[PATCH v3 12/19] x86: Fix strstr ifunc on clang

[Adhemerval Zanella]

clang triggers multiple issue on how ifunc macro are used:

  ../sysdeps/x86_64/multiarch/strstr.c:38:54: error: attribute declaration must precede definition [-Werror,-Wignored-attributes]
     38 | extern __typeof (__redirect_strstr) __strstr_generic attribute_hidden;
        |                                                      ^
  ./../include/libc-symbols.h:356:43: note: expanded from macro 'attribute_hidden'
    356 | # define attribute_hidden __attribute__ ((visibility ("hidden")))
        |                                           ^
  ../string/strstr.c:76:1: note: previous definition is here
     76 | STRSTR (const char *haystack, const char *needle)
        | ^
  ../sysdeps/x86_64/multiarch/strstr.c:27:16: note: expanded from macro 'STRSTR'
     27 | #define STRSTR __strstr_generic
        |                ^
  ../sysdeps/x86_64/multiarch/strstr.c:65:43: error: redefinition of '__libc_strstr'
     65 | libc_ifunc_redirected (__redirect_strstr, __libc_strstr, IFUNC_SELECTOR ());
        |                                           ^

And

  ../sysdeps/x86_64/multiarch/strstr.c:65:43: error: redefinition of '__libc_strstr'
     65 | libc_ifunc_redirected (__redirect_strstr, __libc_strstr, IFUNC_SELECTOR ());
        |                                           ^
  ../sysdeps/x86_64/multiarch/strstr.c:59:13: note: previous definition is here
     59 | libc_ifunc (__libc_strstr,
        |             ^

Refactor to use a auxiliary function like other selection (for instance,
x86_64/multiarch/strcmp.c).
---
 sysdeps/x86_64/multiarch/strstr.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/sysdeps/x86_64/multiarch/strstr.c b/sysdeps/x86_64/multiarch/strstr.c
index e18e6418aec..f669a57689e 100644
--- a/sysdeps/x86_64/multiarch/strstr.c
+++ b/sysdeps/x86_64/multiarch/strstr.c
@@ -31,19 +31,24 @@
   __hidden_ver1 (__strstr_generic, __GI_strstr, __strstr_generic);
 #endif
 
-#include "string/strstr.c"
-
 extern __typeof (__redirect_strstr) __strstr_sse2_unaligned attribute_hidden;
 extern __typeof (__redirect_strstr) __strstr_generic attribute_hidden;
 
+#include "string/strstr.c"
+
 #include "init-arch.h"
 
-/* Avoid DWARF definition DIE on ifunc symbol so that GDB can handle
-   ifunc symbol properly.  */
-extern __typeof (__redirect_strstr) __libc_strstr;
-libc_ifunc (__libc_strstr,
-	    HAS_ARCH_FEATURE (Fast_Unaligned_Load)
-	    ? __strstr_sse2_unaligned
-	    : __strstr_generic)
+static inline void *
+IFUNC_SELECTOR (void)
+{
+  const struct cpu_features *cpu_features = __get_cpu_features ();
+
+  if (CPU_FEATURES_ARCH_P (cpu_features, Fast_Unaligned_Load))
+    return __strstr_sse2_unaligned;
+
+  return __strstr_generic;
+}
+
+libc_ifunc_redirected (__redirect_strstr, __libc_strstr, IFUNC_SELECTOR ());
 #undef strstr
 strong_alias (__libc_strstr, strstr)
-- 
2.43.0