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

[Joey Gouly]

Ben Kramer committed r191673 and r191674, which should fix this by using an
RAII object, so the flags don't need to be set manually.


-----Original Message-----
From: Bob Wilson [mailto:bob.wilson at apple.com] 
Sent: 01 October 2013 19:40
To: Shuxin Yang
Cc: Joey Gouly; Commit Messages and Patches for LLVM
Subject: Re: [llvm] r191668 - Fix a bug in InstCombine where it attempted to
cast a Value* to an Instruction*

Can one of you please audit the other casts and fix any of them with the
same problem?

On Oct 1, 2013, at 11:03 AM, Shuxin Yang <shuxin.llvm at gmail.com> wrote:

> 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/InstCombin
e/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/InstCombi
ne/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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>> 
> 
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