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Handle passing constant integers to functions much more efficiently. Instead 

of generating this code:

        mov %EAX, 4
        mov DWORD PTR [%ESP], %EAX
        mov %AX, 123
        movsx %EAX, %AX
        mov DWORD PTR [%ESP + 4], %EAX
        call Y

we now generate:
        mov DWORD PTR [%ESP], 4
        mov DWORD PTR [%ESP + 4], 123
        call Y

Which hurts the eyes less.  :)

Considering that register pressure around call sites is already high (with all
of the callee clobber registers n stuff), this may help a lot.

llvm-svn: 12028
This commit is contained in:
Chris Lattner 2004-03-01 02:42:43 +00:00
parent b19dcc6651
commit 1f4642c47c
1 changed files with 23 additions and 10 deletions
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33
llvm/lib/Target/X86/InstSelectSimple.cpp
View File

@ -1101,18 +1101,31 @@ void ISel::doCall(const ValueRecord &Ret, MachineInstr *CallMI,
unsigned ArgReg;
switch (getClassB(Args[i].Ty)) {
case cByte:
case cShort: {
// Promote arg to 32 bits wide into a temporary register...
unsigned R = makeAnotherReg(Type::UIntTy);
promote32(R, Args[i]);
addRegOffset(BuildMI(BB, X86::MOV32mr, 5),
X86::ESP, ArgOffset).addReg(R);
case cShort:
if (Args[i].Val && isa<ConstantInt>(Args[i].Val)) {
// Zero/Sign extend constant, then stuff into memory.
ConstantInt *Val = cast<ConstantInt>(Args[i].Val);
Val = cast<ConstantInt>(ConstantExpr::getCast(Val, Type::IntTy));
addRegOffset(BuildMI(BB, X86::MOV32mi, 5), X86::ESP, ArgOffset)
.addImm(Val->getRawValue() & 0xFFFFFFFF);
} else {
// Promote arg to 32 bits wide into a temporary register...
ArgReg = makeAnotherReg(Type::UIntTy);
promote32(ArgReg, Args[i]);
addRegOffset(BuildMI(BB, X86::MOV32mr, 5),
X86::ESP, ArgOffset).addReg(ArgReg);
}
break;
}
case cInt:
ArgReg = Args[i].Val ? getReg(Args[i].Val) : Args[i].Reg;
addRegOffset(BuildMI(BB, X86::MOV32mr, 5),
X86::ESP, ArgOffset).addReg(ArgReg);
if (Args[i].Val && isa<ConstantInt>(Args[i].Val)) {
unsigned Val = cast<ConstantInt>(Args[i].Val)->getRawValue();
addRegOffset(BuildMI(BB, X86::MOV32mi, 5),
X86::ESP, ArgOffset).addImm(Val);
} else {
ArgReg = Args[i].Val ? getReg(Args[i].Val) : Args[i].Reg;
addRegOffset(BuildMI(BB, X86::MOV32mr, 5),
X86::ESP, ArgOffset).addReg(ArgReg);
}
break;
case cLong:
ArgReg = Args[i].Val ? getReg(Args[i].Val) : Args[i].Reg;