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authorMichael S. Tsirkin <mst@redhat.com>2019-01-02 23:57:49 +0300
committerMiguel Ojeda <miguel.ojeda.sandonis@gmail.com>2019-01-09 13:36:41 +0300
commit3e2ffd655cc6a694608d997738989ff5572a8266 (patch)
tree404f9e5008513f378ebfb74b94e8723ca63113b5 /include/linux
parentbfeffd155283772bbe78c6a05dec7c0128ee500c (diff)
downloadlinux-3e2ffd655cc6a694608d997738989ff5572a8266.tar.xz
include/linux/compiler*.h: fix OPTIMIZER_HIDE_VAR
Since commit 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") clang no longer reuses the OPTIMIZER_HIDE_VAR macro from compiler-gcc - instead it gets the version in include/linux/compiler.h. Unfortunately that version doesn't actually prevent compiler from optimizing out the variable. Fix up by moving the macro out from compiler-gcc.h to compiler.h. Compilers without incline asm support will keep working since it's protected by an ifdef. Also fix up comments to match reality since we are no longer overriding any macros. Build-tested with gcc and clang. Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") Cc: Eli Friedman <efriedma@codeaurora.org> Cc: Joe Perches <joe@perches.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/compiler-clang.h5
-rw-r--r--include/linux/compiler-gcc.h4
-rw-r--r--include/linux/compiler-intel.h4
-rw-r--r--include/linux/compiler.h4
4 files changed, 6 insertions, 11 deletions
diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
index 39f668d5066b..333a6695a918 100644
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -3,9 +3,8 @@
#error "Please don't include <linux/compiler-clang.h> directly, include <linux/compiler.h> instead."
#endif
-/* Some compiler specific definitions are overwritten here
- * for Clang compiler
- */
+/* Compiler specific definitions for Clang compiler */
+
#define uninitialized_var(x) x = *(&(x))
/* same as gcc, this was present in clang-2.6 so we can assume it works
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 5776da43da97..7b834e37d0c0 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -58,10 +58,6 @@
(typeof(ptr)) (__ptr + (off)); \
})
-/* Make the optimizer believe the variable can be manipulated arbitrarily. */
-#define OPTIMIZER_HIDE_VAR(var) \
- __asm__ ("" : "=r" (var) : "0" (var))
-
/*
* A trick to suppress uninitialized variable warning without generating any
* code
diff --git a/include/linux/compiler-intel.h b/include/linux/compiler-intel.h
index 517bd14e1222..b17f3cd18334 100644
--- a/include/linux/compiler-intel.h
+++ b/include/linux/compiler-intel.h
@@ -5,9 +5,7 @@
#ifdef __ECC
-/* Some compiler specific definitions are overwritten here
- * for Intel ECC compiler
- */
+/* Compiler specific definitions for Intel ECC compiler */
#include <asm/intrinsics.h>
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index fc5004a4b07d..445348facea9 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -161,7 +161,9 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
#endif
#ifndef OPTIMIZER_HIDE_VAR
-#define OPTIMIZER_HIDE_VAR(var) barrier()
+/* Make the optimizer believe the variable can be manipulated arbitrarily. */
+#define OPTIMIZER_HIDE_VAR(var) \
+ __asm__ ("" : "=r" (var) : "0" (var))
#endif
/* Not-quite-unique ID. */