Implement cmp+branch instruction fusion

[Robbepop]

Closes #712

Improves performance across the board, especially for realistic computations that are compute heavy.
Critically this improves performance of the count_until.wat benchmark by roughly 40%.

TODO

• Additionally fixed potential bug in local.set optimization.
• Write more and proper tests for all or most cases.
• Try to find other ways to introduce cmp+branch instruction fusion.
• Fuse cmp+branch instruction for branch_nez encoding.
• Fuse cmp+branch instruction for branch_eqz encoding.
• Find ways to allow for fusion with uninitialized branch offsets with might exceed 16-bit encoding.
• Fix bugs: the wasm-coremark benchmark returns 0 with these changes, so there are some bugs still.

[paritytech-cicd-pr]

BENCHMARKS

	NATIVE			WASMTIME
BENCHMARK	MASTER	PR	DIFF	MASTER	PR	DIFF	WASMTIME OVERHEAD
execute/ bare_call_0	1.54ms	1.54ms	🔴 -0.11%	1.10ms	1.13ms	🔴 2.82%	🟢 -27%
execute/ bare_call_0/typed	1.30ms	1.37ms	🔴 5.09%	798.34µs	827.93µs	🔴 3.25%	🟢 -40%
execute/ bare_call_1	1.61ms	1.61ms	🔴 0.25%	1.23ms	1.26ms	🔴 2.41%	🟢 -22%
execute/ bare_call_16	2.69ms	2.63ms	🔴 -2.11%	3.43ms	3.40ms	⚪ -0.73%	🟢 29%
execute/ bare_call_16/typed	1.54ms	1.58ms	🔴 2.75%	1.91ms	1.92ms	⚪ 0.42%	🟢 22%
execute/ bare_call_1/typed	1.30ms	1.27ms	🟢 -1.69%	972.02µs	965.37µs	⚪ -0.77%	🟢 -24%
execute/ bare_call_4	1.78ms	1.78ms	🔴 -0.57%	1.66ms	1.71ms	🔴 2.97%	🟢 -4%
execute/ bare_call_4/typed	1.26ms	1.36ms	🔴 8.13%	1.04ms	1.06ms	⚪ 1.04%	🟢 -22%
execute/ br_table	1.58ms	1.38ms	🟢 -12.61%	1.13ms	1.14ms	⚪ 1.03%	🟢 -17%
execute/ count_until	650.62µs	547.43µs	🟢 -15.93%	2.01ms	1.75ms	🟢 -12.74%	🔴 220%
execute/ factorial_iterative	320.12µs	320.63µs	⚪ 0.14%	797.30µs	799.73µs	⚪ 0.33%	🔴 149%
execute/ factorial_recursive	491.24µs	495.53µs	⚪ 0.75%	966.88µs	978.33µs	🔴 1.16%	🟡 97%
execute/ fibonacci_iter	1.40ms	1.40ms	⚪ -0.14%	3.77ms	3.83ms	🔴 1.75%	🔴 174%
execute/ fibonacci_rec	3.97ms	3.97ms	⚪ -0.15%	8.61ms	8.49ms	🟢 -1.30%	🔴 114%
execute/ fibonacci_tail	855.27µs	858.20µs	⚪ 0.30%	2.20ms	2.17ms	⚪ -0.97%	🔴 153%
execute/ global_bump	751.14µs	747.38µs	⚪ -0.76%	2.19ms	2.19ms	⚪ 0.07%	🔴 193%
execute/ global_const	661.24µs	659.12µs	⚪ -0.25%	2.44ms	2.38ms	🟢 -2.32%	🔴 262%
execute/ host_calls	37.27µs	36.97µs	⚪ -2.57%	39.85µs	39.33µs	🟢 -1.35%	🟢 6%
execute/ memory_fill	1.21ms	1.15ms	🟢 -5.18%	3.32ms	3.29ms	⚪ -0.79%	🔴 186%
execute/ memory_sum	1.18ms	1.14ms	🟢 -4.02%	3.28ms	3.28ms	⚪ -0.09%	🔴 189%
execute/ memory_vec_add	2.34ms	2.34ms	⚪ 0.02%	7.39ms	7.35ms	⚪ -0.51%	🔴 214%
execute/ recursive_is_even	662.09µs	663.67µs	⚪ 0.25%	1.45ms	1.45ms	⚪ -0.09%	🔴 118%
execute/ recursive_ok	94.26µs	94.35µs	⚪ 0.25%	200.12µs	199.83µs	⚪ -0.09%	🔴 112%
execute/ recursive_scan	129.60µs	129.34µs	⚪ -0.17%	283.87µs	286.44µs	⚪ 0.83%	🔴 121%
execute/ recursive_trap	9.04µs	8.85µs	⚪ -1.68%	20.92µs	20.84µs	⚪ -0.29%	🔴 136%
execute/ regex_redux	456.75µs	459.31µs	⚪ 0.58%	1.24ms	1.24ms	⚪ -0.26%	🔴 169%
execute/ rev_complement	426.15µs	420.76µs	🟢 -1.23%	1.14ms	1.14ms	⚪ -0.12%	🔴 171%
execute/ tiny_keccak	323.40µs	330.22µs	🔴 2.00%	1.10ms	1.10ms	⚪ 0.87%	🔴 235%
execute/ trunc_f2i	740.51µs	737.28µs	⚪ -0.14%	1.71ms	1.71ms	⚪ -0.20%	🔴 132%
instantiate/ wasm_kernel	56.18µs	55.87µs	⚪ -0.26%	57.87µs	57.84µs	⚪ -0.14%	🟢 4%
translate/ erc1155	207.98µs	213.02µs	🔴 2.52%	361.74µs	368.23µs	🔴 1.85%	🟡 73%
translate/ erc20	103.29µs	105.61µs	🔴 2.50%	175.89µs	178.74µs	🔴 1.69%	🟡 69%
translate/ erc721	145.71µs	148.91µs	🔴 2.11%	253.85µs	258.63µs	🔴 1.81%	🟡 74%
translate/ spidermonkey	64.85ms	64.56ms	⚪ -0.62%	0.00ns	0.00ns	🔴 2.35%	🟢 -100%
translate/ wasm_kernel	4.44ms	4.22ms	🟢 -4.23%	6.53ms	6.69ms	🔴 2.43%	🟡 58%

