From: Jonathan Wakely <jwakely@redhat.com>
Date: Wed, 27 Nov 2024 11:52:40 +0000 (+0000)
Subject: libstdc++: Add cold attribute to assertion failure functions [PR117650]
X-Git-Tag: basepoints/gcc-16~3821
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=17db5742a555d4f8fd5fa324adb6d1e5c55374be;p=thirdparty%2Fgcc.git

libstdc++: Add cold attribute to assertion failure functions [PR117650]

This helps the compiler to split the cold path into a separate clone, so
that the hot path is a smaller function that uses less icache, and the
cold path is only fetched into the icache if actually executed.

libstdc++-v3/ChangeLog:

	PR libstdc++/117650
	* include/bits/c++config (__glibcxx_assert_fail): Add cold
	attribute.
	* include/debug/formatter.h (_Error_formatter::_M_error):
	Likewise.
---

diff --git a/libstdc++-v3/include/bits/c++config b/libstdc++-v3/include/bits/c++config
index 236906d2f79f..c74b03013fdb 100644
--- a/libstdc++-v3/include/bits/c++config
+++ b/libstdc++-v3/include/bits/c++config
@@ -610,7 +610,7 @@ namespace std
 {
 #pragma GCC visibility push(default)
   // Don't use <cassert> because this should be unaffected by NDEBUG.
-  extern "C++" _GLIBCXX_NORETURN
+  extern "C++" _GLIBCXX_NORETURN __attribute__((__cold__))
   void
   __glibcxx_assert_fail /* Called when a precondition violation is detected. */
     (const char* __file, int __line, const char* __function,
diff --git a/libstdc++-v3/include/debug/formatter.h b/libstdc++-v3/include/debug/formatter.h
index 4f5a4539bb9f..df7f6965a4c8 100644
--- a/libstdc++-v3/include/debug/formatter.h
+++ b/libstdc++-v3/include/debug/formatter.h
@@ -571,7 +571,7 @@ namespace __gnu_debug
     _Error_formatter&
     _M_message(_Debug_msg_id __id) const throw ();
 
-    _GLIBCXX_NORETURN void
+    _GLIBCXX_NORETURN __attribute__((__cold__)) void
     _M_error() const;
 
 #if !_GLIBCXX_INLINE_VERSION