From 1e30bf8621cc123a7afba3246a36187c5ce3c836 Mon Sep 17 00:00:00 2001
From: Eli Friedman <efriedma@quicinc.com>
Date: Mon, 12 Jul 2021 15:11:01 -0700
Subject: [PATCH] [SelectionDAG] Add an overload of getStepVector that assumes
 step 1.

This is mostly a minor convenience, but the pattern seems frequent
enough to be worthwhile (and we'll probably add more uses in the
future).

Differential Revision: https://reviews.llvm.org/D105850
---
 llvm/include/llvm/CodeGen/SelectionDAG.h              | 4 ++++
 llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp        | 5 +++++
 llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 5 +----
 llvm/lib/Target/AArch64/AArch64ISelLowering.cpp       | 6 ++----
 4 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/SelectionDAG.h b/llvm/include/llvm/CodeGen/SelectionDAG.h
index 5e12da6..8cbdf7e 100644
--- a/llvm/include/llvm/CodeGen/SelectionDAG.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAG.h
@@ -837,6 +837,10 @@ public:
   ///   <0, Step, Step * 2, Step * 3, ...>
   SDValue getStepVector(const SDLoc &DL, EVT ResVT, SDValue Step);
 
+  /// Returns a vector of type ResVT whose elements contain the linear sequence
+  ///   <0, 1, 2, 3, ...>
+  SDValue getStepVector(const SDLoc &DL, EVT ResVT);
+
   /// Returns an ISD::VECTOR_SHUFFLE node semantically equivalent to
   /// the shuffle node in input but with swapped operands.
   ///
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 0dbcfef..e194e1b 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1747,6 +1747,11 @@ SDValue SelectionDAG::getCondCode(ISD::CondCode Cond) {
   return SDValue(CondCodeNodes[Cond], 0);
 }
 
+SDValue SelectionDAG::getStepVector(const SDLoc &DL, EVT ResVT) {
+  EVT OpVT = TLI->getTypeToTransformTo(*getContext(), ResVT.getScalarType());
+  return getStepVector(DL, ResVT, getConstant(1, DL, OpVT));
+}
+
 SDValue SelectionDAG::getStepVector(const SDLoc &DL, EVT ResVT, SDValue Step) {
   if (ResVT.isScalableVector())
     return getNode(ISD::STEP_VECTOR, DL, ResVT, Step);
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 58e691a..d56d4bc 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -11074,10 +11074,7 @@ void SelectionDAGBuilder::visitStepVector(const CallInst &I) {
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
   auto DL = getCurSDLoc();
   EVT ResultVT = TLI.getValueType(DAG.getDataLayout(), I.getType());
-  EVT OpVT =
-      TLI.getTypeToTransformTo(*DAG.getContext(), ResultVT.getScalarType());
-  SDValue Step = DAG.getConstant(1, DL, OpVT);
-  setValue(&I, DAG.getStepVector(DL, ResultVT, Step));
+  setValue(&I, DAG.getStepVector(DL, ResultVT));
 }
 
 void SelectionDAGBuilder::visitVectorReverse(const CallInst &I) {
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index 7bc73a9..8cda50d 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -9503,7 +9503,7 @@ SDValue AArch64TargetLowering::LowerDUPQLane(SDValue Op,
   SDValue SplatOne = DAG.getNode(ISD::SPLAT_VECTOR, DL, MVT::nxv2i64, One);
 
   // create the vector 0,1,0,1,...
-  SDValue SV = DAG.getNode(ISD::STEP_VECTOR, DL, MVT::nxv2i64, One);
+  SDValue SV = DAG.getStepVector(DL, MVT::nxv2i64);
   SV = DAG.getNode(ISD::AND, DL, MVT::nxv2i64, SV, SplatOne);
 
   // create the vector idx64,idx64+1,idx64,idx64+1,...
@@ -13998,9 +13998,7 @@ static SDValue LowerSVEIntrinsicIndex(SDNode *N, SelectionDAG &DAG) {
     ScalarTy = MVT::i32;
 
   // Lower index_vector(base, step) to mul(step step_vector(1)) + splat(base).
-  SDValue One = DAG.getConstant(1, DL, ScalarTy);
-  SDValue StepVector =
-      DAG.getNode(ISD::STEP_VECTOR, DL, N->getValueType(0), One);
+  SDValue StepVector = DAG.getStepVector(DL, N->getValueType(0));
   SDValue Step = DAG.getNode(ISD::SPLAT_VECTOR, DL, N->getValueType(0), Op2);
   SDValue Mul = DAG.getNode(ISD::MUL, DL, N->getValueType(0), StepVector, Step);
   SDValue Base = DAG.getNode(ISD::SPLAT_VECTOR, DL, N->getValueType(0), Op1);
-- 
2.7.4