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When rewriting frame instructions, emit the appropriate small-immediate 

instruction when possible.

llvm-svn: 25938
This commit is contained in:
Chris Lattner 2006-02-03 18:20:04 +00:00
parent 2bcfc52af6
commit c408558638
1 changed files with 21 additions and 13 deletions
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34
llvm/lib/Target/X86/X86RegisterInfo.cpp
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@ -467,9 +467,11 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
// factor out the amount the callee already popped.
unsigned CalleeAmt = Old->getOperand(1).getImmedValue();
Amount -= CalleeAmt;
if (Amount)
New = BuildMI(X86::ADD32ri, 1, X86::ESP,
if (Amount) {
unsigned Opc = Amount < 128 ? X86::ADD32ri8 : X86::ADD32ri;
New = BuildMI(Opc, 1, X86::ESP,
MachineOperand::UseAndDef).addZImm(Amount);
}
}
// Replace the pseudo instruction with a new instruction...
@ -480,8 +482,9 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
// something off the stack pointer, add it back. We do this until we have
// more advanced stack pointer tracking ability.
if (unsigned CalleeAmt = I->getOperand(1).getImmedValue()) {
unsigned Opc = CalleeAmt < 128 ? X86::SUB32ri8 : X86::SUB32ri;
MachineInstr *New =
BuildMI(X86::SUB32ri, 1, X86::ESP,
BuildMI(Opc, 1, X86::ESP,
MachineOperand::UseAndDef).addZImm(CalleeAmt);
MBB.insert(I, New);
}
@ -541,8 +544,8 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
int EBPOffset = MFI->getObjectOffset(MFI->getObjectIndexBegin())+4;
if (NumBytes) { // adjust stack pointer: ESP -= numbytes
MI= BuildMI(X86::SUB32ri, 1, X86::ESP, MachineOperand::UseAndDef)
.addZImm(NumBytes);
unsigned Opc = NumBytes < 128 ? X86::SUB32ri8 : X86::SUB32ri;
MI = BuildMI(Opc, 1, X86::ESP,MachineOperand::UseAndDef).addImm(NumBytes);
MBB.insert(MBBI, MI);
}
@ -578,8 +581,8 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
if (NumBytes) {
// adjust stack pointer: ESP -= numbytes
MI= BuildMI(X86::SUB32ri, 1, X86::ESP, MachineOperand::UseAndDef)
.addZImm(NumBytes);
unsigned Opc = NumBytes < 128 ? X86::SUB32ri8 : X86::SUB32ri;
MI= BuildMI(Opc, 1, X86::ESP, MachineOperand::UseAndDef).addImm(NumBytes);
MBB.insert(MBBI, MI);
}
}
@ -619,11 +622,13 @@ void X86RegisterInfo::emitEpilogue(MachineFunction &MF,
// instruction, merge the two instructions.
if (MBBI != MBB.begin()) {
MachineBasicBlock::iterator PI = prior(MBBI);
if (PI->getOpcode() == X86::ADD32ri &&
if ((PI->getOpcode() == X86::ADD32ri ||
PI->getOpcode() == X86::ADD32ri8) &&
PI->getOperand(0).getReg() == X86::ESP) {
NumBytes += PI->getOperand(1).getImmedValue();
MBB.erase(PI);
} else if (PI->getOpcode() == X86::SUB32ri &&
} else if ((PI->getOpcode() == X86::SUB32ri ||
PI->getOpcode() == X86::SUB32ri8) &&
PI->getOperand(0).getReg() == X86::ESP) {
NumBytes -= PI->getOperand(1).getImmedValue();
MBB.erase(PI);
@ -633,12 +638,15 @@ void X86RegisterInfo::emitEpilogue(MachineFunction &MF,
}
}
if (NumBytes > 0)
BuildMI(MBB, MBBI, X86::ADD32ri, 2)
if (NumBytes > 0) {
unsigned Opc = NumBytes < 128 ? X86::ADD32ri8 : X86::ADD32ri;
BuildMI(MBB, MBBI, Opc, 2)
.addReg(X86::ESP, MachineOperand::UseAndDef).addZImm(NumBytes);
else if ((int)NumBytes < 0)
BuildMI(MBB, MBBI, X86::SUB32ri, 2)
} else if ((int)NumBytes < 0) {
unsigned Opc = -NumBytes < 128 ? X86::SUB32ri8 : X86::SUB32ri;
BuildMI(MBB, MBBI, Opc, 2)
.addReg(X86::ESP, MachineOperand::UseAndDef).addZImm(-NumBytes);
}
}
}
}