[clang] [TableGen] Use heterogenous lookups with std::map (NFC) (PR #115633)

[Kazu Hirata via cfe-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/115633

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


>From 555068b382041e37e00891416fee3cac7982f071 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Sat, 9 Nov 2024 14:59:35 -0800
Subject: [PATCH] [TableGen] Use heterogenous lookups with std::map (NFC)

Heterogenous lookups allow us to call find with StringRef, avoiding a
temporary heap allocation of std::string.
---
 clang/utils/TableGen/NeonEmitter.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/clang/utils/TableGen/NeonEmitter.cpp b/clang/utils/TableGen/NeonEmitter.cpp
index c6d82646b40de2..7081e5c9ae93e8 100644
--- a/clang/utils/TableGen/NeonEmitter.cpp
+++ b/clang/utils/TableGen/NeonEmitter.cpp
@@ -578,7 +578,7 @@ class Intrinsic {
 class NeonEmitter {
   const RecordKeeper &Records;
   DenseMap<const Record *, ClassKind> ClassMap;
-  std::map<std::string, std::deque<Intrinsic>> IntrinsicMap;
+  std::map<std::string, std::deque<Intrinsic>, std::less<>> IntrinsicMap;
   unsigned UniqueNumber;
 
   void createIntrinsic(const Record *R, SmallVectorImpl<Intrinsic *> &Out);
@@ -1937,9 +1937,9 @@ void Intrinsic::indexBody() {
 Intrinsic &NeonEmitter::getIntrinsic(StringRef Name, ArrayRef<Type> Types,
                                      std::optional<std::string> MangledName) {
   // First, look up the name in the intrinsic map.
-  assert_with_loc(IntrinsicMap.find(Name.str()) != IntrinsicMap.end(),
+  assert_with_loc(IntrinsicMap.find(Name) != IntrinsicMap.end(),
                   ("Intrinsic '" + Name + "' not found!").str());
-  auto &V = IntrinsicMap.find(Name.str())->second;
+  auto &V = IntrinsicMap.find(Name)->second;
   std::vector<Intrinsic *> GoodVec;
 
   // Create a string to print if we end up failing.