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X86: Only use 'lea' in Win64 epilogues if a frame pointer exists

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We can only use 'add' in epilogues, 'lea' is not permitted unless we've
established a frame pointer in the prologue.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230286 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer
2015-02-24 00:11:32 +00:00
parent f922d9cfe4
commit fbdee9f0c0
2 changed files with 32 additions and 13 deletions
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28
lib/Target/X86/X86FrameLowering.cpp
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@ -250,7 +250,7 @@ void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
}
}
uint64_t ThisVal = (Offset > Chunk) ? Chunk : Offset;
uint64_t ThisVal = std::min(Offset, Chunk);
if (ThisVal == (Is64BitTarget ? 8 : 4)) {
// Use push / pop instead.
unsigned Reg = isSub
@ -980,8 +980,8 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
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();
bool UseLEA = STI.useLeaForSP();
unsigned SlotSize = RegInfo->getSlotSize();
unsigned FramePtr = RegInfo->getFrameRegister(MF);
unsigned MachineFramePtr =
@ -991,6 +991,20 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
bool IsWinEH = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
bool NeedsWinEH = IsWinEH && MF.getFunction()->needsUnwindTableEntry();
bool UseLEAForSP = false;
// 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) {
default:
@ -1084,8 +1098,8 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
}
} else if (NumBytes) {
// Adjust stack pointer back: ESP += numbytes.
emitSPUpdate(MBB, MBBI, StackPtr, NumBytes, Is64Bit, Uses64BitFramePtr, UseLEA,
TII, *RegInfo);
emitSPUpdate(MBB, MBBI, StackPtr, NumBytes, Is64Bit, Uses64BitFramePtr,
UseLEAForSP, TII, *RegInfo);
--MBBI;
}
@ -1131,7 +1145,7 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
// Check for possible merge with preceding ADD instruction.
Offset += mergeSPUpdates(MBB, MBBI, StackPtr, true);
emitSPUpdate(MBB, MBBI, StackPtr, Offset, Is64Bit, Uses64BitFramePtr,
UseLEA, TII, *RegInfo);
UseLEAForSP, TII, *RegInfo);
}
// Jump to label or value in register.
@ -1179,8 +1193,8 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
// Check for possible merge with preceding ADD instruction.
delta += mergeSPUpdates(MBB, MBBI, StackPtr, true);
emitSPUpdate(MBB, MBBI, StackPtr, delta, Is64Bit, Uses64BitFramePtr, UseLEA, TII,
*RegInfo);
emitSPUpdate(MBB, MBBI, StackPtr, delta, Is64Bit, Uses64BitFramePtr,
UseLEAForSP, TII, *RegInfo);
}
}