'into' instruction should not be decoded as valid in 64-bit mode

[avt77]

Summary

It's a tiny patch to close https://bugs.llvm.org/show_bug.cgi?id=32808. Hope it will be accepted quickly.

[craig.topper]

lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp

761

We don't need to do this here. Just add Requires<[Not64BitMode]> to the end of the instruction definition in X86InstrSystem.td.

[avt77]

I re-implemented the fix accordingly to Craig suggest.

[craig.topper]

LGTM

[avt77]

r313735

lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp

if (current == 0x38) {
         return -1;
 
       insn->opcodeType = THREEBYTE_3A;
     } else {
       dbgprintf(insn, "Didn't find a three-byte escape prefix");
 
       insn->opcodeType = TWOBYTE;
     }
+  } else if (current == 0xce && (insn->mode == MODE_64BIT)) {
+    // TODO: Do we need real error diagnostic in disassembler?
+    dbgprintf(insn, "Invalid instruction 'into' in 64-bit mode");
+    return -1;
   }
 
   /*
    * At this point we have consumed the full opcode.
    * Anything we consume from here on must be unconsumed.
    */
 
   insn->opcode = current;

test/MC/Disassembler/X86/x86-64-err.txt

+# RUN: llvm-mc --disassemble %s -triple=x86_64 2>&1 | FileCheck --check-prefix=64 %s
+# RUN: llvm-mc --disassemble %s -triple=i386 | FileCheck --check-prefix=32 %s
+
+# 64: warning: invalid instruction encoding
+# 32: into
+0xce