rust/compiler_builtins.rs

   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     __gesf2,
  44     __lesf2,
  45     __ltsf2,
  46     __mulsf3,
  47     __nesf2,
  48     __unordsf2,
  49 });
  50
  51 define_panicking_intrinsics!("`f64` should not be used", {
  52     __adddf3,
  53     __ledf2,
  54     __ltdf2,
  55     __muldf3,
  56     __unorddf2,
  57 });
  58
  59 define_panicking_intrinsics!("`i128` should not be used", {
  60     __ashrti3,
  61     __muloti4,
  62     __multi3,
  63 });
  64
  65 define_panicking_intrinsics!("`u128` should not be used", {
  66     __ashlti3,
  67     __lshrti3,
  68     __udivmodti4,
  69     __udivti3,
  70     __umodti3,
  71 });
  72
  73 // NOTE: if you are adding a new intrinsic here, you should also add it to
  74 // `redirect-intrinsics` in `rust/Makefile`.