[all-commits] [llvm/llvm-project] d604c5: [NFC] Use find_last_of when seraching for code in ...

Kugan via All-commits all-commits at lists.llvm.org
Tue Feb 21 08:26:06 PST 2023

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: d604c57164ecdb3084c8d00f9575158fddc30f81
  Author: Kugan Vivekanandarajah <kuganv at gmail.com>
  Date:   2023-02-21 (Tue, 21 Feb 2023)

  Changed paths:
    M clang/lib/AST/ASTContext.cpp

  Log Message:
  [NFC] Use find_last_of when seraching for code in getRawCommentForDeclNoCacheImpl

ASTContext::getRawCommentForDeclNoCacheImpl in this case, extracts the text between
the comment and declaration to make sure if there are  no other declarations or preprocessor
directives between  comment or declarations.

While using Text.find_first_of or Text.find_last_of  is functionally the same,
 using Text.find_last_of terminates fast in the presence of such.

Especially in generated code with sparse comments, it takes longer
to bailout when there is code in-between. Searching from last
(with find_last_of) bails out faster.

This shows up in perf profiles with clangd in some auto-generated code.
ASTContext::getRawCommentForDeclNoCacheImpl showing as much as 18.2% in this
case. With find_last_of, this drops to 2.8%.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D141950

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