[llvm-commits] [llvm] r45620 - /llvm/trunk/lib/Target/X86/X86InstrInfo.cpp

[Evan Cheng]

On Jan 4, 2008, at 9:19 PM, Chris Lattner wrote:

> Author: lattner
> Date: Fri Jan  4 23:19:56 2008
> New Revision: 45620
>
> URL: http://llvm.org/viewvc/llvm-project?rev=45620&view=rev
> Log:
> factor some code better to avoid redundancy between
> isReallySideEffectFree and isReallyTriviallyReMaterializable.  Why  
> is a load from
> a global considered side-effect-free but not rematable?

No reason they should be different. I just haven't move remat over.

Although, isReallySideEffectFree looks wrong. How is this checked?

       // Loads from global addresses which aren't redefined in the  
function are
      // side effect free.
if (Reg != 0 && MRegisterInfo::isVirtualRegister(Reg) &&
           MI->getOperand(2).isImmediate() &&
           MI->getOperand(3).isRegister() &&
           MI->getOperand(4).isGlobalAddress() &&
           MI->getOperand(2).getImm() == 1 &&
           MI->getOperand(3).getReg() == 0)
         return true;

Bill, how are you checking the Global address isn't redefined  
anywhere else?

Evan

>
> Modified:
>     llvm/trunk/lib/Target/X86/X86InstrInfo.cpp
>
> Modified: llvm/trunk/lib/Target/X86/X86InstrInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/ 
> X86InstrInfo.cpp?rev=45620&r1=45619&r2=45620&view=diff
>
> ====================================================================== 
> ========
> --- llvm/trunk/lib/Target/X86/X86InstrInfo.cpp (original)
> +++ llvm/trunk/lib/Target/X86/X86InstrInfo.cpp Fri Jan  4 23:19:56  
> 2008
> @@ -135,11 +135,13 @@
>    case X86::MMX_MOVD64rm:
>    case X86::MMX_MOVQ64rm:
>      // Loads from constant pools are trivially rematerializable.
> -    return MI->getOperand(1).isRegister() && MI->getOperand 
> (2).isImmediate() &&
> -           MI->getOperand(3).isRegister() && MI->getOperand 
> (4).isConstantPoolIndex() &&
> -           MI->getOperand(1).getReg() == 0 &&
> -           MI->getOperand(2).getImm() == 1 &&
> -           MI->getOperand(3).getReg() == 0;
> +    if (MI->getOperand(1).isReg() && MI->getOperand(2).isImm() &&
> +        MI->getOperand(3).isReg() && MI->getOperand(4).isCPI() &&
> +        MI->getOperand(1).getReg() == 0 &&
> +        MI->getOperand(2).getImm() == 1 &&
> +        MI->getOperand(3).getReg() == 0)
> +      return true;
> +    return false;
>    }
>    // All other instructions marked M_REMATERIALIZABLE are always  
> trivially
>    // rematerializable.
> @@ -168,32 +170,11 @@
>            MI->getOperand(3).getReg() == 0)
>          return true;
>      }
> -    // FALLTHROUGH
> -  case X86::MOV8rm:
> -  case X86::MOV16rm:
> -  case X86::MOV16_rm:
> -  case X86::MOV32_rm:
> -  case X86::MOV64rm:
> -  case X86::LD_Fp64m:
> -  case X86::MOVSSrm:
> -  case X86::MOVSDrm:
> -  case X86::MOVAPSrm:
> -  case X86::MOVAPDrm:
> -  case X86::MMX_MOVD64rm:
> -  case X86::MMX_MOVQ64rm:
> -    // Loads from constant pools have no side effects
> -    return MI->getOperand(1).isRegister() &&
> -           MI->getOperand(2).isImmediate() &&
> -           MI->getOperand(3).isRegister() &&
> -           MI->getOperand(4).isConstantPoolIndex() &&
> -           MI->getOperand(1).getReg() == 0 &&
> -           MI->getOperand(2).getImm() == 1 &&
> -           MI->getOperand(3).getReg() == 0;
> +    break;
>    }
>
> -  // All other instances of these instructions are presumed to  
> have side
> -  // effects.
> -  return false;
> +  // Anything that is rematerializable obviously has no side effects.
> +  return isReallyTriviallyReMaterializable(MI);
>  }
>
>  /// hasLiveCondCodeDef - True if MI has a condition code def, e.g.  
> EFLAGS, that
>
>
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