previously, every time the VMState was created, it will also create
new stateDB, and this action will nullify the advantages of cached accounts.
the new changes will conserve the accounts cache if the executed blocks
are contiguous. if not the stateDB need to be reinited.
this changes also allow rpcCallEvm and rpcEstimateGas executed properly
using current stateDB instead of creating new one each time they are called.
why:
the v2 prefix of the file name was used as a visual aid when
comparing vm2 against vm sources
details:
all renamed v2*.nim sources compile locally with the -d:kludge:1 flag
set or without (some work with either)
only sources not renamed yet: v2state_transactions.nim
why:
these files provide part of the externally accessible interface
provided by vm_cpmputation.nim, vm_internals.nim. so the
new filename indicates that the source code belongs to vm2 (rather
than vm).
why:
these files provide part of the externally accessible interface
provided by vm_types*.nim. so the new filename indicates that the
source code belongs to vm2 (rather than vm).
why:
vm2 enabled by ENABLE_VM2=1 behaves as vm without ENABLE_EVMC=1 until
it doesn't in some future fatch set. this leaves some wiggle room
to work on a vm copy without degrading the original implementation.
details:
+ additional make flag ENABLE_VM2=1 (or ENABLE_VM2=0 to explicitely disable)
+ when both flags ENABLE_EVMC=1 and ENABLE_VM2=1 are present, the former
flag ENABLE_EVMC=1 takes precedence, this is implemented at the NIM
compiler level for -d:evmc_enabled and -d:vm2_enabled