rustc vs clang | llvm production | lib

lib-min.rs

pub fn foo(a: i64, b: i64) -> i64 {
    (a % 239082) % b
}

pub fn bar(a: i64) -> i64 {
    foo(a, 77)
}

lib.cpp

#include <cstdint>

auto foo(int64_t a, int64_t b) -> int64_t
{
  return (a % 239082) % b;
}

auto bar(int64_t a) -> int64_t
{
  return foo(a, 77);
}

lib.rs

pub fn foo(a: i64, b: i64) -> i64 {
    (a % 239082) % b
}

pub fn bar(a: i64) -> i64 {
    foo(a, 77)
}

pub fn moop() {
    std::process::exit(bar(std::env::args().len() as i64) as i32);
}

result-lib.md

compiler | version

command

• name | instruction count | time

---

clang++ | 6.0.1

perf stat clang++ -O3 -shared lib.cpp -o cpp-lib-full.so

• full | 331m | 147ms

perf stat clang -O3 lib.cpp -emit-llvm -S -o cpp-lib.ll

• emit | 218m | 95ms

perf stat llc -O3 -filetype=obj cpp-lib.ll -o cpp-lib.so

• llvm compile | 56m | 45ms

---

rustc | 1.29.0-nightly

perf stat rustc -O --crate-type=lib lib.rs -o rust-lib-full.so

• full | 549m | 200ms

perf stat rustc -O --crate-type=lib lib.rs --emit=llvm-ir -o rust-lib.ll

• emit | 411m | 145ms

perf stat llc -O3 -filetype=obj rust-lib.ll -o rust-lib.so

• llvm compile | 64m | 50ms

---

rustc | 1.29.0-nightly

perf stat rustc -O --crate-type=lib lib-min.rs -o rust-lib-min-full.so

• full | 248m | 105ms

perf stat rustc -O --crate-type=lib lib-min.rs --emit=llvm-ir -o rust-lib-min.ll

• emit | 231m | 90ms

perf stat llc -O3 -filetype=obj rust-lib-min.ll -o rust-lib-min.so

• llvm compile | 54m | 44ms