[GitHub] [tvm] ganler commented on a diff in pull request #12515: [TIR][Arith] Add more strict checking in imm construction and folding.

[GitBox <gi...@apache.org>]

ganler commented on code in PR #12515:
URL: https://github.com/apache/tvm/pull/12515#discussion_r950711151


##########
tests/python/unittest/test_tir_imm_values.py:
##########
@@ -0,0 +1,155 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+import math
+import numpy as np
+import tvm
+import tvm.testing
+import pytest
+from tvm import tir
+from tvm.script import tir as T
+import pytest
+
+
+@pytest.mark.parametrize(
+    "dtype, literals",
+    [
+        ["int8", [-128, 0, 127]],
+        ["uint8", [0, 255]],
+        ["int32", [-2147483648, 2147483647]],
+        ["uint32", [0, 4294967295]],
+        ["int64", [-9223372036854775808, 9223372036854775807]],
+        ["uint64", [0, 9223372036854775807]],
+    ],
+)
+def test_tir_make_intimm(dtype, literals):
+    for l in literals:
+        imm = tir.const(l, dtype)
+        assert imm.value == l, imm
+
+
+@pytest.mark.parametrize(
+    "dtype, literals",
+    [
+        ["int8", [-129, 128]],
+        ["uint8", [-1, 256]],
+        ["int32", [-2147483650, 2147483648]],
+        ["uint32", [-1, 4294967296]],
+        ["uint64", [-1, 18446744073709551616]],
+    ],
+)
+def test_tir_invalid_intimm(dtype, literals):
+    for l in literals:
+        with pytest.raises(tvm.TVMError):
+            tir.const(l, dtype)
+
+
+@pytest.mark.parametrize(
+    "dtype, literals",
+    [
+        [
+            "int64",
+            {
+                -9223372036854775810: 9223372036854775806,
+                9223372036854775808: -9223372036854775808,
+            },
+        ],
+        [
+            "uint64",
+            {
+                9223372036854775807: 9223372036854775807,
+                18446744073709551615: 18446744073709551615,
+            },
+        ],
+    ],
+)
+def test_tir_large_py_int_literals(dtype, literals):
+    """
+    For large uint value, use LargeUIntImm intrin,
+    For large int value exceed int64_t value range, the value is wrapped back.
+    """
+    for l in literals:
+        x = tir.const(l, dtype)
+        if isinstance(x, (tir.IntImm, tir.FloatImm)):
+            assert x.value == literals[l]
+        else:
+            # LargeUIntImm(low32, hi32)
+            assert (int(x.args[1]) << 32) + int(x.args[0]) == literals[l]
+
+
+def test_tir_intimm_overflow():
+    assert int(tir.const(127, "int8") + tir.const(1, "int8")) == -128
+    assert int(tir.const(127, "int8") + tir.const(2, "int8")) == -127
+    assert int(tir.const(255, "uint8") + tir.const(1, "uint8")) == 0
+    assert int(tir.const(2 ** 31 - 1, "int32") + tir.const(1, "int32")) == -(2 ** 31)
+    assert int(tir.const(2 ** 32 - 1, "uint32") + tir.const(1, "uint32")) == 0
+    assert int(tir.const(2 ** 63 - 1, "int64") + tir.const(1, "int64")) == -(2 ** 63)
+    assert int(tir.const(2 ** 32, "uint64") * tir.const(2 ** 32, "uint64")) == 0
+
+
+def compare_float_value(value, expect):
+    if math.isfinite(value):
+        assert value == expect
+    elif math.isnan(value):
+        assert math.isnan(expect)
+    elif math.isinf(value):
+        assert math.isinf(expect)
+
+
+@pytest.mark.parametrize("dtype", ["float16", "float32", "float64"])
+@pytest.mark.parametrize("literal", [3.14, np.nan, np.inf])
+def test_tir_special_floatimms(dtype, literal):
+    x = tir.const(literal, dtype)
+    compare_float_value(x.value, literal)
+
+
+@tvm.testing.requires_llvm()
+def test_tir_floatimm_overflow():
+    # Behavior check: if literal value is out of dtype range, the
+    # object is still constructed, and eval to infinity.
+    @T.prim_func
+    def imm_overflow_fp16() -> T.float16:
+        T.evaluate(T.ret(T.float16(65536), dtype="float16"))

Review Comment:
   Just curious, should we just raise an exception or warning to tell the user that this is actually an ill-formed behavior, i.e., constructing an out-of-bound constant? For example, gcc 12 will warn such behaviors. 



##########
include/tvm/tir/op.h:
##########
@@ -911,7 +911,9 @@ inline PrimExpr MakeConstScalar(DataType t, ValueType value, Span span = Span())
   if (t.is_uint()) {
     // Use IntImm if it is a small integer
     uint64_t uval = static_cast<uint64_t>(value);
-    if (uval <= static_cast<uint64_t>(std::numeric_limits<int64_t>::max())) {
+    if (value < 0) {

Review Comment:
   What if `value` is greater than `numeric_limit<int64_t>::max()`? Is it possible to keep the sign information. If it is from Python end, `int` in Python is of unlimited length so catching the sign is easy. The sign information in C++ probably can be catched from the type information, i.e., ValueType.



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