SSA CFG: stack to memory spilling#16767
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Nice! I have just a few small comments, but I think we can merge this today!
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@clonker can you update the PR description to use the new method name instead of |
Dual to `dupDeepSlotIfRequired`: A deep, still-incorrect target slot whose wanted value is not on the stack at all. A push/dup grows the stack, pushing that slot one deeper. So if the deepest incorrect args slot would be pushed out of reach by growing, shrink first to keep it reachable.
…ng what to swap into a specific offset
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Implements stack to memory spilling for the SSA CFG pipeline in a simple stupid version.
Adds:
ssa/spill/MemoryAddressingis a per-subobject owner of spill memorynumSpilled()across each CFGsSpillSetand bumps memory guard accordingly, allocates non-overlapping memory addresses for spilled valuesssa/spill/Emitteremits bytecode against the symbolic stack for spilled valuesssa/spill/SpillSetgot a new methodcloseUnderReachabilityConstraintswhich will check for all spilled values whether they can be feasibly spilled at the point of origin, may add more things to spill accordinglyModifies
ssa/StackLayoutGeneratorsgenerate()to return{layout, spillSet}instead of just the layout and also validates back-edges asserting that back-edge targets can be safely shuffled tossa/CodeTransformis reworked to first generate per-CFG layouts and spill sets (and close them under reachability constraints), then build a single globalMemoryAddressingto hand into theCodeTransforminstanceTest
SpillTestsuite undertest/libyul/ssa/spillwhich runs thegenerate->closeUnderReachabilityConstraints->addresssequence and emits that plus a text representation of the input object. does not generate any code.