[LLVMbugs] [Bug 10702] New: [x86 disassembler] crc32 not disassembled correctly

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=10702

           Summary: [x86 disassembler] crc32 not disassembled correctly
           Product: libraries
           Version: trunk
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: X86
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: kkhoo at perfwizard.com
                CC: llvmbugs at cs.uiuc.edu


>From the "Intel® 64 and IA-32 Architectures Software Developer’s Manual
Volume 2 (2A & 2B): Instruction Set Reference, A-Z", p. 3-236:
CRC32 — Accumulate CRC32 Value
F2 0F 38 F0 /r 

Clang on OSX assembles:
crc32 %al, %eax

To:
F2 0F 38 F0 C0 

With llvm-mc built from trunk revision 135913:
$ echo '0xf2 0x0f 0x38 0xf0 0xc0'| ./llvm-mc -disassemble -triple="x86_64"
<stdin>:1:1: warning: invalid instruction encoding
0xf2 0x0f 0x38 0xf0 0xc0
^
<stdin>:1:21: warning: invalid instruction encoding
0xf2 0x0f 0x38 0xf0 0xc0

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