[llvm-commits] [llvm] r170024 - /llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp

[Michael Ilseman]

Attached is a patch to correctly call the optimization.  Included are a test case to help prevent this and a test case to test the optimization itself.

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On Dec 13, 2012, at 6:27 AM, NAKAMURA Takumi <geek4civic at gmail.com> wrote:

> Thanks, Eric!
> 
> Michael, I am sorry I mistook wording. :(
> 
> ...Takumi
> 
> 2012/12/13 Eric Christopher <echristo at gmail.com>:
>> I've gone ahead and reverted it here temporarily:
>> 
>>        M       lib/Transforms/InstCombine/InstCombineAddSub.cpp
>> Committed r170106
>> 
>> To get some of the bots back since it's been a while.
>> 
>> Hopefully the PR will help Michael with a testcase.
>> 
>> Thanks all.
>> 
>> -eric
>> 
>> 
>> On Wed, Dec 12, 2012 at 8:51 PM, Will Dietz <w at wdtz.org> wrote:
>>> 
>>> Ah, wish I saw this thread earlier today :).
>>> 
>>> Please see: http://llvm.org/bugs/show_bug.cgi?id=14592 .
>>> 
>>> Note that while it does break selfhosting for me, it also breaks
>>> llvm/clang when built with gcc (4.4.6).
>>> 
>>> Reverting this commit locally un-breaks my build.
>>> 
>>> ~Will
>>> 
>>> On Wed, Dec 12, 2012 at 7:12 PM, Michael Ilseman <milseman at apple.com>
>>> wrote:
>>>> 
>>>> On Dec 12, 2012, at 5:02 PM, NAKAMURA Takumi <geek4civic at gmail.com>
>>>> wrote:
>>>> 
>>>>> Michael, it broke self hosting.
>>>>> 
>>>> 
>>>> Do you mean this commit broke it, or that my prior commit broke it and
>>>> this fixed it?
>>>> 
>>>>> ...Takumi
>>>>> 
>>>>> 2012/12/13 Michael Ilseman <milseman at apple.com>:
>>>>>> Author: milseman
>>>>>> Date: Wed Dec 12 14:59:36 2012
>>>>>> New Revision: 170024
>>>>>> 
>>>>>> URL: http://llvm.org/viewvc/llvm-project?rev=170024&view=rev
>>>>>> Log:
>>>>>> Restore the PHI optimization I accidently removed
>>>>>> 
>>>>>> Modified:
>>>>>>   llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
>>>>>> 
>>>>>> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
>>>>>> URL:
>>>>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp?rev=170024&r1=170023&r2=170024&view=diff
>>>>>> 
>>>>>> ==============================================================================
>>>>>> --- llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
>>>>>> (original)
>>>>>> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp Wed
>>>>>> Dec 12 14:59:36 2012
>>>>>> @@ -354,6 +354,10 @@
>>>>>>  if (Value *V = SimplifyFAddInst(LHS, RHS, I.getFastMathFlags(), TD))
>>>>>>    return ReplaceInstUsesWith(I, V);
>>>>>> 
>>>>>> +  if (isa<PHINode>(LHS))
>>>>>> +    if (Instruction *NV = FoldOpIntoPhi(I))
>>>>>> +      return NV;
>>>>>> +
>>>>>>  // -A + B  -->  B - A
>>>>>>  // -A + -B  -->  -(A + B)
>>>>>>  if (Value *LHSV = dyn_castFNegVal(LHS))
>>>>>> 
>>>>>> 
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