motiejus/zig
1
Fork 0
Code Releases Activity

big.int: fix yet another truncate bug

Browse Source 
Too many bugs have been found with `truncate` at this point, so it was
rewritten from scratch.

Based on the doc comment, the utility of `convertToTwosComplement` over
`r.truncate(a, .unsigned, bit_count)` is unclear and it has a subtle
behavior difference that is almost certainly a bug, so it was deleted.
This commit is contained in:
Jacob Young
2025-03-11 08:56:45 -04:00
parent 9c9d3931df
commit ed284c1f98
3 changed files with 108 additions and 113 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
src/codegen/c.zig
View File

@@ -8175,7 +8175,7 @@ fn formatIntLiteral(
try writer.writeAll(string);
} else {
try data.ctype.renderLiteralPrefix(writer, data.kind, ctype_pool);
wrap.convertToTwosComplement(int, data.int_info.signedness, c_bits);
wrap.truncate(int, .unsigned, c_bits);
@memset(wrap.limbs[wrap.len..], 0);
wrap.len = wrap.limbs.len;
const limbs_per_c_limb = @divExact(wrap.len, c_limb_info.count);
@@ -8207,7 +8207,6 @@ fn formatIntLiteral(
c_limb_int_info.signedness = .signed;
c_limb_ctype = c_limb_info.ctype.toSigned();
c_limb_mut.positive = wrap.positive;
c_limb_mut.truncate(
c_limb_mut.toConst(),
.signed,