[llvm-commits] [llvm] r155853 - in /llvm/trunk: lib/Target/X86/X86ISelLowering.cpp test/CodeGen/X86/select.ll

[Duncan Sands]

Hi Manman, it looks like this commit caused PR12721.  Can you please take a
look.

Ciao, Duncan.

> Author: mren
> Date: Mon Apr 30 17:51:25 2012
> New Revision: 155853
>
> URL: http://llvm.org/viewvc/llvm-project?rev=155853&view=rev
> Log:
> X86: optimization for -(x != 0)
>
> This patch will optimize -(x != 0) on X86
> FROM
> cmpl	$0x01,%edi
> sbbl	%eax,%eax
> notl	%eax
> TO
> negl %edi
> sbbl %eax %eax
>
> Modified:
>      llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
>      llvm/trunk/test/CodeGen/X86/select.ll
>
> Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=155853&r1=155852&r2=155853&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
> +++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Mon Apr 30 17:51:25 2012
> @@ -8589,6 +8589,22 @@
>         SDValue Y = isAllOnes(Op2) ? Op1 : Op2;
>
>         SDValue CmpOp0 = Cmp.getOperand(0);
> +      // further optimization for special cases
> +      // (select (x != 0), -1, 0) ->  neg&  sbb
> +      // (select (x == 0), 0, -1) ->  neg&  sbb
> +      if (ConstantSDNode *YC = dyn_cast<ConstantSDNode>(Y))
> +        if (YC->isNullValue()&&
> +            (isAllOnes(Op1) == (CondCode == X86::COND_NE))) {
> +          SDVTList VTs = DAG.getVTList(CmpOp0.getValueType(), MVT::i32);
> +          SDValue Neg = DAG.getNode(ISD::SUB, DL, VTs,
> +                                    DAG.getConstant(0, CmpOp0.getValueType()),
> +                                    CmpOp0);
> +          SDValue Res = DAG.getNode(X86ISD::SETCC_CARRY, DL, Op.getValueType(),
> +                                    DAG.getConstant(X86::COND_B, MVT::i8),
> +                                    SDValue(Neg.getNode(), 1));
> +          return Res;
> +        }
> +
>         Cmp = DAG.getNode(X86ISD::CMP, DL, MVT::i32,
>                           CmpOp0, DAG.getConstant(1, CmpOp0.getValueType()));
>         Cmp = ConvertCmpIfNecessary(Cmp, DAG);
>
> Modified: llvm/trunk/test/CodeGen/X86/select.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/select.ll?rev=155853&r1=155852&r2=155853&view=diff
> ==============================================================================
> --- llvm/trunk/test/CodeGen/X86/select.ll (original)
> +++ llvm/trunk/test/CodeGen/X86/select.ll Mon Apr 30 17:51:25 2012
> @@ -218,3 +218,24 @@
>   ; CHECK-NEXT: ret
>   }
>
> +; rdar://10961709
> +define i32 @test15(i32 %x) nounwind {
> +entry:
> +  %cmp = icmp ne i32 %x, 0
> +  %sub = sext i1 %cmp to i32
> +  ret i32 %sub
> +; CHECK: test15:
> +; CHECK: negl
> +; CHECK: sbbl
> +}
> +
> +define i32 @test16(i32 %x) nounwind {
> +entry:
> +  %c = icmp eq i32 %x, 0
> +  %d = select i1 %c, i32 0, i32 -1
> +  ret i32 %d
> +; CHECK: test16:
> +; CHECK: negl
> +; CHECK: sbbl
> +}
> +
>
>
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