[llvm] r177011 - Teach X86 MC instruction lowering that VMOVAPSrr and other VEX-encoded register to register moves should be switched from using the MRMSrcReg form to the MRMDestReg form if the source register is a 64-bit extended register and the destination register is not. This allows the instruction to be encoded using the 2-byte VEX form instead of the 3-byte VEX form. The GNU assembler has similar behavior.

Craig Topper craig.topper at gmail.com
Fri Mar 15 19:18:59 PDT 2013


This doesn't look right. Shouldn't that be getOperand(CurOp)?

     if (X86II::isX86_64ExtendedReg(MI.getOperand(1).getReg()))
       VEX_R = 0x0;
+    CurOp++;


I'll go ahead and finish this up. I'll also fix the old JIT code emitter.

On Fri, Mar 15, 2013 at 6:43 PM, Michael Liao <michael.liao at intel.com>wrote:

> Here is the revised patch. VMOVSS/VMOVSD should check operand 0 and 2
> and operand 1 is encoded in VEX.vvvv.
>
> Yours
> - Michael
>
> On Fri, 2013-03-15 at 18:32 -0700, Michael Liao wrote:
> > Hi Craig
> >
> > It's turned out that VEX.vvvv is not supported in DstReg form. I add
> > quick fix to that. It won't crash during code emission on VMOVSS. Test
> > case is added as well. Please have a look.
> >
> > Yours
> > - Michael
> >
> > On Fri, 2013-03-15 at 15:38 -0700, Craig Topper wrote:
> > > What assertion is failing?
> > >
> > > On Fri, Mar 15, 2013 at 2:31 PM, Nadav Rotem <nrotem at apple.com> wrote:
> > >         Hi Craig,
> > >
> > >
> > >         This commit causes an assertion failure in the X86 code
> > >         emitter and one of the build bots is failing. I attached a
> > >         test case.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >         Thanks,
> > >         - Nadav
> > >
> > >
> > >
> > >         On Mar 14, 2013, at 12:09 AM, Craig Topper
> > >         <craig.topper at gmail.com> wrote:
> > >
> > >         > Author: ctopper
> > >         > Date: Thu Mar 14 02:09:57 2013
> > >         > New Revision: 177011
> > >         >
> > >         > URL: http://llvm.org/viewvc/llvm-project?rev=177011&view=rev
> > >         > Log:
> > >         > Teach X86 MC instruction lowering that VMOVAPSrr and other
> > >         > VEX-encoded register to register moves should be switched
> > >         > from using the MRMSrcReg form to the MRMDestReg form if the
> > >         > source register is a 64-bit extended register and the
> > >         > destination register is not. This allows the instruction to
> > >         > be encoded using the 2-byte VEX form instead of the 3-byte
> > >         > VEX form. The GNU assembler has similar behavior.
> > >         >
> > >         > Modified:
> > >         >    llvm/trunk/lib/Target/X86/X86MCInstLower.cpp
> > >         >
> > >         > Modified: llvm/trunk/lib/Target/X86/X86MCInstLower.cpp
> > >         > URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86MCInstLower.cpp?rev=177011&r1=177010&r2=177011&view=diff
> > >         >
> ==============================================================================
> > >         > --- llvm/trunk/lib/Target/X86/X86MCInstLower.cpp (original)
> > >         > +++ llvm/trunk/lib/Target/X86/X86MCInstLower.cpp Thu Mar 14
> > >         > 02:09:57 2013
> > >         > @@ -407,6 +407,48 @@ ReSimplify:
> > >         >     LowerUnaryToTwoAddr(OutMI, X86::XOR32rr); // MOV32r0 ->
> > >         > XOR32rr
> > >         >     break;
> > >         >
> > >         > +  // Commute operands to get a smaller encoding by using
