Zero pad from calldata #1605
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Zero pad from calldata #1605
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charles-cooper
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Sep 8, 2019
fubuloubu
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charles-cooper
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Sep 10, 2019
charles-cooper
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Run against ETH2.0 deposit contract |
jacqueswww
approved these changes
Sep 30, 2019
fubuloubu
reviewed
Oct 1, 2019
The semantics of calldatacopy is that copying data from past-the-end writes zero bytes to memory. So we can avoid the loop, making the code more gas-efficient and easier to reason about.
(no longer needed with calldatacopy zeroer)
maxlen was confusingly named. maxlen referred to the static size of the entire packed log. instead, the maxlen of the current item should be passed to zero_pad.
It's a red herring. byte arrays should always be padded to the runtime length and not maxlen.
Callers should make this optimization
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I ran the eth2.0 tests and they passed, although I'm not sure that's a great indicator because they also pass under master and 0.1.0b12. |
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@charles-cooper @fubuloubu I think this can be merged? |
fubuloubu
approved these changes
Oct 23, 2019
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Only replaces existing plumbing, with better pipes ;) |
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What I did
Increase clarity and efficiency of zero-padder. Currently overlaps with #1611 - fixes #1599, #1610. See the discussion in those issues as well as #1603 (comment).
How I did it
CALLDATACOPY writes zero bytes into memory when the location in calldata is >= calldatasize.
How to verify it
Description for the changelog
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