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[X86] Refactor the prologue emission to prepare for shrink-wrapping.

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- Add a late pass to expand pseudo instructions (tail call and EH returns).
  Instead of doing it in the prologue emission.
- Factor some static methods in X86FrameLowering to ease code sharing.

NFC.

Related to <rdar://problem/20821487>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237977 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Quentin Colombet
2015-05-22 00:12:31 +00:00
parent fcf7993d4a
commit ab0b15dff8
7 changed files with 250 additions and 111 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
lib/Target/X86/CMakeLists.txt
View File

@@ -15,6 +15,7 @@ add_public_tablegen_target(X86CommonTableGen)
set(sources
X86AsmPrinter.cpp
X86CallFrameOptimization.cpp
X86ExpandPseudo.cpp
X86FastISel.cpp
X86FloatingPoint.cpp
X86FrameLowering.cpp

5
lib/Target/X86/X86.h
View File

@@ -75,6 +75,11 @@ FunctionPass *createX86CallFrameOptimization();
/// preparation.
FunctionPass *createX86WinEHStatePass();
/// Return a Machine IR pass that expands X86-specific pseudo
/// instructions into a sequence of actual instructions. This pass
/// must run after prologue/epilogue insertion and before lowering
/// the MachineInstr to MC.
FunctionPass *createX86ExpandPseudoPass();
} // End llvm namespace
#endif

