llvm-project/llvm/lib/Target/ARM/ARMConstantPoolValue.cpp
James Molloy 1ce54d6be2 [ARM] Promote small global constants to constant pools
If a constant is unamed_addr and is only used within one function, we can save
on the code size and runtime cost of an indirection by changing the global's storage
to inside the constant pool. For example, instead of:

      ldr r0, .CPI0
      bl printf
      bx lr
    .CPI0: &format_string
    format_string: .asciz "hello, world!\n"

We can emit:

      adr r0, .CPI0
      bl printf
      bx lr
    .CPI0: .asciz "hello, world!\n"

This can cause significant code size savings when many small strings are used in one
function (4 bytes per string).

This recommit contains fixes for a nasty bug related to fast-isel fallback - because
fast-isel doesn't know about this optimization, if it runs and emits references to
a string that we inline (because fast-isel fell back to SDAG) we will end up
with an inlined string and also an out-of-line string, and we won't emit the
out-of-line string, causing backend failures.

It also contains fixes for emitting .text relocations which made the sanitizer
bots unhappy.

llvm-svn: 282241
2016-09-23 12:15:58 +00:00

283 lines
11 KiB
C++

//===-- ARMConstantPoolValue.cpp - ARM constantpool value -----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the ARM specific constantpool value class.
//
//===----------------------------------------------------------------------===//
#include "ARMConstantPoolValue.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/raw_ostream.h"
#include <cstdlib>
using namespace llvm;
//===----------------------------------------------------------------------===//
// ARMConstantPoolValue
//===----------------------------------------------------------------------===//
ARMConstantPoolValue::ARMConstantPoolValue(Type *Ty, unsigned id,
ARMCP::ARMCPKind kind,
unsigned char PCAdj,
ARMCP::ARMCPModifier modifier,
bool addCurrentAddress)
: MachineConstantPoolValue(Ty), LabelId(id), Kind(kind),
PCAdjust(PCAdj), Modifier(modifier),
AddCurrentAddress(addCurrentAddress) {}
ARMConstantPoolValue::ARMConstantPoolValue(LLVMContext &C, unsigned id,
ARMCP::ARMCPKind kind,
unsigned char PCAdj,
ARMCP::ARMCPModifier modifier,
bool addCurrentAddress)
: MachineConstantPoolValue((Type*)Type::getInt32Ty(C)),
LabelId(id), Kind(kind), PCAdjust(PCAdj), Modifier(modifier),
AddCurrentAddress(addCurrentAddress) {}
ARMConstantPoolValue::~ARMConstantPoolValue() {}
const char *ARMConstantPoolValue::getModifierText() const {
switch (Modifier) {
// FIXME: Are these case sensitive? It'd be nice to lower-case all the
// strings if that's legal.
case ARMCP::no_modifier:
return "none";
case ARMCP::TLSGD:
return "tlsgd";
case ARMCP::GOT_PREL:
return "GOT_PREL";
case ARMCP::GOTTPOFF:
return "gottpoff";
case ARMCP::TPOFF:
return "tpoff";
case ARMCP::SBREL:
return "SBREL";
case ARMCP::SECREL:
return "secrel32";
}
llvm_unreachable("Unknown modifier!");
}
int ARMConstantPoolValue::getExistingMachineCPValue(MachineConstantPool *CP,
unsigned Alignment) {
llvm_unreachable("Shouldn't be calling this directly!");
}
void
ARMConstantPoolValue::addSelectionDAGCSEId(FoldingSetNodeID &ID) {
