py/misc: Change sizeof to offsetof for variable-length alloc. #12866
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Code size report: |
Codecov Report
@@ Coverage Diff @@
## master #12866 +/- ##
=======================================
Coverage 98.39% 98.39%
=======================================
Files 158 158
Lines 20971 20973 +2
=======================================
+ Hits 20635 20637 +2
Misses 336 336
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This fixes the case where e.g.
struct foo_t {
mp_obj_t x;
uint16_t y;
char buf[];
};
will have `sizeof(struct foo_t)==8`, but `offsetof(struct foo_t, buf)==6`.
When computing the size to allocate for `m_new_obj_var` we need to use
offsetof to avoid over-allocating. This is important especially when it
might cause it to spill over into another GC block.
This work was funded through GitHub Sponsors.
Signed-off-by: Jim Mussared <[email protected]>
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This fixes the case where e.g.
will have
sizeof(struct foo_t)==8, butoffsetof(struct foo_t, buf)==6.When computing the size to allocate for
m_new_obj_varwe need to use offsetof to avoid over-allocating. This is important especially when it might cause it to spill over into another GC block.All of the places that
m_new_obj_varis currently used will be unchanged as the variable length field always follows a word-size field, but see e.g. #12836 which requires this.This work was funded through GitHub Sponsors.