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InstCombine: Defensively avoid undefined shifts by limiting the amount to the bit width.
No test case, undefined shifts get folded early, but can occur when other transforms generate a constant. Thanks to Duncan for bringing this up. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162755 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -467,7 +467,7 @@ Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
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Value *X;
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ConstantInt *C1;
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if (match(Op0, m_LShr(m_Value(X), m_ConstantInt(C1)))) {
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APInt NC = C2->getValue().shl(C1->getZExtValue());
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APInt NC = C2->getValue().shl(C1->getLimitedValue(C1->getBitWidth()-1));
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return BinaryOperator::CreateUDiv(X, Builder->getInt(NC));
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}
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}
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@ -548,7 +548,7 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
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Value *X;
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ConstantInt *C1;
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if (match(Op0, m_AShr(m_Value(X), m_ConstantInt(C1)))) {
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APInt NC = C2->getValue().shl(C1->getZExtValue());
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APInt NC = C2->getValue().shl(C1->getLimitedValue(C1->getBitWidth()-1));
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return BinaryOperator::CreateSDiv(X, Builder->getInt(NC));
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}
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}
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