[LLVMbugs] [Bug 10917] New: [x86 disassembler] vpblendvb operands incorrect

bugzilla-daemon at llvm.org bugzilla-daemon at llvm.org
Mon Sep 12 15:35:01 PDT 2011


           Summary: [x86 disassembler] vpblendvb operands incorrect
           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

According to the "Intel® 64 and IA-32 Architectures Software Developer’s Manual
Volume 2 (2A & 2B): Instruction Set Reference, A-Z", p. 4-69:
VEX.NDS.128.66.0F3A.W0 4C /r /is4
VPBLENDVB xmm1, xmm2, xmm3/m128, xmm4

Select byte values from xmm2 and xmm3/m128 using mask bits in the
specified mask register, xmm4, and store the values into xmm1.

Clang on OSX assembles this:
vpblendvb %xmm0, %xmm1, %xmm2, %xmm3

C4 E3 69 4C D9 00 

But llvm-mc built from r139522 shows:
$ echo '0xc4 0xe3 0x69 0x4c 0xd9 0x00'| ./llvm-mc -disassemble -triple="x86_64"
    vpblendvb    XMM3, XMM2, XMM1, 0

$ echo '0xc4 0xe3 0x69 0x4c 0xd9 0x00'| ./llvm-mc -disassemble -triple="x86_64" 
    vpblendvb    $0, %xmm1, %xmm2, %xmm3

The mask register appears to be printed as an immediate operand.

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