diff options
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 10 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/2008-01-21-MulTrunc.ll | 11 |
2 files changed, 21 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 2ad592a..3e009eb 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -6512,6 +6512,15 @@ static bool CanEvaluateInDifferentType(Value *V, const IntegerType *Ty, CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc, NumCastsRemoved); + case Instruction::Mul: + break; + // A multiply can be truncated by truncating its operands. + return Ty->getBitWidth() < OrigTy->getBitWidth() && + CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc, + NumCastsRemoved) && + CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc, + NumCastsRemoved); + case Instruction::Shl: // If we are truncating the result of this SHL, and if it's a shift of a // constant amount, we can always perform a SHL in a smaller type. @@ -6571,6 +6580,7 @@ Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty, switch (I->getOpcode()) { case Instruction::Add: case Instruction::Sub: + case Instruction::Mul: case Instruction::And: case Instruction::Or: case Instruction::Xor: diff --git a/test/Transforms/InstCombine/2008-01-21-MulTrunc.ll b/test/Transforms/InstCombine/2008-01-21-MulTrunc.ll new file mode 100644 index 0000000..8de0959 --- /dev/null +++ b/test/Transforms/InstCombine/2008-01-21-MulTrunc.ll @@ -0,0 +1,11 @@ +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | notcast + +define i16 @test1(i16 %a) { + %tmp = zext i16 %a to i32 ; <i32> [#uses=2] + %tmp21 = lshr i32 %tmp, 8 ; <i32> [#uses=1] + %tmp5 = mul i32 %tmp, 5 ; <i32> [#uses=1] + %tmp.upgrd.32 = or i32 %tmp21, %tmp5 ; <i32> [#uses=1] + %tmp.upgrd.3 = trunc i32 %tmp.upgrd.32 to i16 ; <i16> [#uses=1] + ret i16 %tmp.upgrd.3 +} + |