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Fix the Red Zone calculation for functions with frame pointers.

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Don't use the Red Zone when dynamic stack realignment is needed.
This could be implemented, but most x86-64 ABIs don't require
dynamic stack realignment so it isn't urgent.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@63074 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-01-27 00:40:06 +00:00
parent d9660b5f9e
commit 336b636dd7
1 changed files with 15 additions and 12 deletions
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27
lib/Target/X86/X86RegisterInfo.cpp
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@ -721,24 +721,27 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
// Get desired stack alignment
uint64_t MaxAlign = MFI->getMaxAlignment();
// If this is x86-64 and the Red Zone is not disabled, if we are a leaf
// function, and use up to 128 bytes of stack space, don't have a frame
// pointer, calls, or dynamic alloca then we do not need to adjust the
// stack pointer (we fit in the Red Zone).
if (Is64Bit && !DisableRedZone &&
!MFI->hasVarSizedObjects() && // No dynamic alloca.
!MFI->hasCalls()) { // No calls.
StackSize = std::max((uint64_t)X86FI->getCalleeSavedFrameSize(),
StackSize > 128 ? StackSize - 128 : 0);
MFI->setStackSize(StackSize);
}
// Add RETADDR move area to callee saved frame size.
int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta();
if (TailCallReturnAddrDelta < 0)
X86FI->setCalleeSavedFrameSize(
X86FI->getCalleeSavedFrameSize() +(-TailCallReturnAddrDelta));
// If this is x86-64 and the Red Zone is not disabled, if we are a leaf
// function, and use up to 128 bytes of stack space, don't have a frame
// pointer, calls, or dynamic alloca then we do not need to adjust the
// stack pointer (we fit in the Red Zone).
if (Is64Bit && !DisableRedZone &&
!needsStackRealignment(MF) &&
!MFI->hasVarSizedObjects() && // No dynamic alloca.
!MFI->hasCalls()) { // No calls.
uint64_t MinSize = X86FI->getCalleeSavedFrameSize();
if (hasFP(MF)) MinSize += SlotSize;
StackSize = std::max(MinSize,
StackSize > 128 ? StackSize - 128 : 0);
MFI->setStackSize(StackSize);
}
// Insert stack pointer adjustment for later moving of return addr. Only
// applies to tail call optimized functions where the callee argument stack
// size is bigger than the callers.