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

[Chris Lattner]

On Nov 12, 2012, at 1:08 PM, Evan Cheng <evan.cheng at apple.com> wrote:

> 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.

This patch isn't "obvious", and Shuxin is still new to this part of the code.  Unless it's been reviewed it shouldn't go in.

-Chris


> 
> 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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