[mlir] NFC - Add some more static value utils

[nicolasvasilache]

Landed as 8afe6f7bd548188ee534def57cf9895ccfb71c08

mlir/include/mlir/Dialect/Utils/StaticValueUtils.h

void dispatchIndexOpFoldResults(ArrayRef<OpFoldResult> ofrs,
                                 SmallVectorImpl<int64_t> &staticVec);
 
 /// Extract int64_t values from the assumed ArrayAttr of IntegerAttr.
 SmallVector<int64_t, 4> extractFromI64ArrayAttr(Attribute attr);
 
 /// Given a value, try to extract a constant Attribute. If this fails, return
 /// the original value.
 OpFoldResult getAsOpFoldResult(Value val);
-
 /// Given an array of values, try to extract a constant Attribute from each
 /// value. If this fails, return the original value.
 SmallVector<OpFoldResult> getAsOpFoldResult(ValueRange values);
-
 /// Convert `arrayAttr` to a vector of OpFoldResult.
 SmallVector<OpFoldResult> getAsOpFoldResult(ArrayAttr arrayAttr);
 
+/// Convert int64_t to integer attributes of index type and return them as
+/// OpFoldResult.
+OpFoldResult getAsIndexOpFoldResult(MLIRContext *ctx, int64_t val);
+SmallVector<OpFoldResult> getAsIndexOpFoldResult(MLIRContext *ctx,
+                                                 ArrayRef<int64_t> values);
+
 /// If ofr is a constant integer or an IntegerAttr, return the integer.
 std::optional<int64_t> getConstantIntValue(OpFoldResult ofr);
 
 /// Return true if `ofr` is constant integer equal to `value`.
 bool isConstantIntValue(OpFoldResult ofr, int64_t value);
 
 /// Return true if ofr1 and ofr2 are the same integer constant attribute
 /// values or the same SSA value. Ignore integer bitwitdh and type mismatch

mlir/lib/Dialect/Utils/StaticValueUtils.cpp

 SmallVector<OpFoldResult> getAsOpFoldResult(ArrayAttr arrayAttr) {
   SmallVector<OpFoldResult> res;
   res.reserve(arrayAttr.size());
   for (Attribute a : arrayAttr)
     res.push_back(a);
   return res;
 }
 
+OpFoldResult getAsIndexOpFoldResult(MLIRContext *ctx, int64_t val) {
+  return IntegerAttr::get(IndexType::get(ctx), val);
+}
+
+SmallVector<OpFoldResult> getAsIndexOpFoldResult(MLIRContext *ctx,
+                                                 ArrayRef<int64_t> values) {
+  return llvm::to_vector<4>(llvm::map_range(
+      values, [ctx](int64_t v) { return getAsIndexOpFoldResult(ctx, v); }));
+}
+
 /// If ofr is a constant integer or an IntegerAttr, return the integer.
 std::optional<int64_t> getConstantIntValue(OpFoldResult ofr) {
   // Case 1: Check for Constant integer.
   if (auto val = ofr.dyn_cast<Value>()) {
     APSInt intVal;
     if (matchPattern(val, m_ConstantInt(&intVal)))
       return intVal.getSExtValue();
     return std::nullopt;