[PATCH 5/6] Optimize i386 syscall inlining

[H.J. Lu]

On Thu, Oct 15, 2015 at 12:54 PM, Roland McGrath <roland@hack.frob.com> wrote:
> This needs comments explaining why the compiler version conditional
> makes sense.

How about this?

-- 
H.J.
----
diff --git a/sysdeps/unix/sysv/linux/i386/sysdep.h
b/sysdeps/unix/sysv/linux/i386/sysdep.h
index 5324da6..76db7b8 100644
--- a/sysdeps/unix/sysv/linux/i386/sysdep.h
+++ b/sysdeps/unix/sysv/linux/i386/sysdep.h
@@ -227,6 +227,10 @@
 extern int __syscall_error (int)
   attribute_hidden __attribute__ ((__regparm__ (1)));

+/* Since GCC 5 and above can properly spill %ebx with PIC when needed,
+   we can inline syscalls with 6 arguments if GCC 5 or above is used
+   to compile glibc.  */
+
 #if !__GNUC_PREREQ (5,0)
 /* We need some help from the assembler to generate optimal code.  We
    define some macros here which later will be used.  */