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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.
This commit is contained in:
H.J. Lu 2017-06-05 08:28:01 -07:00
parent 30cb625a21
commit 9cd30491dd
2 changed files with 51 additions and 0 deletions
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11
ChangeLog
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@ -1,3 +1,14 @@
2017-06-05 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.
2017-06-05 H.J. Lu <hongjiu.lu@intel.com>
* sysdeps/x86_64/strlen.S (PMINU): New.

40
sysdeps/x86/init-arch.h
View File

@ -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