[llvm-commits] [llvm] r155809 - in /llvm/trunk: lib/Transforms/Scalar/LoopStrengthReduce.cpp test/Transforms/LoopStrengthReduce/pr12691.ll

[Bill Wendling]

Argh! I just kicked off rc2 testing last night. I suppose I can sneak this in. What is the risk of this patch and how often will this problem be hit?

-bw

On May 3, 2012, at 1:13 PM, Evan Cheng <evan.cheng at apple.com> wrote:

> I agree. Bill?
> 
> Evan
> 
> On Apr 29, 2012, at 9:10 PM, Rafael Espíndola wrote:
> 
>> This was a regression from 3.0, we might want to include this patch in 3.1.
>> 
>> On 29 April 2012 23:53, Rafael Espindola <rafael.espindola at gmail.com> wrote:
>>> Author: rafael
>>> Date: Sun Apr 29 22:53:06 2012
>>> New Revision: 155809
>>> 
>>> URL: http://llvm.org/viewvc/llvm-project?rev=155809&view=rev
>>> Log:
>>> Make sure HoistInsertPosition finds a position that is dominated by all
>>> inputs.
>>> 
>>> Added:
>>>   llvm/trunk/test/Transforms/LoopStrengthReduce/pr12691.ll
>>> Modified:
>>>   llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
>>> 
>>> Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=155809&r1=155808&r2=155809&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
>>> +++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Sun Apr 29 22:53:06 2012
>>> @@ -4140,7 +4140,7 @@
>>>      // Attempt to find an insert position in the middle of the block,
>>>      // instead of at the end, so that it can be used for other expansions.
>>>      if (IDom == Inst->getParent() &&
>>> -          (!BetterPos || DT.dominates(BetterPos, Inst)))
>>> +          (!BetterPos || !DT.dominates(Inst, BetterPos)))
>>>        BetterPos = llvm::next(BasicBlock::iterator(Inst));
>>>    }
>>>    if (!AllDominate)
>>> 
>>> Added: llvm/trunk/test/Transforms/LoopStrengthReduce/pr12691.ll
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopStrengthReduce/pr12691.ll?rev=155809&view=auto
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LoopStrengthReduce/pr12691.ll (added)
>>> +++ llvm/trunk/test/Transforms/LoopStrengthReduce/pr12691.ll Sun Apr 29 22:53:06 2012
>>> @@ -0,0 +1,34 @@
>>> +; RUN: opt < %s -loop-reduce -S | FileCheck %s
>>> +
>>> + at d = common global i32 0, align 4
>>> +
>>> +define void @fn2(i32 %x) nounwind uwtable {
>>> +entry:
>>> +  br label %for.cond
>>> +
>>> +for.cond:
>>> +  %g.0 = phi i32 [ 0, %entry ], [ %dec, %for.cond ]
>>> +  %tobool = icmp eq i32 %x, 0
>>> +  %dec = add nsw i32 %g.0, -1
>>> +  br i1 %tobool, label %for.cond, label %for.end
>>> +
>>> +for.end:
>>> +; CHECK:  %tmp1 = load i32* @d, align 4
>>> +; CHECK-NEXT:  %tmp2 = load i32* @d, align 4
>>> +; CHECK-NEXT:  %0 = sub i32 %tmp1, %tmp2
>>> +
>>> +  %tmp1 = load i32* @d, align 4
>>> +  %add = add nsw i32 %tmp1, %g.0
>>> +  %tmp2 = load i32* @d, align 4
>>> +  %tobool26 = icmp eq i32 %x, 0
>>> +  br i1 %tobool26, label %for.end5, label %for.body.lr.ph
>>> +
>>> +for.body.lr.ph:
>>> +  %tobool3 = icmp ne i32 %tmp2, %add
>>> +  br label %for.end5
>>> +
>>> +for.end5:
>>> +  ret void
>>> +}
>>> +
>>> +
>> 
>> 
>> Cheers,
>> Rafael
>> 
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>