[ThinLTO] Use heterogenous lookups with std::map (NFC) (llvm#115812)

Heterogenous lookups allow us to call find with StringRef, avoiding a
temporary heap allocation of std::string.

Author: kazutakahirata

llvm/include/llvm/IR/ModuleSummaryIndex.h

@@ -1399,8 +1399,8 @@ class ModuleSummaryIndex {
   /// True if some of the FunctionSummary contains a ParamAccess.
   bool HasParamAccess = false;
 
-  std::set<std::string> CfiFunctionDefs;
-  std::set<std::string> CfiFunctionDecls;
+  std::set<std::string, std::less<>> CfiFunctionDefs;
+  std::set<std::string, std::less<>> CfiFunctionDecls;
 
   // Used in cases where we want to record the name of a global, but
   // don't have the string owned elsewhere (e.g. the Strtab on a module).
@@ -1647,11 +1647,19 @@ class ModuleSummaryIndex {
     return I == OidGuidMap.end() ? 0 : I->second;
   }
 
-  std::set<std::string> &cfiFunctionDefs() { return CfiFunctionDefs; }
-  const std::set<std::string> &cfiFunctionDefs() const { return CfiFunctionDefs; }
+  std::set<std::string, std::less<>> &cfiFunctionDefs() {
+    return CfiFunctionDefs;
+  }
+  const std::set<std::string, std::less<>> &cfiFunctionDefs() const {
+    return CfiFunctionDefs;
+  }
 
-  std::set<std::string> &cfiFunctionDecls() { return CfiFunctionDecls; }
-  const std::set<std::string> &cfiFunctionDecls() const { return CfiFunctionDecls; }
+  std::set<std::string, std::less<>> &cfiFunctionDecls() {
+    return CfiFunctionDecls;
+  }
+  const std::set<std::string, std::less<>> &cfiFunctionDecls() const {
+    return CfiFunctionDecls;
+  }
 
   /// Add a global value summary for a value.
   void addGlobalValueSummary(const GlobalValue &GV,

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -7959,15 +7959,17 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
       break;
 
     case bitc::FS_CFI_FUNCTION_DEFS: {
-      std::set<std::string> &CfiFunctionDefs = TheIndex.cfiFunctionDefs();
+      std::set<std::string, std::less<>> &CfiFunctionDefs =
+          TheIndex.cfiFunctionDefs();
       for (unsigned I = 0; I != Record.size(); I += 2)
         CfiFunctionDefs.insert(
             {Strtab.data() + Record[I], static_cast<size_t>(Record[I + 1])});
       break;
     }
 
     case bitc::FS_CFI_FUNCTION_DECLS: {
-      std::set<std::string> &CfiFunctionDecls = TheIndex.cfiFunctionDecls();
+      std::set<std::string, std::less<>> &CfiFunctionDecls =
+          TheIndex.cfiFunctionDecls();
       for (unsigned I = 0; I != Record.size(); I += 2)
         CfiFunctionDecls.insert(
             {Strtab.data() + Record[I], static_cast<size_t>(Record[I + 1])});

llvm/lib/Transforms/IPO/LowerTypeTests.cpp

@@ -2037,10 +2037,9 @@ bool LowerTypeTestsModule::lower() {
       // have the same name, but it's not the one we are looking for.
       if (F.hasLocalLinkage())
         continue;
-      if (ImportSummary->cfiFunctionDefs().count(std::string(F.getName())))
+      if (ImportSummary->cfiFunctionDefs().count(F.getName()))
         Defs.push_back(&F);
-      else if (ImportSummary->cfiFunctionDecls().count(
-                   std::string(F.getName())))
+      else if (ImportSummary->cfiFunctionDecls().count(F.getName()))
         Decls.push_back(&F);
     }