[PATCH] D135440: [SourceManager] Speedup getFileIDLocal with a separate Offset Table.

[Haojian Wu via Phabricator via cfe-commits]

hokein added a comment.

More data on clang memory usage (measured with the `clang -cc1 -fsyntax-only -print-stats`, AST size = ASTContext + Decl + Stmt/Expr; Total = AST size + SourceManager size)

The memory increase for C++ is negligible (< 1%), but for C, we have ~5% memory increase.

|                | AST size | SourceManager size | Total               |
| SemaExpr.cpp   | 275.1 MB | 15MB -> 16.6 MB    | 290.1MB-> 291.7MB   |
| FindTarget.cpp | 131.9MB  | 14.3MB -> 15.9MB   | 146.2MB -> 147.8 MB |
| drm_property.c | 11.4MB   | 3.6MB -> 4.4 MB    | 15MB -> 15.8MB      |
| nl80211.c      | 28.4MB   | 26.4MB -> 29.6MB   | 54.8MB -> 58MB      |


Repository:
  rG LLVM Github Monorepo

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