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Unsupported operand-size prefix on ENTER #88

@nezetic

Description

@nezetic

It looks like REX prefix on x86 instruction ENTER is not supported by LLVM...

Our validator is failing on due to this.

@0xAcid confirmed this issue:

gdb-peda$ x/i 0x41935a
0x41935a <test_enter+2727>: enterw 0x8,0x1f
gdb-peda$ x/5b 0x41935a
0x41935a <test_enter+2727>: 0x66 0xc8 0x08 0x00 0x1f

Prefix is skipped by LLVM:

ax@ax:~$ llvm-mc-3.8 --disassemble --show-inst --show-encoding
0x66, 0xc8, 0x08, 0x00, 0x1f
    .text
    enter    $8, $31                 # encoding: [0xc8,0x08,0x00,0x1f]
                                        # <MCInst #780 ENTER
                                        #  <MCOperand Imm:8>
                                        #  <MCOperand Imm:31>>

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