rustc vs clang | llvm production | app

main.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);
}

int main(int argc, const char* argv[])
{
  return bar(argc);
}

main.rs

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

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

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

result-app.md

compiler | version

command

• name | instruction count | time

---

clang++ | 6.0.1

perf stat clang -O3 main.cpp -o cpp-app-full

• full | 266m | 110ms

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

• emit | 219m | 95ms

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

• llvm compile | 56m | 45ms

couldn't figure this one out

• llvm link

---

rustc | 1.27.1

perf stat rustc -O main.rs -o rust-app-full

• full | 1870m | 575ms

perf stat rustc -O main.rs --emit=llvm-ir -o rust.ll

• emit | 520m | 200ms

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

• llvm compile | 55m | 50ms

---

rustc | 1.29.0-nightly

perf stat rustc -O main.rs -o rust-app-full

• full | 1340m | 405ms

perf stat rustc -O main.rs --emit=llvm-ir -o rust.ll

• emit | 422m | 145ms

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

• llvm compile | 66m | 50ms