->getSubtarget().getRegisterInfo() : nullptr;
OS << WSMP << "callsites:\n";
for (const auto &CSI : CSInfos) {
const LocationVec &CSLocs = CSI.Locations;
const LiveOutVec &LiveOuts = CSI.LiveOuts;
OS << WSMP << "callsite " << CSI.ID << "\n";
OS << WSMP << " has " << CSLocs.size() << " locations\n";
unsigned Idx = 0;
for (const auto &Loc : CSLocs) {
OS << WSMP << "\t\tLoc " << Idx << ": ";
switch (Loc.Type) {
case Location::Unprocessed:
OS << "<Unprocessed operand>";
break;
case Location::Register:
OS << "Register ";
if (TRI)
OS << printReg(Loc.Reg, TRI);
else
OS << Loc.Reg;
break;
case Location::Direct:
OS << "Direct ";
if (TRI)
OS << printReg(Loc.Reg, TRI);
else
OS << Loc.Reg;
if (Loc.Offset)
OS << " + " << Loc.Offset;
break;
case Location::Indirect:
OS << "Indirect ";
if (TRI)
OS << printReg(Loc.Reg, TRI);
else
OS << Loc.Reg;
OS << "+" << Loc.Offset;
break;
case Location::Constant:
OS << "Constant " << Loc.Offset;
break;
case Location::ConstantIndex:
OS << "Constant Index " << Loc.Offset;
break;
}
OS << "\t[encoding: .byte " << Loc.Type << ", .byte 0"
<< ", .short " << Loc.Size << ", .short " << Loc.Reg << ", .short 0"
<< ", .int " << Loc.Offset << "]\n";
Idx++;
}
OS << WSMP << "\thas " << LiveOuts.size() << " live-out registers\n";
Idx = 0;
for (const auto &LO : LiveOuts) {
OS << WSMP << "\t\tLO " << Idx << ": ";
if (TRI)
OS << printReg(LO.Reg, TRI);
else
OS << LO.Reg;
OS << "\t[encoding: .short " << LO.DwarfRegNum << ", .byte 0, .byte "
<< LO.Size << "]\n";
Idx++;
}
}
}
/// Create a live-out register record for the given register Reg.
StackMaps::LiveOutReg
StackMaps::createLiveOutReg(unsigned Reg, const TargetRegisterInfo *TRI) const {
unsigned DwarfRegNum = getDwarfRegNum(Reg, TRI);
unsigned Size = TRI->getSpillSize(*TRI->getMinimalPhysRegClass(Reg));
return LiveOutReg(Reg, DwarfRegNum, Size);
}
/// Parse the register live-out mask and return a vector of live-out registers
/// that need to be recorded in the stackmap.
StackMaps::LiveOutVec
StackMaps::parseRegisterLiveOutMask(const uint32_t *Mask) const {
assert(Mask && "No register mask specified");
const TargetRegisterInfo *TRI = AP.MF->getSubtarget().getRegisterInfo();
LiveOutVec LiveOuts;
// Create a LiveOutReg for each bit that is set in the register mask.
for (unsigned Reg = 0, NumRegs = TRI->getNumRegs(); Reg != NumRegs; ++Reg)
if ((Mask[Reg / 32] >> (Reg % 32)) & 1)
LiveOuts.push_back(createLiveOutReg(Reg, TRI));
// We don't need to keep track of a register if its super-register is already
// in the list. Merge entries that refer to the same dwarf register and use
// the maximum size that needs to be spilled.
llvm::sort(LiveOuts, [](const LiveOutReg &LHS, const LiveOutReg &RHS) {
// Only sort by the dwarf register number.
return LHS.DwarfRegNum < RHS.DwarfRegNum;
});
for (auto I = LiveOuts.begin(), E = LiveOuts.end(); I != E; ++I) {
for (auto *II = std::next(I); II != E; ++II) {
if (I->DwarfRegNum != II->DwarfRegNum) {
// Skip all the now invalid entries.
I = --II;
break;
}
I->Size = std::max(I->Size, II->Size);
if (I->Reg && TRI->isSuperRegister(I->Reg, II->Reg))
I->Reg = II->Reg;
II->Reg = 0; // mark for deletion.
