fixes

test/unit/test_uop_symbolic.py

@@ -1096,5 +1096,60 @@ class TestFuzzFailure(unittest.TestCase):
     rn = expr.substitute({v1:v1_val, v2:v2_val, v3:v3_val}).ssimplify()
     assert num==rn, f"{num} != {rn}"
 
+class TestBitcast(unittest.TestCase):
+  def test_bitcast_preserves_signaling_nan_bits(self):
+    # Signaling NaN in f32: exponent all 1s, mantissa non-zero with MSB clear
+    snan_bits = 0x7f800001
+    bits = UOp.const(dtypes.uint32, snan_bits)
+    # BITCAST uint32 -> float32 should NOT fold (would corrupt NaN bits)
+    bf = bits.bitcast(dtypes.float32)
+    result = bf.simplify()
+    self.assertEqual(result.op, Ops.BITCAST, "signaling NaN bitcast should not fold to CONST")
+    self.assertEqual(result.src[0].arg, snan_bits)
+
+  def test_bitcast_double_preserves_bits(self):
+    # BITCAST(BITCAST(x)) where outer dtype == x.dtype should fold back to x
+    snan_bits = 0x7f800001
+    bits = UOp.const(dtypes.uint32, snan_bits)
+    bf1 = bits.bitcast(dtypes.float32)
+    bf2 = bf1.bitcast(dtypes.uint32)
+    result = bf2.simplify()
+    self.assertEqual(result.op, Ops.CONST)
+    self.assertEqual(result.arg, snan_bits, "double bitcast should preserve original bits")
+
+  def test_bitcast_quiet_nan_folds(self):
+    # Quiet NaN in f32: can be folded since Python's nan preserves these bits
+    qnan_bits = 0x7fc00000
+    bits = UOp.const(dtypes.uint32, qnan_bits)
+    bf = bits.bitcast(dtypes.float32)
+    result = bf.simplify()
+    self.assertEqual(result.op, Ops.CONST)
+    self.assertTrue(math.isnan(result.arg))
+
+  def test_bitcast_normal_float_folds(self):
+    # Normal float values should fold
+    bits = UOp.const(dtypes.uint32, 0x40490fdb)  # pi
+    bf = bits.bitcast(dtypes.float32)
+    result = bf.simplify()
+    self.assertEqual(result.op, Ops.CONST)
+    self.assertAlmostEqual(result.arg, 3.14159265, places=5)
+
+  def test_bitcast_f64_signaling_nan(self):
+    # Signaling NaN in f64
+    snan_bits = 0x7ff0000000000001
+    bits = UOp.const(dtypes.uint64, snan_bits)
+    bf = bits.bitcast(dtypes.float64)
+    result = bf.simplify()
+    self.assertEqual(result.op, Ops.BITCAST, "f64 signaling NaN bitcast should not fold")
+
+  def test_bitcast_f64_double_preserves_bits(self):
+    snan_bits = 0x7ff0000000000001
+    bits = UOp.const(dtypes.uint64, snan_bits)
+    bf1 = bits.bitcast(dtypes.float64)
+    bf2 = bf1.bitcast(dtypes.uint64)
+    result = bf2.simplify()
+    self.assertEqual(result.op, Ops.CONST)
+    self.assertEqual(result.arg, snan_bits)
+
 if __name__ == '__main__':
   unittest.main()