188
lib/Target/X86/X86ExpandPseudo.cpp Normal file
View File

@@ -0,0 +1,188 @@
//===------- X86ExpandPseudo.cpp - Expand pseudo instructions -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains a pass that expands pseudo instructions into target
// instructions to allow proper scheduling, if-conversion, other late
// optimizations, or simply the encoding of the instructions.
//
//===----------------------------------------------------------------------===//
#include "X86.h"
#include "X86FrameLowering.h"
#include "X86InstrBuilder.h"
#include "X86InstrInfo.h"
#include "X86MachineFunctionInfo.h"
#include "X86Subtarget.h"
#include "llvm/CodeGen/Passes.h" // For IDs of passes that are preserved.
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/IR/GlobalValue.h"
using namespace llvm;
#define DEBUG_TYPE "x86-pseudo"
namespace {
class X86ExpandPseudo : public MachineFunctionPass {
public:
static char ID;
X86ExpandPseudo() : MachineFunctionPass(ID) {}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addPreservedID(MachineLoopInfoID);
AU.addPreservedID(MachineDominatorsID);
MachineFunctionPass::getAnalysisUsage(AU);
}
const X86Subtarget *STI;
const X86InstrInfo *TII;
const X86RegisterInfo *TRI;
const X86FrameLowering *X86FrameLowering;
bool runOnMachineFunction(MachineFunction &Fn) override;
const char *getPassName() const override {
return "X86 pseudo instruction expansion pass";
}
private:
bool ExpandMI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI);
bool ExpandMBB(MachineBasicBlock &MBB);
};
char X86ExpandPseudo::ID = 0;
} // End anonymous namespace.
/// If \p MBBI is a pseudo instruction, this method expands
/// it to the corresponding (sequence of) actual instruction(s).
/// \returns true if \p MBBI has been expanded.
bool X86ExpandPseudo::ExpandMI(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI) {
MachineInstr &MI = *MBBI;
unsigned Opcode = MI.getOpcode();
DebugLoc DL = MBBI->getDebugLoc();
switch (Opcode) {
default:
return false;
case X86::TCRETURNdi:
case X86::TCRETURNri:
case X86::TCRETURNmi:
case X86::TCRETURNdi64:
case X86::TCRETURNri64:
case X86::TCRETURNmi64: {
bool isMem = Opcode == X86::TCRETURNmi || Opcode == X86::TCRETURNmi64;
MachineOperand &JumpTarget = MBBI->getOperand(0);
MachineOperand &StackAdjust = MBBI->getOperand(isMem ? 5 : 1);
assert(StackAdjust.isImm() && "Expecting immediate value.");
// Adjust stack pointer.
int StackAdj = StackAdjust.getImm();
if (StackAdj) {
bool Is64Bit = STI->is64Bit();
// standard x86_64 and NaCl use 64-bit frame/stack pointers, x32 - 32-bit.
const bool Uses64BitFramePtr =
STI->isTarget64BitLP64() || STI->isTargetNaCl64();
bool UseLEAForSP =
X86FrameLowering->useLEAForSPInProlog(*MBB.getParent());
unsigned StackPtr = TRI->getStackRegister();
// Check for possible merge with preceding ADD instruction.
StackAdj += X86FrameLowering::mergeSPUpdates(MBB, MBBI, StackPtr, true);
X86FrameLowering::emitSPUpdate(MBB, MBBI, StackPtr, StackAdj, Is64Bit,
Uses64BitFramePtr, UseLEAForSP, *TII,
*TRI);
}
// Jump to label or value in register.
bool IsWin64 = STI->isTargetWin64();
if (Opcode == X86::TCRETURNdi || Opcode == X86::TCRETURNdi64) {
unsigned Op = (Opcode == X86::TCRETURNdi)
? X86::TAILJMPd
: (IsWin64 ? X86::TAILJMPd64_REX : X86::TAILJMPd64);
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII->get(Op));
if (JumpTarget.isGlobal())
MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
JumpTarget.getTargetFlags());
else {
assert(JumpTarget.isSymbol());
MIB.addExternalSymbol(JumpTarget.getSymbolName(),
JumpTarget.getTargetFlags());
}
} else if (Opcode == X86::TCRETURNmi || Opcode == X86::TCRETURNmi64) {
unsigned Op = (Opcode == X86::TCRETURNmi)
? X86::TAILJMPm
: (IsWin64 ? X86::TAILJMPm64_REX : X86::TAILJMPm64);
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII->get(Op));
for (unsigned i = 0; i != 5; ++i)
MIB.addOperand(MBBI->getOperand(i));
} else if (Opcode == X86::TCRETURNri64) {
BuildMI(MBB, MBBI, DL,
TII->get(IsWin64 ? X86::TAILJMPr64_REX : X86::TAILJMPr64))
.addReg(JumpTarget.getReg(), RegState::Kill);
} else {
BuildMI(MBB, MBBI, DL, TII->get(X86::TAILJMPr))
.addReg(JumpTarget.getReg(), RegState::Kill);
}
MachineInstr *NewMI = std::prev(MBBI);
NewMI->copyImplicitOps(*MBBI->getParent()->getParent(), MBBI);
// Delete the pseudo instruction TCRETURN.
MBB.erase(MBBI);
return true;
}
case X86::EH_RETURN:
case X86::EH_RETURN64: {
MachineOperand &DestAddr = MBBI->getOperand(0);
assert(DestAddr.isReg() && "Offset should be in register!");
const bool Uses64BitFramePtr =
STI->isTarget64BitLP64() || STI->isTargetNaCl64();
unsigned StackPtr = TRI->getStackRegister();
BuildMI(MBB, MBBI, DL,
TII->get(Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr), StackPtr)
.addReg(DestAddr.getReg());
// The EH_RETURN pseudo is really removed during the MC Lowering.
return true;
}
}
llvm_unreachable("Previous switch has a fallthrough?");
}
/// Expand all pseudo instructions contained in \p MBB.
/// \returns true if any expansion occurred for \p MBB.
bool X86ExpandPseudo::ExpandMBB(MachineBasicBlock &MBB) {
bool Modified = false;
// MBBI may be invalidated by the expansion.
MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
while (MBBI != E) {
MachineBasicBlock::iterator NMBBI = std::next(MBBI);
Modified |= ExpandMI(MBB, MBBI);
MBBI = NMBBI;
}
return Modified;
}
bool X86ExpandPseudo::runOnMachineFunction(MachineFunction &MF) {
STI = &static_cast<const X86Subtarget &>(MF.getSubtarget());
TII = STI->getInstrInfo();
TRI = STI->getRegisterInfo();
X86FrameLowering = STI->getFrameLowering();
bool Modified = false;
for (MachineBasicBlock &MBB : MF)
Modified |= ExpandMBB(MBB);
return Modified;
}
/// Returns an instance of the pseudo instruction expansion pass.
FunctionPass *llvm::createX86ExpandPseudoPass() {
return new X86ExpandPseudo();
}

