[all-commits] [llvm/llvm-project] 1306e1: [-Wunsafe-buffer-usage] Speed up warning a bit (#2...

[Nico Weber via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1306e151f1b7874b0dee2e8b037a5a117e6e809b
      https://github.com/llvm/llvm-project/commit/1306e151f1b7874b0dee2e8b037a5a117e6e809b
  Author: Nico Weber <thakis at chromium.org>
  Date:   2026-09-28 (Mon, 28 Sep 2026)

  Changed paths:
    M clang/lib/Analysis/UnsafeBufferUsage.cpp

  Log Message:
  -----------
  [-Wunsafe-buffer-usage] Speed up warning a bit (#226605)

Checking a type is faster than calling ignoreUnsafeBufferIn...(). The
latter has to get the Stmt's begin loc, look up diagnostic state and
suppression, etc. And the type check lets us skip most Stmts cheaply, so
do that first.

In a sampling profile of 48 Chromium TUs (which are built with
-Wunsafe-buffer-usage), UnsafeBufferUsageReporter's
ignoreUnsafeBufferInLibcCall() and ignoreUnsafeBufferInContainer() were
1.35% and 1.29% of the total compile time, and 3.75% for
checkUnsafeBufferUsage() as a whole.

For 60 random Chromium TUs drawn with probability proportional to their
compile time, sum over all TUs:

    CPU time: 242.9 s => 237.5 s, -2.2%
    instructions: 2452.6e9 => 2371.8e9, -3.3%

No behavior change.



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