Fix crash from [CGData] Global Merge Functions (#112671) (#116241)

Module summary index is optional for this pass, and we shouldn't run it,
but import it as necessary.

Author: kyulee-com

llvm/include/llvm/CodeGen/GlobalMergeFunctions.h

@@ -78,6 +78,10 @@ class GlobalMergeFunc {
 
 /// Global function merging pass for new pass manager.
 struct GlobalMergeFuncPass : public PassInfoMixin<GlobalMergeFuncPass> {
+  const ModuleSummaryIndex *ImportSummary = nullptr;
+  GlobalMergeFuncPass() = default;
+  GlobalMergeFuncPass(const ModuleSummaryIndex *ImportSummary)
+      : ImportSummary(ImportSummary) {}
   PreservedAnalyses run(Module &M, AnalysisManager<Module> &);
 };
 

llvm/lib/CodeGen/GlobalMergeFunctions.cpp

@@ -637,7 +637,6 @@ bool GlobalMergeFuncPassWrapper::runOnModule(Module &M) {
 
 PreservedAnalyses GlobalMergeFuncPass::run(Module &M,
                                            AnalysisManager<Module> &AM) {
-  ModuleSummaryIndex *Index = &(AM.getResult<ModuleSummaryIndexAnalysis>(M));
-  bool Changed = GlobalMergeFunc(Index).run(M);
+  bool Changed = GlobalMergeFunc(ImportSummary).run(M);
   return Changed ? PreservedAnalyses::none() : PreservedAnalyses::all();
 }

llvm/test/CodeGen/Generic/cgdata-merge-crash.ll

@@ -0,0 +1,6 @@
+; This test checks if the global merge func pass should not build module summary.
+
+; RUN: opt --passes=global-merge-func %s -o /dev/null
+
+@0 = global { { ptr, i32, i32 } } { { ptr, i32, i32 } { ptr null, i32 19, i32 5 } }
+@1 = global { { ptr, i32, i32 } } { { ptr, i32, i32 } { ptr null, i32 22, i32 5 } }