133
lib/Target/X86/X86FrameLowering.cpp
View File

@@ -205,11 +205,12 @@ static bool isEAXLiveIn(MachineFunction &MF) {
/// emitSPUpdate - Emit a series of instructions to increment / decrement the
/// stack pointer by a constant value.
static
void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
void X86FrameLowering::emitSPUpdate(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
unsigned StackPtr, int64_t NumBytes,
bool Is64BitTarget, bool Is64BitStackPtr, bool UseLEA,
const TargetInstrInfo &TII, const TargetRegisterInfo &TRI) {
bool Is64BitTarget, bool Is64BitStackPtr,
bool UseLEA, const TargetInstrInfo &TII,
const TargetRegisterInfo &TRI) {
bool isSub = NumBytes < 0;
uint64_t Offset = isSub ? -NumBytes : NumBytes;
unsigned Opc;
@@ -312,12 +313,9 @@ void mergeSPUpdatesUp(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
}
}
/// mergeSPUpdates - Checks the instruction before/after the passed
/// instruction. If it is an ADD/SUB/LEA instruction it is deleted argument and
/// the stack adjustment is returned as a positive value for ADD/LEA and a
/// negative for SUB.
static int mergeSPUpdates(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI, unsigned StackPtr,
int X86FrameLowering::mergeSPUpdates(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
unsigned StackPtr,
bool doMergeWithPrevious) {
if ((doMergeWithPrevious && MBBI == MBB.begin()) ||
(!doMergeWithPrevious && MBBI == MBB.end()))
@@ -967,6 +965,17 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF,
}
}
bool X86FrameLowering::useLEAForSPInProlog(const MachineFunction &MF) const {
// We can't use LEA instructions for adjusting the stack pointer if this is a
// leaf function in the Win64 ABI. Only ADD instructions may be used to
// deallocate the stack.
// This means that we can use LEA for SP in two situations:
// 1. We *aren't* using the Win64 ABI which means we are free to use LEA.
// 2. We *have* a frame pointer which means we are permitted to use LEA.
return MF.getSubtarget<X86Subtarget>().useLeaForSP() &&
(!MF.getTarget().getMCAsmInfo()->usesWindowsCFI() || hasFP(MF));
}
void X86FrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
@@ -974,14 +983,12 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
const X86RegisterInfo *RegInfo = STI.getRegisterInfo();
const TargetInstrInfo &TII = *STI.getInstrInfo();
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
MachineBasicBlock::iterator MBBI = MBB.getFirstTerminator();
assert(MBBI != MBB.end() && "Returning block has no instructions");
unsigned RetOpcode = MBBI->getOpcode();
DebugLoc DL = MBBI->getDebugLoc();
bool Is64Bit = STI.is64Bit();
// standard x86_64 and NaCl use 64-bit frame/stack pointers, x32 - 32-bit.
const bool Uses64BitFramePtr = STI.isTarget64BitLP64() || STI.isTargetNaCl64();
bool HasFP = hasFP(MF);
const bool Is64BitILP32 = STI.isTarget64BitILP32();
unsigned SlotSize = RegInfo->getSlotSize();
unsigned FramePtr = RegInfo->getFrameRegister(MF);
@@ -992,22 +999,9 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
bool IsWinEH = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
bool NeedsWinEH = IsWinEH && MF.getFunction()->needsUnwindTableEntry();
bool UseLEAForSP = false;
bool UseLEAForSP = useLEAForSPInProlog(MF);
// We can't use LEA instructions for adjusting the stack pointer if this is a
// leaf function in the Win64 ABI. Only ADD instructions may be used to
// deallocate the stack.
if (STI.useLeaForSP()) {
if (!IsWinEH) {
// We *aren't* using the Win64 ABI which means we are free to use LEA.
UseLEAForSP = true;
} else if (HasFP) {
// We *have* a frame pointer which means we are permitted to use LEA.
UseLEAForSP = true;
}
}
switch (RetOpcode) {
switch (MBBI->getOpcode()) {
default:
llvm_unreachable("Can only insert epilogue into returning blocks");
