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Simplify ARM callee-saved register handling by removing the distinction

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between the high and low registers for prologue/epilogue code. This was
a Darwin-only thing that wasn't providing a realistic benefit anymore.
Combining the save areas simplifies the compiler code and results in better
ARM/Thumb2 codegen.

For example, previously we would generate code like:
        push    {r4, r5, r6, r7, lr}
        add     r7, sp, #12
        stmdb   sp!, {r8, r10, r11}
With this change, we combine the register saves and generate:
        push    {r4, r5, r6, r7, r8, r10, r11, lr}
        add     r7, sp, #12

rdar://8445635



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114340 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jim Grosbach
2010-09-20 19:32:20 +00:00
parent 43779dcfef
commit 1dc335a79f
5 changed files with 66 additions and 175 deletions
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38
lib/Target/ARM/Thumb1RegisterInfo.cpp
View File

@@ -597,10 +597,8 @@ Thumb1RegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
int Offset = MF.getFrameInfo()->getObjectOffset(FrameIndex) +
MF.getFrameInfo()->getStackSize() + SPAdj;
if (AFI->isGPRCalleeSavedArea1Frame(FrameIndex))
Offset -= AFI->getGPRCalleeSavedArea1Offset();
else if (AFI->isGPRCalleeSavedArea2Frame(FrameIndex))
Offset -= AFI->getGPRCalleeSavedArea2Offset();
if (AFI->isGPRCalleeSavedAreaFrame(FrameIndex))
Offset -= AFI->getGPRCalleeSavedAreaOffset();
else if (MF.getFrameInfo()->hasVarSizedObjects()) {
assert(SPAdj == 0 && hasFP(MF) && "Unexpected");
// There are alloca()'s in this function, must reference off the frame
@@ -709,7 +707,7 @@ void Thumb1RegisterInfo::emitPrologue(MachineFunction &MF) const {
// Determine the sizes of each callee-save spill areas and record which frame
// belongs to which callee-save spill areas.
unsigned GPRCS1Size = 0, GPRCS2Size = 0, DPRCSSize = 0;
unsigned GPRCSSize = 0, DPRCSSize = 0;
int FramePtrSpillFI = 0;
if (VARegSaveSize)
@@ -729,25 +727,15 @@ void Thumb1RegisterInfo::emitPrologue(MachineFunction &MF) const {
case ARM::R5:
case ARM::R6:
case ARM::R7:
case ARM::LR:
if (Reg == FramePtr)
FramePtrSpillFI = FI;
AFI->addGPRCalleeSavedArea1Frame(FI);
GPRCS1Size += 4;
break;
case ARM::R8:
case ARM::R9:
case ARM::R10:
case ARM::R11:
case ARM::LR:
if (Reg == FramePtr)
FramePtrSpillFI = FI;
if (STI.isTargetDarwin()) {
AFI->addGPRCalleeSavedArea2Frame(FI);
GPRCS2Size += 4;
} else {
AFI->addGPRCalleeSavedArea1Frame(FI);
GPRCS1Size += 4;
}
AFI->addGPRCalleeSavedAreaFrame(FI);
GPRCSSize += 4;
break;
default:
AFI->addDPRCalleeSavedAreaFrame(FI);
@@ -769,12 +757,10 @@ void Thumb1RegisterInfo::emitPrologue(MachineFunction &MF) const {
}
// Determine starting offsets of spill areas.
unsigned DPRCSOffset = NumBytes - (GPRCS1Size + GPRCS2Size + DPRCSSize);
unsigned GPRCS2Offset = DPRCSOffset + DPRCSSize;
unsigned GPRCS1Offset = GPRCS2Offset + GPRCS2Size;
unsigned DPRCSOffset = NumBytes - (GPRCSSize + DPRCSSize);
unsigned GPRCSOffset = DPRCSOffset + DPRCSSize;
AFI->setFramePtrSpillOffset(MFI->getObjectOffset(FramePtrSpillFI) + NumBytes);
AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
AFI->setGPRCalleeSavedArea2Offset(GPRCS2Offset);
AFI->setGPRCalleeSavedAreaOffset(GPRCSOffset);
AFI->setDPRCalleeSavedAreaOffset(DPRCSOffset);
NumBytes = DPRCSOffset;
@@ -787,8 +773,7 @@ void Thumb1RegisterInfo::emitPrologue(MachineFunction &MF) const {
MFI->setOffsetAdjustment(MFI->getOffsetAdjustment() -
AFI->getFramePtrSpillOffset());
AFI->setGPRCalleeSavedArea1Size(GPRCS1Size);
AFI->setGPRCalleeSavedArea2Size(GPRCS2Size);
AFI->setGPRCalleeSavedAreaSize(GPRCSSize);
AFI->setDPRCalleeSavedAreaSize(DPRCSSize);
// If we need a base pointer, set it up here. It's whatever the value
@@ -849,8 +834,7 @@ void Thumb1RegisterInfo::emitEpilogue(MachineFunction &MF,
}
// Move SP to start of FP callee save spill area.
NumBytes -= (AFI->getGPRCalleeSavedArea1Size() +
AFI->getGPRCalleeSavedArea2Size() +
NumBytes -= (AFI->getGPRCalleeSavedAreaSize() +
AFI->getDPRCalleeSavedAreaSize());
if (AFI->shouldRestoreSPFromFP()) {