[clang] [clang][builtins] Return a `SmallString` from `Builtin::Context::getQuotedName()` (PR #227963)

[Chandler Carruth via cfe-commits]

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@@ -96,11 +96,13 @@ std::string Builtin::Context::getName(unsigned ID) const {
   return I.getName(Shard);
 }
 
-std::string Builtin::Context::getQuotedName(unsigned ID) const {
+SmallString<64> Builtin::Context::getQuotedName(unsigned ID) const {
   const auto &[Shard, I] = getShardAndInfo(ID);
-  return (Twine("'") + Shard.NamePrefix + (*Shard.Strings)[I.Offsets.Name] +
-          "'")
-      .str();
+  SmallString<64> Result("'");
+  Result += Shard.NamePrefix;
+  Result += (*Shard.Strings)[I.Offsets.Name];
+  Result += '\'';
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chandlerc wrote:

Could we use a twine or `formatv` here so that we compute the final size before initializing it? Or does this end up being faster in practice?

https://github.com/llvm/llvm-project/pull/227963