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Improve codegen of long == and != comparisons against constants. Before,

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comparing a long against zero got us this:

        sub %ESP, 8
        mov DWORD PTR [%ESP + 4], %ESI
        mov DWORD PTR [%ESP], %EDI
        mov %EAX, DWORD PTR [%ESP + 12]
        mov %EDX, DWORD PTR [%ESP + 16]
        mov %ECX, 0
        mov %ESI, 0
        mov %EDI, %EAX
        xor %EDI, %ECX
        mov %ECX, %EDX
        xor %ECX, %ESI
        or %EDI, %ECX
        sete %CL
        test %CL, %CL
        je .LBB2 # PC rel: F

Now it gets us this:

        mov %EAX, DWORD PTR [%ESP + 4]
        mov %EDX, DWORD PTR [%ESP + 8]
        mov %ECX, %EAX
        or %ECX, %EDX
        sete %CL
        test %CL, %CL
        je .LBB2 # PC rel: F

llvm-svn: 12696
This commit is contained in:
Chris Lattner 2004-04-06 16:02:27 +00:00
parent 1aa66730ad
commit 2d9b28ac0b
1 changed files with 23 additions and 3 deletions
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26
lib/Target/X86/InstSelectSimple.cpp
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@ -806,9 +806,9 @@ unsigned ISel::EmitComparison(unsigned OpNum, Value *Op0, Value *Op1,
unsigned Op0r = getReg(Op0, MBB, IP);
// Special case handling of: cmp R, i
if (Class == cByte || Class == cShort || Class == cInt)
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
uint64_t Op1v = cast<ConstantInt>(CI)->getRawValue();
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
if (Class == cByte || Class == cShort || Class == cInt) {
unsigned Op1v = CI->getRawValue();
// Mask off any upper bits of the constant, if there are any...
Op1v &= (1ULL << (8 << Class)) - 1;
@ -833,7 +833,27 @@ unsigned ISel::EmitComparison(unsigned OpNum, Value *Op0, Value *Op1,
BuildMI(*MBB, IP, CMPTab[Class], 2).addReg(Op0r).addImm(Op1v);
return OpNum;
} else {
assert(Class == cLong && "Unknown integer class!");
unsigned LowCst = CI->getRawValue();
unsigned HiCst = CI->getRawValue() >> 32;
if (OpNum < 2) { // seteq, setne
unsigned LoTmp = Op0r;
if (LowCst != 0) {
LoTmp = makeAnotherReg(Type::IntTy);
BuildMI(*MBB, IP, X86::XOR32ri, 2, LoTmp).addReg(Op0r).addImm(LowCst);
}
unsigned HiTmp = Op0r+1;
if (HiCst != 0) {
HiTmp = makeAnotherReg(Type::IntTy);
BuildMI(*MBB, IP, X86::XOR32rr, 2,HiTmp).addReg(Op0r+1).addImm(HiCst);
}
unsigned FinalTmp = makeAnotherReg(Type::IntTy);
BuildMI(*MBB, IP, X86::OR32rr, 2, FinalTmp).addReg(LoTmp).addReg(HiTmp);
return OpNum;
}
}
}
// Special case handling of comparison against +/- 0.0
if (ConstantFP *CFP = dyn_cast<ConstantFP>(Op1))