re PR rtl-optimization/8178 (__builtin_ffs broken with -march=k6)

	PR optimization/8178
	* config/i386/i386.md (*movsi_zero): New insn to set
	a register to zero on TARGET_USE_MOV0 targets.

From-SVN: r72634

gcc/ChangeLog

+2003-10-18  Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+	PR optimization/8178
+	* config/i386/i386.md (*movsi_zero): New insn to set
+	a register to zero on TARGET_USE_MOV0 targets.
+
 2003-10-18  Kelley Cook  <kcook@gcc.gnu.org>
 
 	* Makefile.in (Makefile): Depend on the all Make-lang.in fragments.
@@ -16,7 +22,6 @@
 	* doc/install.texi: Document that zsh does not work when 
 	configuring gcc.
 
-
 2003-10-17  Nathanael Nerode  <neroden@gcc.gnu.org>
 
 	* config/ptx4.h: Switch to DWARF 2; update comments.

gcc/config/i386/i386.md

@@ -1162,6 +1162,15 @@
    (set_attr "mode" "SI")
    (set_attr "length_immediate" "0")])
 
+(define_insn "*movsi_zero"
+  [(set (match_operand:SI 0 "register_operand" "=r")
+	(match_operand:SI 1 "const0_operand" "i"))
+   (clobber (reg:CC 17))]
+  "reload_completed && (TARGET_USE_MOV0 && !optimize_size)"
+  "mov{l}\t{%1, %0|%0, %1}"
+  [(set_attr "type" "imov")
+   (set_attr "mode" "SI")])
+ 
 (define_insn "*movsi_or"
   [(set (match_operand:SI 0 "register_operand" "=r")
 	(match_operand:SI 1 "immediate_operand" "i"))