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Implement the optimization for the Red Zone on Darwin. This removes the

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unnecessary SP manipulation in leaf routines that don't need it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22522 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman 2005-07-27 06:06:29 +00:00
parent 45ff4faeed
commit 54eed36da5
2 changed files with 8 additions and 4 deletions
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11
lib/Target/PowerPC/PPCRegisterInfo.cpp
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@ -245,8 +245,13 @@ void PPC32RegisterInfo::emitPrologue(MachineFunction &MF) const {
NumBytes += MFI->getMaxCallFrameSize(); NumBytes += MFI->getMaxCallFrameSize();
} }
// Do we need to allocate space on the stack? // If we are a leaf function, and use up to 224 bytes of stack space,
if (NumBytes == 0) return; // and don't have a frame pointer, then we do not need to adjust the stack
// pointer (we fit in the Red Zone).
if ((NumBytes == 0) || (NumBytes <= 224 && !hasFP(MF) && !MFI->hasCalls())) {
MFI->setStackSize(0);
return;
}
// Add the size of R1 to NumBytes size for the store of R1 to the bottom // Add the size of R1 to NumBytes size for the store of R1 to the bottom
// of the stack and round the size to a multiple of the alignment. // of the stack and round the size to a multiple of the alignment.
@ -258,7 +263,7 @@ void PPC32RegisterInfo::emitPrologue(MachineFunction &MF) const {
// Update frame info to pretend that this is part of the stack... // Update frame info to pretend that this is part of the stack...
MFI->setStackSize(NumBytes); MFI->setStackSize(NumBytes);
// adjust stack pointer: r1 -= numbytes // If , adjust stack pointer: r1 -= numbytes.
if (NumBytes <= 32768) { if (NumBytes <= 32768) {
MI=BuildMI(PPC::STWU,3).addReg(PPC::R1).addSImm(-NumBytes).addReg(PPC::R1); MI=BuildMI(PPC::STWU,3).addReg(PPC::R1).addSImm(-NumBytes).addReg(PPC::R1);
MBB.insert(MBBI, MI); MBB.insert(MBBI, MI);

1
lib/Target/PowerPC/README.txt
View File

@ -3,7 +3,6 @@ TODO:
* implement do-loop -> bdnz transform * implement do-loop -> bdnz transform
* implement powerpc-64 for darwin * implement powerpc-64 for darwin
* use stfiwx in float->int * use stfiwx in float->int
* take advantage of the darwin red zone in PPC32RegisterInfo.cpp
* be able to combine sequences like the following into 2 instructions: * be able to combine sequences like the following into 2 instructions:
lis r2, ha16(l2__ZTV4Cell) lis r2, ha16(l2__ZTV4Cell)
la r2, lo16(l2__ZTV4Cell)(r2) la r2, lo16(l2__ZTV4Cell)(r2)