wasmtime_asm_macros/
lib.rs

1//! This crate defines a macro named `asm_func!` which is suitable for
2//! generating a single `global_asm!`-defined function.
3//!
4//! This macro takes care of platform-specific directives to get the symbol
5//! attributes correct (e.g. ELF symbols get a size and are flagged as a
6//! function) and additionally handles visibility across platforms. All symbols
7//! should be visible to Rust but not visible externally outside of a `*.so`.
8
9cfg_if::cfg_if! {
10    if #[cfg(target_os = "macos")] {
11        #[macro_export]
12        macro_rules! asm_func {
13            ($name:expr, $body:expr $(, $($args:tt)*)?) => {
14                std::arch::global_asm!(
15                    concat!(
16                        ".p2align 4\n",
17                        ".private_extern _", $name, "\n",
18                        ".global _", $name, "\n",
19                        "_", $name, ":\n",
20                        $body,
21                    ),
22                    $($($args)*)?
23                );
24            };
25        }
26    } else if #[cfg(target_os = "windows")] {
27        #[macro_export]
28        macro_rules! asm_func {
29            ($name:expr, $body:expr $(, $($args:tt)*)?) => {
30                std::arch::global_asm!(
31                    concat!(
32                        ".def ", $name, "\n",
33                        ".scl 2\n",
34                        ".type 32\n",
35                        ".endef\n",
36                        ".global ", $name, "\n",
37                        ".p2align 4\n",
38                        $name, ":\n",
39                        $body
40                    ),
41                    $($($args)*)?
42                );
43            };
44        }
45    } else {
46        // Note that for now this "else" clause just assumes that everything
47        // other than macOS is ELF and has the various directives here for
48        // that.
49        cfg_if::cfg_if! {
50            if #[cfg(target_arch = "arm")] {
51                #[macro_export]
52                macro_rules! elf_func_type_header {
53                    ($name:tt) => (concat!(".type ", $name, ",%function\n"))
54                }
55            } else {
56                #[macro_export]
57                macro_rules! elf_func_type_header {
58                    ($name:tt) => (concat!(".type ", $name, ",@function\n"))
59                }
60            }
61        }
62
63        #[macro_export]
64        macro_rules! asm_func {
65            ($name:expr, $body:expr $(, $($args:tt)*)?) => {
66                std::arch::global_asm!(
67                    concat!(
68                        ".p2align 4\n",
69                        ".hidden ", $name, "\n",
70                        ".global ", $name, "\n",
71                        $crate::elf_func_type_header!($name),
72                        $name, ":\n",
73                        $body,
74                        ".size ", $name, ",.-", $name,
75                    )
76                    $(, $($args)*)?
77                );
78            };
79        }
80    }
81}
wasmtime_asm_macros/lib.rs

wasmtime_asm_macros/
lib.rs
