x86: consistently print prefixes explicitly which are invalid with VEX etc

All of data size, rep, lock, and rex prefixes are invalid with VEX- and
alike encoded insns. Make sure they get printed explicitly in all cases,
to signal the anomaly. With this, do away with "rex_ignored" - if there
is a rex prefix, we want to print it anyway for VEX etc (and there's
nothing "ignored" about it in the first place - such an instruction will
raise #UD).

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 78ffd807ce3ad95c73a10ff91c4cf87923897674..8b78964f8155155f0c0c07513e5cb6decbc8be1e 100644 (file)
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,9 @@
+2020-06-09  Jan Beulich  <jbeulich@suse.com>
+
+       * testsuite/gas/i386/prefix.s: Add bogus prefix-with-VEX/EVEX
+       encoding tests.
+       * testsuite/gas/i386/prefix.d: Adjust expectations.
+
 2020-06-09  Jan Beulich  <jbeulich@suse.com>
 
        * testsuite/gas/i386/prefix.s: Add bogus REP / EVEX.W prefix

diff --git a/gas/testsuite/gas/i386/prefix.d b/gas/testsuite/gas/i386/prefix.d
index 9e293bce2a75c66cce4f261aa9db7046511bd120..02e1813ea7bb48be96db04e2abca60df87baa197 100644 (file)
--- a/gas/testsuite/gas/i386/prefix.d
+++ b/gas/testsuite/gas/i386/prefix.d
@@ -86,8 +86,11 @@ Disassembly of section .text:
 [      ]*[a-f0-9]+:    ff cc                   dec    %esp
 [      ]*[a-f0-9]+:    62 f1 ff 08 28          \(bad\) *
 [      ]*[a-f0-9]+:    ff cc                   dec    %esp
+[      ]*[a-f0-9]+:    66 c5 f8 28 c0          data16 vmovaps %xmm0,%xmm0
+[      ]*[a-f0-9]+:    f3 c4 e1 78 28 c0       repz vmovaps %xmm0,%xmm0
+[      ]*[a-f0-9]+:    f2 c5 f8 28 c0          repnz vmovaps %xmm0,%xmm0
+[      ]*[a-f0-9]+:    f0 62 f1 7c 08 28 c0    lock vmovaps %xmm0,%xmm0
 [      ]*[a-f0-9]+:    c5 fb e6 40 20          vcvtpd2dqx 0x20\(%eax\),%xmm0
 [      ]*[a-f0-9]+:    62 f1 ff 18 e6 40 04    vcvtpd2dq 0x20\(%eax\)\{1to2\},%xmm0
 [      ]*[a-f0-9]+:    c5 fb e6 40 20          vcvtpd2dqx 0x20\(%eax\),%xmm0
-       ...
 #pass

diff --git a/gas/testsuite/gas/i386/prefix.s b/gas/testsuite/gas/i386/prefix.s
index 78fd478c3fb27581ea26f00fd965744d498aeb48..8d563e1626749ab60300d89352c06a3c724b3823 100644 (file)
--- a/gas/testsuite/gas/i386/prefix.s
+++ b/gas/testsuite/gas/i386/prefix.s
@@ -451,6 +451,11 @@
 
        int $3
 
+       .byte 0x66; vmovaps %xmm0, %xmm0
+       repz; {vex3} vmovaps %xmm0, %xmm0
+       repnz; vmovaps %xmm0, %xmm0
+       lock; {evex} vmovaps %xmm0, %xmm0
+
        vcvtpd2dqx 0x20(%eax),%xmm0
        vcvtpd2dq 0x20(%eax){1to2},%xmm0
        vcvtpd2dqx 0x20(%eax),%xmm0

diff --git a/opcodes/ChangeLog b/opcodes/ChangeLog
index c6f1d2691e6f1056aa3fa63e4ff58ef8b318814f..6b3869f0f01569a310745619d9c8143ed8a9b9ca 100644 (file)
--- a/opcodes/ChangeLog
+++ b/opcodes/ChangeLog
@@ -1,3 +1,11 @@
+2020-06-09  Jan Beulich  <jbeulich@suse.com>
+
+       * i386-dis.c (rex_ignored): Delete.
+       (ckprefix): Drop rex_ignored initialization.
+       (get_valid_dis386): Drop setting of rex_ignored.
+       (print_insn): Drop checking of rex_ignored. Don't record data
+       size prefix as used with VEX-and-alike encodings.
+
 2020-06-09  Jan Beulich  <jbeulich@suse.com>
 
