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Add another optimization from PR2330. Also catch some missing cases that are

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similar.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53451 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2008-07-11 07:20:53 +00:00
parent 71ca353ae6
commit 4bf1e59819
2 changed files with 58 additions and 0 deletions
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39
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -5480,6 +5480,45 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
return R;
}
// See if it's the same type of instruction on the left and right.
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
if (Op0I->getOpcode() == Op1I->getOpcode() && Op0I->hasOneUse() &&
Op1I->hasOneUse() && Op0I->getOperand(1) == Op1I->getOperand(1) &&
I.isEquality()) {
switch (Op0I->getOpcode()) {
default: break;
case Instruction::Add:
case Instruction::Sub:
case Instruction::Xor:
// a+x icmp eq/ne b+x --> a icmp b
return new ICmpInst(I.getPredicate(), Op0I->getOperand(0),
Op1I->getOperand(0));
break;
case Instruction::Mul:
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
// a * Cst icmp eq/ne b * Cst --> a & 0x7f icmp b & 0x7f
if (!CI->isZero() && !CI->isOne()) {
const APInt &AP = CI->getValue();
ConstantInt *Mask = ConstantInt::get(
APInt::getLowBitsSet(AP.getBitWidth(),
AP.getBitWidth() -
AP.countTrailingZeros()));
Instruction *And1 = BinaryOperator::CreateAnd(Op0I->getOperand(0),
Mask);
Instruction *And2 = BinaryOperator::CreateAnd(Op1I->getOperand(0),
Mask);
InsertNewInstBefore(And1, I);
InsertNewInstBefore(And2, I);
return new ICmpInst(I.getPredicate(), And1, And2);
}
}
break;
}
}
}
}
// ~x < ~y --> y < x
{ Value *A, *B;
if (match(Op0, m_Not(m_Value(A))) &&

19
test/Transforms/InstCombine/2008-07-10-ICmpBinOp.ll Normal file
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@ -0,0 +1,19 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep add
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep mul
; PR2330
define i1 @f(i32 %x, i32 %y) nounwind {
entry:
%A = add i32 %x, 5
%B = add i32 %y, 5
%C = icmp eq i32 %A, %B
ret i1 %C
}
define i1 @g(i32 %x, i32 %y) nounwind {
entry:
%A = mul i32 %x, 5
%B = mul i32 %y, 5
%C = icmp eq i32 %A, %B
ret i1 %C
}