YulUtilFunctions: assert combined byte slice extent in updateByteSliceFunction#16753
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YulUtilFunctions: assert combined byte slice extent in updateByteSliceFunction#16753msooseth wants to merge 1 commit into
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…eFunction The two existing solAsserts bound _numBytes and _shiftBytes individually, but the emitted mask ((1 << numBits) - 1) << shiftBits is only well-defined when _numBytes + _shiftBytes <= 32. Add the combined assert as a guard against future regressions. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
updateByteSliceFunction(_numBytes, _shiftBytes)currently asserts_numBytes <= 32and_shiftBytes <= 32independently, but not their combination.((1 << numBits) - 1) << shiftBitsis only well-defined when_numBytes + _shiftBytes <= 32— otherwise the mask spans bits ≥ 256 and Yul silently truncates it mod 2^256, producing a wrong storage update.updateStorageValueFunction) already respect this invariant, so this is not a current bug — just a guard against future regressions.Test plan
solAssertnext to two existing ones with the same bound).