[PATCH] D100331: [Dependence Analysis] Fix ExactSIV producing wrong analysis

Tue Apr 20 07:16:22 PDT 2021

bmahjour added a comment.

Most of the changes in DA results look good to me, except a few I've noted. Perhaps those can be improved in the future, since this patch is making an improvement overall.

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Comment at: llvm/test/Analysis/DependenceAnalysis/Coupled.ll:253
 ; CHECK: da analyze - none!
-; CHECK: da analyze - flow [<]!
+; CHECK: da analyze - flow [=|<]!
 ; CHECK: da analyze - confused!
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this one was wrong before, and is still wrong but in a different way....same thing with couple14.

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Comment at: llvm/test/Analysis/DependenceAnalysis/ExactSIV.ll:19
 ; CHECK: da analyze - none!
-; CHECK: da analyze - flow [>]!
+; CHECK: da analyze - flow [<=|<]!
 ; CHECK: da analyze - confused!
----------------
The `<=` part is correct, but I'm not sure about the `|<` part. The dependence is loop carried for the most part (except when i = 9). I think this might be because we treat the existence of an `EQ` as signifying loop independent dependence, which should probably be reconsidered in a separate patch.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D100331/new/

https://reviews.llvm.org/D100331