}
}
llvm::erase_if(LiveOuts, [](const LiveOutReg &LO) { return LO.Reg == 0; });
return LiveOuts;
}
// See statepoint MI format description in StatepointOpers' class comment
// in include/llvm/CodeGen/StackMaps.h
void StackMaps::parseStatepointOpers(const MachineInstr &MI,
MachineInstr::const_mop_iterator MOI,
MachineInstr::const_mop_iterator MOE,
LocationVec &Locations,
LiveOutVec &LiveOuts) {
LLVM_DEBUG(dbgs() << "record statepoint : " << MI << "\n");
StatepointOpers SO(&MI);
MOI = parseOperand(MOI, MOE, Locations, LiveOuts); // CC
MOI = parseOperand(MOI, MOE, Locations, LiveOuts); // Flags
MOI = parseOperand(MOI, MOE, Locations, LiveOuts); // Num Deopts
// Record Deopt Args.
unsigned NumDeoptArgs = Locations.back().Offset;
assert(Locations.back().Type == Location::Constant);
assert(NumDeoptArgs == SO.getNumDeoptArgs());
while (NumDeoptArgs--)
MOI = parseOperand(MOI, MOE, Locations, LiveOuts);
// Record gc base/derived pairs
assert(MOI->isImm() && MOI->getImm() == StackMaps::ConstantOp);
++MOI;
assert(MOI->isImm());
unsigned NumGCPointers = MOI->getImm();
++MOI;
if (NumGCPointers) {
// Map logical index of GC ptr to MI operand index.
SmallVector<unsigned, 8> GCPtrIndices;
unsigned GCPtrIdx = (unsigned)SO.getFirstGCPtrIdx();
assert((int)GCPtrIdx != -1);
assert(MOI - MI.operands_begin() == GCPtrIdx + 0LL);
while (NumGCPointers--) {
GCPtrIndices.push_back(GCPtrIdx);
GCPtrIdx = StackMaps::getNextMetaArgIdx(&MI, GCPtrIdx);
}
SmallVector<std::pair<unsigned, unsigned>, 8> GCPairs;
unsigned NumGCPairs = SO.getGCPointerMap(GCPairs);
(void)NumGCPairs;
LLVM_DEBUG(dbgs() << "NumGCPairs = " << NumGCPairs << "\n");
auto MOB = MI.operands_begin();
for (auto &P : GCPairs) {
assert(P.first < GCPtrIndices.size() && "base pointer index not found");
assert(P.second < GCPtrIndices.size() &&
"derived pointer index not found");
unsigned BaseIdx = GCPtrIndices[P.first];
unsigned DerivedIdx = GCPtrIndices[P.second];
LLVM_DEBUG(dbgs() << "Base : " << BaseIdx << " Derived : " << DerivedIdx
<< "\n");
(void)parseOperand(MOB + BaseIdx, MOE, Locations, LiveOuts);
(void)parseOperand(MOB + DerivedIdx, MOE, Locations, LiveOuts);
}
MOI = MOB + GCPtrIdx;
}
// Record gc allocas
assert(MOI < MOE);
assert(MOI->isImm() && MOI->getImm() == StackMaps::ConstantOp);
++MOI;
unsigned NumAllocas = MOI->getImm();
++MOI;
while (NumAllocas--) {
MOI = parseOperand(MOI, MOE, Locations, LiveOuts);
assert(MOI < MOE);
}
}
void StackMaps::recordStackMapOpers(const MCSymbol &MILabel,
const MachineInstr &MI, uint64_t ID,
MachineInstr::const_mop_iterator MOI,
MachineInstr::const_mop_iterator MOE,
bool recordResult) {
MCContext &OutContext = AP.OutStreamer->getContext();
LocationVec Locations;
LiveOutVec LiveOuts;
if (recordResult) {
assert(PatchPointOpers(&MI).hasDef() && "Stackmap has no return value.");
parseOperand(MI.operands_begin(), std::next(MI.operands_begin()), Locations,
LiveOuts);
}
// Parse operands.
if (MI.getOpcode() == TargetOpcode::STATEPOINT)
parseStatepointOpers(MI, MOI, MOE, Locations, LiveOuts);
else
while (MOI != MOE)
MOI = parseOperand(MOI, MOE, Locations, LiveOuts);
// Create an expression to calculate the offset of the callsite from function
// entry.
const MCExpr *CSOffsetExpr = MCBinaryExpr::createSub(
MCSymbolRefExpr::create(&MILabel, OutContext),
MCSymbolRefExpr::create(AP.CurrentFnSymForSize, OutContext), OutContext);
CSInfos.emplace_back(CSOffsetExpr, ID, std::move(Locations),
std::move(LiveOuts));
// Record the stack size of the current function and update callsite count.