ID.AddInteger(LabelId);
ID.AddInteger(PCAdjust);
}
bool
ARMConstantPoolValue::hasSameValue(ARMConstantPoolValue *ACPV) {
if (ACPV->Kind == Kind &&
ACPV->PCAdjust == PCAdjust &&
ACPV->Modifier == Modifier &&
ACPV->LabelId == LabelId &&
ACPV->AddCurrentAddress == AddCurrentAddress) {
// Two PC relative constpool entries containing the same GV address or
// external symbols. FIXME: What about blockaddress?
if (Kind == ARMCP::CPValue || Kind == ARMCP::CPExtSymbol)
return true;
}
return false;
}
LLVM_DUMP_METHOD void ARMConstantPoolValue::dump() const {
errs() << " " << *this;
}
void ARMConstantPoolValue::print(raw_ostream &O) const {
if (Modifier) O << "(" << getModifierText() << ")";
if (PCAdjust != 0) {
O << "-(LPC" << LabelId << "+" << (unsigned)PCAdjust;
if (AddCurrentAddress) O << "-.";
O << ")";
}
}
//===----------------------------------------------------------------------===//
// ARMConstantPoolConstant
//===----------------------------------------------------------------------===//
ARMConstantPoolConstant::ARMConstantPoolConstant(Type *Ty,
const Constant *C,
unsigned ID,
ARMCP::ARMCPKind Kind,
unsigned char PCAdj,
ARMCP::ARMCPModifier Modifier,
bool AddCurrentAddress)
: ARMConstantPoolValue(Ty, ID, Kind, PCAdj, Modifier, AddCurrentAddress),
CVal(C) {}
ARMConstantPoolConstant::ARMConstantPoolConstant(const Constant *C,
unsigned ID,
ARMCP::ARMCPKind Kind,
unsigned char PCAdj,
ARMCP::ARMCPModifier Modifier,
bool AddCurrentAddress)
: ARMConstantPoolValue((Type*)C->getType(), ID, Kind, PCAdj, Modifier,
AddCurrentAddress),
CVal(C) {}
ARMConstantPoolConstant::ARMConstantPoolConstant(const GlobalVariable *GV,
const Constant *C)
: ARMConstantPoolValue((Type *)C->getType(), 0, ARMCP::CPPromotedGlobal, 0,
ARMCP::no_modifier, false),
CVal(C), GVar(GV) {}
ARMConstantPoolConstant *
ARMConstantPoolConstant::Create(const Constant *C, unsigned ID) {
return new ARMConstantPoolConstant(C, ID, ARMCP::CPValue, 0,
ARMCP::no_modifier, false);
}
ARMConstantPoolConstant *
ARMConstantPoolConstant::Create(const GlobalVariable *GVar,
const Constant *Initializer) {
return new ARMConstantPoolConstant(GVar, Initializer);
}
ARMConstantPoolConstant *
ARMConstantPoolConstant::Create(const GlobalValue *GV,
ARMCP::ARMCPModifier Modifier) {
return new ARMConstantPoolConstant((Type*)Type::getInt32Ty(GV->getContext()),
GV, 0, ARMCP::CPValue, 0,
Modifier, false);
}
ARMConstantPoolConstant *
ARMConstantPoolConstant::Create(const Constant *C, unsigned ID,
ARMCP::ARMCPKind Kind, unsigned char PCAdj) {
return new ARMConstantPoolConstant(C, ID, Kind, PCAdj,
ARMCP::no_modifier, false);
}
ARMConstantPoolConstant *
ARMConstantPoolConstant::Create(const Constant *C, unsigned ID,
ARMCP::ARMCPKind Kind, unsigned char PCAdj,
ARMCP::ARMCPModifier Modifier,
bool AddCurrentAddress) {
return new ARMConstantPoolConstant(C, ID, Kind, PCAdj, Modifier,
AddCurrentAddress);
}
const GlobalValue *ARMConstantPoolConstant::getGV() const {
return dyn_cast_or_null<GlobalValue>(CVal);
}
const BlockAddress *ARMConstantPoolConstant::getBlockAddress() const {
return dyn_cast_or_null<BlockAddress>(CVal);
}
int ARMConstantPoolConstant::getExistingMachineCPValue(MachineConstantPool *CP,
unsigned Alignment) {
