[PATCH] D88731: [AArch64] Combine UADDVs to generate vector add

[Vinay Madhusudan via Phabricator via llvm-commits]

mivnay updated this revision to Diff 295832.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D88731/new/

https://reviews.llvm.org/D88731

Files:
  llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
  llvm/test/CodeGen/AArch64/aarch64-addv.ll


Index: llvm/test/CodeGen/AArch64/aarch64-addv.ll
===================================================================
--- llvm/test/CodeGen/AArch64/aarch64-addv.ll
+++ llvm/test/CodeGen/AArch64/aarch64-addv.ll
@@ -68,3 +68,18 @@
   %r = call i32 @llvm.experimental.vector.reduce.add.v16i32(<16 x i32> %bin.rdx)
   ret i32 %r
 }
+
+define i32 @addv_combine(i32* nocapture readonly %a1, i32* nocapture readonly %a2) {
+; CHECK-LABEL: addv_combine
+; CHECK: add {{v[0-9]+}}.4s, {{v[0-9]+}}.4s, {{v[0-9]+}}.4s
+; CHECK: addv {{s[0-9]+}}, {{v[0-9]+}}.4s
+entry:
+  %0 = bitcast i32* %a1 to <4 x i32>*
+  %1 = load <4 x i32>, <4 x i32>* %0
+  %2 = bitcast i32* %a2 to <4 x i32>*
+  %3 = load <4 x i32>, <4 x i32>* %2
+  %4 = call i32 @llvm.experimental.vector.reduce.add.v4i32(<4 x i32> %1)
+  %5 = call i32 @llvm.experimental.vector.reduce.add.v4i32(<4 x i32> %3)
+  %6 = add i32 %4, %5
+  ret i32 %6
+}
Index: llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -12212,6 +12212,43 @@
   return DAG.getNode(AArch64ISD::CSEL, dl, VT, RHS, LHS, CCVal, Cmp);
 }
 
+// ADD(UADDV a, UADDV b) -->  UADDV((ADD a, b))
+static SDValue performUADDVCombine(SDNode *N,
+                                   TargetLowering::DAGCombinerInfo &DCI,
+                                   SelectionDAG &DAG) {
+  EVT VT = N->getValueType(0);
+  // TODO: Currently handled for 32 bit integer vectors.
+  if (N->getOpcode() != ISD::ADD || VT != MVT::i32)
+    return SDValue();
+
+  SDValue LHS = N->getOperand(0);
+  SDValue RHS = N->getOperand(1);
+  if (LHS.getOpcode() != ISD::EXTRACT_VECTOR_ELT ||
+      RHS.getOpcode() != ISD::EXTRACT_VECTOR_ELT || LHS.getValueType() != VT)
+    return SDValue();
+
+  auto *LHSN1 = dyn_cast<ConstantSDNode>(LHS->getOperand(1));
+  auto *RHSN1 = dyn_cast<ConstantSDNode>(RHS->getOperand(1));
+  if (!LHSN1 || !RHSN1 || !LHSN1->isNullValue() || !RHSN1->isNullValue())
+    return SDValue();
+
+  SDValue Op1 = LHS->getOperand(0);
+  SDValue Op2 = RHS->getOperand(0);
+  if (Op1.getOpcode() != AArch64ISD::UADDV ||
+      Op1.getValueType() != MVT::v4i32 ||
+      Op2.getOpcode() != AArch64ISD::UADDV || Op2.getValueType() != MVT::v4i32)
+    return SDValue();
+
+  SDValue Val1 = Op1.getOperand(0);
+  SDValue Val2 = Op2.getOperand(0);
+  EVT ValVT = Val1->getValueType(0);
+  SDLoc DL(N);
+  SDValue AddVal = DAG.getNode(ISD::ADD, DL, ValVT, Val1, Val2);
+  return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, VT,
+                     DAG.getNode(AArch64ISD::UADDV, DL, ValVT, AddVal),
+                     DAG.getConstant(0, DL, MVT::i64));
+}
+
 // The basic add/sub long vector instructions have variants with "2" on the end
 // which act on the high-half of their inputs. They are normally matched by
 // patterns like:
@@ -12265,6 +12302,18 @@
   return DAG.getNode(N->getOpcode(), SDLoc(N), VT, LHS, RHS);
 }
 
+static SDValue performAddSubCombine(SDNode *N,
+                                    TargetLowering::DAGCombinerInfo &DCI,
+                                    SelectionDAG &DAG) {
+  // Try to change sum of two reductions.
+  SDValue Val = performUADDVCombine(N, DCI, DAG);
+  if (Val.getNode()) {
+    return Val;
+  }
+
+  return performAddSubLongCombine(N, DCI, DAG);
+}
+
 // Massage DAGs which we can use the high-half "long" operations on into
 // something isel will recognize better. E.g.
 //
@@ -14613,7 +14662,7 @@
     break;
   case ISD::ADD:
   case ISD::SUB:
-    return performAddSubLongCombine(N, DCI, DAG);
+    return performAddSubCombine(N, DCI, DAG);
   case ISD::XOR:
     return performXorCombine(N, DAG, DCI, Subtarget);
   case ISD::MUL:


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