const MachineFrameInfo &MFI = AP.MF->getFrameInfo();
const TargetRegisterInfo *RegInfo = AP.MF->getSubtarget().getRegisterInfo();
bool HasDynamicFrameSize =
MFI.hasVarSizedObjects() || RegInfo->hasStackRealignment(*(AP.MF));
uint64_t FrameSize = HasDynamicFrameSize ? UINT64_MAX : MFI.getStackSize();
auto CurrentIt = FnInfos.find(AP.CurrentFnSym);
if (CurrentIt != FnInfos.end())
CurrentIt->second.RecordCount++;
else
FnInfos.insert(std::make_pair(AP.CurrentFnSym, FunctionInfo(FrameSize)));
}
void StackMaps::recordStackMap(const MCSymbol &L, const MachineInstr &MI) {
assert(MI.getOpcode() == TargetOpcode::STACKMAP && "expected stackmap");
StackMapOpers opers(&MI);
const int64_t ID = MI.getOperand(PatchPointOpers::IDPos).getImm();
recordStackMapOpers(L, MI, ID, std::next(MI.operands_begin(),
opers.getVarIdx()),
MI.operands_end());
}
void StackMaps::recordPatchPoint(const MCSymbol &L, const MachineInstr &MI) {
assert(MI.getOpcode() == TargetOpcode::PATCHPOINT && "expected patchpoint");
PatchPointOpers opers(&MI);
const int64_t ID = opers.getID();
auto MOI = std::next(MI.operands_begin(), opers.getStackMapStartIdx());
recordStackMapOpers(L, MI, ID, MOI, MI.operands_end(),
opers.isAnyReg() && opers.hasDef());
#ifndef NDEBUG
// verify anyregcc
auto &Locations = CSInfos.back().Locations;
if (opers.isAnyReg()) {
unsigned NArgs = opers.getNumCallArgs();
for (unsigned i = 0, e = (opers.hasDef() ? NArgs + 1 : NArgs); i != e; ++i)
assert(Locations[i].Type == Location::Register &&
"anyreg arg must be in reg.");
}
#endif
}
void StackMaps::recordStatepoint(const MCSymbol &L, const MachineInstr &MI) {
assert(MI.getOpcode() == TargetOpcode::STATEPOINT && "expected statepoint");
StatepointOpers opers(&MI);
const unsigned StartIdx = opers.getVarIdx();
recordStackMapOpers(L, MI, opers.getID(), MI.operands_begin() + StartIdx,
MI.operands_end(), false);
}
/// Emit the stackmap header.
///
/// Header {
/// uint8 : Stack Map Version (currently 3)
/// uint8 : Reserved (expected to be 0)
/// uint16 : Reserved (expected to be 0)
/// }
/// uint32 : NumFunctions
/// uint32 : NumConstants
/// uint32 : NumRecords
void StackMaps::emitStackmapHeader(MCStreamer &OS) {
// Header.
OS.emitIntValue(StackMapVersion, 1); // Version.
OS.emitIntValue(0, 1); // Reserved.
OS.emitInt16(0); // Reserved.
// Num functions.
LLVM_DEBUG(dbgs() << WSMP << "#functions = " << FnInfos.size() << '\n');
OS.emitInt32(FnInfos.size());
// Num constants.
LLVM_DEBUG(dbgs() << WSMP << "#constants = " << ConstPool.size() << '\n');
OS.emitInt32(ConstPool.size());
// Num callsites.
LLVM_DEBUG(dbgs() << WSMP << "#callsites = " << CSInfos.size() << '\n');
OS.emitInt32(CSInfos.size());
}
/// Emit the function frame record for each function.
///
/// StkSizeRecord[NumFunctions] {
/// uint64 : Function Address
/// uint64 : Stack Size
/// uint64 : Record Count
/// }
void StackMaps::emitFunctionFrameRecords(MCStreamer &OS) {
// Function Frame records.
LLVM_DEBUG(dbgs() << WSMP << "functions:\n");
for (auto const &FR : FnInfos) {
LLVM_DEBUG(dbgs() << WSMP << "function addr: " << FR.first
<< " frame size: " << FR.second.StackSize
<< " callsite count: " << FR.second.RecordCount << '\n');
OS.emitSymbolValue(FR.first, 8);
OS.emitIntValue(FR.second.StackSize, 8);
OS.emitIntValue(FR.second.RecordCount, 8);
}
}
/// Emit the constant pool.
///
/// int64 : Constants[NumConstants]
void StackMaps::emitConstantPoolEntries(MCStreamer &OS) {
// Constant pool entries.
