[LLVMbugs] [Bug 11027] New: [x86 disassembler] rdrand not recognized

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=11027

           Summary: [x86 disassembler] rdrand not recognized
           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. 4-309, dated May 2011:

RDRAND—Read Random Number

0F C7 /6
RDRAND r16

0F C7 /6
RDRAND r32

REX.W + 0F C7 /6
RDRAND r64

See also: http://en.wikipedia.org/wiki/RdRand

Using llvm-mc built from r140537:
$ echo '0x0f 0xc7 0xc0'| ./llvm-mc -disassemble -triple="x86_64"
<stdin>:1:1: warning: invalid instruction encoding
0x0f 0xc7 0xc0
^

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