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| author | Chris Lattner <sabre@nondot.org> | 2009-06-21 01:15:55 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2009-06-21 01:15:55 +0000 |
| commit | 1db6866147b6b3028fdc77bc242de8f44edd71d9 (patch) | |
| tree | 5571ed155bd82f9ffc8b4d968e6ba4b0e1145ece | |
| parent | 5c0b16d0c40bb95e572e5d24db587ed8ca4bde71 (diff) | |
implement PR4424: 0/x is always 0 for integer division.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73835 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/VMCore/ConstantFold.cpp | 7 | ||||
| -rw-r--r-- | test/Transforms/ConstProp/div-zero.ll | 12 |
2 files changed, 19 insertions, 0 deletions
diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp index 6c392145a5..dc8fb39f17 100644 --- a/lib/VMCore/ConstantFold.cpp +++ b/lib/VMCore/ConstantFold.cpp @@ -773,6 +773,13 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, } } } + + // 0 / x -> 0. + if ((Opcode == Instruction::UDiv || + Opcode == Instruction::SDiv) && + CI1->isZero()) + return const_cast<Constant*>(C1); + } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) { if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) { APFloat C1V = CFP1->getValueAPF(); diff --git a/test/Transforms/ConstProp/div-zero.ll b/test/Transforms/ConstProp/div-zero.ll new file mode 100644 index 0000000000..166c643dcc --- /dev/null +++ b/test/Transforms/ConstProp/div-zero.ll @@ -0,0 +1,12 @@ +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {ret i32 0} +; PR4424 +declare void @ext() + +define i32 @foo(i32 %ptr) { +entry: + %zero = sub i32 %ptr, %ptr ; <i32> [#uses=1] + %div_zero = sdiv i32 %zero, ptrtoint (i32* getelementptr (i32* null, +i32 1) to i32) ; <i32> [#uses=1] + ret i32 %div_zero +} + |