Distinguish between INVALID opcode and unknown opcodes in aleth-interpreter

[gumb0]

This fixes the failure of evm.invalid test, which expects EVMC_INVALID_INSTRUCTION to be returned for INVALID (0xfe) opcode and EVMC_UNKNOWN_INSTRUCTION for all not defined opcodes.

[ RUN      ] evm.invalid
/home/andrei/dev/evmone/test/unittests/evm_test.cpp:668: Failure
Expected equality of these values:
  result.status_code
    Which is: 5
  EVMC_INVALID_INSTRUCTION
    Which is: 4
[  FAILED  ] evm.invalid (0 ms)

[chfast]

Shouln't it be just

CASE(INVALID)
  throwInvalidInstruction();
DEFAULT
  throwUndefinedInstruction();

[gumb0]

No, this doesn't work on gcc/clang, because the jump table is populated with INVALID opcode for all unknown ones

aleth/libaleth-interpreter/VMConfig.h

Line 154 in 089e7dd

static const void* const jumpTable[256] = { \

[chfast]

Can't we change that by having &&UNDEFINED everywhere and &&INVALID in

aleth/libaleth-interpreter/VMConfig.h

Line 409 in 089e7dd

&&INVALID, \

?

[gumb0]

There's no such thing as UNDEFINED, and this enum is 8 bit-wide

aleth/libevm/Instruction.h

Line 28 in 2b11ce5

enum class Instruction : uint8_t

So we can't really add UNDEFINED unless we change the width

[codecov-io]

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