[Hexagon] Convert HVX vector constants of i1 to i8

Certain operations require vector of i1 values. However, for Hexagon
architecture compatibility, they need to be represented as vector of i8.

Patch by Suyog Sarda.

llvm-svn: 309677

llvm/lib/Target/Hexagon/HexagonISelLowering.cpp

@@ -1364,10 +1364,44 @@ HexagonTargetLowering::LowerVSELECT(SDValue Op, SelectionDAG &DAG) const {
   return SDValue();
 }
 
+static Constant *convert_i1_to_i8(const Constant *ConstVal) {
+  SmallVector<Constant *, 128> NewConst;
+  const ConstantVector *CV = dyn_cast<ConstantVector>(ConstVal);
+  if (!CV)
+    return nullptr;
+
+  LLVMContext &Ctx = ConstVal->getContext();
+  IRBuilder<> IRB(Ctx);
+  unsigned NumVectorElements = CV->getNumOperands();
+  assert(isPowerOf2_32(NumVectorElements) &&
+         "conversion only supported for pow2 VectorSize!");
+
+  for (unsigned i = 0; i < NumVectorElements / 8; ++i) {
+    uint8_t x = 0;
+    for (unsigned j = 0; j < 8; ++j) {
+      uint8_t y = CV->getOperand(i * 8 + j)->getUniqueInteger().getZExtValue();
+      x |= y << (7 - j);
+    }
+    assert((x == 0 || x == 255) && "Either all 0's or all 1's expected!");
+    NewConst.push_back(IRB.getInt8(x));
+  }
+  return ConstantVector::get(NewConst);
+}
+
 SDValue
 HexagonTargetLowering::LowerConstantPool(SDValue Op, SelectionDAG &DAG) const {
   EVT ValTy = Op.getValueType();
   ConstantPoolSDNode *CPN = cast<ConstantPoolSDNode>(Op);
+  Constant *CVal = nullptr;
+  bool isVTi1Type = false;
+  if (const Constant *ConstVal = dyn_cast<Constant>(CPN->getConstVal())) {
+    Type *CValTy = ConstVal->getType();
+    if (CValTy->isVectorTy() &&
+        CValTy->getVectorElementType()->isIntegerTy(1)) {
+      CVal = convert_i1_to_i8(ConstVal);
+      isVTi1Type = (CVal != nullptr);
+    }
+  }
   unsigned Align = CPN->getAlignment();
   bool IsPositionIndependent = isPositionIndependent();
   unsigned char TF = IsPositionIndependent ? HexagonII::MO_PCREL : 0;
@@ -1377,6 +1411,8 @@ HexagonTargetLowering::LowerConstantPool(SDValue Op, SelectionDAG &DAG) const {
   if (CPN->isMachineConstantPoolEntry())
     T = DAG.getTargetConstantPool(CPN->getMachineCPVal(), ValTy, Align, Offset,
                                   TF);
+  else if (isVTi1Type)
+    T = DAG.getTargetConstantPool(CVal, ValTy, Align, Offset, TF);
   else
     T = DAG.getTargetConstantPool(CPN->getConstVal(), ValTy, Align, Offset,
                                   TF);