[PATCH] D78225: [MustExecute] checkForAllContext(): use pre-increment

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri created this revision.
lebedev.ri added a reviewer: jdoerfert.
lebedev.ri added a project: LLVM.

You'd think there is no difference, but this halves (yikes!) compiler memory usage
on `test-suite/MultiSource/Applications/SPASS/top.c` test,
because `MustBeExecutedIterator operator++()` is, well, post-increment,
it must create a duplicate of existing `MustBeExecutedIterator`,
which involves duplicating `VisitedSetTy Visited` which is `DenseSet`..

Old

  0.3573 ( 42.9%)   0.0264 ( 33.7%)   0.3837 ( 42.1%)   0.3837 ( 42.1%)  Deduce and propagate attributes (CGSCC pass)
  0.1011 ( 12.1%)   0.0199 ( 25.4%)   0.1210 ( 13.3%)   0.1210 ( 13.3%)  Deduce and propagate attributes

  total runtime: 20.04s.
  bytes allocated in total (ignoring deallocations): 1.09GB (54.63MB/s)
  calls to allocation functions: 1142410 (57020/s)
  temporary memory allocations: 500538 (24983/s)
  peak heap memory consumption: 26.68MB
  peak RSS (including heaptrack overhead): 944.85MB
  total memory leaked: 8.85MB

New:

  0.3309 ( 39.8%)   0.0164 ( 33.3%)   0.3473 ( 39.5%)   0.3473 ( 39.5%)  Deduce and propagate attributes (CGSCC pass)
  0.1152 ( 13.9%)   0.0076 ( 15.5%)   0.1229 ( 14.0%)   0.1229 ( 14.0%)  Deduce and propagate attributes

  total runtime: 19.49s.
  bytes allocated in total (ignoring deallocations): 575.07MB (29.51MB/s)
  calls to allocation functions: 909059 (46651/s)
  temporary memory allocations: 276923 (14211/s)
  peak heap memory consumption: 26.68MB
  peak RSS (including heaptrack overhead): 942.90MB
  total memory leaked: 8.85MB

Diff:

  total runtime: -0.55s.
  bytes allocated in total (ignoring deallocations): -519.41MB (946.11MB/s)
  calls to allocation functions: -233351 (425047/s)
  temporary memory allocations: -223615 (407313/s)
  peak heap memory consumption: 0B
  peak RSS (including heaptrack overhead): 0B
  total memory leaked: 0B


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D78225

Files:
  llvm/include/llvm/Analysis/MustExecute.h


Index: llvm/include/llvm/Analysis/MustExecute.h
===================================================================
--- llvm/include/llvm/Analysis/MustExecute.h
+++ llvm/include/llvm/Analysis/MustExecute.h
@@ -469,7 +469,7 @@
   /// true if \p Pred holds in every instruction.
   bool checkForAllContext(const Instruction *PP,
                           const function_ref<bool(const Instruction *)> &Pred) {
-    for (auto EIt = begin(PP), EEnd = end(PP); EIt != EEnd; EIt++)
+    for (auto EIt = begin(PP), EEnd = end(PP); EIt != EEnd; ++EIt)
       if (!Pred(*EIt))
         return false;
     return true;


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