chore(interpreter): add debug assertions to unsafe ExtBytecode methods#3545
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0xMars42 wants to merge 1 commit intobluealloy:mainfrom
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chore(interpreter): add debug assertions to unsafe ExtBytecode methods#35450xMars42 wants to merge 1 commit intobluealloy:mainfrom
0xMars42 wants to merge 1 commit intobluealloy:mainfrom
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Closes bluealloy#3487 Add debug_assert! bounds checks to all unsafe pointer operations in Jumps and Immediates implementations for ExtBytecode. Zero cost in release builds, catches out-of-bounds arithmetic during development. Introduces bytecode_bounds() and pc_unchecked() helpers to keep assertions safe and avoid recursive panics in error messages.
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Closes #3487
Add
debug_assert!bounds checks to all unsafe operations inJumpsandImmediatesimplementations forExtBytecode. This catches out-of-bounds pointer arithmetic during development/testing without any runtime cost in release builds.The safe public API currently allows constructing UB via
relative_jump,absolute_jump, and theImmediatesmethods, confirmed by Miri. These assertions follow the same pattern established in #2832 forset_action.Two private helpers keep the assertions clean:
bytecode_bounds()returns(base_ptr, end_ptr)usingwrapping_add(no unsafe in assertions)pc_unchecked()computes the program counter via integer arithmetic to avoid recursive panics when an assertion fails inside a method that would callpc()Known limitations
debug_assert!only, the unsoundness technically remains reachable in release builds via the safe API. A full fix would require making the trait methodsunsafe(breaking change) or adding runtime checks.is_valid_legacy_jumpassertsjt.is_some()but theunwrap_uncheckedstill exists for release.