feat[venom]: add codesize optimization pass #4333
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harkal
reviewed
Oct 29, 2024
Comment on lines
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| i = 0 | ||
| while i < len(bb.instructions): | ||
| inst = bb.instructions[i] | ||
| i += 1 |
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Suggested change
| i = 0 | |
| while i < len(bb.instructions): | |
| inst = bb.instructions[i] | |
| i += 1 | |
| for inst in bb.instructions: |
harkal
reviewed
Oct 29, 2024
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| val = op.value | ||
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| if val == (2**256 - 1): |
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Make use of constants that we have for numbers like these
harkal
reviewed
Oct 29, 2024
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| # transform things like 0xffff...01 to (not 0xfe) | ||
| binz = bin(val)[2:] | ||
| if (ix := binz.find("0")) > 8: # `not` is 1 byte |
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Maybe, extract 8 and 24 to constants like BITS_FOR_SHL and BITS_FOR_NOT?
harkal
reviewed
Oct 29, 2024
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| inst.opcode = "shl" | ||
| # sanity check | ||
| assert (val >> ix) << ix == val, val | ||
| assert (val >> ix) & 1 == 1 | ||
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| inst.operands = [IRLiteral(val >> ix), IRLiteral(ix)] |
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Suggested change
| inst.opcode = "shl" | |
| # sanity check | |
| assert (val >> ix) << ix == val, val | |
| assert (val >> ix) & 1 == 1 | |
| inst.operands = [IRLiteral(val >> ix), IRLiteral(ix)] | |
| # sanity check | |
| assert (val >> ix) << ix == val, val | |
| assert (val >> ix) & 1 == 1 | |
| inst.opcode = "shl" | |
| inst.operands = [IRLiteral(val >> ix), IRLiteral(ix)] |
harkal
reviewed
Oct 29, 2024
| for bb in self.function.get_basic_blocks(): | ||
| self._process_bb(bb) | ||
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| def _process_bb(self, bb): |
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For readability, it might be a good thing to add comments to "separate" the three rules the processing applies, or make them separate methods?
harkal
requested changes
Oct 29, 2024
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What I did
basic codesize optimization which strengthens large literals to evm computations which are shorter
How I did it
How to verify it
saves 450 bytes (2.5%) on https://gist.github.com/charles-cooper/eed70340aee2a47478ca0fc2ea6d5140
Commit message
Commit message for the final, squashed PR. (Optional, but reviewers will appreciate it! Please see our commit message style guide for what we would ideally like to see in a commit message.)
Description for the changelog
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