If you are seeing this because of “decompiled” code, keep in mind that this code is built from the debug_info or abstract_code chunks of the beam files. I am not sure those contain all optimizations done by the compiler.
lud
slouchpie
That makes more sense.
I am honestly kind of shocked if compiler doesn’t change %{a: 1}.a to 1. That seems like the entire job of the compiler.
0
eksperimental
Here’s the code.
you can clone it GitHub - eksperimental-help/slouchpie · GitHub
Unoptimized: slouchpie/lib/foo_big.ex at main · eksperimental-help/slouchpie · GitHub
Optimized: slouchpie/lib/foo_small.ex at main · eksperimental-help/slouchpie · GitHub
$ mix compile
$ touch lib/foo_big.ex && rm _build/dev/lib/slouchpie/ebin/Elixir.Foo.Big.beam
$ time mix compile
Compiling 1 file (.ex)
Compiling lib/foo_big.ex (its taking more than 10s)
real 0m33.185s
user 0m28.222s
sys 0m4.836s
$ touch lib/foo_small.ex && rm _build/dev/lib/slouchpie/ebin/Elixir.Foo.Small.beam
$ time mix compile
Compiling 1 file (.ex)
real 0m2.502s
user 0m2.306s
sys 0m0.331s
$ ls -alh _build/dev/lib/slouchpie/ebin/Elixir.Foo.*.beam
23M Dec 15 14:14 _build/dev/lib/slouchpie/ebin/Elixir.Foo.Big.beam
2.1K Dec 15 14:15 _build/dev/lib/slouchpie/ebin/Elixir.Foo.Small.beam
$ elixir --version
Erlang/OTP 24 [erts-12.1.2] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [jit]
Elixir 1.13.0 (compiled with Erlang/OTP 24)
UPDATE:
Here are the benchmarks
https://github.com/eksperimental-help/slouchpie/blob/main/benchmarks/foo.exs
Elixir 1.13.0
Erlang 24.1.2
Benchmark suite executing with the following configuration:
warmup: 2 s
time: 5 s
memory time: 5 s
parallel: 1
inputs: none specified
Estimated total run time: 24 s
Benchmarking Unoptimized: Foo.Big...
Benchmarking Optimized: Foo.Small...
Name ips average deviation median 99th %
Optimized: Foo.Small 292.62 K 3.42 μs ±436.00% 2.46 μs 6.48 μs
Unoptimized: Foo.Big 83.26 K 12.01 μs ±123.18% 7.73 μs 30.17 μs
Comparison:
Optimized: Foo.Small 292.62 K
Unoptimized: Foo.Big 83.26 K - 3.51x slower +8.59 μs
Memory usage statistics:
Name Memory usage
Optimized: Foo.Small 4.53 KB
Unoptimized: Foo.Big 9.09 KB - 2.01x memory usage +4.56 KB
**All measurements for memory usage were the same**
4
slouchpie
WOWOWOWOWOW!
That’s beautiful.
You have taught me to not have ultimate trust in the compiler now.
I really appreciate all the effort you put in to this.
I’m marking your answer as solution since I consider it the most complete answer.
1