The patch titled
Subject: linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP*
has been added to the -mm tree. Its filename is
linux-compiler-clangh-define-have_builtin_bswap.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/linux-compiler-clangh-define-have_builtin_bswap.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/linux-compiler-clangh-define-have_builtin_bswap.patch
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------------------------------------------------------
From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP*
Separating compiler-clang.h from compiler-gcc.h inadventently dropped the
definitions of the three HAVE_BUILTIN_BSWAP macros, which requires falling
back to the open-coded version and hoping that the compiler detects it.
Since all versions of clang support the __builtin_bswap interfaces, add
back the flags and have the headers pick these up automatically.
This results in a 4% improvement of compilation speed for arm defconfig.
Link: https://lkml.kernel.org/r/20210225164513.3667778-1-arnd@xxxxxxxxxx
Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Cc: Nathan Chancellor <nathan@xxxxxxxxxx>
Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Miguel Ojeda <ojeda@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
Cc: Arvind Sankar <nivedita@xxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/compiler-clang.h | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/include/linux/compiler-clang.h~linux-compiler-clangh-define-have_builtin_bswap
+++ a/include/linux/compiler-clang.h
@@ -31,6 +31,16 @@
#define __no_sanitize_thread
#endif
+/*
+ * sparse (__CHECKER__) pretends to be gcc, but can't do constant
+ * folding in __builtin_bswap*() (yet), so don't set these for it.
+ */
+#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__)
+#define __HAVE_BUILTIN_BSWAP32__
+#define __HAVE_BUILTIN_BSWAP64__
+#define __HAVE_BUILTIN_BSWAP16__
+#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */
+
#if __has_feature(undefined_behavior_sanitizer)
/* GCC does not have __SANITIZE_UNDEFINED__ */
#define __no_sanitize_undefined \
_
Patches currently in -mm which might be from arnd@xxxxxxxx are
linux-compiler-clangh-define-have_builtin_bswap.patch
