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[PATCH 1/8] x86: Add macros to implement ifunce selection in C
- From: "H.J. Lu" <hongjiu dot lu at intel dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Date: Fri, 2 Jun 2017 12:42:59 -0700
- Subject: [PATCH 1/8] x86: Add macros to implement ifunce selection in C
- Authentication-results: sourceware.org; auth=none
- Reply-to: "H.J. Lu" <hjl dot tools at gmail dot com>
Should they go into include/libc-symbols.h so that they are available
everywhere?
H.J.
---
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 ());
2017-06-02 Adhemerval Zanella <adhemerval.zanella@linaro.org>
H.J. Lu <hongjiu.lu@intel.com>
* sysdeps/x86/init-arch.h (PASTER1): New.
(EVALUATOR1): Likewise.
(PASTER2): Likewise.
(EVALUATOR2): Likewise.
(REDIRECT_NAME): Likewise.
(OPTIMIZE): Likewise.
(IFUNC_SELECTOR): Likewise.
---
sysdeps/x86/init-arch.h | 40 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)
diff --git a/sysdeps/x86/init-arch.h b/sysdeps/x86/init-arch.h
index 6cbc16b..15d3f09 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
--
2.9.4