[PATCH 04/10] x86: "prefix_extra" can't really be "2"

[Jan Beulich via Gcc-patches]

In the three remaining instances separate "prefix_0f" and "prefix_rep"
are what is wanted instead.

gcc/

        * config/i386/i386.md (rd<fsgs>base<mode>): Add "prefix_0f" and
        "prefix_rep". Drop "prefix_extra".
        (wr<fsgs>base<mode>): Likewise.
        (ptwrite<mode>): Likewise.

--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -25914,7 +25914,8 @@
   "TARGET_64BIT && TARGET_FSGSBASE"
   "rd<fsgs>base\t%0"
   [(set_attr "type" "other")
-   (set_attr "prefix_extra" "2")])
+   (set_attr "prefix_0f" "1")
+   (set_attr "prefix_rep" "1")])
 
 (define_insn "wr<fsgs>base<mode>"
   [(unspec_volatile [(match_operand:SWI48 0 "register_operand" "r")]
@@ -25922,7 +25923,8 @@
   "TARGET_64BIT && TARGET_FSGSBASE"
   "wr<fsgs>base\t%0"
   [(set_attr "type" "other")
-   (set_attr "prefix_extra" "2")])
+   (set_attr "prefix_0f" "1")
+   (set_attr "prefix_rep" "1")])
 
 (define_insn "ptwrite<mode>"
   [(unspec_volatile [(match_operand:SWI48 0 "nonimmediate_operand" "rm")]
@@ -25930,7 +25932,8 @@
   "TARGET_PTWRITE"
   "ptwrite\t%0"
   [(set_attr "type" "other")
-   (set_attr "prefix_extra" "2")])
+   (set_attr "prefix_0f" "1")
+   (set_attr "prefix_rep" "1")])
 
 (define_insn "@rdrand<mode>"
   [(set (match_operand:SWI248 0 "register_operand" "=r")