[TVMScript] Use tir::Evaluate if expression is in statement context (#…

…13396)

* [TVMScript] Use tir::Evaluate if expression is in statement context

For the previous version of the parser, this was special-cased for
some intrinsic operators.  After the new TVMScript was enabled in
#12496, any `PrimExpr` that appears
in the body of a statement is silently ignored.  This commit updates
the parser to instead wrap the bare `PrimExpr` in a `tir::Evaluate`
node.

This change effectively allows [expression
statements](https://docs.python.org/3/reference/simple_stmts.html#expression-statements)
in TVMScript, which are converted to `tir::Evaluate` nodes during
parsing.

* Update to print T.evaluate() for readability, except for CallNode

python/tvm/script/parser/tir/parser.py

@@ -20,6 +20,7 @@
 from functools import partial
 from typing import Any
 
+import tvm
 from tvm.ir import PrimType
 from tvm.tir import Buffer, IterVar, PrimExpr, Var
 
@@ -411,6 +412,10 @@ def visit_expr_stmt(self: Parser, node: doc.Expr) -> None:
     if isinstance(res, Frame):
         res.add_callback(partial(res.__exit__, None, None, None))
         res.__enter__()
+    elif isinstance(res, PrimExpr):
+        T.evaluate(res)
+    elif isinstance(res, (int, bool)):
+        T.evaluate(tvm.tir.const(res))
 
 
 @dispatch.register(token="tir", type_name="If")

src/printer/tvmscript_printer.cc

@@ -1275,16 +1275,17 @@ Doc TVMScriptPrinter::VisitStmt_(const SeqStmtNode* op) {
 }
 
 Doc TVMScriptPrinter::VisitStmt_(const EvaluateNode* op) {
-  if (auto* call = op->value.as<CallNode>()) {
-    if (call->op.same_as(builtin::assume())) {
-      Doc doc;
-      doc << tir_prefix_ << ".assume(" << Print(call->args[0]) << ")";
-      return doc;
-    }
-  }
-
+  // When parsing TVMScript, a PrimExpr that occurs as a statement is
+  // automatically wrapped in `tir::Evaluate`.  Therefore, when
+  // printing, it's only necessary to print the value.  For
+  // readability, though, we still print T.evaluate() when the
+  // expression is something other than a call node.
   Doc doc;
-  doc << tir_prefix_ << ".evaluate(" << Print(op->value) << ")";
+  if (op->value.as<CallNode>()) {
+    doc << Print(op->value);
+  } else {
+    doc << tir_prefix_ << ".evaluate(" << Print(op->value) << ")";
+  }
   return doc;
 }
 

tests/python/unittest/test_tvmscript_roundtrip.py

@@ -3458,6 +3458,15 @@ def func() -> None:
     return func
 
 
+def implicit_evaluate():
+    @T.prim_func
+    def func(A: T.Buffer[1, "int32"]):
+        T.evaluate(T.assume(A[0] == 5))
+        A[0] = 10
+
+    return func
+
+
 ir_generator = tvm.testing.parameter(
     opt_gemm_normalize,
     opt_gemm_lower,
@@ -3509,6 +3518,7 @@ def func() -> None:
     bool_primitive,
     bool_cast,
     return_none,
+    implicit_evaluate,
 )
 
 

tests/python/unittest/test_tvmscript_syntax_sugar.py

@@ -402,5 +402,31 @@ def int64_grid_expanded(
     assert_structural_equal(int64_grid, int64_grid_expanded)
 
 
+def test_implicit_evaluate_assume():
+    @T.prim_func
+    def explicit(A: T.Buffer[1, "int32"]):
+        T.evaluate(T.assume(A[0] == 5))
+        A[0] = 10
+
+    @T.prim_func
+    def implicit(A: T.Buffer[1, "int32"]):
+        T.assume(A[0] == 5)
+        A[0] = 10
+
+    assert_structural_equal(implicit, explicit)
+
+
+def test_implicit_evaluate_call_extern():
+    @T.prim_func
+    def explicit(A: T.Buffer[1, "int32"]):
+        T.evaluate(T.call_extern("extern_func", A.data, dtype="int32"))
+
+    @T.prim_func
+    def implicit(A: T.Buffer[1, "int32"]):
+        T.call_extern("extern_func", A.data, dtype="int32")
+
+    assert_structural_equal(implicit, explicit)
+
+
 if __name__ == "__main__":
     tvm.testing.main()