[PATCH] D84997: [AutoFDO] Avoid merging inlinee samples multiple times

[Hongtao Yu via Phabricator via llvm-commits]

hoyFB created this revision.
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A function call can be replicated by optimizations like loop unroll and jump threading and the replicates end up sharing the sample nested callee profile. Therefore when it comes to merging samples for uninlined callees in the sample profile inliner, a callee profile can be merged multiple times which will cause an assert to fire.

This change avoids merging same callee profile for duplicate callsites by filtering out callee profiles with a non-zero head sample count.

This change also fixes another issue when merging profiles. New profile may be created for a function to merge uninlined samples for the function, if it does not come with a standalone profile. The `GUIDToFuncNameMap` which is used in compact binary profile should be populated during the merge.

Test Plan:


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D84997

Files:
  llvm/include/llvm/ProfileData/SampleProf.h
  llvm/lib/Transforms/IPO/SampleProfile.cpp


Index: llvm/lib/Transforms/IPO/SampleProfile.cpp
===================================================================
--- llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -1104,16 +1104,21 @@
     }
 
     if (ProfileMergeInlinee) {
-      // Use entry samples as head samples during the merge, as inlinees
-      // don't have head samples.
-      assert(FS->getHeadSamples() == 0 && "Expect 0 head sample for inlinee");
-      const_cast<FunctionSamples *>(FS)->addHeadSamples(FS->getEntrySamples());
-
-      // Note that we have to do the merge right after processing function.
-      // This allows OutlineFS's profile to be used for annotation during
-      // top-down processing of functions' annotation.
-      FunctionSamples *OutlineFS = Reader->getOrCreateSamplesFor(*Callee);
-      OutlineFS->merge(*FS);
+      if (FS->getHeadSamples() == 0) {
+        // Use entry samples as head samples during the merge, as inlinees
+        // don't have head samples.
+        const_cast<FunctionSamples *>(FS)->addHeadSamples(
+            FS->getEntrySamples());
+
+        // Note that we have to do the merge right after processing function.
+        // This allows OutlineFS's profile to be used for annotation during
+        // top-down processing of functions' annotation.
+        FunctionSamples *OutlineFS = Reader->getOrCreateSamplesFor(*Callee);
+        OutlineFS->merge(*FS);
+      } else
+        assert(FS->getHeadSamples() == FS->getEntrySamples() &&
+               "Expect same head and entry sample counts for profiles already "
+               "merged.");
     } else {
       auto pair =
           notInlinedCallInfo.try_emplace(Callee, NotInlinedProfileInfo{0});
Index: llvm/include/llvm/ProfileData/SampleProf.h
===================================================================
--- llvm/include/llvm/ProfileData/SampleProf.h
+++ llvm/include/llvm/ProfileData/SampleProf.h
@@ -515,6 +515,8 @@
   sampleprof_error merge(const FunctionSamples &Other, uint64_t Weight = 1) {
     sampleprof_error Result = sampleprof_error::success;
     Name = Other.getName();
+    if (!GUIDToFuncNameMap)
+      GUIDToFuncNameMap = Other.GUIDToFuncNameMap;
     MergeResult(Result, addTotalSamples(Other.getTotalSamples(), Weight));
     MergeResult(Result, addHeadSamples(Other.getHeadSamples(), Weight));
     for (const auto &I : Other.getBodySamples()) {


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