This combines two things, a C stack usage change with EVM nested calls
via EVMC, and changes to host call tracing.
Feature-wise, the tracing is improved:
- Storage keys and values are make more sense.
- The message/result/context objects are shown with all relevant fields.
- `call` trace is split into entry/exit, so these can be shown around the
called contract's operations, instead of only showing the `call` parameters
after the nested call is finished.
- Nested calls are indented, which helps to highlight the flow.
- C stack usage considerably reduced in nested calls when more functionality
is enabled (either tracing here, or other things to come).
This will seem like a minor patch, but C stack usage was the real motivation,
after plenty of time in the debugger.
Nobody cares about stack when `showTxCalls` (you can just use a big stack when
debugging). But these subtle changes around the `call` path were found to be
necessary for passing all tests when the EVMC nested call code is completed,
and that's a prerequisite for many things: async EVM, dynamic EVM, Beam Sync,
and to fix https://github.com/status-im/nimbus-eth1/issues/345.
Signed-off-by: Jamie Lokier <jamie@shareable.org>