[MemProf] Match function's summary and definition strictly (#83665)

Problem description:
#81008 (comment)
Solution:
#81008 (comment)
(choose plan2)

Author: lifengxiang1025

llvm/lib/Passes/PassBuilderPipelines.cpp

@@ -299,9 +299,7 @@ static cl::opt<bool> UseLoopVersioningLICM(
     cl::desc("Enable the experimental Loop Versioning LICM pass"));
 
 namespace llvm {
-cl::opt<bool> EnableMemProfContextDisambiguation(
-    "enable-memprof-context-disambiguation", cl::init(false), cl::Hidden,
-    cl::ZeroOrMore, cl::desc("Enable MemProf context disambiguation"));
+extern cl::opt<bool> EnableMemProfContextDisambiguation;
 
 extern cl::opt<bool> EnableInferAlignmentPass;
 } // namespace llvm

llvm/lib/Transforms/IPO/FunctionImport.cpp

@@ -163,6 +163,10 @@ static cl::opt<std::string> WorkloadDefinitions(
              "}"),
     cl::Hidden);
 
+namespace llvm {
+extern cl::opt<bool> EnableMemProfContextDisambiguation;
+}
+
 // Load lazily a module from \p FileName in \p Context.
 static std::unique_ptr<Module> loadFile(const std::string &FileName,
                                         LLVMContext &Context) {
@@ -1643,7 +1647,9 @@ Expected<bool> FunctionImporter::importFunctions(
       if (Import) {
         if (Error Err = F.materialize())
           return std::move(Err);
-        if (EnableImportMetadata) {
+        // MemProf should match function's definition and summary,
+        // 'thinlto_src_module' is needed.
+        if (EnableImportMetadata || EnableMemProfContextDisambiguation) {
           // Add 'thinlto_src_module' and 'thinlto_src_file' metadata for
           // statistics and debugging.
           F.setMetadata(
@@ -1693,7 +1699,7 @@ Expected<bool> FunctionImporter::importFunctions(
         LLVM_DEBUG(dbgs() << "Is importing aliasee fn " << GO->getGUID() << " "
                           << GO->getName() << " from "
                           << SrcModule->getSourceFileName() << "\n");
-        if (EnableImportMetadata) {
+        if (EnableImportMetadata || EnableMemProfContextDisambiguation) {
           // Add 'thinlto_src_module' and 'thinlto_src_file' metadata for
           // statistics and debugging.
           Fn->setMetadata(

llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp

@@ -122,6 +122,10 @@ static cl::opt<unsigned>
                                  "frames through tail calls."));
 
 namespace llvm {
+cl::opt<bool> EnableMemProfContextDisambiguation(
+    "enable-memprof-context-disambiguation", cl::init(false), cl::Hidden,
+    cl::ZeroOrMore, cl::desc("Enable MemProf context disambiguation"));
+
 // Indicate we are linking with an allocator that supports hot/cold operator
 // new interfaces.
 cl::opt<bool> SupportsHotColdNew(
@@ -3375,10 +3379,22 @@ bool MemProfContextDisambiguation::applyImport(Module &M) {
 
     auto *GVSummary =
         ImportSummary->findSummaryInModule(TheFnVI, M.getModuleIdentifier());
-    if (!GVSummary)
-      // Must have been imported, use the first summary (might be multiple if
-      // this was a linkonce_odr).
-      GVSummary = TheFnVI.getSummaryList().front().get();
+    if (!GVSummary) {
+      // Must have been imported, use the summary which matches the definition。
+      // (might be multiple if this was a linkonce_odr).
+      auto SrcModuleMD = F.getMetadata("thinlto_src_module");
+      assert(SrcModuleMD &&
+             "enable-import-metadata is needed to emit thinlto_src_module");
+      StringRef SrcModule =
+          dyn_cast<MDString>(SrcModuleMD->getOperand(0))->getString();
+      for (auto &GVS : TheFnVI.getSummaryList()) {
+        if (GVS->modulePath() == SrcModule) {
+          GVSummary = GVS.get();
+          break;
+        }
+      }
+      assert(GVSummary && GVSummary->modulePath() == SrcModule);
+    }
 
     // If this was an imported alias skip it as we won't have the function
     // summary, and it should be cloned in the original module.