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get llvm libcall optimizations working #9541
Description
It doesn't like that our libc signatures don't quite match, and we also currently have to mark all of the wrappers as inline(never) to prevent fixed_stack_segment from being too aggressively bubbled up.
Specifically, I really want dead-store-elimination working on unique pointers like it does with runtimeless Rust:
#[no_std];
#[allow(ctypes, cstack)];
extern {
fn malloc(size: uint) -> *mut u8;
fn free(ptr: *mut u8);
fn abort() -> !;
}
#[lang = "exchange_malloc"]
#[inline(always)]
unsafe fn exchange_malloc(size: uint) -> *mut u8 {
let ptr = malloc(size);
if ptr == 0 as *mut u8 {
abort()
}
ptr
}
#[lang = "exchange_free"]
#[inline(always)]
unsafe fn exchange_free(ptr: *mut u8) {
free(ptr)
}
#[start]
fn main(_: int, _: **u8) -> int {
let mut _a = ~5;
0
}LLVM eliminates the allocation here.
Activity
thestinger commentedon Oct 3, 2013
This is also going to prevent the upcoming escape analysis implementation in LLVM from working.
thestinger commentedon Jan 20, 2014
This is fixed for
mallocandfree, at least.Auto merge of rust-lang#9541 - Alexendoo:declare-proc-macro, r=flip1995
chore: remove remove-unnecessary-files
Auto merge of rust-lang#9709 - koka831:chore/remove-unnecessary-files…
Auto merge of rust-lang#9712 - Alexendoo:old-generated-files, r=flip1995
Merge rust-lang#9541