[PATCH 1/1] SelectionDAG: Add sext_inreg optimizations

[Matt Arsenault]

On 10/13/2014 02:39 PM, Jan Vesely wrote:
> v2: use dyn_cast
>      fixup comments
> v3: use cast
>
> Signed-off-by: Jan Vesely <jan.vesely at rutgers.edu>
> ---
>   lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 22 ++++++++++++++++++++++
>   test/CodeGen/R600/sext-eliminate.ll      | 26 ++++++++++++++++++++++++++
>   2 files changed, 48 insertions(+)
>   create mode 100644 test/CodeGen/R600/sext-eliminate.ll

LGTM

>
> diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> index 76442fb..c131599 100644
> --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> @@ -1680,6 +1680,17 @@ SDValue DAGCombiner::visitADD(SDNode *N) {
>       return DAG.getNode(ISD::SUB, DL, VT, N1, ZExt);
>     }
>   
> +  // add X, (sextinreg Y i1) -> sub X, (and Y 1)
> +  if (N1.getOpcode() == ISD::SIGN_EXTEND_INREG) {
> +    VTSDNode *TN = cast<VTSDNode>(N1.getOperand(1));
> +    if (TN->getVT() == MVT::i1) {
> +      SDLoc DL(N);
> +      SDValue ZExt = DAG.getNode(ISD::AND, DL, VT, N1.getOperand(0),
> +                                 DAG.getConstant(1, VT));
> +      return DAG.getNode(ISD::SUB, DL, VT, N0, ZExt);
> +    }
> +  }
> +
>     return SDValue();
>   }
>   
> @@ -1845,6 +1856,17 @@ SDValue DAGCombiner::visitSUB(SDNode *N) {
>                                    VT);
>       }
>   
> +  // sub X, (sextinreg Y i1) -> add X, (and Y 1)
> +  if (N1.getOpcode() == ISD::SIGN_EXTEND_INREG) {
> +    VTSDNode *TN = cast<VTSDNode>(N1.getOperand(1));
> +    if (TN->getVT() == MVT::i1) {
> +      SDLoc DL(N);
> +      SDValue ZExt = DAG.getNode(ISD::AND, DL, VT, N1.getOperand(0),
> +                                 DAG.getConstant(1, VT));
> +      return DAG.getNode(ISD::ADD, DL, VT, N0, ZExt);
> +    }
> +  }
> +
>     return SDValue();
>   }
>   
> diff --git a/test/CodeGen/R600/sext-eliminate.ll b/test/CodeGen/R600/sext-eliminate.ll
> new file mode 100644
> index 0000000..0c17a7a
> --- /dev/null
> +++ b/test/CodeGen/R600/sext-eliminate.ll
> @@ -0,0 +1,26 @@
> +; RUN: llc -march=r600 -mcpu=cypress -verify-machineinstrs < %s | FileCheck -check-prefix=EG -check-prefix=FUNC %s
> +
> +
> +; FUNC-LABEL: {{^}}sext_in_reg_i1_i32_add:
> +
> +; EG: MEM_{{.*}} STORE_{{.*}} [[RES:T[0-9]+\.[XYZW]]], [[ADDR:T[0-9]+.[XYZW]]]
> +; EG: SUB_INT {{[* ]*}}[[RES]]
> +; EG-NOT: BFE
> +define void @sext_in_reg_i1_i32_add(i32 addrspace(1)* %out, i1 %a, i32 %b) {
> +  %sext = sext i1 %a to i32
> +  %res = add i32 %b, %sext
> +  store i32 %res, i32 addrspace(1)* %out
> +  ret void
> +}
> +
> +; FUNC-LABEL: {{^}}sext_in_reg_i1_i32_sub:
> +
> +; EG: MEM_{{.*}} STORE_{{.*}} [[RES:T[0-9]+\.[XYZW]]], [[ADDR:T[0-9]+.[XYZW]]]
> +; EG: ADD_INT {{[* ]*}}[[RES]]
> +; EG-NOT: BFE
> +define void @sext_in_reg_i1_i32_sub(i32 addrspace(1)* %out, i1 %a, i32 %b) {
> +  %sext = sext i1 %a to i32
> +  %res = sub i32 %b, %sext
> +  store i32 %res, i32 addrspace(1)* %out
> +  ret void
> +}