[Mlir-commits] [mlir] [mlir][Interfaces][NFC] `ValueBoundsConstraintSet`: Add columns for constant values/dims (PR #86097)

[Matthias Springer]

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@@ -107,25 +107,47 @@ AffineExpr ValueBoundsConstraintSet::getExpr(Value value,
   assertValidValueDim(value, dim);
 #endif // NDEBUG
 
+  // Check if the value/dim is statically known. In that case, an affine
+  // constant expression should be returned. This allows us to support
+  // multiplications with constants. (Multiplications of two columns in the
+  // constraint set is not supported.)
+  std::optional<int64_t> constSize = std::nullopt;
   auto shapedType = dyn_cast<ShapedType>(value.getType());
   if (shapedType) {
-    // Static dimension: return constant directly.
     if (shapedType.hasRank() && !shapedType.isDynamicDim(*dim))
-      return builder.getAffineConstantExpr(shapedType.getDimSize(*dim));
-  } else {
-    // Constant index value: return directly.
-    if (auto constInt = ::getConstantIntValue(value))
-      return builder.getAffineConstantExpr(*constInt);
+      constSize = shapedType.getDimSize(*dim);
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matthias-springer wrote:

I don't fully understand the different between symbols and dimensions in `IntegerRelation`. The limitations that I am aware of:

- `getSliceBounds` can only be called on a dimensions, so the first "column" that I add to the constraint set (for which we want to compute LB/UB) is a dimension.
- `projectOut` works on both symbols and dimensions, so all other values are added as symbols.

Basically we have only one dimension and everything else is a symbol. (But the current implementation would make it easy to change this.) This seems to work well so far.


https://github.com/llvm/llvm-project/pull/86097