Open axch opened 1 year ago
Manifestation:
big = 2147483647 rem (big + 1) big > 4294967295
Expected the answer to be 1.
(Note that big + 1 doesn't overflow the underlying Word32 -- it's just the rem operation messing up).
big + 1
rem
The cause is https://github.com/google-research/dex-lang/blob/c996e988d07f4bec0495136c9d4ca51bcb0c431c/src/lib/ImpToLLVM.hs#L614, which unconditionally emits a signed remainder instruction, regardless of whether the Dex type is meant to be signed or unsigned.
By inspection, I expect IDiv to have the same problem.
IDiv
Manifestation:
Expected the answer to be 1.
(Note that
big + 1
doesn't overflow the underlying Word32 -- it's just therem
operation messing up).The cause is https://github.com/google-research/dex-lang/blob/c996e988d07f4bec0495136c9d4ca51bcb0c431c/src/lib/ImpToLLVM.hs#L614, which unconditionally emits a signed remainder instruction, regardless of whether the Dex type is meant to be signed or unsigned.