[Mlir-commits] [mlir] [mlir][Vector] Add utility for computing scalable value bounds (PR #83876)

[Benjamin Maxwell]

================
@@ -0,0 +1,104 @@
+//===- ScalableValueBoundsConstraintSet.cpp - Scalable Value Bounds -------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Dialect/Vector/IR/ScalableValueBoundsConstraintSet.h"
+
+#include "mlir/Dialect/Vector/IR/VectorOps.h"
+
+namespace mlir::vector {
+
+FailureOr<ConstantOrScalableBound::BoundSize>
+ConstantOrScalableBound::getSize() const {
+  if (map.isSingleConstant())
+    return BoundSize{map.getSingleConstantResult(), /*scalable=*/false};
+  if (map.getNumResults() != 1 || map.getNumInputs() != 1)
+    return failure();
+  auto binop = dyn_cast<AffineBinaryOpExpr>(map.getResult(0));
+  if (!binop || binop.getKind() != AffineExprKind::Mul)
+    return failure();
+  auto matchConstant = [&](AffineExpr expr, int64_t &constant) -> bool {
+    if (auto cst = dyn_cast<AffineConstantExpr>(expr)) {
+      constant = cst.getValue();
+      return true;
+    }
+    return false;
+  };
+  // Match `s0 * cst` or `cst * s0`:
----------------
MacDue wrote:

No, it can only be `*` it would not make sense to match anything else. 
```mlir
  if (!binop || binop.getKind() != AffineExprKind::Mul)
    return failure();
```

A scalable quantity (i.e. something in units of `vscale`) has to be a `constant * vscale`. 


https://github.com/llvm/llvm-project/pull/83876