[llvm] [MemProf] Add option to print function GUIDs during matching (PR #170946)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-pgo

Author: Teresa Johnson (teresajohnson)

<details>
<summary>Changes</summary>

For debugging, add -memprof-function-guids option that will cause
memprof matching to emit the computed function GUID for every function
definition in the module to stderr. This is helpful because the profile
only contains the function GUID and not the names.


---
Full diff: https://github.com/llvm/llvm-project/pull/170946.diff


2 Files Affected:

- (modified) llvm/lib/Transforms/Instrumentation/MemProfUse.cpp (+8) 
- (modified) llvm/test/Transforms/PGOProfile/memprof-dump-matched-alloc-site.ll (+8-1) 


``````````diff
diff --git a/llvm/lib/Transforms/Instrumentation/MemProfUse.cpp b/llvm/lib/Transforms/Instrumentation/MemProfUse.cpp
index b72d41a748857..5592f190a7e55 100644
--- a/llvm/lib/Transforms/Instrumentation/MemProfUse.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemProfUse.cpp
@@ -62,6 +62,11 @@ static cl::opt<bool>
                                      "context in this module's profiles"),
                             cl::Hidden, cl::init(false));
 
+static cl::opt<bool>
+    PrintFunctionGuids("memprof-function-guids",
+                       cl::desc("Print function GUIDs computed for matching"),
+                       cl::Hidden, cl::init(false));
+
 static cl::opt<bool>
     SalvageStaleProfile("memprof-salvage-stale-profile",
                         cl::desc("Salvage stale MemProf profile"),
@@ -562,6 +567,9 @@ static void readMemprof(Module &M, Function &F,
   // linkage function.
   auto FuncName = F.getName();
   auto FuncGUID = Function::getGUIDAssumingExternalLinkage(FuncName);
+  if (PrintFunctionGuids)
+    errs() << "MemProf: Function GUID " << FuncGUID << " is " << FuncName
+           << "\n";
   std::optional<memprof::MemProfRecord> MemProfRec;
   auto Err = MemProfReader->getMemProfRecord(FuncGUID).moveInto(MemProfRec);
   if (Err) {
diff --git a/llvm/test/Transforms/PGOProfile/memprof-dump-matched-alloc-site.ll b/llvm/test/Transforms/PGOProfile/memprof-dump-matched-alloc-site.ll
index 2dcaa9d492869..b6afcf6de922e 100644
--- a/llvm/test/Transforms/PGOProfile/memprof-dump-matched-alloc-site.ll
+++ b/llvm/test/Transforms/PGOProfile/memprof-dump-matched-alloc-site.ll
@@ -26,7 +26,7 @@
 ; REQUIRES: x86_64-linux
 ; RUN: split-file %s %t
 ; RUN: llvm-profdata merge %t/memprof-dump-matched-alloc-site.yaml -o %t/memprof-dump-matched-alloc-site.memprofdata
-; RUN: opt < %t/memprof-dump-matched-alloc-site.ll -passes='memprof-use<profile-filename=%t/memprof-dump-matched-alloc-site.memprofdata>' -memprof-print-match-info -S 2>&1 | FileCheck %s
+; RUN: opt < %t/memprof-dump-matched-alloc-site.ll -passes='memprof-use<profile-filename=%t/memprof-dump-matched-alloc-site.memprofdata>' -memprof-print-match-info -memprof-function-guids -S 2>&1 | FileCheck %s
 
 ;--- memprof-dump-matched-alloc-site.yaml
 ---
@@ -77,6 +77,13 @@ HeapProfileRecords:
       # Kept empty here because this section is irrelevant for this test.
 ...
 ;--- memprof-dump-matched-alloc-site.ll
+
+;; From -memprof-function-guids
+; CHECK: MemProf: Function GUID 4708092051066754107 is _Z2f1v
+; CHECK: MemProf: Function GUID 14255129117669598641 is _Z2f2v
+; CHECK: MemProf: Function GUID 2771528421763978342 is _Z2f3v
+
+;; From -memprof-print-match-info
 ; CHECK: MemProf notcold context with id 5736731103568718490 has total profiled size 3 is matched with 1 frames
 ; CHECK: MemProf notcold context with id 5736731103568718490 has total profiled size 3 is matched with 2 frames
 ; CHECK: MemProf notcold context with id 5736731103568718490 has total profiled size 3 is matched with 3 frames

``````````

</details>


https://github.com/llvm/llvm-project/pull/170946