> > >         > VEX.R instead of VEX.B
> > >         > +  // if one of the registers is extended, but other isn't.
> > >         > +  case X86::VMOVAPDrr:
> > >         > +  case X86::VMOVAPDYrr:
> > >         > +  case X86::VMOVAPSrr:
> > >         > +  case X86::VMOVAPSYrr:
> > >         > +  case X86::VMOVDQArr:
> > >         > +  case X86::VMOVDQAYrr:
> > >         > +  case X86::VMOVDQUrr:
> > >         > +  case X86::VMOVDQUYrr:
> > >         > +  case X86::VMOVSDrr:
> > >         > +  case X86::VMOVSSrr:
> > >         > +  case X86::VMOVUPDrr:
> > >         > +  case X86::VMOVUPDYrr:
> > >         > +  case X86::VMOVUPSrr:
> > >         > +  case X86::VMOVUPSYrr: {
> > >         > +    if
> > >         > (X86II::isX86_64ExtendedReg(OutMI.getOperand(0).getReg()) &&
> > >         > +        !
> > >         > X86II::isX86_64ExtendedReg(OutMI.getOperand(1).getReg()))
> > >         > +      break;
> > >         > +
> > >         > +    unsigned NewOpc;
> > >         > +    switch (OutMI.getOpcode()) {
> > >         > +    default: llvm_unreachable("Invalid opcode");
> > >         > +    case X86::VMOVAPDrr:  NewOpc = X86::VMOVAPDrr_REV;
> > >         >  break;
> > >         > +    case X86::VMOVAPDYrr: NewOpc = X86::VMOVAPDYrr_REV;
> > >         > break;
> > >         > +    case X86::VMOVAPSrr:  NewOpc = X86::VMOVAPSrr_REV;
> > >         >  break;
> > >         > +    case X86::VMOVAPSYrr: NewOpc = X86::VMOVAPSYrr_REV;
> > >         > break;
> > >         > +    case X86::VMOVDQArr:  NewOpc = X86::VMOVDQArr_REV;
> > >         >  break;
> > >         > +    case X86::VMOVDQAYrr: NewOpc = X86::VMOVDQAYrr_REV;
> > >         > break;
> > >         > +    case X86::VMOVDQUrr:  NewOpc = X86::VMOVDQUrr_REV;
> > >         >  break;
> > >         > +    case X86::VMOVDQUYrr: NewOpc = X86::VMOVDQUYrr_REV;
> > >         > break;
> > >         > +    case X86::VMOVSDrr:   NewOpc = X86::VMOVSDrr_REV;
> > >         >   break;
> > >         > +    case X86::VMOVSSrr:   NewOpc = X86::VMOVSSrr_REV;
> > >         >   break;
> > >         > +    case X86::VMOVUPDrr:  NewOpc = X86::VMOVUPDrr_REV;
> > >         >  break;
> > >         > +    case X86::VMOVUPDYrr: NewOpc = X86::VMOVUPDYrr_REV;
> > >         > break;
> > >         > +    case X86::VMOVUPSrr:  NewOpc = X86::VMOVUPSrr_REV;
> > >         >  break;
> > >         > +    case X86::VMOVUPSYrr: NewOpc = X86::VMOVUPSYrr_REV;
> > >         > break;
> > >         > +    }
> > >         > +    OutMI.setOpcode(NewOpc);
> > >         > +    break;
> > >         > +  }
> > >         > +
> > >         >   // TAILJMPr64, CALL64r, CALL64pcrel32 - These instructions
> > >         > have register
> > >         >   // inputs modeled as normal uses instead of implicit
> > >         > uses.  As such, truncate
> > >         >   // off all but the first operand (the callee).  FIXME:
> > >         > Change isel.
> > >         >
> > >         >
> > >         > _______________________________________________
> > >         > llvm-commits mailing list
> > >         > llvm-commits at cs.uiuc.edu
> > >         > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > --
> > > ~Craig
> > > _______________________________________________
> > > llvm-commits mailing list
> > > llvm-commits at cs.uiuc.edu
> > > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>
>


-- 
~Craig
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