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author | Mike Frysinger <vapier@gentoo.org> | 2024-01-06 23:16:41 -0500 |
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committer | Mike Frysinger <vapier@gentoo.org> | 2024-01-08 20:01:05 -0500 |
commit | b2ea48df925a6d41f63e88b26dbf3f17cde0f252 (patch) | |
tree | 90faff9a96d7518eb11b590eaa2327c3b28c67c8 /include/splay-tree.h | |
parent | 707877ab59c6d0cbcb58cb5d467ab5f0d071a935 (diff) | |
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sim: cgen: rework DI macros to avoid signed left shifts
The cgen code uses DI as int64_t and UDI as uint64_t. The DI macros
are used to construct 64-bit values from 32-bit values (for the low
and high parts). The MAKEDI macro casts the high 32-bit value to a
signed 32-bit value before shifting. If this created a negative
value, this would be undefined behavior according to the C standard.
All we care about is shifting the 32-bits as they are to the high
32-bits, not caring about sign extension (since there's nothing left
to shift into), and the low 32-bits being empty. This is what we
get from shifting an unsigned value, so cast it to unsigned 32-bit
to avoid undefined behavior.
While we're here, change the SETLODI macro to truncate the lower
value to 32-bits before we set it. If it was passing in a 64-bit
value, those high bits would get included too, and that's not what
we want.
Similarly, tweak the SETHIDI macro to cast the value to an unsigned
64-bit instead of a signed 64-bit. If the value was only 32-bits,
the behavior would be the same. If it happened to be signed 64-bit,
it would trigger the undefined behavior too.
Diffstat (limited to 'include/splay-tree.h')
0 files changed, 0 insertions, 0 deletions