From 3e56c9d4260b091ecb0332e96615f1186605ac99 Mon Sep 17 00:00:00 2001
From: Krzysztof Parzyszek <kparzysz@quicinc.com>
Date: Mon, 1 Jul 2019 15:50:09 +0000
Subject: [PATCH] [Hexagon] Custom-lower UADDO(x, 1) and USUBO(x, 1)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364790 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/Hexagon/HexagonISelLowering.cpp | 43 +++++++++++++++++++++-
 lib/Target/Hexagon/HexagonISelLowering.h   |  1 +
 test/CodeGen/Hexagon/isel-uaddo-1.ll       | 37 +++++++++++++++++++
 3 files changed, 79 insertions(+), 2 deletions(-)
 create mode 100644 test/CodeGen/Hexagon/isel-uaddo-1.ll

diff --git a/lib/Target/Hexagon/HexagonISelLowering.cpp b/lib/Target/Hexagon/HexagonISelLowering.cpp
index b72498777ed..fef5a98cdb0 100644
--- a/lib/Target/Hexagon/HexagonISelLowering.cpp
+++ b/lib/Target/Hexagon/HexagonISelLowering.cpp
@@ -1334,8 +1334,8 @@ HexagonTargetLowering::HexagonTargetLowering(const TargetMachine &TM,
   // Hexagon has A4_addp_c and A4_subp_c that take and generate a carry bit,
   // but they only operate on i64.
   for (MVT VT : MVT::integer_valuetypes()) {
-    setOperationAction(ISD::UADDO,    VT, Expand);
-    setOperationAction(ISD::USUBO,    VT, Expand);
+    setOperationAction(ISD::UADDO,    VT, Custom);
+    setOperationAction(ISD::USUBO,    VT, Custom);
     setOperationAction(ISD::SADDO,    VT, Expand);
     setOperationAction(ISD::SSUBO,    VT, Expand);
     setOperationAction(ISD::ADDCARRY, VT, Expand);
@@ -2691,6 +2691,43 @@ HexagonTargetLowering::LowerUnalignedLoad(SDValue Op, SelectionDAG &DAG)
   return M;
 }
 
+SDValue
+HexagonTargetLowering::LowerUAddSubO(SDValue Op, SelectionDAG &DAG) const {
+  SDValue X = Op.getOperand(0), Y = Op.getOperand(1);
+  auto *CY = dyn_cast<ConstantSDNode>(Y);
+  if (!CY)
+    return SDValue();
+
+  const SDLoc &dl(Op);
+  SDVTList VTs = Op.getNode()->getVTList();
+  assert(VTs.NumVTs == 2);
+  assert(VTs.VTs[1] == MVT::i1);
+  unsigned Opc = Op.getOpcode();
+
+  if (CY) {
+    uint32_t VY = CY->getZExtValue();
+    assert(VY != 0 && "This should have been folded");
+    // X +/- 1
+    if (VY != 1)
+      return SDValue();
+
+    if (Opc == ISD::UADDO) {
+      SDValue Op = DAG.getNode(ISD::ADD, dl, VTs.VTs[0], {X, Y});
+      SDValue Ov = DAG.getSetCC(dl, MVT::i1, Op, getZero(dl, ty(Op), DAG),
+                                ISD::SETEQ);
+      return DAG.getMergeValues({Op, Ov}, dl);
+    }
+    if (Opc == ISD::USUBO) {
+      SDValue Op = DAG.getNode(ISD::SUB, dl, VTs.VTs[0], {X, Y});
+      SDValue Ov = DAG.getSetCC(dl, MVT::i1, Op,
+                                DAG.getConstant(-1, dl, ty(Op)), ISD::SETEQ);
+      return DAG.getMergeValues({Op, Ov}, dl);
+    }
+  }
+
+  return SDValue();
+}
+
 SDValue
 HexagonTargetLowering::LowerAddSubCarry(SDValue Op, SelectionDAG &DAG) const {
   const SDLoc &dl(Op);
@@ -2768,6 +2805,8 @@ HexagonTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
     case ISD::BITCAST:              return LowerBITCAST(Op, DAG);
     case ISD::LOAD:                 return LowerLoad(Op, DAG);
     case ISD::STORE:                return LowerStore(Op, DAG);
+    case ISD::UADDO:
+    case ISD::USUBO:                return LowerUAddSubO(Op, DAG);
     case ISD::ADDCARRY:
     case ISD::SUBCARRY:             return LowerAddSubCarry(Op, DAG);
     case ISD::SRA:
diff --git a/lib/Target/Hexagon/HexagonISelLowering.h b/lib/Target/Hexagon/HexagonISelLowering.h
index 7c86bbf62a3..4e467cb2272 100644
--- a/lib/Target/Hexagon/HexagonISelLowering.h
+++ b/lib/Target/Hexagon/HexagonISelLowering.h
@@ -167,6 +167,7 @@ namespace HexagonISD {
     SDValue LowerLoad(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerStore(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerUnalignedLoad(SDValue Op, SelectionDAG &DAG) const;
+    SDValue LowerUAddSubO(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerAddSubCarry(SDValue Op, SelectionDAG &DAG) const;
 
     SDValue LowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const;
diff --git a/test/CodeGen/Hexagon/isel-uaddo-1.ll b/test/CodeGen/Hexagon/isel-uaddo-1.ll
new file mode 100644
index 00000000000..092fb60e041
--- /dev/null
+++ b/test/CodeGen/Hexagon/isel-uaddo-1.ll
@@ -0,0 +1,37 @@
+; RUN: llc -march=hexagon < %s | FileCheck %s
+
+; Check that a hardware loop is generated.
+; CHECK: loop0
+
+target triple = "hexagon"
+
+; Function Attrs: norecurse nounwind
+define dso_local void @f0(i32* nocapture readonly %a0, i32* nocapture %a1) local_unnamed_addr #0 {
+b0:
+  br label %b1
+
+b1:                                               ; preds = %b1, %b0
+  %v0 = phi i32 [ %v3, %b1 ], [ 100, %b0 ]
+  %v1 = phi i32* [ %v6, %b1 ], [ %a1, %b0 ]
+  %v2 = phi i32* [ %v4, %b1 ], [ %a0, %b0 ]
+  %v3 = add nsw i32 %v0, -1
+  %v4 = getelementptr inbounds i32, i32* %v2, i32 1
+  %v5 = load i32, i32* %v2, align 4, !tbaa !1
+  %v6 = getelementptr inbounds i32, i32* %v1, i32 1
+  store i32 %v5, i32* %v1, align 4, !tbaa !1
+  %v7 = icmp eq i32 %v3, 0
+  br i1 %v7, label %b2, label %b1
+
+b2:                                               ; preds = %b1
+  ret void
+}
+
+attributes #0 = { norecurse nounwind "target-cpu"="hexagonv62" }
+
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{!2, !2, i64 0}
+!2 = !{!"int", !3, i64 0}
+!3 = !{!"omnipotent char", !4, i64 0}
+!4 = !{!"Simple C/C++ TBAA"}
-- 
2.40.0