I don't get different output for the attached patch before and after
the patch, and the test fails.
On Jan 21, 2008, at 9:08 PM, Nick Lewycky wrote:
> =
> =
> =
> =
> =
> =
> =
> =
> ======================================================================
> --- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
> (original)
> +++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Mon
> Jan 21 23:08:48 2008
> @@ -6512,6 +6512,15 @@
> CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
> NumCastsRemoved);
>
> + case Instruction::Mul:
> + break;
Probably due to this 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 @@
> switch (I->getOpcode()) {
> case Instruction::Add:
> case Instruction::Sub:
> + case Instruction::Mul:
> case Instruction::And:
> case Instruction::Or:
> case Instruction::Xor:
>
> Added: llvm/trunk/test/Transforms/InstCombine/2008-01-21-MulTrunc.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/2008-01-21-MulTrunc.ll?rev=46244&view=auto
>
> =
> =
> =
> =
> =
> =
> =
> =
> ======================================================================
> --- llvm/trunk/test/Transforms/InstCombine/2008-01-21-MulTrunc.ll
> (added)
> +++ llvm/trunk/test/Transforms/InstCombine/2008-01-21-MulTrunc.ll
> Mon Jan 21 23:08:48 2008
> @@ -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
> +}
> +
>
>
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