        * i386-dis.c (MOD_0F12_PREFIX_2, MOD_0F16_PREFIX_2,

diff --git a/opcodes/i386-dis.c b/opcodes/i386-dis.c
index 3861371ed4e2d567ccac5898cef5ac20937a6dbb..be6958a236cda93c9d43ac7d7dd0d2b4287aea0e 100644 (file)
--- a/opcodes/i386-dis.c
+++ b/opcodes/i386-dis.c
@@ -153,8 +153,6 @@ static int prefixes;
 static int rex;
 /* Bits of REX we've already used.  */
 static int rex_used;
-/* REX bits in original REX prefix ignored.  */
-static int rex_ignored;
 /* Mark parts used in the REX prefix.  When we are testing for
    empty prefix (for 8bit register REX extension), just mask it
    out.  Otherwise test for REX bit is excuse for existence of REX
@@ -11057,7 +11055,6 @@ ckprefix (void)
 {
   int newrex, i, length;
   rex = 0;
-  rex_ignored = 0;
   prefixes = 0;
   used_prefixes = 0;
   rex_used = 0;
@@ -11517,8 +11514,6 @@ get_valid_dis386 (const struct dis386 *dp, disassemble_info *info)
 
     case USE_XOP_8F_TABLE:
       FETCH_DATA (info, codep + 3);
-      /* All bits in the REX prefix are ignored.  */
-      rex_ignored = rex;
       rex = ~(*codep >> 5) & 0x7;
 
       /* VEX_TABLE_INDEX is the mmmmm part of the XOP byte 1 "RCB.mmmmm".  */
@@ -11580,8 +11575,6 @@ get_valid_dis386 (const struct dis386 *dp, disassemble_info *info)
     case USE_VEX_C4_TABLE:
       /* VEX prefix.  */
       FETCH_DATA (info, codep + 3);
-      /* All bits in the REX prefix are ignored.  */
-      rex_ignored = rex;
       rex = ~(*codep >> 5) & 0x7;
       switch ((*codep & 0x1f))
        {
@@ -11647,8 +11640,6 @@ get_valid_dis386 (const struct dis386 *dp, disassemble_info *info)
     case USE_VEX_C5_TABLE:
       /* VEX prefix.  */
       FETCH_DATA (info, codep + 2);
-      /* All bits in the REX prefix are ignored.  */
-      rex_ignored = rex;
       rex = (*codep & 0x80) ? 0 : REX_R;
 
       /* For the 2-byte VEX prefix in 32-bit mode, the highest bit in
@@ -11697,8 +11688,6 @@ get_valid_dis386 (const struct dis386 *dp, disassemble_info *info)
       /* EVEX prefix.  */
       vex.evex = 1;
       FETCH_DATA (info, codep + 4);
-      /* All bits in the REX prefix are ignored.  */
-      rex_ignored = rex;
       /* The first byte after 0x62.  */
       rex = ~(*codep >> 5) & 0x7;
       vex.r = *codep & 0x10;
@@ -12179,7 +12168,7 @@ print_insn (bfd_vma pc, disassemble_info *info)
     }
 
   /* Check if the REX prefix is used.  */
-  if (rex_ignored == 0 && (rex ^ rex_used) == 0 && last_rex_prefix >= 0)
+  if ((rex ^ rex_used) == 0 && !need_vex && last_rex_prefix >= 0)
     all_prefixes[last_rex_prefix] = 0;
 
   /* Check if the SEG prefix is used.  */
@@ -12195,7 +12184,8 @@ print_insn (bfd_vma pc, disassemble_info *info)
 
   /* Check if the DATA prefix is used.  */
   if ((prefixes & PREFIX_DATA) != 0
-      && (used_prefixes & PREFIX_DATA) != 0)
+      && (used_prefixes & PREFIX_DATA) != 0
+      && !need_vex)
     all_prefixes[last_data_prefix] = 0;
 
   /* Print the extra prefixes.  */