[PATCH] SelectionDAG: Expand i64 = FP_TO_SINT i32

[Tom Stellard]

Ping.

On Tue, May 06, 2014 at 02:32:35AM -0400, Tom Stellard wrote:
> ---
>  lib/CodeGen/SelectionDAG/LegalizeDAG.cpp | 59 ++++++++++++++++++++++++++++++++
>  lib/Target/R600/AMDGPUISelLowering.cpp   |  2 ++
>  test/CodeGen/R600/fp_to_sint_i64.ll      | 12 +++++++
>  3 files changed, 73 insertions(+)
>  create mode 100644 test/CodeGen/R600/fp_to_sint_i64.ll
> 
> diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
> index 745ed4a..13c71fc 100644
> --- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
> +++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
> @@ -3128,6 +3128,65 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node) {
>                                  Node->getOperand(0), Node->getValueType(0), dl);
>      Results.push_back(Tmp1);
>      break;
> +  case ISD::FP_TO_SINT: {
> +    EVT VT = Node->getOperand(0).getValueType();
> +    EVT NVT = Node->getValueType(0);
> +
> +    // FIXME: Only f32 to i64 conversions are supported.
> +    if (VT != MVT::f32 || NVT != MVT::i64)
> +      break;
> +
> +    // Expand f32 -> i64 conversion
> +    // This algorithm comes from compiler-rt's implementation of fixsfdi:
> +    // https://github.com/llvm-mirror/compiler-rt/blob/master/lib/builtins/fixsfdi.c
> +    EVT IntVT = EVT::getIntegerVT(*DAG.getContext(),
> +                                  VT.getSizeInBits());
> +    SDValue ExponentMask = DAG.getConstant(0x7F800000, IntVT);
> +    SDValue ExponentLoBit = DAG.getConstant(23, IntVT);
> +    SDValue Bias = DAG.getConstant(127, IntVT);
> +    SDValue SignMask = DAG.getConstant(APInt::getSignBit(VT.getSizeInBits()),
> +                                       IntVT);
> +    SDValue SignLowBit = DAG.getConstant(VT.getSizeInBits() - 1, IntVT);
> +    SDValue MantissaMask = DAG.getConstant(0x007FFFFF, IntVT);
> +
> +    SDValue Bits = DAG.getNode(ISD::BITCAST, dl, IntVT, Node->getOperand(0));
> +
> +    SDValue ExponentBits = DAG.getNode(ISD::SRL, dl, IntVT,
> +        DAG.getNode(ISD::AND, dl, IntVT, Bits, ExponentMask),
> +        DAG.getZExtOrTrunc(ExponentLoBit, dl, TLI.getShiftAmountTy(IntVT)));
> +    SDValue Exponent = DAG.getNode(ISD::SUB, dl, IntVT, ExponentBits, Bias);
> +
> +    SDValue Sign = DAG.getNode(ISD::SRA, dl, IntVT,
> +        DAG.getNode(ISD::AND, dl, IntVT, Bits, SignMask),
> +        DAG.getZExtOrTrunc(SignLowBit, dl, TLI.getShiftAmountTy(IntVT)));
> +    Sign = DAG.getSExtOrTrunc(Sign, dl, NVT);
> +
> +    SDValue R = DAG.getNode(ISD::OR, dl, IntVT,
> +        DAG.getNode(ISD::AND, dl, IntVT, Bits, MantissaMask),
> +        DAG.getConstant(0x00800000, IntVT));
> +
> +    R = DAG.getZExtOrTrunc(R, dl, NVT);
> +
> +
> +    R = DAG.getSelectCC(dl, Exponent, ExponentLoBit,
> +       DAG.getNode(ISD::SHL, dl, NVT, R,
> +                   DAG.getZExtOrTrunc(
> +                      DAG.getNode(ISD::SUB, dl, IntVT, Exponent, ExponentLoBit),
> +                      dl, TLI.getShiftAmountTy(IntVT))),
> +       DAG.getNode(ISD::SRL, dl, NVT, R,
> +                   DAG.getZExtOrTrunc(
> +                      DAG.getNode(ISD::SUB, dl, IntVT, ExponentLoBit, Exponent),
> +                      dl, TLI.getShiftAmountTy(IntVT))),
> +       ISD::SETGT);
> +
> +    SDValue Ret = DAG.getNode(ISD::SUB, dl, NVT,
> +        DAG.getNode(ISD::XOR, dl, NVT, R, Sign),
> +        Sign);
> +
> +    Results.push_back(DAG.getSelectCC(dl, Exponent, DAG.getConstant(0, IntVT),
> +        DAG.getConstant(0, NVT), Ret, ISD::SETLT));
> +    break;
> +  }
>    case ISD::FP_TO_UINT: {
>      SDValue True, False;
>      EVT VT =  Node->getOperand(0).getValueType();
> diff --git a/lib/Target/R600/AMDGPUISelLowering.cpp b/lib/Target/R600/AMDGPUISelLowering.cpp
> index 7ee4ccd..50856cd 100644
> --- a/lib/Target/R600/AMDGPUISelLowering.cpp
> +++ b/lib/Target/R600/AMDGPUISelLowering.cpp
> @@ -196,6 +196,8 @@ AMDGPUTargetLowering::AMDGPUTargetLowering(TargetMachine &TM) :
>  
>    setOperationAction(ISD::BR_CC, MVT::i1, Expand);
>  
> +  setOperationAction(ISD::FP_TO_SINT, MVT::i64, Expand);
> +
>    setOperationAction(ISD::FNEG, MVT::v2f32, Expand);
>    setOperationAction(ISD::FNEG, MVT::v4f32, Expand);
>  
> diff --git a/test/CodeGen/R600/fp_to_sint_i64.ll b/test/CodeGen/R600/fp_to_sint_i64.ll
> new file mode 100644
> index 0000000..ec3e198
> --- /dev/null
> +++ b/test/CodeGen/R600/fp_to_sint_i64.ll
> @@ -0,0 +1,12 @@
> +; FIXME: Merge into fp_to_sint.ll when EG/NI supports 64-bit types
> +; RUN: llc < %s -march=r600 -mcpu=SI -verify-machineinstrs | FileCheck --check-prefix=SI %s
> +
> +; SI-LABEL: @fp_to_sint_i64
> +; Check that the compiler doesn't crash with a "cannot select" error
> +; SI: S_ENDPGM
> +define void @fp_to_sint_i64 (i64 addrspace(1)* %out, float %in) {
> +entry:
> +  %0 = fptosi float %in to i64
> +  store i64 %0, i64 addrspace(1)* %out
> +  ret void
> +}
> -- 
> 1.8.1.5
> 
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