[mlir] Expose simplifyAffineExpr through python api (#133926)

Author: Hardcode84

mlir/include/mlir-c/AffineExpr.h

@@ -104,6 +104,16 @@ MLIR_CAPI_EXPORTED MlirAffineExpr
 mlirAffineExprShiftSymbols(MlirAffineExpr affineExpr, uint32_t numSymbols,
                            uint32_t shift, uint32_t offset);
 
+/// Simplify an affine expression by flattening and some amount of simple
+/// analysis. This has complexity linear in the number of nodes in 'expr'.
+/// Returns the simplified expression, which is the same as the input expression
+/// if it can't be simplified. When `expr` is semi-affine, a simplified
+/// semi-affine expression is constructed in the sorted order of dimension and
+/// symbol positions.
+MLIR_CAPI_EXPORTED MlirAffineExpr mlirSimplifyAffineExpr(MlirAffineExpr expr,
+                                                         uint32_t numDims,
+                                                         uint32_t numSymbols);
+
 //===----------------------------------------------------------------------===//
 // Affine Dimension Expression.
 //===----------------------------------------------------------------------===//

mlir/lib/Bindings/Python/IRAffine.cpp

@@ -599,6 +599,16 @@ void mlir::python::populateIRAffine(nb::module_ &m) {
           },
           nb::arg("num_symbols"), nb::arg("shift"),
           nb::arg("offset").none() = 0)
+      .def_static(
+          "simplify_affine_expr",
+          [](PyAffineExpr &self, uint32_t numDims, uint32_t numSymbols) {
+            return PyAffineExpr(
+                self.getContext(),
+                mlirSimplifyAffineExpr(self, numDims, numSymbols));
+          },
+          nb::arg("expr"), nb::arg("num_dims"), nb::arg("num_symbols"),
+          "Simplify an affine expression by flattening and some amount of "
+          "simple analysis.")
       .def_static(
           "get_add", &PyAffineAddExpr::get,
           "Gets an affine expression containing a sum of two expressions.")

mlir/lib/CAPI/IR/AffineExpr.cpp

@@ -73,6 +73,11 @@ MlirAffineExpr mlirAffineExprShiftSymbols(MlirAffineExpr affineExpr,
   return wrap(unwrap(affineExpr).shiftSymbols(numSymbols, shift, offset));
 }
 
+MlirAffineExpr mlirSimplifyAffineExpr(MlirAffineExpr expr, uint32_t numDims,
+                                      uint32_t numSymbols) {
+  return wrap(simplifyAffineExpr(unwrap(expr), numDims, numSymbols));
+}
+
 //===----------------------------------------------------------------------===//
 // Affine Dimension Expression.
 //===----------------------------------------------------------------------===//

mlir/test/python/ir/affine_expr.py

@@ -416,3 +416,11 @@ def testAffineExprShift():
 
         assert (dims[2] + dims[3]) == (dims[0] + dims[1]).shift_dims(2, 2)
         assert (syms[2] + syms[3]) == (syms[0] + syms[1]).shift_symbols(2, 2, 0)
+
+
+# CHECK-LABEL: TEST: testAffineExprSimplify
+@run
+def testAffineExprSimplify():
+    with Context() as ctx:
+        expr = AffineExpr.get_dim(0) + AffineExpr.get_symbol(0)
+        assert expr == AffineExpr.simplify_affine_expr(expr, 1, 1)