[SelectionDAG][X86] Explicitly store the scale in the gather/scatter ISD nodes

Currently we infer the scale at isel time by analyzing whether the base is a constant 0 or not. If it is we assume scale is 1, else we take it from the element size of the pass thru or stored value. This seems a little weird and I think it makes more sense to make it explicit in the DAG rather than doing tricky things in the backend.

Most of this patch is just making sure we copy the scale around everywhere.

Differential Revision: https://reviews.llvm.org/D40055

llvm-svn: 322210

1 files changed, 15 insertions, 7 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index bd8d7670465..1c15a3ce13c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -3867,7 +3867,7 @@ void SelectionDAGBuilder::visitMaskedStore(const CallInst &I,
 // 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,
-                           SelectionDAGBuilder* SDB) {
+                           SDValue &Scale, SelectionDAGBuilder* SDB) {
   SelectionDAG& DAG = SDB->DAG;
   LLVMContext &Context = *DAG.getContext();
 
@@ -3897,6 +3897,10 @@ static bool getUniformBase(const Value* &Ptr, SDValue& Base, SDValue& Index,
   if (!SDB->findValue(Ptr) || !SDB->findValue(IndexVal))
     return false;
 
+  const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+  const DataLayout &DL = DAG.getDataLayout();
+  Scale = DAG.getTargetConstant(DL.getTypeAllocSize(GEP->getResultElementType()),
+                                SDB->getCurSDLoc(), TLI.getPointerTy(DL));
   Base = SDB->getValue(Ptr);
   Index = SDB->getValue(IndexVal);
 
@@ -3926,8 +3930,9 @@ void SelectionDAGBuilder::visitMaskedScatter(const CallInst &I) {
 
   SDValue Base;
   SDValue Index;
+  SDValue Scale;
   const Value *BasePtr = Ptr;
-  bool UniformBase = getUniformBase(BasePtr, Base, Index, this);
+  bool UniformBase = getUniformBase(BasePtr, Base, Index, Scale, this);
 
   const Value *MemOpBasePtr = UniformBase ? BasePtr : nullptr;
   MachineMemOperand *MMO = DAG.getMachineFunction().
@@ -3935,10 +3940,11 @@ void SelectionDAGBuilder::visitMaskedScatter(const CallInst &I) {
                          MachineMemOperand::MOStore,  VT.getStoreSize(),
                          Alignment, AAInfo);
   if (!UniformBase) {
-    Base = DAG.getTargetConstant(0, sdl, TLI.getPointerTy(DAG.getDataLayout()));
+    Base = DAG.getConstant(0, sdl, TLI.getPointerTy(DAG.getDataLayout()));
     Index = getValue(Ptr);
+    Scale = DAG.getTargetConstant(1, sdl, TLI.getPointerTy(DAG.getDataLayout()));
   }
-  SDValue Ops[] = { getRoot(), Src0, Mask, Base, Index };
+  SDValue Ops[] = { getRoot(), Src0, Mask, Base, Index, Scale };
   SDValue Scatter = DAG.getMaskedScatter(DAG.getVTList(MVT::Other), VT, sdl,
                                          Ops, MMO);
   DAG.setRoot(Scatter);
@@ -4025,8 +4031,9 @@ void SelectionDAGBuilder::visitMaskedGather(const CallInst &I) {
   SDValue Root = DAG.getRoot();
   SDValue Base;
   SDValue Index;
+  SDValue Scale;
   const Value *BasePtr = Ptr;
-  bool UniformBase = getUniformBase(BasePtr, Base, Index, this);
+  bool UniformBase = getUniformBase(BasePtr, Base, Index, Scale, this);
   bool ConstantMemory = false;
   if (UniformBase &&
       AA && AA->pointsToConstantMemory(MemoryLocation(
@@ -4044,10 +4051,11 @@ void SelectionDAGBuilder::visitMaskedGather(const CallInst &I) {
                          Alignment, AAInfo, Ranges);
 
   if (!UniformBase) {
-    Base = DAG.getTargetConstant(0, sdl, TLI.getPointerTy(DAG.getDataLayout()));
+    Base = DAG.getConstant(0, sdl, TLI.getPointerTy(DAG.getDataLayout()));
     Index = getValue(Ptr);
+    Scale = DAG.getTargetConstant(1, sdl, TLI.getPointerTy(DAG.getDataLayout()));
   }
-  SDValue Ops[] = { Root, Src0, Mask, Base, Index };
+  SDValue Ops[] = { Root, Src0, Mask, Base, Index, Scale };
   SDValue Gather = DAG.getMaskedGather(DAG.getVTList(VT, MVT::Other), VT, sdl,
                                        Ops, MMO);