Bounds checks for exponentiation#2072
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iamdefinitelyahuman merged 11 commits intoJun 30, 2020
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Co-authored by: Bryant Eisenbach <fubuloubu@gmail.com>
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Co-authored-by: Bryant Eisenbach <3859395+fubuloubu@users.noreply.github.com>
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What I did
Add overflow checks for exponentiation
Closes #1684
Closes #1685
How I did it
Given
a ** b:aorbis a literal, calculate the highest possible variable value at compile-time, and perform a check against that value at runtime. The logic for finding the upper limits is thanks to @fubuloubu's proof of concept 🙏 I'm just a copy-pasteraandbare variables, raise an exception suggesting the use ofpow_mod256pow_mod256that allows access to theEXPinstruction without any overflow checksHow to verify it
Run tests. I added quite a few new cases.
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