1 // SPDX-License-Identifier: GPL-2.0
2 
3 //! Our own `compiler_builtins`.
4 //!
5 //! Rust provides [`compiler_builtins`] as a port of LLVM's [`compiler-rt`].
6 //! Since we do not need the vast majority of them, we avoid the dependency
7 //! by providing this file.
8 //!
9 //! At the moment, some builtins are required that should not be. For instance,
10 //! [`core`] has 128-bit integers functionality which we should not be compiling
11 //! in. We will work with upstream [`core`] to provide feature flags to disable
12 //! the parts we do not need. For the moment, we define them to [`panic!`] at
13 //! runtime for simplicity to catch mistakes, instead of performing surgery
14 //! on `core.o`.
15 //!
16 //! In any case, all these symbols are weakened to ensure we do not override
17 //! those that may be provided by the rest of the kernel.
18 //!
19 //! [`compiler_builtins`]: https://github.com/rust-lang/compiler-builtins
20 //! [`compiler-rt`]: https://compiler-rt.llvm.org/
21 
22 #![allow(internal_features)]
23 #![feature(compiler_builtins)]
24 #![compiler_builtins]
25 #![no_builtins]
26 #![no_std]
27 
28 macro_rules! define_panicking_intrinsics(
29     ($reason: tt, { $($ident: ident, )* }) => {
30         $(
31             #[doc(hidden)]
32             #[export_name = concat!("__rust", stringify!($ident))]
33             pub extern "C" fn $ident() {
34                 panic!($reason);
35             }
36         )*
37     }
38 );
39 
40 define_panicking_intrinsics!("`f32` should not be used", {
41     __addsf3,
42     __eqsf2,
43     __extendsfdf2,
44     __gesf2,
45     __lesf2,
46     __ltsf2,
47     __mulsf3,
48     __nesf2,
49     __truncdfsf2,
50     __unordsf2,
51 });
52 
53 define_panicking_intrinsics!("`f64` should not be used", {
54     __adddf3,
55     __eqdf2,
56     __ledf2,
57     __ltdf2,
58     __muldf3,
59     __unorddf2,
60 });
61 
62 define_panicking_intrinsics!("`i128` should not be used", {
63     __ashrti3,
64     __muloti4,
65     __multi3,
66 });
67 
68 define_panicking_intrinsics!("`u128` should not be used", {
69     __ashlti3,
70     __lshrti3,
71     __udivmodti4,
72     __udivti3,
73     __umodti3,
74 });
75 
76 // NOTE: if you are adding a new intrinsic here, you should also add it to
77 // `redirect-intrinsics` in `rust/Makefile`.
78