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Canonicalize ConstantInts to the right operand of commutative 

operators.

The test difference is just due to the multiplication operands
being commuted (and thus requiring a more elaborate match). In
optimized code, that expression would be folded.

llvm-svn: 96816
This commit is contained in:
Dan Gohman 2010-02-22 22:43:23 +00:00
parent 85ef93f130
commit 6c5ac6de5c
3 changed files with 7 additions and 3 deletions
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4
llvm/lib/Analysis/ConstantFolding.cpp
View File

@ -794,8 +794,8 @@ Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
// it is casted back to a pointer, see if the expression can be
// converted into a GEP.
if (CE->getOpcode() == Instruction::Add)
if (ConstantInt *L = dyn_cast<ConstantInt>(CE->getOperand(0)))
if (ConstantExpr *R = dyn_cast<ConstantExpr>(CE->getOperand(1)))
if (ConstantInt *L = dyn_cast<ConstantInt>(CE->getOperand(1)))
if (ConstantExpr *R = dyn_cast<ConstantExpr>(CE->getOperand(0)))
if (R->getOpcode() == Instruction::PtrToInt)
if (GlobalVariable *GV =
dyn_cast<GlobalVariable>(R->getOperand(0))) {

4
llvm/lib/VMCore/ConstantFold.cpp
View File

@ -1105,6 +1105,10 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
return ConstantExpr::getLShr(C1, C2);
break;
}
} else if (isa<ConstantInt>(C1)) {
// If C1 is a ConstantInt and C2 is not, swap the operands.
if (Instruction::isCommutative(Opcode))
return ConstantExpr::get(Opcode, C2, C1);
}
// At this point we know neither constant is an UndefValue.

2
llvm/test/CodeGen/X86/ptrtoint-constexpr.ll
View File

@ -9,6 +9,6 @@
; CHECK: .globl x
; CHECK: x:
; CHECK: .quad 3
; CHECK: .quad ((0+1)&4294967295)*3
@x = global i64 mul (i64 3, i64 ptrtoint (i2* getelementptr (i2* null, i64 1) to i64))