Hybrid EVM Stack Experiment

[holgerd77]

This is a pretty extensive experiment switching the current BigInt based EVM stack with a hybrid stack which stores either the Bytes or the BigInt values and - if matches - serves the respetive values without conversion.

Results are unfortunately a lot more mixed than I anticipated. One opcode significantly increases in performance (MLOAD, going from 2.9 to 4.4 or so), but other values are mixed throughout the range, some somewhat faster, some somewhat slower.

Might come back to this with some distance, atm I am bit baffled that there is "not more to see".

Here is e.g. a resultset on the same block (left is with the hybrid stack).

My initial idea was to keep the old stack, but introduce a flag which would allow to switch to the new one. If results remain this mixed this might be obsolete though.

This work might nevertheless be useful for some things, e.g. it is now extremely easily possible to switch e.g. arithmetic operations from being done bigint based to byte based and see how performance reacts.

[holgerd77]

• This stack implementation is significantly more performant than the single type stack. Atm it is however
• not activated by default for backwards compatibility reasons.

I was so confident in the outcome here that I had even already written class documentation before I had first results mentioning the increased performance. 😆

[codecov[bot]]

Codecov Report

Merging #3029 (e71f171) into master (67a20de) will increase coverage by 3.39%. The diff coverage is n/a.

Additional details and impacted files

Flag	Coverage Δ
block	88.73% <ø> (ø)
blockchain	92.58% <ø> (ø)
client	87.47% <ø> (+0.04%)	:arrow_up:
common	98.18% <ø> (ø)
ethash	∅ <ø> (∅)
evm	?
rlp	∅ <ø> (∅)
statemanager	89.91% <ø> (ø)
trie	90.18% <ø> (ø)
tx	96.35% <ø> (ø)
util	86.78% <ø> (ø)
vm	?

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