[PATCH] nptl: x86_64: Use stackinfo.h definition for CURRENT_STACK_FRAME

[Adhemerval Zanella]

It avoids the possible warning of uninitialized 'frame' variable when
building with clang:

  ../sysdeps/nptl/jmp-unwind.c:27:42: error: variable 'frame' is
  uninitialized when used here [-Werror,-Wuninitialized]
    __pthread_cleanup_upto (env->__jmpbuf, CURRENT_STACK_FRAME);

It increases the generated code by one instruction:

--- master
+++ patch
@@ -25068,11 +25068,11 @@ Disassembly of section .text:
    3db1b:      00 00
    3db1d:      48 89 44 24 08          mov    %rax,0x8(%rsp)
    3db22:      31 c0                   xor    %eax,%eax
-   3db24:      48 8b 44 24 08          mov    0x8(%rsp),%rax
-   3db29:      64 48 2b 04 25 28 00    sub    %fs:0x28,%rax
-   3db30:      00 00
-   3db32:      75 0c                   jne    3db40
    <_longjmp_unwind+0x30>
-   3db34:      48 89 e6                mov    %rsp,%rsi
+   3db24:      48 89 e6                mov    %rsp,%rsi
+   3db27:      48 8b 44 24 08          mov    0x8(%rsp),%rax
+   3db2c:      64 48 2b 04 25 28 00    sub    %fs:0x28,%rax
+   3db33:      00 00
+   3db35:      75 09                   jne    3db40
    <_longjmp_unwind+0x30>
    3db37:      48 83 c4 18             add    $0x18,%rsp
    3db3b:      e9 60 31 05 00          jmp    90ca0
<__GI___pthread_cleanup_upto>
    3db40:      e8 4b ec 0e 00          call   12c790 <__stack_chk_fail>

Checked on x86_64-linux-gnu.
---
 sysdeps/x86/nptl/pthreaddef.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysdeps/x86/nptl/pthreaddef.h b/sysdeps/x86/nptl/pthreaddef.h
index 63fdbcb27c..3ff95efee6 100644
--- a/sysdeps/x86/nptl/pthreaddef.h
+++ b/sysdeps/x86/nptl/pthreaddef.h
@@ -42,7 +42,7 @@
 #ifdef __x86_64__
 /* The frame pointer is not usable.  */
 # define CURRENT_STACK_FRAME \
-  ({ register char *frame __asm__("rsp"); frame; })
+  ({ void *p__; asm volatile ("mov %%" RSP_REG ", %0" : "=r" (p__)); p__; })
 #else
 # define CURRENT_STACK_FRAME	__builtin_frame_address (0)
 #endif
-- 
2.34.1