[gcc/devel/omp/gcc-12] Come up with {,UN}LIKELY macros.

[Thomas Schwinge]

https://gcc.gnu.org/g:44b77201a5431450f608b4538fefb1319127de13

commit 44b77201a5431450f608b4538fefb1319127de13
Author: Martin Liska <mliska@suse.cz>
Date:   Thu Feb 3 10:58:18 2022 +0100

    Come up with {,UN}LIKELY macros.
    
    gcc/ChangeLog:
    
            * system.h (LIKELY): Define.
            (UNLIKELY): Likewise.
    
    (cherry picked from commit 22d9c8802add09a93308319fc37dd3a0f1125393, partial)

Diff:
---
 gcc/ChangeLog.omp | 8 ++++++++
 gcc/system.h      | 3 +++
 2 files changed, 11 insertions(+)

diff --git a/gcc/ChangeLog.omp b/gcc/ChangeLog.omp
index 4f80bcbd356..30c3abfc15b 100644
--- a/gcc/ChangeLog.omp
+++ b/gcc/ChangeLog.omp
@@ -1,3 +1,11 @@
+2022-09-23  Thomas Schwinge  <thomas@codesourcery.com>
+
+	Backport from master branch:
+	2022-05-09  Martin Liska  <mliska@suse.cz>
+
+	* system.h (LIKELY): Define.
+	(UNLIKELY): Likewise.
+
 2022-09-12  Tobias Burnus  <tobias@codesourcery.com>
 
 	Backport from mainline:
diff --git a/gcc/system.h b/gcc/system.h
index e10c34f70ec..6b6868d0bbf 100644
--- a/gcc/system.h
+++ b/gcc/system.h
@@ -736,6 +736,9 @@ extern int vsnprintf (char *, size_t, const char *, va_list);
 #define __builtin_expect(a, b) (a)
 #endif
 
+#define LIKELY(x) (__builtin_expect ((x), 1))
+#define UNLIKELY(x) (__builtin_expect ((x), 0))
+
 /* Some of the headers included by <memory> can use "abort" within a
    namespace, e.g. "_VSTD::abort();", which fails after we use the
    preprocessor to redefine "abort" as "fancy_abort" below.  */