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[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions #90739

Merged
merged 2 commits into from
Aug 17, 2023
Merged

[release/8.0] JIT: Disallow mismatched GC-ness for physical promotions #90739

merged 2 commits into from
Aug 17, 2023

Commits on Aug 17, 2023

  1. JIT: Disallow mismatched GC-ness for physical promotions 

    Physical promotion was working under the assumption that reinterpreting
GC pointers is undefined behavior, and would happily promote GC pointers
as integers if it saw such accesses. However, physical promotion is
function wide while the UB accesses can be happening in a restricted
(dynamically unreachable) scope. This exact situation happens in
MemoryExtensions.Contains. The issue was uncovered under jit stress
where we did not fold away the guard early enough, meaning that
promotion then saw a `TYP_LONG` access of a `struct { object, int }` and
proceeded to promote it as such.

Fix #90602
    @jakobbotsch
    jakobbotsch authored and github-actions committed Aug 17, 2023
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  2. Address feedback

    @jakobbotsch
    jakobbotsch authored and github-actions committed Aug 17, 2023
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    ada908f View commit details
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