Link to pipeline

[codecov-commenter]

Codecov Report

Attention: 208 lines in your changes are missing coverage. Please review.

Comparison is base (d1bc10c) 81.41% compared to head (9522600) 81.25%.

Files	Patch %	Lines
...mi/src/engine/regmach/translator/visit_register.rs	0.00%	56 Missing ⚠️
.../wasmi/src/engine/regmach/translator/result_mut.rs	1.92%	51 Missing ⚠️
...smi/src/engine/regmach/translator/instr_encoder.rs	84.80%	38 Missing ⚠️
crates/wasmi/src/engine/regmach/executor/instrs.rs	44.23%	29 Missing ⚠️
...wasmi/src/engine/regmach/executor/instrs/branch.rs	68.57%	11 Missing ⚠️
...rates/wasmi/src/engine/regmach/translator/visit.rs	52.38%	10 Missing ⚠️
crates/wasmi/src/engine/regmach/tests/wasm_type.rs	0.00%	6 Missing ⚠️
crates/wasmi/src/engine/regmach/tests/op/mod.rs	0.00%	3 Missing ⚠️
...tes/wasmi/src/engine/regmach/bytecode/immediate.rs	50.00%	2 Missing ⚠️
crates/wasmi/src/engine/regmach/bytecode/utils.rs	95.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #789      +/-   ##
==========================================
- Coverage   81.41%   81.25%   -0.16%     
==========================================
  Files         271      273       +2     
  Lines       24236    25072     +836     
==========================================
+ Hits        19732    20373     +641     
- Misses       4504     4699     +195     

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