VZERO{ALL,UPPER} modify YMM registers despite having no operands.
While {,V}{LD,ST}MXCSR don't modify XMM registers, MXCSR and XMMn
collectively form underlying machine state.
+2021-02-16  Jan Beulich  <jbeulich@suse.com>
+
+       * config/tc-i386.c (output_insn): Handle ldmxcsr, stmxcsr,
+       vldmxcsr, vstmxcsr, vzeroall, and vzeroupper.
+       * testsuite/gas/i386/property-ldmxcsr.s,
+       testsuite/gas/i386/property-ldmxcsr.d,
+       testsuite/gas/i386/property-vldmxcsr.s,
+       testsuite/gas/i386/property-vldmxcsr.d,
+       testsuite/gas/i386/property-vzeroall.s,
+       testsuite/gas/i386/property-vzeroall.d: New.
+       * testsuite/gas/i386/i386.exp: Run new tests.
+
 2021-02-16  Jan Beulich  <jbeulich@suse.com>
 
        * testsuite/gas/i386/i386.exp: Move bitness-independent property
 
          || i.tm.cpu_flags.bitfield.cpu687
          || i.tm.cpu_flags.bitfield.cpufisttp)
        x86_feature_2_used |= GNU_PROPERTY_X86_FEATURE_2_X87;
+
       if ((i.xstate & xstate_mmx)
          || i.tm.base_opcode == 0xf77 /* emms */
          || i.tm.base_opcode == 0xf0e /* femms */)
        x86_feature_2_used |= GNU_PROPERTY_X86_FEATURE_2_MMX;
+
       if (i.index_reg)
        {
          if (i.index_reg->reg_type.bitfield.zmmword)
          else if (i.index_reg->reg_type.bitfield.xmmword)
            i.xstate |= xstate_xmm;
        }
+
+      /* vzeroall / vzeroupper */
+      if (i.tm.base_opcode == 0x77 && i.tm.cpu_flags.bitfield.cpuavx)
+       i.xstate |= xstate_ymm;
+
       if ((i.xstate & xstate_xmm)
+         /* ldmxcsr / stmxcsr */
+         || (i.tm.base_opcode == 0xfae && i.tm.cpu_flags.bitfield.cpusse)
+         /* vldmxcsr / vstmxcsr */
+         || (i.tm.base_opcode == 0xae && i.tm.cpu_flags.bitfield.cpuavx)
          || i.tm.cpu_flags.bitfield.cpuwidekl
          || i.tm.cpu_flags.bitfield.cpukl)
        x86_feature_2_used |= GNU_PROPERTY_X86_FEATURE_2_XMM;
+
       if ((i.xstate & xstate_ymm) == xstate_ymm)
        x86_feature_2_used |= GNU_PROPERTY_X86_FEATURE_2_YMM;
       if ((i.xstate & xstate_zmm) == xstate_zmm)
 
     run_dump_test "property-11"
     run_dump_test "property-12"
     run_dump_test "property-13"
+    run_dump_test "property-ldmxcsr"
+    run_dump_test "property-vldmxcsr"
+    run_dump_test "property-vzeroall"
 
     if {![istarget "*-*-dragonfly*"]
        && ![istarget "*-*-gnu*"]
 
--- /dev/null
+#name: i386 property ldmxcsr
+#as: -mx86-used-note=yes --generate-missing-build-notes=no
+#readelf: -n
+
+Displaying notes found in: .note.gnu.property
+[      ]+Owner[        ]+Data size[    ]+Description
+  GNU                  0x[0-9a-f]+     NT_GNU_PROPERTY_TYPE_0
+      Properties: x86 ISA used: x86-64-baseline
+       x86 feature used: x86, XMM
 
--- /dev/null
+       .text
+       ldmxcsr (%eax)
 
--- /dev/null
+#name: i386 property vldmxcsr
+#as: -mx86-used-note=yes --generate-missing-build-notes=no
+#readelf: -n
+
+Displaying notes found in: .note.gnu.property
+[      ]+Owner[        ]+Data size[    ]+Description
+  GNU                  0x[0-9a-f]+     NT_GNU_PROPERTY_TYPE_0
+      Properties: x86 ISA used: x86-64-baseline, x86-64-v3
+       x86 feature used: x86, XMM
 
--- /dev/null
+       .text
+       vldmxcsr (%eax)
 
--- /dev/null
+#name: i386 property vzeroall
+#as: -mx86-used-note=yes --generate-missing-build-notes=no
+#readelf: -n
+
+Displaying notes found in: .note.gnu.property
+[      ]+Owner[        ]+Data size[    ]+Description
+  GNU                  0x[0-9a-f]+     NT_GNU_PROPERTY_TYPE_0
+      Properties: x86 ISA used: x86-64-baseline, x86-64-v3
+       x86 feature used: x86, XMM, YMM
 
--- /dev/null
+       .text
+       vzeroall