Optimize AND/SHL

[chriseth]

trafficstars

and(shl(A, X), shl(A, Y)) should be optimized to shl(A, and(X, Y))

or even

and(shl(Z, X), shl(Z, Y)) should be optimized to shl(Z, and(X, Y))

[k06a]

@chriseth I can't find any difference between the 2 provided examples? Is it a typo?

[ekpyron]

The difference stems from how we internally formulate simplification rules in https://github.com/ethereum/solidity/blob/develop/libevmasm/RuleList.h and isn't clear in the issue description - we use A, B, C, ... for constants and X, Y, Z, ... for arbitrary expressions when pattern matching simplification rules.

[k06a]

@ekpyron thx!