[llvm-commits] [llvm] r65289 - /llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp

[Dan Gohman]

On Feb 23, 2009, at 2:30 PM, Chris Lattner wrote:

>
> On Feb 22, 2009, at 10:06 AM, Dan Gohman wrote:
>
>> Author: djg
>> Date: Sun Feb 22 12:06:32 2009
>> New Revision: 65289
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=65289&view=rev
>> Log:
>> Revert the part of 64623 that attempted to align the source in a
>> memcpy to match the alignment of the destination. It isn't necessary
>> for making loads and stores handled like the SSE loadu/storeu
>> intrinsics, and it was causing a performance regression in
>> MultiSource/Applications/JM/lencod.
>>
>> The problem appears to have been a memcpy that copies from some
>> highly aligned array into an alloca; the alloca was then being
>> assigned a large alignment, which required codegen to perform
>> dynamic stack-pointer re-alignment, which forced the enclosing
>> function to have a frame pointer, which led to increased spilling.
>
> testcase?


I can probably construct an artificial testcase if you think it'd be  
useful,
but I don't have anything handy smaller than lencod itself.

Dan