Fwd: [llvm] r191668 - Fix a bug in InstCombine where it attempted to cast a Value* to an Instruction*

[Shuxin Yang]

Thanks! That is my bug:-)
> Author: joey
> Date: Mon Sep 30 09:18:35 2013
> New Revision: 191668
>
> URL:http://llvm.org/viewvc/llvm-project?rev=191668&view=rev
> Log:
> Fix a bug in InstCombine where it attempted to cast a Value* to an Instruction*
> when it was actually a Constant*.
>
> There are quite a few other casts to Instruction that might have the same problem,
> but this is the only one I have a test case for.
>
> Modified:
>      llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
>      llvm/trunk/test/Transforms/InstCombine/fmul.ll
>
> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
> URL:http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp?rev=191668&r1=191667&r2=191668&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp (original)
> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp Mon Sep 30 09:18:35 2013
> @@ -519,10 +519,10 @@ Instruction *InstCombiner::visitFMul(Bin
>         if (Opnd0->hasOneUse()) {
>           // -X * Y => -(X*Y) (Promote negation as high as possible)
>           Value *T = Builder->CreateFMul(N0, Opnd1);
> -        cast<Instruction>(T)->setDebugLoc(I.getDebugLoc());
>           Instruction *Neg = BinaryOperator::CreateFNeg(T);
>           if (I.getFastMathFlags().any()) {
> -          cast<Instruction>(T)->copyFastMathFlags(&I);
> +          if (Instruction *TI = dyn_cast<Instruction>(T))
> +            TI->copyFastMathFlags(&I);
>             Neg->copyFastMathFlags(&I);
>           }
>           return Neg;
>
> Modified: llvm/trunk/test/Transforms/InstCombine/fmul.ll
> URL:http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/fmul.ll?rev=191668&r1=191667&r2=191668&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/InstCombine/fmul.ll (original)
> +++ llvm/trunk/test/Transforms/InstCombine/fmul.ll Mon Sep 30 09:18:35 2013
> @@ -70,3 +70,26 @@ define float @test7(float %x, float %y)
>   ; CHECK-LABEL: @test7(
>   ; CHECK: fsub float -0.000000e+00, %x
>   }
> +
> +; Don't crash when attempting to cast a constant FMul to an instruction.
> +define void @test8(i32* %inout) {
> +entry:
> +  %0 = load i32* %inout, align 4
> +  %conv = uitofp i32 %0 to float
> +  %vecinit = insertelement <4 x float> <float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float undef>, float %conv, i32 3
> +  %sub = fsub <4 x float> <float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00>, %vecinit
> +  %1 = shufflevector <4 x float> %sub, <4 x float> undef, <4 x i32> <i32 1, i32 1, i32 1, i32 1>
> +  %mul = fmul <4 x float> zeroinitializer, %1
> +  br label %for.cond
> +
> +for.cond:                                         ; preds = %for.body, %entry
> +  %local_var_7.0 = phi <4 x float> [ %mul, %entry ], [ %2, %for.body ]
> +  br i1 undef, label %for.body, label %for.end
> +
> +for.body:                                         ; preds = %for.cond
> +  %2 = insertelement <4 x float> %local_var_7.0, float 0.000000e+00, i32 2
> +  br label %for.cond
> +
> +for.end:                                          ; preds = %for.cond
> +  ret void
> +}
>
>
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