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Reapply r237520 with another fix for infinite looping
SimplifyDemandedBits was "simplifying" a constant by removing just sign bits. This caused a canonicalization race between different parts of instcombine. Fix and regression test added - third time lucky? git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237539 91177308-0d34-0410-b5e6-96231b3b80d8
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@@ -1154,18 +1154,30 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
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}
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// See if we can fold the select into one of our operands.
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if (SI.getType()->isIntegerTy()) {
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if (SI.getType()->isIntOrIntVectorTy()) {
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if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal))
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return FoldI;
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Value *LHS, *RHS, *LHS2, *RHS2;
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SelectPatternFlavor SPF = matchSelectPattern(&SI, LHS, RHS);
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Instruction::CastOps CastOp;
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SelectPatternFlavor SPF = matchSelectPattern(&SI, LHS, RHS, &CastOp);
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// MAX(MAX(a, b), a) -> MAX(a, b)
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// MIN(MIN(a, b), a) -> MIN(a, b)
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// MAX(MIN(a, b), a) -> a
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// MIN(MAX(a, b), a) -> a
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if (SPF) {
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// Canonicalize so that type casts are outside select patterns.
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if (LHS->getType()->getPrimitiveSizeInBits() !=
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SI.getType()->getPrimitiveSizeInBits()) {
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CmpInst::Predicate Pred = getICmpPredicateForMinMax(SPF);
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Value *Cmp = Builder->CreateICmp(Pred, LHS, RHS);
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Value *NewSI = Builder->CreateCast(CastOp,
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Builder->CreateSelect(Cmp, LHS, RHS),
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SI.getType());
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return ReplaceInstUsesWith(SI, NewSI);
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}
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// MAX(MAX(a, b), a) -> MAX(a, b)
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// MIN(MIN(a, b), a) -> MIN(a, b)
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// MAX(MIN(a, b), a) -> a
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// MIN(MAX(a, b), a) -> a
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if (SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2))
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if (Instruction *R = FoldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2,
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SI, SPF, RHS))
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