--- a/gcc/config/i386/mmx.md
+++ b/gcc/config/i386/mmx.md
@@ -3863,7 +3863,6 @@
     }
 }
   [(set_attr "isa" "noavx,avx")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "type" "sselog")
    (set_attr "length_immediate" "1")
@@ -3950,7 +3949,6 @@
 }
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "sselog")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "prefix" "orig,vex")
@@ -4002,7 +4000,6 @@
    %vpextrb\t{%2, %1, %k0|%k0, %1, %2}
    %vpextrb\t{%2, %1, %0|%0, %1, %2}"
   [(set_attr "type" "sselog1")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "prefix" "maybe_vex")
@@ -4017,7 +4014,6 @@
   "TARGET_SSE4_1 && TARGET_MMX_WITH_SSE"
   "%vpextrb\t{%2, %1, %k0|%k0, %1, %2}"
   [(set_attr "type" "sselog1")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "prefix" "maybe_vex")
@@ -4035,7 +4031,6 @@
    vpshufb\t{%2, %1, %0|%0, %1, %2}"
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "sselog1")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "orig,maybe_evex")
    (set_attr "btver2_decode" "vector")
@@ -4053,7 +4048,6 @@
    vpshufb\t{%2, %1, %0|%0, %1, %2}"
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "sselog1")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "orig,maybe_evex")
    (set_attr "btver2_decode" "vector")
@@ -4191,7 +4185,6 @@
    (set_attr "mmx_isa" "native,*")
    (set_attr "type" "mmxcvt,sselog1")
    (set_attr "prefix_extra" "1,*")
-   (set_attr "prefix_data16" "*,1")
    (set_attr "length_immediate" "*,1")
    (set_attr "mode" "DI,TI")])
 
@@ -4531,7 +4524,6 @@
 }
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "sselog")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "prefix" "orig,vex")
@@ -4575,7 +4567,6 @@
    %vpextrb\t{%2, %1, %k0|%k0, %1, %2}
    %vpextrb\t{%2, %1, %0|%0, %1, %2}"
   [(set_attr "type" "sselog1")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "prefix" "maybe_vex")
@@ -4590,7 +4581,6 @@
   "TARGET_SSE4_1"
   "%vpextrb\t{%2, %1, %k0|%k0, %1, %2}"
   [(set_attr "type" "sselog1")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "prefix" "maybe_vex")
--- a/gcc/config/i386/sse.md
+++ b/gcc/config/i386/sse.md
@@ -15614,7 +15614,6 @@
    vpmuldq\t{%2, %1, %0<mask_operand3>|%0<mask_operand3>, %1, %2}"
   [(set_attr "isa" "noavx,noavx,avx")
    (set_attr "type" "sseimul")
-   (set_attr "prefix_data16" "1,1,*")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "orig,orig,vex")
    (set_attr "mode" "TI")])
@@ -16688,8 +16687,6 @@
    vp<maxmin_int>w\t{%2, %1, %0|%0, %1, %2}"
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "sseiadd")
-   (set_attr "prefix_data16" "1,*")
-   (set_attr "prefix_extra" "*,1")
    (set_attr "prefix" "orig,vex")
    (set_attr "mode" "TI")])
 
@@ -16772,8 +16769,6 @@
    vp<maxmin_int>b\t{%2, %1, %0|%0, %1, %2}"
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "sseiadd")
-   (set_attr "prefix_data16" "1,*")
-   (set_attr "prefix_extra" "*,1")
    (set_attr "prefix" "orig,vex")
    (set_attr "mode" "TI")])
 
@@ -17001,7 +16996,6 @@
    vpcmpeq<ssemodesuffix>\t{%2, %1, %0|%0, %1, %2}"
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "ssecmp")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix" "orig,vex")
    (set_attr "mode" "TI")])
 
@@ -17063,7 +17057,6 @@
    vpcmpgt<ssemodesuffix>\t{%2, %1, %0|%0, %1, %2}"
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "ssecmp")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix" "orig,vex")
    (set_attr "mode" "TI")])
 
