'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 ↗

(On Diff #113240)

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/X86InstrSystem.td

let mayLoad = 1, mayStore = 0, hasSideEffects = 1 in {
   def UD2B    : I<0xB9, RawFrm, (outs), (ins), "ud2b", []>, TB;
 }
 
 def HLT : I<0xF4, RawFrm, (outs), (ins), "hlt", [], IIC_HLT>;
 def RSM : I<0xAA, RawFrm, (outs), (ins), "rsm", [], IIC_RSM>, TB;
 
 // Interrupt and SysCall Instructions.
 let Uses = [EFLAGS] in
-  def INTO : I<0xce, RawFrm, (outs), (ins), "into", []>;
+  def INTO : I<0xce, RawFrm, (outs), (ins), "into", []>, Requires<[Not64BitMode]>;
 def INT3 : I<0xcc, RawFrm, (outs), (ins), "int3",
               [(int_x86_int (i8 3))], IIC_INT3>;
 } // SchedRW
 
 // The long form of "int $3" turns into int3 as a size optimization.
 // FIXME: This doesn't work because InstAlias can't match immediate constants.
 //def : InstAlias<"int\t$3", (INT3)>;
 

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