LLVM_DEBUG(dbgs() << WSMP << "constants:\n");
for (const auto &ConstEntry : ConstPool) {
LLVM_DEBUG(dbgs() << WSMP << ConstEntry.second << '\n');
OS.emitIntValue(ConstEntry.second, 8);
}
}
/// Emit the callsite info for each callsite.
///
/// StkMapRecord[NumRecords] {
/// uint64 : PatchPoint ID
/// uint32 : Instruction Offset
/// uint16 : Reserved (record flags)
/// uint16 : NumLocations
/// Location[NumLocations] {
/// uint8 : Register | Direct | Indirect | Constant | ConstantIndex
/// uint8 : Size in Bytes
/// uint16 : Dwarf RegNum
/// int32 : Offset
/// }
/// uint16 : Padding
/// uint16 : NumLiveOuts
/// LiveOuts[NumLiveOuts] {
/// uint16 : Dwarf RegNum
/// uint8 : Reserved
/// uint8 : Size in Bytes
/// }
/// uint32 : Padding (only if required to align to 8 byte)
/// }
///
/// Location Encoding, Type, Value:
/// 0x1, Register, Reg (value in register)
/// 0x2, Direct, Reg + Offset (frame index)
/// 0x3, Indirect, [Reg + Offset] (spilled value)
/// 0x4, Constant, Offset (small constant)
/// 0x5, ConstIndex, Constants[Offset] (large constant)
void StackMaps::emitCallsiteEntries(MCStreamer &OS) {
LLVM_DEBUG(print(dbgs()));
// Callsite entries.
for (const auto &CSI : CSInfos) {
const LocationVec &CSLocs = CSI.Locations;
const LiveOutVec &LiveOuts = CSI.LiveOuts;
// Verify stack map entry. It's better to communicate a problem to the
// runtime than crash in case of in-process compilation. Currently, we do
// simple overflow checks, but we may eventually communicate other
// compilation errors this way.
if (CSLocs.size() > UINT16_MAX || LiveOuts.size() > UINT16_MAX) {
OS.emitIntValue(UINT64_MAX, 8); // Invalid ID.
OS.emitValue(CSI.CSOffsetExpr, 4);
OS.emitInt16(0); // Reserved.
OS.emitInt16(0); // 0 locations.
OS.emitInt16(0); // padding.
OS.emitInt16(0); // 0 live-out registers.
OS.emitInt32(0); // padding.
continue;
}
OS.emitIntValue(CSI.ID, 8);
OS.emitValue(CSI.CSOffsetExpr, 4);
// Reserved for flags.
OS.emitInt16(0);
OS.emitInt16(CSLocs.size());
for (const auto &Loc : CSLocs) {
OS.emitIntValue(Loc.Type, 1);
OS.emitIntValue(0, 1); // Reserved
OS.emitInt16(Loc.Size);
OS.emitInt16(Loc.Reg);
OS.emitInt16(0); // Reserved
OS.emitInt32(Loc.Offset);
}
// Emit alignment to 8 byte.
OS.emitValueToAlignment(Align(8));
// Num live-out registers and padding to align to 4 byte.
OS.emitInt16(0);
OS.emitInt16(LiveOuts.size());
for (const auto &LO : LiveOuts) {
OS.emitInt16(LO.DwarfRegNum);
OS.emitIntValue(0, 1);
OS.emitIntValue(LO.Size, 1);
}
// Emit alignment to 8 byte.
OS.emitValueToAlignment(Align(8));
}
}
/// Serialize the stackmap data.
void StackMaps::serializeToStackMapSection() {
(void)WSMP;
// Bail out if there's no stack map data.
assert((!CSInfos.empty() || ConstPool.empty()) &&
"Expected empty constant pool too!");
assert((!CSInfos.empty() || FnInfos.empty()) &&
"Expected empty function record too!");
if (CSInfos.empty())
return;
MCContext &OutContext = AP.OutStreamer->getContext();
MCStreamer &OS = *AP.OutStreamer;
// Create the section.
MCSection *StackMapSection =
OutContext.getObjectFileInfo()->getStackMapSection();
OS.switchSection(StackMapSection);
// Emit a dummy symbol to force section inclusion.
OS.emitLabel(OutContext.getOrCreateSymbol(Twine("__LLVM_StackMaps")));
// Serialize data.
LLVM_DEBUG(dbgs() << "********** Stack Map Output **********\n");
emitStackmapHeader(OS);
emitFunctionFrameRecords(OS);
emitConstantPoolEntries(OS);
emitCallsiteEntries(OS);
OS.addBlankLine();
// Clean up.
CSInfos.clear();
ConstPool.clear();
}
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