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Implement InstCombine/sub.ll:test15: X % -Y === X % Y

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Also, remove X % -1 = 0, because it's not true for unsigneds, and the
signed case is superceeded by this new handling.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@14637 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-07-06 07:01:22 +00:00
parent f77afbb275
commit 5b73c08896
1 changed files with 9 additions and 2 deletions
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11
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -844,11 +844,18 @@ Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
Instruction *InstCombiner::visitRem(BinaryOperator &I) {
if (I.getType()->isSigned())
if (Value *RHSNeg = dyn_castNegVal(I.getOperand(1)))
if (RHSNeg != I.getOperand(1)) { // Avoid problems with MININT
// X % -Y -> X % Y
AddUsesToWorkList(I);
I.setOperand(1, RHSNeg);
return &I;
}
if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
if (RHS->equalsInt(1)) // X % 1 == 0
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
if (RHS->isAllOnesValue()) // X % -1 == 0
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
// Check to see if this is an unsigned remainder with an exact power of 2,
// if so, convert to a bitwise and.