[SelectionDAG] Extend base addressing modes supported by MGATHER/MSCATTER

Summary:
Before this patch MGATHER/MSCATTER is capable of representing all
common addressing modes, but only when illegal types are used.
This patch adds an IndexType property so more representations
are available when using legal types only.

Original modes:
 vector of bases
 base + vector of signed scaled offsets

New modes:
 base + vector of signed unscaled offsets
 base + vector of unsigned scaled offsets
 base + vector of unsigned unscaled offsets

The current behaviour of addressing modes for gather/scatter remains
unchanged.

Patch by Paul Walker.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D65636

llvm-svn: 368008

1 files changed, 14 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index a52e5ea..a3c3715 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4308,8 +4308,9 @@ void SelectionDAGBuilder::visitMaskedStore(const CallInst &I,
 // are looking for. If first operand of the GEP is a splat vector - we
 // extract the splat value and use it as a uniform base.
 // In all other cases the function returns 'false'.
-static bool getUniformBase(const Value* &Ptr, SDValue& Base, SDValue& Index,
-                           SDValue &Scale, SelectionDAGBuilder* SDB) {
+static bool getUniformBase(const Value *&Ptr, SDValue &Base, SDValue &Index,
+                           ISD::MemIndexType &IndexType, SDValue &Scale,
+                           SelectionDAGBuilder *SDB) {
   SelectionDAG& DAG = SDB->DAG;
   LLVMContext &Context = *DAG.getContext();
 
@@ -4345,6 +4346,7 @@ static bool getUniformBase(const Value* &Ptr, SDValue& Base, SDValue& Index,
                                 SDB->getCurSDLoc(), TLI.getPointerTy(DL));
   Base = SDB->getValue(Ptr);
   Index = SDB->getValue(IndexVal);
+  IndexType = ISD::SIGNED_SCALED;
 
   if (!Index.getValueType().isVector()) {
     unsigned GEPWidth = GEP->getType()->getVectorNumElements();
@@ -4372,9 +4374,11 @@ void SelectionDAGBuilder::visitMaskedScatter(const CallInst &I) {
 
   SDValue Base;
   SDValue Index;
+  ISD::MemIndexType IndexType;
   SDValue Scale;
   const Value *BasePtr = Ptr;
-  bool UniformBase = getUniformBase(BasePtr, Base, Index, Scale, this);
+  bool UniformBase = getUniformBase(BasePtr, Base, Index, IndexType, Scale,
+                                    this);
 
   const Value *MemOpBasePtr = UniformBase ? BasePtr : nullptr;
   MachineMemOperand *MMO = DAG.getMachineFunction().
@@ -4384,11 +4388,12 @@ void SelectionDAGBuilder::visitMaskedScatter(const CallInst &I) {
   if (!UniformBase) {
     Base = DAG.getConstant(0, sdl, TLI.getPointerTy(DAG.getDataLayout()));
     Index = getValue(Ptr);
+    IndexType = ISD::SIGNED_SCALED;
     Scale = DAG.getTargetConstant(1, sdl, TLI.getPointerTy(DAG.getDataLayout()));
   }
   SDValue Ops[] = { getRoot(), Src0, Mask, Base, Index, Scale };
   SDValue Scatter = DAG.getMaskedScatter(DAG.getVTList(MVT::Other), VT, sdl,
-                                         Ops, MMO);
+                                         Ops, MMO, IndexType);
   DAG.setRoot(Scatter);
   setValue(&I, Scatter);
 }
@@ -4475,9 +4480,11 @@ void SelectionDAGBuilder::visitMaskedGather(const CallInst &I) {
   SDValue Root = DAG.getRoot();
   SDValue Base;
   SDValue Index;
+  ISD::MemIndexType IndexType;
   SDValue Scale;
   const Value *BasePtr = Ptr;
-  bool UniformBase = getUniformBase(BasePtr, Base, Index, Scale, this);
+  bool UniformBase = getUniformBase(BasePtr, Base, Index, IndexType, Scale,
+                                    this);
   bool ConstantMemory = false;
   if (UniformBase && AA &&
       AA->pointsToConstantMemory(
@@ -4499,11 +4506,12 @@ void SelectionDAGBuilder::visitMaskedGather(const CallInst &I) {
   if (!UniformBase) {
     Base = DAG.getConstant(0, sdl, TLI.getPointerTy(DAG.getDataLayout()));
     Index = getValue(Ptr);
+    IndexType = ISD::SIGNED_SCALED;
     Scale = DAG.getTargetConstant(1, sdl, TLI.getPointerTy(DAG.getDataLayout()));
   }
   SDValue Ops[] = { Root, Src0, Mask, Base, Index, Scale };
   SDValue Gather = DAG.getMaskedGather(DAG.getVTList(VT, MVT::Other), VT, sdl,
-                                       Ops, MMO);
+                                       Ops, MMO, IndexType);
 
   SDValue OutChain = Gather.getValue(1);
   if (!ConstantMemory)