On 06/29/2015 08:07 PM, Uros Bizjak wrote:
Index: lex.c
===================================================================
--- lex.c (revision 225138)
+++ lex.c (working copy)
@@ -450,15 +450,30 @@ search_line_sse42 (const uchar *s, const uchar *en
s = (const uchar *)((si + 16) & -16);
}
- /* Main loop, processing 16 bytes at a time. By doing the whole loop
- in inline assembly, we can make proper use of the flags set. */
- __asm ( "sub $16, %1\n"
- " .balign 16\n"
+ /* Main loop, processing 16 bytes at a time. */
+#ifdef __GCC_ASM_FLAG_OUTPUTS__
+ while (1)
+ {
+ char f;
+ __asm ("%vpcmpestri\t$0, %2, %3"
+ : "=c"(index), "=@ccc"(f)
+ : "m"(*s), "x"(search), "a"(4), "d"(16));
+ if (f)
+ break;
+
+ s += 16;
+ }
This change looks good. Modulo keeping a comment mentioning why we can't use
the builtin.
+#else
+ s -= 16;
+ /* By doing the whole loop in inline assembly,
+ we can make proper use of the flags set. */
+ __asm ( ".balign 16\n"
"0: add $16, %1\n"
- " %vpcmpestri $0, (%1), %2\n"
+ " %vpcmpestri\t$0, (%1), %2\n"
" jnc 0b"
: "=&c"(index), "+r"(s)
: "x"(search), "a"(4), "d"(16));
+#endif
I do wonder about keeping this bit around. Surely we only really care about
the performance of search_line after a full bootstrap, at which point we've got
the new path.
I think maybe better to adjust the #ifdef HAVE_SSE4 line above to include the
G_A_F_O check.
r~
