[clang] [clang][modules] Avoid allocations when reading blob paths (PR #113984)

[Jan Svoboda via cfe-commits]

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@@ -1341,9 +1341,22 @@ class ASTReader
   serialization::InputFile getInputFile(ModuleFile &F, unsigned ID,
                                         bool Complain = true);
 
+  /// Buffer we use as temporary storage backing resolved paths.
+  SmallString<256> PathBuf;
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jansvoboda11 wrote:

Because if callers construct fresh buffers all the time, each call to `ResolveImportedPath()` allocates. If the buffer is global, the function never allocates again after the longest path has been resolved.

https://github.com/llvm/llvm-project/pull/113984