[LLVMbugs] [Bug 23455] New: Intel parser doesn't recognize cmp${cc}ss

[bugzilla-daemon at llvm.org]

https://llvm.org/bugs/show_bug.cgi?id=23455

            Bug ID: 23455
           Summary: Intel parser doesn't recognize cmp${cc}ss
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: ahmed.bougacha at gmail.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

Consider:

 $ echo 'cmpnless xmm0, xmm1' | ./bin/llvm-mc -x86-asm-syntax=intel
    .section    __TEXT,__text,regular,pure_instructions
<stdin>:1:1: error: invalid operand for instruction
cmpnless xmm0, xmm1

 $ echo 'cmpnless %xmm1, %xmm0' | ./bin/llvm-mc
    .section    __TEXT,__text,regular,pure_instructions
    cmpnless    %xmm1, %xmm0


This is an old problem, that is now triggered because we started actually
parsing the cmpCCss forms, rather than just string-replacing the CC to an
immediate (as of r229266).

Here's the relevant part of the matchers:

  { 1170 /* cmp */, X86::CMPSSrr, Convert__Reg1_2__Tie0__Reg1_3__Imm1_0, 0, {
MCK_Imm, MCK_SS, MCK_FR32, MCK_FR32 }, },

And here's the same matcher for AT&T syntax:

  { 1170 /* cmp */, X86::CMPSSrr, Convert__Reg1_3__Tie0__Reg1_2__Imm1_0, 0, {
MCK_Imm, MCK_ss, MCK_FR32, MCK_FR32 }, },


Notice _ss vs _SS: with Intel syntax, when TableGen generates the matcher from
the AsmString, it splits "cmp${cc}ss" into tokens, and the "ss" suffix is
recognized as a register ...the SS segment register.

It should probably know that when the token ("ss") doesn't follow a space, it's
not a register (I can't think of a case where that would make sense).

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