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implement pointer arithmetic with GEP

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Closes #8118, #7136

~~~rust
extern mod extra;

use std::vec;
use std::ptr;

fn bench_from_elem(b: &mut extra::test::BenchHarness) {
    do b.iter {
        let v: ~[u8] = vec::from_elem(1024, 0u8);
    }
}

fn bench_set_memory(b: &mut extra::test::BenchHarness) {
    do b.iter {
        let mut v: ~[u8] = vec::with_capacity(1024);
        unsafe {
            let vp = vec::raw::to_mut_ptr(v);
            ptr::set_memory(vp, 0, 1024);
            vec::raw::set_len(&mut v, 1024);
        }
    }
}

fn bench_vec_repeat(b: &mut extra::test::BenchHarness) {
    do b.iter {
        let v: ~[u8] = ~[0u8, ..1024];
    }
}
~~~

Before:

    test bench_from_elem ... bench: 415 ns/iter (+/- 17)
    test bench_set_memory ... bench: 85 ns/iter (+/- 4)
    test bench_vec_repeat ... bench: 83 ns/iter (+/- 3)

After:

    test bench_from_elem ... bench: 84 ns/iter (+/- 2)
    test bench_set_memory ... bench: 84 ns/iter (+/- 5)
    test bench_vec_repeat ... bench: 84 ns/iter (+/- 3)
This commit is contained in:
Daniel Micay
2013-07-30 00:33:52 -04:00
parent e94e4d51ca
commit ef870d37a5
19 changed files with 131 additions and 80 deletions
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6
src/libstd/os.rs
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@@ -1114,7 +1114,7 @@ pub fn set_exit_status(code: int) {
unsafe fn load_argc_and_argv(argc: c_int, argv: **c_char) -> ~[~str] {
let mut args = ~[];
for uint::range(0, argc as uint) |i| {
args.push(str::raw::from_c_str(*argv.offset(i)));
args.push(str::raw::from_c_str(*argv.offset(i as int)));
}
args
}
@@ -1165,9 +1165,9 @@ pub fn real_args() -> ~[~str] {
for uint::range(0, nArgs as uint) |i| {
unsafe {
// Determine the length of this argument.
let ptr = *szArgList.offset(i);
let ptr = *szArgList.offset(i as int);
let mut len = 0;
while *ptr.offset(len) != 0 { len += 1; }
while *ptr.offset(len as int) != 0 { len += 1; }
// Push it onto the list.
args.push(vec::raw::buf_as_slice(ptr, len,