case X86::RETQ:
@@ -1112,90 +1106,17 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
if (NeedsWinEH)
BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_Epilogue));
// We're returning from function via eh_return.
if (RetOpcode == X86::EH_RETURN || RetOpcode == X86::EH_RETURN64) {
MBBI = MBB.getLastNonDebugInstr();
MachineOperand &DestAddr = MBBI->getOperand(0);
assert(DestAddr.isReg() && "Offset should be in register!");
BuildMI(MBB, MBBI, DL,
TII.get(Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr),
StackPtr).addReg(DestAddr.getReg());
} else if (RetOpcode == X86::TCRETURNri || RetOpcode == X86::TCRETURNdi ||
RetOpcode == X86::TCRETURNmi ||
RetOpcode == X86::TCRETURNri64 || RetOpcode == X86::TCRETURNdi64 ||
RetOpcode == X86::TCRETURNmi64) {
bool isMem = RetOpcode == X86::TCRETURNmi || RetOpcode == X86::TCRETURNmi64;
// Tail call return: adjust the stack pointer and jump to callee.
MBBI = MBB.getLastNonDebugInstr();
MachineOperand &JumpTarget = MBBI->getOperand(0);
MachineOperand &StackAdjust = MBBI->getOperand(isMem ? 5 : 1);
assert(StackAdjust.isImm() && "Expecting immediate value.");
// Adjust stack pointer.
int StackAdj = StackAdjust.getImm();
int MaxTCDelta = X86FI->getTCReturnAddrDelta();
int Offset = 0;
assert(MaxTCDelta <= 0 && "MaxTCDelta should never be positive");
// Incoporate the retaddr area.
Offset = StackAdj-MaxTCDelta;
assert(Offset >= 0 && "Offset should never be negative");
// Add the return addr area delta back since we are not tail calling.
int Offset = -1 * X86FI->getTCReturnAddrDelta();
assert(Offset >= 0 && "TCDelta should never be positive");
if (Offset) {
MBBI = MBB.getFirstTerminator();
// Check for possible merge with preceding ADD instruction.
Offset += mergeSPUpdates(MBB, MBBI, StackPtr, true);
emitSPUpdate(MBB, MBBI, StackPtr, Offset, Is64Bit, Uses64BitFramePtr,
UseLEAForSP, TII, *RegInfo);
}
// Jump to label or value in register.
bool IsWin64 = STI.isTargetWin64();
if (RetOpcode == X86::TCRETURNdi || RetOpcode == X86::TCRETURNdi64) {
unsigned Op = (RetOpcode == X86::TCRETURNdi)
? X86::TAILJMPd
: (IsWin64 ? X86::TAILJMPd64_REX : X86::TAILJMPd64);
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII.get(Op));
if (JumpTarget.isGlobal())
MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
JumpTarget.getTargetFlags());
else {
assert(JumpTarget.isSymbol());
MIB.addExternalSymbol(JumpTarget.getSymbolName(),
JumpTarget.getTargetFlags());
}
} else if (RetOpcode == X86::TCRETURNmi || RetOpcode == X86::TCRETURNmi64) {
unsigned Op = (RetOpcode == X86::TCRETURNmi)
? X86::TAILJMPm
: (IsWin64 ? X86::TAILJMPm64_REX : X86::TAILJMPm64);
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII.get(Op));
for (unsigned i = 0; i != 5; ++i)
MIB.addOperand(MBBI->getOperand(i));
} else if (RetOpcode == X86::TCRETURNri64) {
BuildMI(MBB, MBBI, DL,
TII.get(IsWin64 ? X86::TAILJMPr64_REX : X86::TAILJMPr64))
.addReg(JumpTarget.getReg(), RegState::Kill);
} else {
BuildMI(MBB, MBBI, DL, TII.get(X86::TAILJMPr)).
addReg(JumpTarget.getReg(), RegState::Kill);
}
MachineInstr *NewMI = std::prev(MBBI);
NewMI->copyImplicitOps(MF, MBBI);
// Delete the pseudo instruction TCRETURN.
MBB.erase(MBBI);
} else if ((RetOpcode == X86::RETQ || RetOpcode == X86::RETL ||
RetOpcode == X86::RETIQ || RetOpcode == X86::RETIL) &&
(X86FI->getTCReturnAddrDelta() < 0)) {
// Add the return addr area delta back since we are not tail calling.
int delta = -1*X86FI->getTCReturnAddrDelta();
MBBI = MBB.getLastNonDebugInstr();
// Check for possible merge with preceding ADD instruction.
delta += mergeSPUpdates(MBB, MBBI, StackPtr, true);
emitSPUpdate(MBB, MBBI, StackPtr, delta, Is64Bit, Uses64BitFramePtr,
UseLEAForSP, TII, *RegInfo);
}
}
int X86FrameLowering::getFrameIndexOffset(const MachineFunction &MF,

