[llvm] [PseudoProbe] Fix cleanup for pseudo probe desc and discriminator (PR #119660)

[Haohai Wen via llvm-commits]

https://github.com/HaohaiWen created https://github.com/llvm/llvm-project/pull/119660

When using -sample-profile-remove-probe, pseudo probe desc should
also be removed and dwarf discriminator for call instruction should
be restored.

>From 2eb4dca3165f664e088dec8aab521edcac449524 Mon Sep 17 00:00:00 2001
From: Haohai Wen <haohai.wen at intel.com>
Date: Thu, 12 Dec 2024 13:36:32 +0800
Subject: [PATCH] [PseudoProbe] Fix cleanup for pseudo probe desc and
 discriminator

When using -sample-profile-remove-probe, pseudo probe desc should
also be removed and dwarf discriminator for call instruction should
be restored.
---
 llvm/lib/Transforms/IPO/SampleProfile.cpp     | 24 +++++++++++++++----
 .../SampleProfile/pseudo-probe-profile.ll     |  2 ++
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Transforms/IPO/SampleProfile.cpp b/llvm/lib/Transforms/IPO/SampleProfile.cpp
index b2fa66f2a6d379..603beb3b883d7f 100644
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -529,7 +529,7 @@ class SampleProfileLoader final : public SampleProfileLoaderBaseImpl<Function> {
   void generateMDProfMetadata(Function &F);
   bool rejectHighStalenessProfile(Module &M, ProfileSummaryInfo *PSI,
                                   const SampleProfileMap &Profiles);
-  void removePseudoProbeInsts(Module &M);
+  void removePseudoProbeInstsDiscriminator(Module &M);
 
   /// Map from function name to Function *. Used to find the function from
   /// the function name. If the function name contains suffix, additional
@@ -2138,13 +2138,25 @@ bool SampleProfileLoader::rejectHighStalenessProfile(
   return false;
 }
 
-void SampleProfileLoader::removePseudoProbeInsts(Module &M) {
+void SampleProfileLoader::removePseudoProbeInstsDiscriminator(Module &M) {
   for (auto &F : M) {
     std::vector<Instruction *> InstsToDel;
     for (auto &BB : F) {
       for (auto &I : BB) {
         if (isa<PseudoProbeInst>(&I))
           InstsToDel.push_back(&I);
+        else if (isa<CallBase>(&I))
+          if (const DILocation *DIL = I.getDebugLoc().get()) {
+            // Restore dwarf discriminator for call.
+            unsigned Discriminator = DIL->getDiscriminator();
+            if (DILocation::isPseudoProbeDiscriminator(Discriminator)) {
+              std::optional<uint32_t> DwarfDiscriminator =
+                  PseudoProbeDwarfDiscriminator::extractDwarfBaseDiscriminator(
+                      Discriminator);
+              I.setDebugLoc(DIL->cloneWithDiscriminator(
+                  DwarfDiscriminator ? *DwarfDiscriminator : 0));
+            }
+          }
       }
     }
     for (auto *I : InstsToDel)
@@ -2224,8 +2236,12 @@ bool SampleProfileLoader::runOnModule(Module &M, ModuleAnalysisManager *AM,
          notInlinedCallInfo)
       updateProfileCallee(pair.first, pair.second.entryCount);
 
-  if (RemoveProbeAfterProfileAnnotation && FunctionSamples::ProfileIsProbeBased)
-    removePseudoProbeInsts(M);
+  if (RemoveProbeAfterProfileAnnotation &&
+      FunctionSamples::ProfileIsProbeBased) {
+    removePseudoProbeInstsDiscriminator(M);
+    if (auto *FuncInfo = M.getNamedMetadata(PseudoProbeDescMetadataName))
+      M.eraseNamedMetadata(FuncInfo);
+  }
 
   return retval;
 }
diff --git a/llvm/test/Transforms/SampleProfile/pseudo-probe-profile.ll b/llvm/test/Transforms/SampleProfile/pseudo-probe-profile.ll
index b52f93763d4926..66dbc49a1d210a 100644
--- a/llvm/test/Transforms/SampleProfile/pseudo-probe-profile.ll
+++ b/llvm/test/Transforms/SampleProfile/pseudo-probe-profile.ll
@@ -4,6 +4,8 @@
 ; RUN: opt < %t -passes=sample-profile -sample-profile-file=%S/Inputs/pseudo-probe-profile.prof -sample-profile-remove-probe -S | FileCheck %s -check-prefix=REMOVE-PROBE
 
 ; REMOVE-PROBE-NOT: call void @llvm.pseudoprobe
+; REMOVE-PROBE-NOT: !llvm.pseudo_probe_desc
+; REMOVE-PROBE:     !DILexicalBlockFile({{.*}}, discriminator: 0)
 
 define dso_local i32 @foo(i32 %x, ptr %f) #0 !dbg !4 {
 entry: