[LLVMbugs] [Bug 10848] New: [x86 disassembler] vmovdqa not disassembled

bugzilla-daemon at llvm.org bugzilla-daemon at llvm.org
Fri Sep 2 15:20:38 PDT 2011


           Summary: [x86 disassembler] vmovdqa not disassembled
           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. 3-671:
VEX.128.66.0F.WIG 6F /r
VMOVDQA xmm1, xmm2/m128

VEX.128.66.0F.WIG 7F /r
VMOVDQA xmm2/m128, xmm1

Clang on OSX assembles the following:
vmovdqa (%rcx), %xmm0
vmovdqa %xmm0, (%rcx)

to these bytes:
C5 F9 6F 01 
C5 F9 7F 01 

But using llvm-mc built from trunk r139013, this byte sequence doesn't
disassemble as expected:

$ echo '0xc5 0xf9 0x6f 0x01'| ./llvm-mc -disassemble -triple="x86_64"
<stdin>:1:1: warning: invalid instruction encoding
0xc5 0xf9 0x6f 0x01

$ echo '0xc5 0xf9 0x7f 0x01'| ./llvm-mc -disassemble -triple="x86_64"
<stdin>:1:1: warning: invalid instruction encoding
0xc5 0xf9 0x7f 0x01

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