[llvm] r326077 - [LoopInterchange] Loops with empty dependency matrix are safe.
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 26 11:35:26 PST 2018
Landed in r326078, ignore this.
On 02/26/2018 11:34 AM, Philip Reames wrote:
> Test case?
> On 02/26/2018 02:45 AM, Florian Hahn via llvm-commits wrote:
>> Author: fhahn
>> Date: Mon Feb 26 02:45:25 2018
>> New Revision: 326077
>> URL: http://llvm.org/viewvc/llvm-project?rev=326077&view=rev
>> [LoopInterchange] Loops with empty dependency matrix are safe.
>> The dependency matrix is only empty if no conflicting load/store
>> instructions have been found. In that case, it is safe to interchange.
>> For the LLVM test-suite, after this change around 1900 loops are
>> interchanged, whereas it is 15 before this change. On cortex-a57,
>> this gives an improvement of -0.57% on the geomean execution
>> time of SPEC2006, SPEC2000 and the test-suite. There are a
>> few small perf regressions, but I think we can improve on those
>> by making the cost model better.
>> Reviewers: karthikthecool, mcrosier
>> Reviewed by: karthikthecool
>> Differential Revision: https://reviews.llvm.org/D43236
>> Modified: llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp
>> --- llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Scalar/LoopInterchange.cpp Mon Feb 26
>> 02:45:25 2018
>> @@ -173,9 +173,6 @@ static bool populateDependencyMatrix(Cha
>> - // We don't have a DepMatrix to check legality return false.
>> - if (DepMatrix.empty())
>> - return false;
>> return true;
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