Introduce ValueStackRef abstraction

[Robbepop]

This allows us to cache the stack_ptr with one fewer indirections for massive speedups across the board according to benchmarks I performed on my local machine.

[paritytech-cicd-pr]

CRITERION BENCHMARKS

BENCHMARK	MASTER	PR	Diff
compile_and_validate_v1	7.0136 ms	7.0864 ms	⚪ +0.9123%
execute_count_until_v1	3.9323 ms	3.0772 ms	🟢 -21.819%
execute_factorial_iterative_v1	2.0458 µs	1.6724 µs	🟢 -18.257%
execute_factorial_recursive_v1	2.3226 µs	2.3794 µs	🔴 +2.3845%
execute_fib_iterative_v1	12.221 ms	10.158 ms	🟢 -16.865%
execute_fib_recursive_v1	20.798 ms	21.174 ms	⚪ +2.5672%
execute_global_bump_v1	4.8491 ms	3.9275 ms	🟢 -17.057%
execute_host_calls_v1	33.730 µs	35.981 µs	🔴 +6.5037%
execute_memory_fill_v1	10.401 ms	9.3987 ms	🟢 -9.5809%
execute_memory_sum_v1	9.5572 ms	9.0792 ms	🟢 -4.7378%
execute_memory_vec_add_v1	18.955 ms	16.358 ms	🟢 -13.615%
execute_recursive_is_even_v1	3.3499 ms	3.5911 ms	🔴 +7.1904%
execute_recursive_ok_v1	409.79 µs	456.29 µs	🔴 +11.720%
execute_recursive_scan_v1	528.40 µs	565.07 µs	🔴 +6.2286%
execute_recursive_trap_v1	38.438 µs	43.610 µs	🔴 +14.906%
execute_regex_redux_v1	3.7412 ms	3.5105 ms	🟢 -6.3376%
execute_rev_complement_v1	3.6065 ms	3.0988 ms	🟢 -13.997%
execute_tiny_keccak_v1	3.1856 ms	2.7039 ms	🟢 -15.140%
execute_trunc_f2i_v1	4.3333 ms	3.9830 ms	🟢 -8.3653%
instantiate_v1	76.424 µs	77.532 µs	⚪ +0.8611%

Link to pipeline

[yjhmelody]

Does it improve performance by reducing indirection address?

[Robbepop]

Does it improve performance by reducing indirection address?

yes, it is similar to the pc cache field.

[codecov-commenter]

Codecov Report

Merging #459 (e59264f) into master (115d308) will increase coverage by 0.03%.
The diff coverage is 93.56%.

@@            Coverage Diff             @@
##           master     #459      +/-   ##
==========================================
+ Coverage   79.42%   79.45%   +0.03%     
==========================================
  Files          71       73       +2     
  Lines        6198     6222      +24     
==========================================
+ Hits         4923     4944      +21     
- Misses       1275     1278       +3     

Impacted Files	Coverage Δ
wasmi_v1/src/engine/stack/mod.rs	79.10% <ø> (ø)
wasmi_v1/src/engine/stack/values/mod.rs	84.12% <84.12%> (ø)
wasmi_v1/src/engine/stack/values/vref.rs	98.43% <98.43%> (ø)
wasmi_v1/src/engine/executor.rs	98.41% <100.00%> (+0.01%)	⬆️
wasmi_v1/src/engine/stack/values/tests.rs	100.00% <100.00%> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more