[release/10.0] Fix off-by-one error in TypePreinit switch instruction handling#127587
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) The switch IL instruction interpreter used > instead of >= when checking if the switch value exceeds the case count. Per ECMA-335, switch should fall through to the next instruction when value >= count, but the code only did this for value > count. When value exactly equals count, the code tried to read a non-existent jump table entry, corrupting the IL reader offset and causing an IndexOutOfRangeException during NativeAOT compilation. Added test case for the boundary condition (value == case count).
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Tagging subscribers to this area: @agocke, @dotnet/ilc-contrib |
MichalStrehovsky
approved these changes
Apr 30, 2026
This was referenced Apr 30, 2026
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/ba-g failures are unrelated |
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Backport of #123911 to release/10.0
/cc @agocke @sbomer
Customer Impact
When the value exactly equals the case count, the code tried to read a non-existent jump table entry, corrupting the IL reader offset and causing an IndexOutOfRangeException during NativeAOT compilation.
Regression
Testing
Unit tests
Risk
Low