[llvm] [memprof] Undrift MemProfRecord (PR #120138)

[Snehasish Kumar via llvm-commits]

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@@ -0,0 +1,47 @@
+; REQUIRES: x86_64-linux
+
+; Make sure that we can undrift the MemProf profile and annotate the IR
+; accordingly.
+
+; RUN: split-file %s %t
+; RUN: llvm-profdata merge %t/memprof_annotate_yaml.yaml -o %t/memprof_annotate_yaml.memprofdata
+; RUN: opt < %t/memprof_annotate_yaml.ll -passes='memprof-use<profile-filename=%t/memprof_annotate_yaml.memprofdata>' -memprof-undrift-profile -S 2>&1 | FileCheck %s
+
+;--- memprof_annotate_yaml.yaml
+---
+HeapProfileRecords:
+  - GUID:            _Z3foov
+    AllocSites:
+      - Callstack:
+          - { Function: _Z3foov, LineOffset: 3, Column: 30, IsInlineFrame: false }
+          - { Function: main, LineOffset: 2, Column: 5, IsInlineFrame: false }
+        MemInfoBlock:
+          # With these numbers, llvm::memprof::getAllocType will determine that
+          # the call to new is cold.  See MemoryProfileInfo.cpp for details.
+          TotalSize:                  400
+          AllocCount:                 1
+          TotalLifetimeAccessDensity: 1
+          TotalLifetime:              1000000
+    CallSites:       []
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snehasish wrote:

Based on the CallSites profile added below bar should have a call to foo (at offset 10) and bar (at offset 20). I don't see these in the IR on L51-L57. I'm expecting that there would be a call to foo with a `!callsite` annotation which we need to check. This would cover the code introduced in MemProfiler.cpp:937. 

Additionally, we also want to cover the case where a `!memprof` annotation is introduced. This happens when a single allocation site has hot and cold allocation stacks. Take a look at llvm/test/Transforms/PGOProfile/memprof.ll for examples.

https://github.com/llvm/llvm-project/pull/120138