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

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/115812

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


>From c4fbc5a094918cc832362459758a607ccb118d88 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Mon, 11 Nov 2024 07:46:13 -0800
Subject: [PATCH] [ThinLTO] Use heterogenous lookups with std::map (NFC)

Heterogenous lookups allow us to call find with StringRef, avoiding a
temporary heap allocation of std::string.
---
 llvm/include/llvm/IR/ModuleSummaryIndex.h  | 20 ++++++++++++++------
 llvm/lib/Bitcode/Reader/BitcodeReader.cpp  |  6 ++++--
 llvm/lib/Transforms/IPO/LowerTypeTests.cpp |  5 ++---
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/llvm/include/llvm/IR/ModuleSummaryIndex.h b/llvm/include/llvm/IR/ModuleSummaryIndex.h
index 1cfe7c15f97dbc..2ff5b4a42643d8 100644
--- a/llvm/include/llvm/IR/ModuleSummaryIndex.h
+++ b/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,
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 3e82aa7188bd67..91b1917a3c0c99 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -7959,7 +7959,8 @@ 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])});
@@ -7967,7 +7968,8 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
     }
 
     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])});
diff --git a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
index 70f83892c37390..bfcf491f36ea1f 100644
--- a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
+++ b/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);
     }