[binutils-gdb] x86: re-work EVEX-z-without-masking check

[Jan Beulich <jbeulich@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=07d618b91f50816f198abac7df116e83d47ca1be

commit 07d618b91f50816f198abac7df116e83d47ca1be
Author: Jan Beulich <jbeulich@suse.com>
Date:   Tue Jul 4 17:00:15 2023 +0200

    x86: re-work EVEX-z-without-masking check
    
    Rather than corrupting disassmbly altogether, flag EVEX.z set as bad
    when masking isn't in effect in the first place at the time the
    destination operand is actually processed.

Diff:
---
 gas/testsuite/gas/i386/avx512f-nondef.d |  3 +--
 opcodes/i386-dis.c                      | 18 ++++++++----------
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/gas/testsuite/gas/i386/avx512f-nondef.d b/gas/testsuite/gas/i386/avx512f-nondef.d
index a062fe335bc..8defd6972e5 100644
--- a/gas/testsuite/gas/i386/avx512f-nondef.d
+++ b/gas/testsuite/gas/i386/avx512f-nondef.d
@@ -15,8 +15,7 @@ Disassembly of section .text:
 [ 	]*[a-f0-9]+:	62 f2 55 1f 3b f4    	vpminud \{rn-bad\},%zmm4,%zmm5,%zmm6\{%k7\}
 [ 	]*[a-f0-9]+:	62 f2 7e 48 31 72 7f 	vpmovdb %zmm6,0x7f0\(%edx\)
 [ 	]*[a-f0-9]+:	62 f2 7e 58 31 72 7f 	vpmovdb %zmm6,0x7f0\(%edx\)\{bad\}
-[ 	]*[a-f0-9]+:	62 f1 7c 88 58       	\(bad\)
-[ 	]*[a-f0-9]+:	c3                   	ret
+[ 	]*[a-f0-9]+:	62 f1 7c 88 58 c3    	(\{evex\} )?vaddps %xmm3,%xmm0,%xmm0\{bad\}
 [ 	]*[a-f0-9]+:	62 f2 7d 4f 92 01    	vgatherdps \(bad\),%zmm0\{%k7\}
 [ 	]*[a-f0-9]+:	67 62 f2 7d 4f 92 01 	addr16 vgatherdps \(bad\),%zmm0\{%k7\}
 [ 	]*[a-f0-9]+:	62 f2 7d cf 92 04 08 	vgatherdps \(%eax,%zmm1(,1)?\),%zmm0\{%k7\}\{z\}/\(bad\)
diff --git a/opcodes/i386-dis.c b/opcodes/i386-dis.c
index 15a0e1b1080..690e336c6bc 100644
--- a/opcodes/i386-dis.c
+++ b/opcodes/i386-dis.c
@@ -9905,9 +9905,15 @@ print_insn (bfd_vma pc, disassemble_info *info, int intel_syntax)
 		      oappend (&ins, "{");
 		      oappend_register (&ins, reg_name);
 		      oappend (&ins, "}");
+
+		      if (ins.vex.zeroing)
+			oappend (&ins, "{z}");
+		    }
+		  else if (ins.vex.zeroing)
+		    {
+		      oappend (&ins, "{bad}");
+		      continue;
 		    }
-		  if (ins.vex.zeroing)
-		    oappend (&ins, "{z}");
 
 		  /* S/G insns require a mask and don't allow
 		     zeroing-masking.  */
@@ -9985,14 +9991,6 @@ print_insn (bfd_vma pc, disassemble_info *info, int intel_syntax)
       goto out;
     }
 
-  /* If EVEX.z is set, there must be an actual mask register in use.  */
-  if (ins.vex.zeroing && ins.vex.mask_register_specifier == 0)
-    {
-      i386_dis_printf (info, dis_style_text, "(bad)");
-      ret = ins.end_codep - priv.the_buffer;
-      goto out;
-    }
-
   switch (dp->prefix_requirement)
     {
     case PREFIX_DATA: