[PATCH] D80281: [MLIR] Add `num_elements` to the shape dialect

[Frederik Gossen via Phabricator via llvm-commits]

frgossen created this revision.
Herald added subscribers: llvm-commits, jurahul, Kayjukh, grosul1, Joonsoo, stephenneuendorffer, liufengdb, aartbik, lucyrfox, mgester, arpith-jacob, nicolasvasilache, antiagainst, shauheen, jpienaar, rriddle, mehdi_amini.
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Herald added a project: LLVM.
frgossen added a child revision: D80283: [MLIR] Fix operand type in `from_extent_tensor` in the shape dialect.
frgossen added reviewers: pifon2a, herhut.

The operation `num_elements` determines the number of elements for a given
shape.
That is the product of its dimensions.
A tensor of the given shape holds this many elements.

Depends On D80280 <https://reviews.llvm.org/D80280>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D80281

Files:
  mlir/include/mlir/Dialect/Shape/IR/ShapeOps.td
  mlir/lib/Dialect/Shape/IR/Shape.cpp
  mlir/test/Dialect/Shape/canonicalize.mlir


Index: mlir/test/Dialect/Shape/canonicalize.mlir
===================================================================
--- mlir/test/Dialect/Shape/canonicalize.mlir
+++ mlir/test/Dialect/Shape/canonicalize.mlir
@@ -139,3 +139,25 @@
   %cs = shape.index_to_size %ci
   return %cs : !shape.size
 }
+
+// -----
+// Fold number of elements computation.
+// CHECK-LABEL: func @num_elements
+func @num_elements() -> !shape.size {
+  // CHECK-NOT: shape.const_shape
+  %shape = shape.const_shape [4, 5, 6]
+  // CHECK-NOT: shape.num_elements
+  %num_elements = shape.num_elements %shape
+  // CHECK: %[[NUM:.*]] = shape.const_size 120
+  // CHECK-NEXT: return %[[NUM]] : !shape.size
+  return %num_elements : !shape.size
+}
+
+// -----
+// No folding.
+// CHECK-LABEL: func @nonfoldable_num_elements
+func @nonfoldable_num_elements(%shape : !shape.shape) -> !shape.size {
+  // CHECK-NOT: shape.const_{{.*}}
+  %num_elements = shape.num_elements %shape
+  return %num_elements : !shape.size
+}
Index: mlir/lib/Dialect/Shape/IR/Shape.cpp
===================================================================
--- mlir/lib/Dialect/Shape/IR/Shape.cpp
+++ mlir/lib/Dialect/Shape/IR/Shape.cpp
@@ -252,6 +252,32 @@
   return success();
 }
 
+//===----------------------------------------------------------------------===//
+// NumElementsOp
+//===----------------------------------------------------------------------===//
+
+OpFoldResult NumElementsOp::fold(ArrayRef<Attribute> operands) {
+
+  // Fold only when argument constant.
+  Attribute shape = operands[0];
+  if (!shape)
+    return {};
+
+  APInt product(64, 1);
+  for (auto value : shape.cast<DenseIntElementsAttr>())
+    product *= value;
+  Builder builder(getContext());
+  return builder.getIndexAttr(product.getLimitedValue());
+}
+
+LogicalResult NumElementsOp::inferReturnTypes(
+    MLIRContext *context, Optional<Location> location, ValueRange operands,
+    DictionaryAttr attributes, RegionRange regions,
+    SmallVectorImpl<Type> &inferredReturnTypes) {
+  inferredReturnTypes.push_back(SizeType::get(context));
+  return success();
+}
+
 //===----------------------------------------------------------------------===//
 // ShapeOfOp
 //===----------------------------------------------------------------------===//
Index: mlir/include/mlir/Dialect/Shape/IR/ShapeOps.td
===================================================================
--- mlir/include/mlir/Dialect/Shape/IR/ShapeOps.td
+++ mlir/include/mlir/Dialect/Shape/IR/ShapeOps.td
@@ -231,6 +231,26 @@
   let results = (outs Shape_SizeType:$result);
 }
 
+def Shape_NumElementsOp : Shape_Op<"num_elements", [
+    NoSideEffect,
+    DeclareOpInterfaceMethods<InferTypeOpInterface>]> {
+
+  let summary = "Returns the number of elements for a given shape";
+  let description = [{
+    Returns the number of elements for a given shape which is the product of its
+    dimensions.
+    A tensor of the given shape will hold this many elements.
+    Expects a `shape.shape` and returns a `shape.size` value.
+  }];
+
+  let arguments = (ins Shape_ShapeType:$shape);
+  let results = (outs Shape_SizeType:$result);
+
+  let assemblyFormat = "attr-dict $shape";
+
+  let hasFolder = 1;
+}
+
 def Shape_ReduceOp : Shape_Op<"reduce", []> {
   let summary = "Returns an expression reduced over a shape";
   let description = [{


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