[all-commits] [llvm/llvm-project] 243bfe: [analyzer][HTMLRewriter] Cache partial rewrite res...

[Artem Dergachev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 243bfed68367263cfc3fb3f396660acf60051fbf
      https://github.com/llvm/llvm-project/commit/243bfed68367263cfc3fb3f396660acf60051fbf
  Author: Artem Dergachev <adergachev at apple.com>
  Date:   2024-02-01 (Thu, 01 Feb 2024)

  Changed paths:
    M clang/include/clang/Rewrite/Core/HTMLRewrite.h
    M clang/lib/Rewrite/HTMLRewrite.cpp
    M clang/lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp
    A clang/test/Analysis/html_diagnostics/counter.c

  Log Message:
  -----------
  [analyzer][HTMLRewriter] Cache partial rewrite results. (#80220)

This is a follow-up for 721dd3bc2 [analyzer] NFC: Don't regenerate
duplicate HTML reports.

Because HTMLRewriter re-runs the Lexer for syntax highlighting and macro
expansion purposes, it may get fairly expensive when the rewriter is
invoked multiple times on the same file. In the static analyzer (which
uses HTMLRewriter for HTML output mode) we only get away with this
because there are usually very few reports emitted per file. But if loud
checkers are enabled, such as `webkit.*`, this may explode in complexity
and even cause the compiler to run over the 32-bit SourceLocation
addressing limit.

This patch caches intermediate results so that re-lexing only needed to
happen once.

As the clever __COUNTER__ test demonstrates, "once" is still too many.
Ideally we shouldn't re-lex anything at all, which remains a TODO.