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Move some rem transforms out of instcombine and into instsimplify.

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This automagically provides a transform noticed by my super-optimizer
as occurring quite often: "rem x, (select cond, x, 1)" -> 0.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130694 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands
2011-05-02 16:27:02 +00:00
parent 2866edf120
commit f24ed77d24
3 changed files with 153 additions and 42 deletions
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61
lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
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@ -492,28 +492,6 @@ Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
return 0;
}
/// This function implements the transforms on rem instructions that work
/// regardless of the kind of rem instruction it is (urem, srem, or frem). It
/// is used by the visitors to those instructions.
/// @brief Transforms common to all three rem instructions
Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (isa<UndefValue>(Op0)) { // undef % X -> 0
if (I.getType()->isFPOrFPVectorTy())
return ReplaceInstUsesWith(I, Op0); // X % undef -> undef (could be SNaN)
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
}
if (isa<UndefValue>(Op1))
return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
// Handle cases involving: rem X, (select Cond, Y, Z)
if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
return &I;
return 0;
}
/// This function implements the transforms common to both integer remainder
/// instructions (urem and srem). It is called by the visitors to those integer
/// remainder instructions.
@ -521,26 +499,11 @@ Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Instruction *common = commonRemTransforms(I))
return common;
// X % X == 0
if (Op0 == Op1)
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
// 0 % X == 0 for integer, we don't need to preserve faults!
if (Constant *LHS = dyn_cast<Constant>(Op0))
if (LHS->isNullValue())
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
// Handle cases involving: rem X, (select Cond, Y, Z)
if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
return &I;
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
// X % 0 == undef, we don't need to preserve faults!
if (RHS->equalsInt(0))
return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
if (RHS->equalsInt(1)) // X % 1 == 0
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
if (Instruction *R = FoldOpIntoSelect(I, SI))
@ -562,6 +525,9 @@ Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
Instruction *InstCombiner::visitURem(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifyURemInst(Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
if (Instruction *common = commonIRemTransforms(I))
return common;
@ -602,6 +568,9 @@ Instruction *InstCombiner::visitURem(BinaryOperator &I) {
Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifySRemInst(Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
// Handle the integer rem common cases
if (Instruction *Common = commonIRemTransforms(I))
return Common;
@ -660,6 +629,14 @@ Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
}
Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
return commonRemTransforms(I);
}
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = SimplifyFRemInst(Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
// Handle cases involving: rem X, (select Cond, Y, Z)
if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
return &I;
return 0;
}