[Mlir-commits] [mlir] [mlir][affine][Analysis] Add conservative bounds for semi-affine mods (PR #93576)

[Kunwar Grover]

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@@ -63,76 +64,150 @@ struct AffineExprFlattener : public SimpleAffineExprFlattener {
     // Update localVarCst.
     localVarCst.addLocalFloorDiv(dividend, divisor);
   }
+
+  // Semi-affine expressions are not supported by all flatteners.
+  LogicalResult addLocalIdSemiAffine(ArrayRef<int64_t> lhs,
+                                     ArrayRef<int64_t> rhs,
+                                     AffineExpr localExpr) override = 0;
+};
+
+// An AffineExprFlattener is an AffineExprFlattenerWithLocalVars that explicitly
+// disallows semi-affine expressions. Flattening will fail if a semi-affine
+// expression is encountered.
+struct AffineExprFlattener : public AffineExprFlattenerWithLocalVars {
+  using AffineExprFlattenerWithLocalVars::AffineExprFlattenerWithLocalVars;
+
+  LogicalResult addLocalIdSemiAffine(ArrayRef<int64_t> lhs,
+                                     ArrayRef<int64_t> rhs,
+                                     AffineExpr localExpr) override {
+    // AffineExprFlattener does not support semi-affine expressions.
+    return failure();
+  }
+};
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Groverkss wrote:

Not sure why we need 3 classes. Can we just have `AffineExprFlattener : public SimpleAffineExprFlattener` (make the default impl of addLocalIdSemiAffine return failure) and `SemiAffineExprFlattener : public AffineExprFlattenerWithLocalVars`.

https://github.com/llvm/llvm-project/pull/93576