[llvm] [ObjectYAML] Avoid repeated hash lookups (NFC) (PR #126187)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/126187

None

>From 72e2b35f3c893fe7fe26df0461eb2da475fdb107 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Thu, 6 Feb 2025 16:29:16 -0800
Subject: [PATCH] [ObjectYAML] Avoid repeated hash lookups (NFC)

---
 llvm/lib/ObjectYAML/DWARFEmitter.cpp | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/llvm/lib/ObjectYAML/DWARFEmitter.cpp b/llvm/lib/ObjectYAML/DWARFEmitter.cpp
index 421dfe7dfa30efb..ec5e08082b0ca59 100644
--- a/llvm/lib/ObjectYAML/DWARFEmitter.cpp
+++ b/llvm/lib/ObjectYAML/DWARFEmitter.cpp
@@ -96,12 +96,11 @@ Error DWARFYAML::emitDebugStr(raw_ostream &OS, const DWARFYAML::Data &DI) {
 StringRef DWARFYAML::Data::getAbbrevTableContentByIndex(uint64_t Index) const {
   assert(Index < DebugAbbrev.size() &&
          "Index should be less than the size of DebugAbbrev array");
-  auto It = AbbrevTableContents.find(Index);
-  if (It != AbbrevTableContents.cend())
+  auto [It, Inserted] = AbbrevTableContents.try_emplace(Index);
+  if (!Inserted)
     return It->second;
 
-  std::string AbbrevTableBuffer;
-  raw_string_ostream OS(AbbrevTableBuffer);
+  raw_string_ostream OS(It->second);
 
   uint64_t AbbrevCode = 0;
   for (const DWARFYAML::Abbrev &AbbrevDecl : DebugAbbrev[Index].Table) {
@@ -123,9 +122,7 @@ StringRef DWARFYAML::Data::getAbbrevTableContentByIndex(uint64_t Index) const {
   // consisting of a 0 byte for the abbreviation code.
   OS.write_zeros(1);
 
-  AbbrevTableContents.insert({Index, AbbrevTableBuffer});
-
-  return AbbrevTableContents[Index];
+  return It->second;
 }
 
 Error DWARFYAML::emitDebugAbbrev(raw_ostream &OS, const DWARFYAML::Data &DI) {