Add support for conditional expressions in TVMScript

This PR adds support for conditional expressions in TVMScript parser,
which allows developers to use Python-style conditional expressions

```python
@T.prim_func
def func(A: T.buffer((128, 128), "float32")):
    for i, j in T.grid(128, 128):
        A[i, j] = i if i < j else j

@T.prim_func
def expected(A: T.buffer((128, 128), "float32")):
    for i, j in T.grid(128, 128):
        A[i, j] = T.if_then_else(i < j, i, j)
```

Author: Hzfengsy

python/tvm/script/parser/core/evaluator.py

@@ -19,6 +19,8 @@
 import ast
 from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Type, Union
 
+import tvm
+
 from . import dispatch, doc
 from .error import ParserError
 
@@ -173,18 +175,19 @@ def _visit(self, node: doc.AST) -> Any:
             isinstance(node, doc.Call)
             and hasattr(node.func, "attr")
             and node.func.attr not in ["reads", "writes", "match_buffer", "realize"]
-        ) or isinstance(node, (doc.BinOp, doc.UnaryOp, doc.Compare, doc.BoolOp)):
+        ) or isinstance(node, (doc.BinOp, doc.UnaryOp, doc.Compare, doc.BoolOp, doc.IfExp)):
             if isinstance(node, doc.BinOp):
                 args = [node.left, node.right]
             elif isinstance(node, doc.UnaryOp):
                 args = [node.operand]
             elif isinstance(node, doc.Compare):
                 args = [node.left, *node.comparators]
-            else:
-                if isinstance(node, doc.Call):
-                    args = node.args
-                elif isinstance(node, doc.BoolOp):
-                    args = node.values
+            elif isinstance(node, doc.IfExp):
+                args = [node.test, node.body, node.orelse]
+            elif isinstance(node, doc.Call):
+                args = node.args
+            elif isinstance(node, doc.BoolOp):
+                args = node.values
         for arg in args:
             if isinstance(arg, doc.Subscript) and isinstance(arg.slice, (doc.Slice, doc.Tuple)):
                 if isinstance(arg.slice, doc.Slice):
@@ -256,6 +259,8 @@ def _visit(self, node: doc.AST) -> Any:
                 value = self._eval_unary_op(fields)
             elif isinstance(node, doc.BinOp):
                 value = self._eval_bin_op(fields)
+            elif isinstance(node, doc.IfExp):
+                value = self._eval_if_exp(fields)
             elif isinstance(node, doc.Slice):
                 value = self._eval_slice(fields)
             else:
@@ -364,6 +369,30 @@ def _eval_bin_op(self, fields: Dict[str, Any]) -> Any:
             ],
         )
 
+    def _eval_if_exp(self, fields: Dict[str, Any]) -> Any:
+        """The doc AST if-else expression node evaluating method.
+
+        Parameters
+        ----------
+        fields : Dict[str, Any]
+            The dictionary of if-else expression information,
+            e.g., test, body, orelse.
+
+        Returns
+        -------
+        res : Any
+            The evaluation result.
+        """
+        test = self._eval_expr(fields["test"])
+        body = self._eval_expr(fields["body"])
+        orelse = self._eval_expr(fields["orelse"])
+        if isinstance(test, bool):
+            return body if test else orelse
+        elif isinstance(test, tvm.tir.PrimExpr) and test.dtype == "bool":
+            return tvm.tir.op.if_then_else(test, body, orelse)
+        else:
+            raise TypeError(f"Expected Python bool or TIR bool, but got {type(test)}")
+
     def _eval_slice(self, fields: Dict[str, Any]) -> slice:
         """The doc AST slice node evaluating method.
 

tests/python/tvmscript/test_tvmscript_parser_tir.py

@@ -612,5 +612,19 @@ def expected() -> None:
     tvm.ir.assert_structural_equal(func, expected)
 
 
+def test_ifexp():
+    @T.prim_func(private=True)
+    def func(A: T.buffer((128, 128), "float32")):
+        for i, j in T.grid(128, 128):
+            A[i, j] = i if i < j else j
+
+    @T.prim_func(private=True)
+    def expected(A: T.buffer((128, 128), "float32")):
+        for i, j in T.grid(128, 128):
+            A[i, j] = T.if_then_else(i < j, i, j)
+
+    tvm.ir.assert_structural_equal(func, expected)
+
+
 if __name__ == "__main__":
     tvm.testing.main()