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Simplified logic of this if-then statement to reduce nesting. No functionality

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change.

llvm-svn: 73143
This commit is contained in:
Bill Wendling 2009-06-09 20:08:51 +00:00
parent 996a7f7f37
commit 23d6f0b5c7
1 changed files with 48 additions and 46 deletions
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30
lib/Target/X86/X86RegisterInfo.cpp
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@ -838,9 +838,9 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
if (MBBI != MBB.end()) if (MBBI != MBB.end())
DL = MBBI->getDebugLoc(); DL = MBBI->getDebugLoc();
if (NumBytes) { // adjust stack pointer: ESP -= numbytes // Adjust stack pointer: ESP -= numbytes.
if (NumBytes >= 4096 && Subtarget->isTargetCygMing()) { if (NumBytes >= 4096 && Subtarget->isTargetCygMing()) {
// Check, whether EAX is livein for this function // Check, whether EAX is livein for this function.
bool isEAXAlive = false; bool isEAXAlive = false;
for (MachineRegisterInfo::livein_iterator for (MachineRegisterInfo::livein_iterator
II = MF.getRegInfo().livein_begin(), II = MF.getRegInfo().livein_begin(),
@ -850,10 +850,10 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
Reg == X86::AH || Reg == X86::AL); Reg == X86::AH || Reg == X86::AL);
} }
// Function prologue calls _alloca to probe the stack when allocating // Function prologue calls _alloca to probe the stack when allocating more
// more than 4k bytes in one go. Touching the stack at 4K increments is // than 4k bytes in one go. Touching the stack at 4K increments is necessary
// necessary to ensure that the guard pages used by the OS virtual memory // to ensure that the guard pages used by the OS virtual memory manager are
// manager are allocated in correct sequence. // allocated in correct sequence.
if (!isEAXAlive) { if (!isEAXAlive) {
BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX) BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX)
.addImm(NumBytes); .addImm(NumBytes);
@ -863,23 +863,26 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
// Save EAX // Save EAX
BuildMI(MBB, MBBI, DL, TII.get(X86::PUSH32r)) BuildMI(MBB, MBBI, DL, TII.get(X86::PUSH32r))
.addReg(X86::EAX, RegState::Kill); .addReg(X86::EAX, RegState::Kill);
// Allocate NumBytes-4 bytes on stack. We'll also use 4 already // Allocate NumBytes-4 bytes on stack. We'll also use 4 already
// allocated bytes for EAX. // allocated bytes for EAX.
BuildMI(MBB, MBBI, DL, BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX)
TII.get(X86::MOV32ri), X86::EAX).addImm(NumBytes-4); .addImm(NumBytes - 4);
BuildMI(MBB, MBBI, DL, TII.get(X86::CALLpcrel32)) BuildMI(MBB, MBBI, DL, TII.get(X86::CALLpcrel32))
.addExternalSymbol("_alloca"); .addExternalSymbol("_alloca");
// Restore EAX // Restore EAX
MachineInstr *MI = addRegOffset(BuildMI(MF, DL, TII.get(X86::MOV32rm), MachineInstr *MI = addRegOffset(BuildMI(MF, DL, TII.get(X86::MOV32rm),
X86::EAX), X86::EAX),
StackPtr, false, NumBytes-4); StackPtr, false, NumBytes - 4);
MBB.insert(MBBI, MI); MBB.insert(MBBI, MI);
} }
} else { } else if (NumBytes) {
// If there is an SUB32ri of ESP immediately before this instruction, // If there is an SUB32ri of ESP immediately before this instruction, merge
// merge the two. This can be the case when tail call elimination is // the two. This can be the case when tail call elimination is enabled and
// enabled and the callee has more arguments then the caller. // the callee has more arguments then the caller.
NumBytes -= mergeSPUpdates(MBB, MBBI, StackPtr, true); NumBytes -= mergeSPUpdates(MBB, MBBI, StackPtr, true);
// If there is an ADD32ri or SUB32ri of ESP immediately after this // If there is an ADD32ri or SUB32ri of ESP immediately after this
// instruction, merge the two instructions. // instruction, merge the two instructions.
mergeSPUpdatesDown(MBB, MBBI, StackPtr, &NumBytes); mergeSPUpdatesDown(MBB, MBBI, StackPtr, &NumBytes);
@ -887,7 +890,6 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
if (NumBytes) if (NumBytes)
emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, TII); emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, TII);
} }
}
if (needsFrameMoves) if (needsFrameMoves)
emitFrameMoves(MF, FrameLabelId, ReadyLabelId); emitFrameMoves(MF, FrameLabelId, ReadyLabelId);