[WIP] Size optimisations

[axic]

Use wasm-snip and wasm-gc

[jakelang]

If we're doing precompiles, size should not matter as much since my understanding is these system contracts will be stored locally. Gas costs are fixed for execution, might as well optimize for performance.

[jakelang]

Needs a step to install wasm-snip and wasm-gc

[axic]

This was my work in progress branch for testing various settings and compilers. Not meant to be merged anytime soon.

k, will leave this be.

[axic]

The identity precompile:

 Shallow Bytes │ Shallow % │ Item
───────────────┼───────────┼────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
         27509 ┊    28.29% ┊ custom section '.debug_str'
         26358 ┊    27.10% ┊ custom section '.debug_info'
         16595 ┊    17.06% ┊ custom section '.debug_pubtypes'
          9879 ┊    10.16% ┊ custom section '.debug_pubnames'
          7470 ┊     7.68% ┊ custom section '.debug_line'
          3458 ┊     3.56% ┊ dlmalloc::dlmalloc::Dlmalloc::malloc::h5891d2855e0d9ebe
          1824 ┊     1.88% ┊ custom section '.debug_ranges'
          1478 ┊     1.52% ┊ custom section '.debug_abbrev'
           829 ┊     0.85% ┊ "function names" subsection
           473 ┊     0.49% ┊ data[0]
           339 ┊     0.35% ┊ dlmalloc::dlmalloc::Dlmalloc::unlink_large_chunk::hf603e4746ddb82d9
           326 ┊     0.34% ┊ dlmalloc::dlmalloc::Dlmalloc::insert_large_chunk::he0b6e9bfcf411f56
           104 ┊     0.11% ┊ data[1]
            82 ┊     0.08% ┊ custom section '.debug_loc'
            73 ┊     0.08% ┊ ewasm_api::unsafe_calldata_copy::h5f6de487f23eefd0
            72 ┊     0.07% ┊ data[2]
            52 ┊     0.05% ┊ main
            27 ┊     0.03% ┊ import ethereum::getCallDataSize
            24 ┊     0.02% ┊ import ethereum::callDataCopy
            18 ┊     0.02% ┊ import ethereum::useGas
            18 ┊     0.02% ┊ import ethereum::finish
            17 ┊     0.02% ┊ custom section '.debug_macinfo'
            13 ┊     0.01% ┊ _$LT$T$u20$as$u20$core..any..Any$GT$::get_type_id::h70a50119ef9c01da
            11 ┊     0.01% ┊ alloc::raw_vec::capacity_overflow::h0432b49d9a8429de
            10 ┊     0.01% ┊ ewasm_api::finish_data::h5496bba85d7111e5
             9 ┊     0.01% ┊ export "memory"
             8 ┊     0.01% ┊ global[0]
             8 ┊     0.01% ┊ global[1]
             8 ┊     0.01% ┊ global[2]
             8 ┊     0.01% ┊ core::panicking::panic::h158c6e3285d6c3fb
             7 ┊     0.01% ┊ export "main"
             7 ┊     0.01% ┊ elem[0]
             7 ┊     0.01% ┊ ewasm_api::consume_gas::haca660fedcbabea6
             6 ┊     0.01% ┊ type[1]
             6 ┊     0.01% ┊ _$LT$alloc..raw_vec..RawVec$LT$T$C$$u20$A$GT$$GT$::allocate_in::_$u7b$$u7b$closure$u7d$$u7d$::h038a550a99ce6b55 (.llvm.3105678208255263009)
             5 ┊     0.01% ┊ type[3]
             5 ┊     0.01% ┊ type[5]
             5 ┊     0.01% ┊ type[7]
             5 ┊     0.01% ┊ ewasm_api::calldata_size::hba1f916f3ba69165
             4 ┊     0.00% ┊ type[0]
             4 ┊     0.00% ┊ type[2]
             4 ┊     0.00% ┊ type[6]
             4 ┊     0.00% ┊ table[0]
             3 ┊     0.00% ┊ type[4]
             3 ┊     0.00% ┊ core::ptr::drop_in_place::h088e8834711f879a (.694)
             2 ┊     0.00% ┊ memory[0]
             1 ┊     0.00% ┊ func[0]
             1 ┊     0.00% ┊ func[1]
             1 ┊     0.00% ┊ func[2]
             1 ┊     0.00% ┊ func[3]
             1 ┊     0.00% ┊ func[4]
             1 ┊     0.00% ┊ func[5]
             1 ┊     0.00% ┊ func[6]
             1 ┊     0.00% ┊ func[7]
             1 ┊     0.00% ┊ func[8]
             1 ┊     0.00% ┊ func[9]
             1 ┊     0.00% ┊ func[10]
             1 ┊     0.00% ┊ func[11]
             1 ┊     0.00% ┊ func[12]

Basically snip/gc cannot remove those debugging sections.

The identity is 97250 bytes long. Out of that debug sections sum to 91212 bytes and the names section (only needed for debugging) is 829 bytes. 94.65% is debugging information. Properly stripping it will result in 5209 bytes for the identity. Still quite big, but not a monster as it is now.

Stripping these sections is where wasmx/wasm-chisel#48 will be useful.

50% of the remaining code is dlmalloc, which we can get rid of my using our own allocator.

[axic]

This is mostly obsolete now.