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authorH.J. Lu <hjl.tools@gmail.com>2017-06-05 08:28:01 -0700
committerH.J. Lu <hjl.tools@gmail.com>2017-06-05 08:28:13 -0700
commit9cd30491dd6d9d4c5e9372d7a5c75f78f3a11260 (patch)
tree9bdc9658b03a2c6038871f6b19eff9838379c382 /sysdeps
parent30cb625a21bc7ad450fdc45d1f682e2b27c353de (diff)
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x86: Add macros to implement ifunce selection in C
These macros are used to implement ifunc selection in C. To implement an ifunc function, foo, which returns the address of __foo_sse2 or __foo_avx2: __foo_avx2: #define foo __redirect_foo #define __foo __redirect___foo #include <foo.h> #undef foo #undef __foo #define SYMBOL_NAME foo #include <init-arch.h> extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden; extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2) attribute_hidden; static inline void * foo_selector (void) { if (use AVX2) return OPTIMIZE (avx2); return OPTIMIZE (sse2); } libc_ifunc_redirected (__redirect_foo, foo, foo_selector ()); * sysdeps/x86/init-arch.h (PASTER1): New. (EVALUATOR1): Likewise. (PASTER2): Likewise. (EVALUATOR2): Likewise. (REDIRECT_NAME): Likewise. (OPTIMIZE): Likewise. (IFUNC_SELECTOR): Likewise.
Diffstat (limited to 'sysdeps')
-rw-r--r--sysdeps/x86/init-arch.h40
1 files changed, 40 insertions, 0 deletions
diff --git a/sysdeps/x86/init-arch.h b/sysdeps/x86/init-arch.h
index 6cbc16b7f6..15d3f0975d 100644
--- a/sysdeps/x86/init-arch.h
+++ b/sysdeps/x86/init-arch.h
@@ -21,6 +21,46 @@
# include <ldsodefs.h>
#endif
+/* These macros are used to implement ifunc selection in C. To implement
+ an ifunc function, foo, which returns the address of __foo_sse2 or
+ __foo_avx2:
+
+ #define foo __redirect_foo
+ #define __foo __redirect___foo
+ #include <foo.h>
+ #undef foo
+ #undef __foo
+ #define SYMBOL_NAME foo
+ #include <init-arch.h>
+
+ extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
+ extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2) attribute_hidden;
+
+ static inline void *
+ foo_selector (void)
+ {
+ if (use AVX2)
+ return OPTIMIZE (avx2);
+
+ return OPTIMIZE (sse2);
+ }
+
+ libc_ifunc_redirected (__redirect_foo, foo, foo_selector ());
+
+*/
+
+#define PASTER1(x,y) x##_##y
+#define EVALUATOR1(x,y) PASTER1 (x,y)
+#define PASTER2(x,y) __##x##_##y
+#define EVALUATOR2(x,y) PASTER2 (x,y)
+
+/* Basically set '__redirect_<symbol>' to use as type definition,
+ '__<symbol>_<variant>' as the optimized implementation and
+ '<symbol>_ifunc_selector' as the IFUNC selector. */
+#define REDIRECT_NAME EVALUATOR1 (__redirect, SYMBOL_NAME)
+#define OPTIMIZE(name) EVALUATOR2 (SYMBOL_NAME, name)
+#define IFUNC_SELECTOR EVALUATOR1 (SYMBOL_NAME, ifunc_selector)
+
#ifndef __x86_64__
/* Due to the reordering and the other nifty extensions in i686, it is
not really good to use heavily i586 optimized code on an i686. It's