rust/compiler/rustc_codegen_llvm
Miguel Ojeda a65ec44779 Add -Zno-jump-tables
This flag mimics GCC/Clang's `-fno-jump-tables` [1][2], which makes
the codegen backend avoid generating jump tables when lowering switches.

In the case of LLVM, the `"no-jump-tables"="true"` function attribute is
added to every function.

The kernel currently needs it for x86 when enabling IBT [3], as well
as for Alpha (plus VDSO objects in MIPS/LoongArch).

[1] https://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html#index-fno-jump-tables
[2] https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-fjump-tables
[3] https://github.com/torvalds/linux/blob/v6.1/arch/x86/Makefile#L75-L83

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2022-12-20 21:42:54 +01:00
..
src Add -Zno-jump-tables 2022-12-20 21:42:54 +01:00
Cargo.toml Rewrite LLVM's archive writer in Rust 2022-11-26 19:35:32 +00:00
README.md

The codegen crate contains the code to convert from MIR into LLVM IR, and then from LLVM IR into machine code. In general it contains code that runs towards the end of the compilation process.

For more information about how codegen works, see the rustc dev guide.