Revert "Revert "New interface function is added to VectorUtils Value *getSplatValue(Value *Val);""

This reverts commit r246379. It seems that the commit was not the culprit,
and the bot will be investigated for instability.

llvm-svn: 246380

llvm/include/llvm/Analysis/VectorUtils.h

@@ -79,6 +79,11 @@ Value *getStrideFromPointer(Value *Ptr, ScalarEvolution *SE, Loop *Lp);
 /// from the vector.
 Value *findScalarElement(Value *V, unsigned EltNo);
 
+/// \brief Get splat value if the input is a splat vector or return nullptr.
+/// The value may be extracted from a splat constants vector or from
+/// a sequence of instructions that broadcast a single value into a vector.
+Value *getSplatValue(Value *V);
+
 } // llvm namespace
 
 #endif

llvm/lib/Analysis/VectorUtils.cpp

@@ -18,6 +18,8 @@
 #include "llvm/IR/GetElementPtrTypeIterator.h"
 #include "llvm/IR/PatternMatch.h"
 #include "llvm/IR/Value.h"
+#include "llvm/IR/Constants.h"
+
 using namespace llvm;
 using namespace llvm::PatternMatch;
 
@@ -406,3 +408,27 @@ Value *llvm::findScalarElement(Value *V, unsigned EltNo) {
   // Otherwise, we don't know.
   return nullptr;
 }
+
+/// \brief Get splat value if the input is a splat vector or return nullptr.
+/// The value may be extracted from a splat constants vector or from
+/// a sequence of instructions that broadcast a single value into a vector.
+llvm::Value *llvm::getSplatValue(Value *V) {
+  llvm::ConstantDataVector *CV = dyn_cast<llvm::ConstantDataVector>(V);
+  if (CV)
+    return CV->getSplatValue();
+  llvm::ShuffleVectorInst *ShuffleInst = dyn_cast<llvm::ShuffleVectorInst>(V);
+  if (!ShuffleInst)
+    return nullptr;
+  // All-zero (our undef) shuffle mask elements.
+  for (int i : ShuffleInst->getShuffleMask())
+    if (i != 0 && i != -1)
+      return nullptr;
+  // The first shuffle source is 'insertelement' with index 0.
+  llvm::InsertElementInst *InsertEltInst =
+    dyn_cast<llvm::InsertElementInst>(ShuffleInst->getOperand(0));
+  if (!InsertEltInst || !isa<ConstantInt>(InsertEltInst->getOperand(2)) ||
+      !cast<ConstantInt>(InsertEltInst->getOperand(2))->isNullValue())
+    return nullptr;
+
+  return InsertEltInst->getOperand(1);
+}

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

@@ -22,6 +22,7 @@
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Analysis/VectorUtils.h"
 #include "llvm/CodeGen/FastISel.h"
 #include "llvm/CodeGen/FunctionLoweringInfo.h"
 #include "llvm/CodeGen/GCMetadata.h"
@@ -3150,37 +3151,32 @@ static bool getUniformBase(Value *& Ptr, SDValue& Base, SDValue& Index,
                            SelectionDAGBuilder* SDB) {
 
   assert(Ptr->getType()->isVectorTy() && "Unexpected pointer type");
-  GetElementPtrInst *Gep = dyn_cast<GetElementPtrInst>(Ptr);
-  if (!Gep || Gep->getNumOperands() > 2)
+  GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr);
+  if (!GEP || GEP->getNumOperands() > 2)
     return false;
-  ShuffleVectorInst *ShuffleInst = 
-    dyn_cast<ShuffleVectorInst>(Gep->getPointerOperand());
-  if (!ShuffleInst || !ShuffleInst->getMask()->isNullValue() ||
-      cast<Instruction>(ShuffleInst->getOperand(0))->getOpcode() !=
-      Instruction::InsertElement)
+  Value *GEPPtrs = GEP->getPointerOperand();
+  if (!(Ptr = getSplatValue(GEPPtrs)))
     return false;
 
-  Ptr = cast<InsertElementInst>(ShuffleInst->getOperand(0))->getOperand(1);
-
   SelectionDAG& DAG = SDB->DAG;
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
   // Check is the Ptr is inside current basic block
   // If not, look for the shuffle instruction
   if (SDB->findValue(Ptr))
     Base = SDB->getValue(Ptr);
-  else if (SDB->findValue(ShuffleInst)) {
-    SDValue ShuffleNode = SDB->getValue(ShuffleInst);
-    SDLoc sdl = ShuffleNode;
-    Base = DAG.getNode(
-        ISD::EXTRACT_VECTOR_ELT, sdl,
-        ShuffleNode.getValueType().getScalarType(), ShuffleNode,
-        DAG.getConstant(0, sdl, TLI.getVectorIdxTy(DAG.getDataLayout())));
+  else if (SDB->findValue(GEPPtrs)) {
+    SDValue GEPPtrsVal = SDB->getValue(GEPPtrs);
+    SDLoc sdl = GEPPtrsVal;
+    EVT IdxVT = TLI.getVectorIdxTy(DAG.getDataLayout());
+    Base = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, sdl,
+                       GEPPtrsVal.getValueType().getScalarType(), GEPPtrsVal,
+                       DAG.getConstant(0, sdl, IdxVT));
     SDB->setValue(Ptr, Base);
   }
   else
     return false;
 
-  Value *IndexVal = Gep->getOperand(1);
+  Value *IndexVal = GEP->getOperand(1);
   if (SDB->findValue(IndexVal)) {
     Index = SDB->getValue(IndexVal);