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Round number of bytes allocated on the stack up to a multiple of 4 so that the 

stack remains aligned

llvm-svn: 5095
This commit is contained in:
Chris Lattner 2002-12-17 03:15:26 +00:00
parent d9c6f2a6d3
commit eaf58b03b2
1 changed files with 5 additions and 2 deletions
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7
llvm/lib/Target/X86/X86RegisterInfo.cpp
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@ -113,10 +113,13 @@ const unsigned* X86RegisterInfo::getCallerSaveRegs() const {
}
void X86RegisterInfo::emitPrologue(MachineFunction &MF,
unsigned numBytes) const {
unsigned NumBytes) const {
MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
MachineBasicBlock::iterator MBBI = MBB.begin();
// Round stack allocation up to a nice alignment to keep the stack aligned
NumBytes = (NumBytes + 3) & ~3;
// PUSH ebp
MachineInstr *MI = BuildMI(X86::PUSHr32, 1).addReg(X86::EBP);
MBBI = ++MBB.insert(MBBI, MI);
@ -126,7 +129,7 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF,
MBBI = ++MBB.insert(MBBI, MI);
// adjust stack pointer: ESP -= numbytes
MI = BuildMI(X86::SUBri32, 2, X86::ESP).addReg(X86::ESP).addZImm(numBytes);
MI = BuildMI(X86::SUBri32, 2, X86::ESP).addReg(X86::ESP).addZImm(NumBytes);
MBBI = ++MBB.insert(MBBI, MI);
}