* Fix ceiling division formula

Signed-off-by: Gideon Kassa <gkassa@nvidia.com>

Author: gideon116

changelog.d/bugfix-cdiv.md

@@ -0,0 +1,2 @@
+Fixed bug in ceiling division calculations. It used to be computed using `(x + y - 1) // y` and
+`(x - 1) // y + 1`, which give incorrect values for when both x and y are negative numbers.

src/cuda/tile/_ir/ops_utils.py

@@ -44,7 +44,7 @@ class MathOpDef:
     "sub": MathOpDef(lambda x, y: x - y, _RD_BASIC, support_flush_to_zero=True),
     "mul": MathOpDef(lambda x, y: x * y, _RD_BASIC, support_flush_to_zero=True),
     "floordiv": MathOpDef(lambda x, y: x // y),
-    "cdiv": MathOpDef(lambda x, y: (x + y - 1) // y),
+    "cdiv": MathOpDef(lambda x, y: -((-x) // y)),
     "truediv": MathOpDef(lambda x, y: x / y, _RD_TRUEDIV, support_flush_to_zero=True),
     "mod": MathOpDef(lambda x, y: x % y),
     "pow": MathOpDef(lambda x, y: x ** y),

src/cuda/tile/_stub.py

@@ -3694,7 +3694,7 @@ def cdiv(x, y, /) -> TileOrScalar:
             3
             2
     """
-    return (x - 1) // y + 1
+    return -((-x) // y)
 
 
 # ======== Comparison ==============