[llvm-commits] [llvm] r167740 - in /llvm/trunk: lib/Transforms/Scalar/Reassociate.cpp test/Transforms/Reassociate/mul_neg.ll test/Transforms/Reassociate/multistep.ll

[Evan Cheng]

Hi Eli,

The approach seems sound to me. Since no one has raised design concerns at this point and the fact this is a a bug fix for a crash, I think it's appropriate for review after commit.

Thanks,

Evan

On Nov 12, 2012, at 11:40 AM, Eli Friedman <eli.friedman at gmail.com> wrote:

> On Mon, Nov 12, 2012 at 11:34 AM, Shuxin Yang <shuxin.llvm at gmail.com> wrote:
>> Author: shuxin_yang
>> Date: Mon Nov 12 13:34:11 2012
>> New Revision: 167740
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=167740&view=rev
>> Log:
>> This change is to fix rdar://12571717 which is about assertion in Reassociate pass.
>> 
>> The assertion is trigged when the Reassociater tries to transform expression
>>     ... + 2 * n * 3 + 2 * m + ...
>>  into:
>>     ... + 2 * (n*3 + m).
>> 
>> In the process of the transformation, a helper routine folds the constant 2*3 into 6,
>> confusing optimizer which is trying the to eliminate the common factor 2, and cannot
>> find 2 any more.
>> 
>> Review is pending. But I'd like commit first in order to help those who are waiting
>> for this fix.
> 
> No; this is not how our review system works; you're not allowed to
> commit without review just because some particular customer needs a
> fix.  We have private branches for that sort of thing.
> 
> -Eli
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