return getExistingMachineCPValueImpl<ARMConstantPoolConstant>(CP, Alignment);
}
bool ARMConstantPoolConstant::hasSameValue(ARMConstantPoolValue *ACPV) {
const ARMConstantPoolConstant *ACPC = dyn_cast<ARMConstantPoolConstant>(ACPV);
return ACPC && ACPC->CVal == CVal && ARMConstantPoolValue::hasSameValue(ACPV);
}
void ARMConstantPoolConstant::addSelectionDAGCSEId(FoldingSetNodeID &ID) {
ID.AddPointer(CVal);
ARMConstantPoolValue::addSelectionDAGCSEId(ID);
}
void ARMConstantPoolConstant::print(raw_ostream &O) const {
O << CVal->getName();
ARMConstantPoolValue::print(O);
}
//===----------------------------------------------------------------------===//
// ARMConstantPoolSymbol
//===----------------------------------------------------------------------===//
ARMConstantPoolSymbol::ARMConstantPoolSymbol(LLVMContext &C, const char *s,
unsigned id,
unsigned char PCAdj,
ARMCP::ARMCPModifier Modifier,
bool AddCurrentAddress)
: ARMConstantPoolValue(C, id, ARMCP::CPExtSymbol, PCAdj, Modifier,
AddCurrentAddress),
S(s) {}
ARMConstantPoolSymbol *
ARMConstantPoolSymbol::Create(LLVMContext &C, const char *s,
unsigned ID, unsigned char PCAdj) {
return new ARMConstantPoolSymbol(C, s, ID, PCAdj, ARMCP::no_modifier, false);
}
int ARMConstantPoolSymbol::getExistingMachineCPValue(MachineConstantPool *CP,
unsigned Alignment) {
return getExistingMachineCPValueImpl<ARMConstantPoolSymbol>(CP, Alignment);
}
bool ARMConstantPoolSymbol::hasSameValue(ARMConstantPoolValue *ACPV) {
const ARMConstantPoolSymbol *ACPS = dyn_cast<ARMConstantPoolSymbol>(ACPV);
return ACPS && ACPS->S == S && ARMConstantPoolValue::hasSameValue(ACPV);
}
void ARMConstantPoolSymbol::addSelectionDAGCSEId(FoldingSetNodeID &ID) {
ID.AddString(S);
ARMConstantPoolValue::addSelectionDAGCSEId(ID);
}
void ARMConstantPoolSymbol::print(raw_ostream &O) const {
O << S;
ARMConstantPoolValue::print(O);
}
//===----------------------------------------------------------------------===//
// ARMConstantPoolMBB
//===----------------------------------------------------------------------===//
ARMConstantPoolMBB::ARMConstantPoolMBB(LLVMContext &C,
const MachineBasicBlock *mbb,
unsigned id, unsigned char PCAdj,
ARMCP::ARMCPModifier Modifier,
bool AddCurrentAddress)
: ARMConstantPoolValue(C, id, ARMCP::CPMachineBasicBlock, PCAdj,
Modifier, AddCurrentAddress),
MBB(mbb) {}
ARMConstantPoolMBB *ARMConstantPoolMBB::Create(LLVMContext &C,
const MachineBasicBlock *mbb,
unsigned ID,
unsigned char PCAdj) {
return new ARMConstantPoolMBB(C, mbb, ID, PCAdj, ARMCP::no_modifier, false);
}
int ARMConstantPoolMBB::getExistingMachineCPValue(MachineConstantPool *CP,
unsigned Alignment) {
return getExistingMachineCPValueImpl<ARMConstantPoolMBB>(CP, Alignment);
}
bool ARMConstantPoolMBB::hasSameValue(ARMConstantPoolValue *ACPV) {
const ARMConstantPoolMBB *ACPMBB = dyn_cast<ARMConstantPoolMBB>(ACPV);
return ACPMBB && ACPMBB->MBB == MBB &&
ARMConstantPoolValue::hasSameValue(ACPV);
}
void ARMConstantPoolMBB::addSelectionDAGCSEId(FoldingSetNodeID &ID) {
ID.AddPointer(MBB);
ARMConstantPoolValue::addSelectionDAGCSEId(ID);
}
void ARMConstantPoolMBB::print(raw_ostream &O) const {
O << "BB#" << MBB->getNumber();
ARMConstantPoolValue::print(O);
}