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Be more careful about when to do dynamic stack realignment. Since we have an

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option to disable base pointer usage, pay attention to it when deciding
if we can realign (if no base pointer and VLAs, we can't).

llvm-svn: 113366
This commit is contained in:
Jim Grosbach
2010-09-08 17:22:12 +00:00
parent 53aa5e31e1
commit 7dfca6fb51
1 changed files with 9 additions and 2 deletions
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11
llvm/lib/Target/ARM/ARMBaseRegisterInfo.cpp
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@@ -667,8 +667,14 @@ bool ARMBaseRegisterInfo::hasBasePointer(const MachineFunction &MF) const {
}
bool ARMBaseRegisterInfo::canRealignStack(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
return (RealignStack && !AFI->isThumb1OnlyFunction());
// We can't realign the stack if:
// 1. Dynamic stack realignment is explicitly disabled,
// 2. This is a Thumb1 function (it's not useful, so we don't bother), or
// 3. There are VLAs in the function and the base pointer is disabled.
return (RealignStack && !AFI->isThumb1OnlyFunction() &&
(!MFI->hasVarSizedObjects() || EnableBasePointer));
}
bool ARMBaseRegisterInfo::
@@ -1890,7 +1896,8 @@ emitPrologue(MachineFunction &MF) const {
AFI->setGPRCalleeSavedArea2Size(GPRCS2Size);
AFI->setDPRCalleeSavedAreaSize(DPRCSSize);
// If we need dynamic stack realignment, do it here.
// If we need dynamic stack realignment, do it here. Be paranoid and make
// sure if we also have VLAs, we have a base pointer for frame access.
if (needsStackRealignment(MF)) {
unsigned MaxAlign = MFI->getMaxAlignment();
assert (!AFI->isThumb1OnlyFunction());