[AsmParser] Gracefully handle non-existent GV summary reference

If the module summary references a global variable that does not
exist, throw a nice error instead of asserting.

Fixes https://github.com/llvm/llvm-project/issues/74726.

llvm/include/llvm/AsmParser/LLParser.h

@@ -407,9 +407,10 @@ namespace llvm {
         std::map<std::vector<uint64_t>, WholeProgramDevirtResolution::ByArg>
             &ResByArg);
     bool parseArgs(std::vector<uint64_t> &Args);
-    void addGlobalValueToIndex(std::string Name, GlobalValue::GUID,
+    bool addGlobalValueToIndex(std::string Name, GlobalValue::GUID,
                                GlobalValue::LinkageTypes Linkage, unsigned ID,
-                               std::unique_ptr<GlobalValueSummary> Summary);
+                               std::unique_ptr<GlobalValueSummary> Summary,
+                               LocTy Loc);
     bool parseOptionalAllocs(std::vector<AllocInfo> &Allocs);
     bool parseMemProfs(std::vector<MIBInfo> &MIBs);
     bool parseAllocType(uint8_t &AllocType);

llvm/lib/AsmParser/LLParser.cpp

@@ -8622,9 +8622,9 @@ static void resolveFwdRef(ValueInfo *Fwd, ValueInfo &Resolved) {
 
 /// Stores the given Name/GUID and associated summary into the Index.
 /// Also updates any forward references to the associated entry ID.
-void LLParser::addGlobalValueToIndex(
+bool LLParser::addGlobalValueToIndex(
     std::string Name, GlobalValue::GUID GUID, GlobalValue::LinkageTypes Linkage,
-    unsigned ID, std::unique_ptr<GlobalValueSummary> Summary) {
+    unsigned ID, std::unique_ptr<GlobalValueSummary> Summary, LocTy Loc) {
   // First create the ValueInfo utilizing the Name or GUID.
   ValueInfo VI;
   if (GUID != 0) {
@@ -8634,7 +8634,9 @@ void LLParser::addGlobalValueToIndex(
     assert(!Name.empty());
     if (M) {
       auto *GV = M->getNamedValue(Name);
-      assert(GV);
+      if (!GV)
+        return error(Loc, "Reference to undefined global \"" + Name + "\"");
+
       VI = Index->getOrInsertValueInfo(GV);
     } else {
       assert(
@@ -8682,6 +8684,8 @@ void LLParser::addGlobalValueToIndex(
       NumberedValueInfos.resize(ID + 1);
     NumberedValueInfos[ID] = VI;
   }
+
+  return false;
 }
 
 /// parseSummaryIndexFlags
@@ -8728,6 +8732,7 @@ bool LLParser::parseGVEntry(unsigned ID) {
       parseToken(lltok::lparen, "expected '(' here"))
     return true;
 
+  LocTy Loc = Lex.getLoc();
   std::string Name;
   GlobalValue::GUID GUID = 0;
   switch (Lex.getKind()) {
@@ -8757,9 +8762,8 @@ bool LLParser::parseGVEntry(unsigned ID) {
     // an external definition. We pass ExternalLinkage since that is only
     // used when the GUID must be computed from Name, and in that case
     // the symbol must have external linkage.
-    addGlobalValueToIndex(Name, GUID, GlobalValue::ExternalLinkage, ID,
-                          nullptr);
-    return false;
+    return addGlobalValueToIndex(Name, GUID, GlobalValue::ExternalLinkage, ID,
+                                 nullptr, Loc);
   }
 
   // Have a list of summaries
@@ -8800,6 +8804,7 @@ bool LLParser::parseGVEntry(unsigned ID) {
 ///         [',' OptionalRefs]? ')'
 bool LLParser::parseFunctionSummary(std::string Name, GlobalValue::GUID GUID,
                                     unsigned ID) {
+  LocTy Loc = Lex.getLoc();
   assert(Lex.getKind() == lltok::kw_function);
   Lex.Lex();
 
@@ -8876,10 +8881,9 @@ bool LLParser::parseFunctionSummary(std::string Name, GlobalValue::GUID GUID,
 
   FS->setModulePath(ModulePath);
 
-  addGlobalValueToIndex(Name, GUID, (GlobalValue::LinkageTypes)GVFlags.Linkage,
-                        ID, std::move(FS));
-
-  return false;
+  return addGlobalValueToIndex(Name, GUID,
+                               (GlobalValue::LinkageTypes)GVFlags.Linkage, ID,
+                               std::move(FS), Loc);
 }
 
 /// VariableSummary
@@ -8887,6 +8891,7 @@ bool LLParser::parseFunctionSummary(std::string Name, GlobalValue::GUID GUID,
 ///         [',' OptionalRefs]? ')'
 bool LLParser::parseVariableSummary(std::string Name, GlobalValue::GUID GUID,
                                     unsigned ID) {
+  LocTy Loc = Lex.getLoc();
   assert(Lex.getKind() == lltok::kw_variable);
   Lex.Lex();
 
@@ -8934,10 +8939,9 @@ bool LLParser::parseVariableSummary(std::string Name, GlobalValue::GUID GUID,
   GS->setModulePath(ModulePath);
   GS->setVTableFuncs(std::move(VTableFuncs));
 
-  addGlobalValueToIndex(Name, GUID, (GlobalValue::LinkageTypes)GVFlags.Linkage,
-                        ID, std::move(GS));
-
-  return false;
+  return addGlobalValueToIndex(Name, GUID,
+                               (GlobalValue::LinkageTypes)GVFlags.Linkage, ID,
+                               std::move(GS), Loc);
 }
 
 /// AliasSummary
@@ -8984,10 +8988,9 @@ bool LLParser::parseAliasSummary(std::string Name, GlobalValue::GUID GUID,
     AS->setAliasee(AliaseeVI, Summary);
   }
 
-  addGlobalValueToIndex(Name, GUID, (GlobalValue::LinkageTypes)GVFlags.Linkage,
-                        ID, std::move(AS));
-
-  return false;
+  return addGlobalValueToIndex(Name, GUID,
+                               (GlobalValue::LinkageTypes)GVFlags.Linkage, ID,
+                               std::move(AS), Loc);
 }
 
 /// Flag

llvm/test/Assembler/summary-parsing-error.ll

@@ -0,0 +1,4 @@
+; RUN: not llvm-as < %s 2>&1 | FileCheck %s
+
+; CHECK: Reference to undefined global "does_not_exist"
+^0 = gv: (name: "does_not_exist")