20
lib/Target/X86/X86FrameLowering.h
View File

@@ -79,6 +79,26 @@ public:
MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI) const override;
/// Check the instruction before/after the passed instruction. If
/// it is an ADD/SUB/LEA instruction it is deleted argument and the
/// stack adjustment is returned as a positive value for ADD/LEA and
/// a negative for SUB.
static int mergeSPUpdates(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
unsigned StackPtr, bool doMergeWithPrevious);
/// Emit a series of instructions to increment / decrement the stack
/// pointer by a constant value.
static void emitSPUpdate(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI, unsigned StackPtr,
int64_t NumBytes, bool Is64BitTarget,
bool Is64BitStackPtr, bool UseLEA,
const TargetInstrInfo &TII,
const TargetRegisterInfo &TRI);
/// Check that LEA can be use on SP in a prologue sequence for \p MF.
bool useLEAForSPInProlog(const MachineFunction &MF) const;
private:
/// convertArgMovsToPushes - This method tries to convert a call sequence
/// that uses sub and mov instructions to put the argument onto the stack

3
lib/Target/X86/X86RegisterInfo.cpp
View File

@@ -492,7 +492,8 @@ X86RegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
unsigned BasePtr;
unsigned Opc = MI.getOpcode();
bool AfterFPPop = Opc == X86::TAILJMPm64 || Opc == X86::TAILJMPm;
bool AfterFPPop = Opc == X86::TAILJMPm64 || Opc == X86::TAILJMPm ||
Opc == X86::TCRETURNmi || Opc == X86::TCRETURNmi64;
if (hasBasePointer(MF))
BasePtr = (FrameIndex < 0 ? FramePtr : getBaseRegister());
else if (needsStackRealignment(MF))

3
lib/Target/X86/X86TargetMachine.cpp
View File

@@ -187,6 +187,7 @@ public:
void addPreRegAlloc() override;
void addPostRegAlloc() override;
void addPreEmitPass() override;
void addPreSched2() override;
};
} // namespace
@@ -235,6 +236,8 @@ void X86PassConfig::addPostRegAlloc() {
addPass(createX86FloatingPointStackifierPass());
}
void X86PassConfig::addPreSched2() { addPass(createX86ExpandPseudoPass()); }
void X86PassConfig::addPreEmitPass() {
if (getOptLevel() != CodeGenOpt::None)
addPass(createExecutionDependencyFixPass(&X86::VR128RegClass));