[llvm-commits] [llvm] r171467 - in /llvm/trunk: lib/Target/X86/X86ISelLowering.cpp test/CodeGen/X86/avx-trunc.ll
Nadav Rotem
nrotem at apple.com
Thu Jan 3 09:20:38 PST 2013
Elena,
How is this correct ? You are taking the result of SETCC which is a vector or v8i32, and you only take the lower 4 elements (v4i32). The SETCC is not all-one or all zero. Only *elements* within the vector are all-one or all zero. Did you test this patch somehow ?
Nadav
On Jan 3, 2013, at 12:49 AM, Elena Demikhovsky <elena.demikhovsky at intel.com> wrote:
> Author: delena
> Date: Thu Jan 3 02:48:33 2013
> New Revision: 171467
>
> URL: http://llvm.org/viewvc/llvm-project?rev=171467&view=rev
> Log:
> Simplified TRUNCATE operation that comes after SETCC. It is possible since SETCC result is 0 or -1.
> Added a test.
>
> Modified:
> llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
> llvm/trunk/test/CodeGen/X86/avx-trunc.ll
>
> Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=171467&r1=171466&r2=171467&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
> +++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Thu Jan 3 02:48:33 2013
> @@ -14661,12 +14661,29 @@
> return EltsFromConsecutiveLoads(VT, Elts, dl, DAG);
> }
>
> -/// PerformTruncateCombine - Converts truncate operation to
> -/// a sequence of vector shuffle operations.
> -/// It is possible when we truncate 256-bit vector to 128-bit vector
> +/// PerformTruncateCombine - In some cases a sequence with "truncate"
> +/// operation may be simplified.
> static SDValue PerformTruncateCombine(SDNode *N, SelectionDAG &DAG,
> TargetLowering::DAGCombinerInfo &DCI,
> const X86Subtarget *Subtarget) {
> + EVT VT = N->getValueType(0);
> + if (DCI.isBeforeLegalize() || !VT.isVector())
> + return SDValue();
> +
> + SDValue In = N->getOperand(0);
> + // Optimize the sequence setcc -> truncate
> + if (In.getOpcode() == ISD::SETCC) {
> + DebugLoc DL = N->getDebugLoc();
> + EVT InVT = In.getValueType();
> +
> + // The vector element is all ones or all zero. Just take a half of it.
> + EVT HalfVT = EVT::getVectorVT(*DAG.getContext(), InVT.getScalarType(),
> + InVT.getVectorNumElements()/2);
> + SDValue HalfVec = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, HalfVT, In,
> + DAG.getIntPtrConstant(0));
> + assert(HalfVT.getSizeInBits() == VT.getSizeInBits());
> + return DAG.getNode(ISD::BITCAST, DL, VT, HalfVec);
> + }
> return SDValue();
> }
>
>
> Modified: llvm/trunk/test/CodeGen/X86/avx-trunc.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/avx-trunc.ll?rev=171467&r1=171466&r2=171467&view=diff
> ==============================================================================
> --- llvm/trunk/test/CodeGen/X86/avx-trunc.ll (original)
> +++ llvm/trunk/test/CodeGen/X86/avx-trunc.ll Thu Jan 3 02:48:33 2013
> @@ -13,3 +13,18 @@
> ret <8 x i16>%B
> }
>
> +define <8 x i16> @trunc_after_setcc(<8 x float> %a, <8 x float> %b, <8 x float> %c, <8 x float> %d) {
> +; CHECK: trunc_after_setcc
> +; CHECK: vcmpltps
> +; CHECK-NOT: vextract
> +; CHECK: vcmpltps
> +; CHECK-NEXT: vandps
> +; CHECK-NEXT: vandps
> +; CHECK: ret
> + %res1 = fcmp olt <8 x float> %a, %b
> + %res2 = fcmp olt <8 x float> %c, %d
> + %andr = and <8 x i1>%res1, %res2
> + %ex = zext <8 x i1> %andr to <8 x i16>
> + ret <8 x i16>%ex
> +}
> +
>
>
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