Closed
Description
Long winded test case using libcore: (build with --crate-type staticlib and --emit asm)
#![feature(no_std, lang_items, asm, core)]
#![no_std]
use core::fmt;
#[macro_use]
extern crate core;
#[lang="panic_fmt"]
extern fn panic_fmt(msg: &fmt::Arguments, file: &'static str, line: u32) -> ! {
loop { }
}
#[lang="stack_exhausted"]
extern fn stack_exhausted() {
loop { }
}
#[lang="eh_personality"]
extern fn eh_personality() {
loop { }
}
#[inline(always)]
fn foo() {
panic!("Das Ist Nümberwang!");
}
fn black_box<T>(mut value: T) -> T {
unsafe {
asm!("" :: "r"(&mut value) :: "volatile");
}
value
}
pub fn main() {
match black_box(5) {
1 => foo(),
48 => foo(),
92 => foo(),
23 => foo(),
4 => foo(),
70 => foo(),
29 => foo(),
36 => foo(),
34 => foo(),
58 => foo(),
_ => { }
}
}This duplicates the following 3 times in the resulting code:
leaq _ZN3foo14_MSG_FILE_LINE20h7545777ae10911d4MaaE(%rip), %rdi
callq _ZN9panicking5panic20hefc2bd49b5114e0db7BE@PLT
This may not seem too bad, but in real world cases you can end up with something on the order of this: https://gist.github.com/Tobba/ab10d5644d3d4ef97917