[Linalg] Remove Optional from getStaticLoopRanges interface method.

[hanchung]

Summary

It is very wrong if the ranges can't be infered. It's also checked in
verifyStructuredOpInterface, so we don't need the Optional return type.

[hanchung]

update comments

[springerm]

mlir/include/mlir/Dialect/Linalg/IR/LinalgInterfaces.td

1012

What if getShapesToLoopsMap fails? Should we maybe assert?

[hanchung]

add asserts

[hanchung]

mlir/include/mlir/Dialect/Linalg/IR/LinalgInterfaces.td

1012

good point, this is expected to only be called by a valid Linalg op. I added an assert and comments to it.

mlir/include/mlir/Dialect/Linalg/IR/LinalgInterfaces.td

let methods = [
     >,
     InterfaceMethod<
       /*desc=*/[{
         Returns the statically-known loop ranges. Composes
         `getShapesToLoopsMap()` with the result of `getStaticShape`.
         Returns None if `getShapesToLoopsMap()` fails. Returns
         ShapeType::kDynamicSize for non-statically-known loop ranges.
       }],
-      /*retTy=*/"Optional<SmallVector<int64_t, 4>>",
+      /*retTy=*/"SmallVector<int64_t, 4>",
       /*methodName=*/"getStaticLoopRanges",
       /*args=*/(ins),
       /*methodBody=*/"",
       /*defaultImplementation=*/[{
         SmallVector<int64_t> viewSizes = getStaticShape();
         AffineMap invertedMap = getShapesToLoopsMap();
         if (!invertedMap)
           return {};
         return invertedMap.compose(viewSizes);
       }]
     >,
     //===------------------------------------------------------------------===//
     // Other static interface methods.
     //===------------------------------------------------------------------===//
     InterfaceMethod<

mlir/lib/Dialect/Linalg/IR/LinalgInterfaces.cpp

for (OpOperand *opOperand : linalgOp.getInputAndOutputOperands()) {
     if (elementType != argType)
       return op->emitOpError("expected type of bb argument #")
              << opOperand->getOperandNumber() << " (" << argType << ")"
              << " to match element or self type of the corresponding operand ("
              << elementType << ")";
   }
 
   // Check if given shapes match to inferred shapes.
-  Optional<SmallVector<int64_t, 4>> endLoopRangeValues =
-      linalgOp.getStaticLoopRanges();
-  if (!endLoopRangeValues)
-    return op->emitOpError("unable to find loop range for operation");
-  SmallVector<int64_t, 4> startLoopRangeValues((*endLoopRangeValues).size(), 0);
+  SmallVector<int64_t, 4> endLoopRangeValues = linalgOp.getStaticLoopRanges();
+  SmallVector<int64_t, 4> startLoopRangeValues(endLoopRangeValues.size(), 0);
 
   // Verify only static cases since we can't get exact dimension sizes and loop
   // ranges for dynamic cases in this stage.
-  if (llvm::none_of(*endLoopRangeValues, ShapedType::isDynamic)) {
-    for (int64_t &range : *endLoopRangeValues)
+  if (llvm::none_of(endLoopRangeValues, ShapedType::isDynamic)) {
+    for (int64_t &range : endLoopRangeValues)
       range -= 1;
     for (OpOperand *opOperand : linalgOp.getInputAndOutputOperands()) {
       AffineMap indexingMap = linalgOp.getTiedIndexingMap(opOperand);
       SmallVector<int64_t, 4> startIndices =
           indexingMap.compose(startLoopRangeValues);
       SmallVector<int64_t, 4> endIndices =
-          indexingMap.compose(*endLoopRangeValues);
+          indexingMap.compose(endLoopRangeValues);
       ArrayRef<int64_t> shape = linalgOp.getShape(opOperand);
       for (auto dim : llvm::seq<int64_t>(0, shape.size())) {
         // Ignore dynamic dimension or the case that the dimension size is 0
         if (ShapedType::isDynamic(shape[dim]) || shape[dim] == 0)
           continue;
 
         // The first index or last index should be the maximum or the minimum in
         // the inferred index ranges since the range is increasing or

mlir/lib/Dialect/Linalg/Transforms/ElementwiseOpFusion.cpp

LogicalResult ExpansionInfo::compute(LinalgOp linalgOp,
                                      ArrayRef<AffineMap> reassociationMaps,
                                      ArrayRef<int64_t> expandedShape,
                                      ArrayRef<int64_t> collapsedShape,
                                      PatternRewriter &rewriter) {
   if (reassociationMaps.empty())
     return failure();
   AffineMap fusedIndexMap = linalgOp.getTiedIndexingMap(fusableOpOperand);
 
-  Optional<SmallVector<int64_t, 4>> originalLoopRange =
-      linalgOp.getStaticLoopRanges();
-  if (!originalLoopRange)
-    return rewriter.notifyMatchFailure(linalgOp, "unable to find loop range");
-  originalLoopExtent.assign(originalLoopRange->begin(),
-                            originalLoopRange->end());
+  SmallVector<int64_t, 4> originalLoopRange = linalgOp.getStaticLoopRanges();
+  originalLoopExtent.assign(originalLoopRange.begin(), originalLoopRange.end());
 
   reassociation.clear();
   expandedShapeMap.clear();
   // Compute the number of dimension in the expanded op that correspond to each
   // dimension of the original op.
   SmallVector<unsigned> numExpandedDims(fusedIndexMap.getNumDims(), 1);
   expandedShapeMap.resize(fusedIndexMap.getNumDims());
   for (const auto &resultExpr : llvm::enumerate(fusedIndexMap.getResults())) {

mlir/lib/Dialect/Linalg/Transforms/SplitReduction.cpp

FailureOr<LinalgOp> mlir::linalg::splitReduction(
   int64_t ratio = control.first;
   unsigned insertDimIndex = control.second;
   if (ratio <= 1)
     return b.notifyMatchFailure(op, "split ratio needs to be greater than 1");
   SmallVector<unsigned> dims;
   op.getReductionDims(dims);
   assert(dims.size() == 1);
   unsigned reductionDim = dims[0];
-  Optional<SmallVector<int64_t, 4>> loopRanges = op.getStaticLoopRanges();
-  if (!loopRanges)
-    return b.notifyMatchFailure(op, "Cannot analyze loops");
-  int64_t reductionDimSize = (*loopRanges)[reductionDim];
+  SmallVector<int64_t, 4> loopRanges = op.getStaticLoopRanges();
+  int64_t reductionDimSize = loopRanges[reductionDim];
   if (reductionDimSize == ShapedType::kDynamicSize ||
-      reductionDimSize % ratio != 0 || insertDimIndex >= loopRanges->size())
+      reductionDimSize % ratio != 0 || insertDimIndex >= loopRanges.size())
     return b.notifyMatchFailure(
         op, "Reduction dimension not divisible by split ratio");
   SmallVector<Operation *, 4> combinerOps;
   if (!matchReduction(op.getRegionOutputArgs(), 0, combinerOps) ||
       combinerOps.size() != 1)
     return b.notifyMatchFailure(op, "Cannot match the reduction pattern");
   Operation *reductionOp = combinerOps[0];
   Optional<Attribute> identity = getIdentity(reductionOp);