@@ -18819,12 +18812,6 @@
 	    (match_test "GET_MODE_NUNITS (<MODE>mode) == 2"))
        (const_string "1")
        (const_string "*")))
-   (set (attr "prefix_data16")
-     (if_then_else
-       (and (not (match_test "TARGET_AVX"))
-	    (match_test "GET_MODE_NUNITS (<MODE>mode) == 8"))
-       (const_string "1")
-       (const_string "*")))
    (set (attr "prefix_extra")
      (if_then_else
        (ior (eq_attr "prefix" "evex")
@@ -19985,7 +19972,6 @@
    %vpextr<ssemodesuffix>\t{%2, %1, %0|%0, %1, %2}"
   [(set_attr "isa" "*,sse4")
    (set_attr "type" "sselog1")
-   (set_attr "prefix_data16" "1")
    (set (attr "prefix_extra")
      (if_then_else
        (eq (const_string "<MODE>mode") (const_string "V8HImode"))
@@ -20006,7 +19992,6 @@
   "TARGET_SSE2"
   "%vpextr<PEXTR_MODE12:ssemodesuffix>\t{%2, %1, %k0|%k0, %1, %2}"
   [(set_attr "type" "sselog1")
-   (set_attr "prefix_data16" "1")
    (set (attr "prefix_extra")
      (if_then_else
        (eq (const_string "<PEXTR_MODE12:MODE>mode") (const_string "V8HImode"))
@@ -20026,7 +20011,6 @@
   "TARGET_SSE4_1"
   "%vpextrb\t{%2, %1, %k0|%k0, %1, %2}"
   [(set_attr "type" "sselog1")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "prefix" "maybe_vex")
@@ -21240,7 +21224,6 @@
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "sseiadd")
    (set_attr "atom_unit" "complex")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "orig,vex")
    (set_attr "mode" "TI")])
@@ -21511,7 +21494,6 @@
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "sseiadd")
    (set_attr "atom_unit" "simul")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "orig,vex")
    (set_attr "mode" "TI")])
@@ -21639,7 +21621,6 @@
    vpmulhrsw\t{%2, %1, %0<mask_operand4>|%0<mask_operand4>, %1, %2}"
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "sseimul")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "orig,maybe_evex")
    (set_attr "mode" "<sseinsnmode>")])
@@ -21763,7 +21744,6 @@
    vpshufb\t{%2, %1, %0<mask_operand3>|%0<mask_operand3>, %1, %2}"
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "sselog1")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "orig,maybe_evex")
    (set_attr "btver2_decode" "vector")
@@ -21830,7 +21810,6 @@
    vpsign<ssemodesuffix>\t{%2, %1, %0|%0, %1, %2}"
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "sselog1")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "orig,vex")
    (set_attr "mode" "<sseinsnmode>")])
@@ -21898,7 +21877,6 @@
   [(set_attr "isa" "noavx,avx")
    (set_attr "type" "sseishft")
    (set_attr "atom_unit" "sishuf")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "prefix" "orig,vex")
@@ -21992,7 +21970,6 @@
   "TARGET_SSSE3"
   "%vpabs<ssemodesuffix>\t{%1, %0|%0, %1}"
   [(set_attr "type" "sselog1")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "maybe_vex")
    (set_attr "mode" "<sseinsnmode>")])
@@ -24244,7 +24221,6 @@
   DONE;
 }
   [(set_attr "type" "sselog")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "memory" "none,load")
@@ -24270,7 +24246,6 @@
   "TARGET_SSE4_2"
   "%vpcmpestri\t{%5, %3, %1|%1, %3, %5}"
   [(set_attr "type" "sselog")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "maybe_vex")
    (set_attr "length_immediate" "1")
@@ -24298,7 +24273,6 @@
   "TARGET_SSE4_2"
   "%vpcmpestrm\t{%5, %3, %1|%1, %3, %5}"
   [(set_attr "type" "sselog")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "prefix" "maybe_vex")
@@ -24324,7 +24298,6 @@
    %vpcmpestri\t{%6, %4, %2|%2, %4, %6}
    %vpcmpestri\t{%6, %4, %2|%2, %4, %6}"
   [(set_attr "type" "sselog")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "memory" "none,load,none,load")
@@ -24379,7 +24352,6 @@
   DONE;
 }
   [(set_attr "type" "sselog")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "memory" "none,load")
@@ -24401,7 +24373,6 @@
   "TARGET_SSE4_2"
   "%vpcmpistri\t{%3, %2, %1|%1, %2, %3}"
   [(set_attr "type" "sselog")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "prefix" "maybe_vex")
@@ -24425,7 +24396,6 @@
   "TARGET_SSE4_2"
   "%vpcmpistrm\t{%3, %2, %1|%1, %2, %3}"
   [(set_attr "type" "sselog")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "prefix" "maybe_vex")
@@ -24449,7 +24419,6 @@
    %vpcmpistri\t{%4, %3, %2|%2, %3, %4}
    %vpcmpistri\t{%4, %3, %2|%2, %3, %4}"
   [(set_attr "type" "sselog")
-   (set_attr "prefix_data16" "1")
    (set_attr "prefix_extra" "1")
    (set_attr "length_immediate" "1")
    (set_attr "memory" "none,load,none,load")
@@ -29268,7 +29237,6 @@
    gf2p8affineinvqb\t{%3, %2, %0| %0, %2, %3}
    vgf2p8affineinvqb\t{%3, %2, %1, %0<mask_operand4>| %0<mask_operand4>, %1, %2, %3}"
   [(set_attr "isa" "noavx,avx")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "orig,maybe_evex")
    (set_attr "mode" "<sseinsnmode>")])
@@ -29285,7 +29253,6 @@
    gf2p8affineqb\t{%3, %2, %0| %0, %2, %3}
    vgf2p8affineqb\t{%3, %2, %1, %0<mask_operand4>| %0<mask_operand4>, %1, %2, %3}"
   [(set_attr "isa" "noavx,avx")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "orig,maybe_evex")
    (set_attr "mode" "<sseinsnmode>")])
@@ -29301,7 +29268,6 @@
    gf2p8mulb\t{%2, %0| %0, %2}
    vgf2p8mulb\t{%2, %1, %0<mask_operand3>| %0<mask_operand3>, %1, %2}"
   [(set_attr "isa" "noavx,avx")
-   (set_attr "prefix_data16" "1,*")
    (set_attr "prefix_extra" "1")
    (set_attr "prefix" "orig,maybe_evex")
    (set_attr "mode" "<sseinsnmode>")])
