Add a method to build affine maps with zero or more results.

[ulysseB]

Summary

The commit provides a single method to build affine maps with zero or more
results. Users of mlir::AffineMap previously had to dispatch between two methods
depending on the number of results.

At the same time, this commit fixes the method for building affine map with zero
results that was previously ignoring its symbolCount argument.

[ftynse]

mlir/include/mlir/IR/AffineMap.h

52

Nit: please use /// for documenting public methods

mlir/lib/IR/MLIRContext.cpp

633

ouch...

[bondhugula]

Thanks for fixing this. In fact, I had review comments along the lines you address on an earlier patch that introduced these but looks like they didn't get in. (For consistency, we do need the ability to create 0 result maps that have an arbitrary number of dimensions and symbols, which your patch addresses.)

mlir/include/mlir/IR/AffineMap.h

52

Doc comment ///
symbolCount -> symbolCount symbols

57

Doc comment ///

Nit: -> 'to the given results, where the number of results can be zero.'

[ulysseB]

Fix comments for AffineMap::get.

mlir/include/mlir/IR/AffineMap.h

public:
   /// Returns a zero result affine map with no dimensions or symbols: () -> ().
   static AffineMap get(MLIRContext *context);
 
   /// Returns a zero result affine map with `dimCount` dimensions and
   /// `symbolCount` symbols, e.g.: `(...) -> ()`.
   static AffineMap get(unsigned dimCount, unsigned symbolCount,
                        MLIRContext *context);
 
+  /// Returns an affine map with `dimCount` dimensions and `symbolCount` symbols
+  /// mapping to the given results. The array of results cannot be empty.
   static AffineMap get(unsigned dimCount, unsigned symbolCount,
                        ArrayRef<AffineExpr> results);
 
+  /// Returns an affine map with `dimCount` dimensions and `symbolCount` mapping
+  /// to the given results, where the number of results can be zero.
+  static AffineMap get(unsigned dimCount, unsigned symbolCount,
+                       ArrayRef<AffineExpr> results, MLIRContext *context);
+
   /// Returns a single constant result affine map.
   static AffineMap getConstantMap(int64_t val, MLIRContext *context);
 
   /// Returns an AffineMap with 'numDims' identity result dim exprs.
   static AffineMap getMultiDimIdentityMap(unsigned numDims,
                                           MLIRContext *context);
 
   /// Returns an AffineMap representing a permutation.

mlir/lib/IR/MLIRContext.cpp

 }
 
 AffineMap AffineMap::get(MLIRContext *context) {
   return getImpl(/*dimCount=*/0, /*symbolCount=*/0, /*results=*/{}, context);
 }
 
 AffineMap AffineMap::get(unsigned dimCount, unsigned symbolCount,
                          MLIRContext *context) {
-  return getImpl(dimCount, /*symbolCount=*/0, /*results=*/{}, context);
+  return getImpl(dimCount, symbolCount, /*results=*/{}, context);
 }
 
 AffineMap AffineMap::get(unsigned dimCount, unsigned symbolCount,
                          ArrayRef<AffineExpr> results) {
   // The number of results can't be zero.
   assert(!results.empty());
   return getImpl(dimCount, symbolCount, results, results[0].getContext());
 }
 
+AffineMap AffineMap::get(unsigned dimCount, unsigned symbolCount,
+                         ArrayRef<AffineExpr> results, MLIRContext *context) {
+  return getImpl(dimCount, symbolCount, results, context);
+}
+
 //===----------------------------------------------------------------------===//
 // Integer Sets: these are allocated into the bump pointer, and are immutable.
 // Unlike AffineMap's, these are uniqued only if they are small.
 //===----------------------------------------------------------------------===//
 
 IntegerSet IntegerSet::get(unsigned dimCount, unsigned symbolCount,
                            ArrayRef<AffineExpr> constraints,
                            ArrayRef<bool> eqFlags) {