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

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-objectyaml

Author: Kazu Hirata (kazutakahirata)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/126187.diff


1 Files Affected:

- (modified) llvm/lib/ObjectYAML/DWARFEmitter.cpp (+4-7) 


``````````diff
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) {

``````````

</details>


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