[PATCH] D74505: [MemorySSA] Don't verify MemorySSA unless VerifyMemorySSA enabled

[Nikita Popov via Phabricator via llvm-commits]

nikic created this revision.
nikic added a reviewer: asbirlea.
Herald added subscribers: llvm-commits, george.burgess.iv, hiraditya, Prazek.
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I noticed that MemorySSA is often taking up an unreasonable fraction of runtime in assertion enabled builds. Turns out that there is one code-path that runs verifyMemorySSA() even if VerifyMemorySSA is not enabled. This patch makes it conditional as well.

For the test case I'm looking at right now:

  Before 
  
    12.5533 ( 21.9%)   0.1048 (  2.9%)  12.6581 ( 20.7%)  12.6539 ( 20.7%)  Memory SSA #2
     6.1540 ( 10.7%)   0.2563 (  7.0%)   6.4103 ( 10.5%)   6.4076 ( 10.5%)  Function Integration/Inlining
     2.3936 (  4.2%)   0.1117 (  3.0%)   2.5053 (  4.1%)   2.5034 (  4.1%)  Global Value Numbering
     1.9745 (  3.4%)   0.0211 (  0.6%)   1.9955 (  3.3%)   1.9949 (  3.3%)  Rotate Loops
     1.6837 (  2.9%)   0.1032 (  2.8%)   1.7869 (  2.9%)   1.7851 (  2.9%)  Induction Variable Simplification
     1.6743 (  2.9%)   0.0324 (  0.9%)   1.7068 (  2.8%)   1.7053 (  2.8%)  Memory SSA #4
     1.4166 (  2.5%)   0.0391 (  1.1%)   1.4558 (  2.4%)   1.4547 (  2.4%)  Memory SSA #5
     1.3661 (  2.4%)   0.0389 (  1.1%)   1.4050 (  2.3%)   1.4037 (  2.3%)  Memory SSA #3
      
  After
   
     6.6570 ( 14.5%)   0.2266 (  6.1%)   6.8836 ( 13.9%)   6.8809 ( 13.9%)  Function Integration/Inlining
     2.7801 (  6.1%)   0.1170 (  3.1%)   2.8972 (  5.8%)   2.8947 (  5.9%)  Global Value Numbering
     2.0526 (  4.5%)   0.0416 (  1.1%)   2.0942 (  4.2%)   2.0932 (  4.2%)  Rotate Loops
     1.8899 (  4.1%)   0.1305 (  3.5%)   2.0203 (  4.1%)   2.0183 (  4.1%)  Induction Variable Simplification

There is a similar report with much more extreme numbers at https://bugs.llvm.org/show_bug.cgi?id=44238 as well.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D74505

Files:
  llvm/lib/Analysis/MemorySSA.cpp


Index: llvm/lib/Analysis/MemorySSA.cpp
===================================================================
--- llvm/lib/Analysis/MemorySSA.cpp
+++ llvm/lib/Analysis/MemorySSA.cpp
@@ -2298,7 +2298,10 @@
   return false;
 }
 
-void MemorySSAWrapperPass::verifyAnalysis() const { MSSA->verifyMemorySSA(); }
+void MemorySSAWrapperPass::verifyAnalysis() const {
+  if (VerifyMemorySSA)
+    MSSA->verifyMemorySSA();
+}
 
 void MemorySSAWrapperPass::print(raw_ostream &OS, const Module *M) const {
   MSSA->print(OS);


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