rust/compiler/rustc_codegen_ssa
Ayrton 3d5b1eeb75 Fix e_flags for 32-bit MIPS targets in generated object file
In #95604 the compiler started generating a temporary symbols.o which is added
to the linker invocation. This object file has an `e_flags` which may be invalid
for 32-bit MIPS targets. Even though symbols.o doesn't contain code, linking
    with [lld fails](https://github.com/llvm/llvm-project/blob/main/lld/ELF/Arch/MipsArchTree.cpp#L79) with
```
rust-lld: error: foo-cgu.0.rcgu.o: ABI 'o32' is incompatible with target ABI 'n64'
```
because it omits the ABI bits (EF_MIPS_ABI_O32) so lld assumes it's using the
N64 ABI. This breaks linking on nightly for the out-of-tree [psx
target](https://github.com/ayrtonm/psx-sdk-rs/issues/9), the builtin
mipsel-sony-psp target (cc @overdrivenpotato) and any other 32-bit MIPS
target using lld.

This PR sets the ABI in `e_flags` to O32 since that's the only ABI for 32-bit
MIPS that LLVM supports. It also sets other `e_flags` bits based on the target.
I had to bump the object crate version since some of these constants were [added
recently](https://github.com/gimli-rs/object/pull/433). I'm not sure if this
PR needs a test, but I can confirm that it fixes the linking issue on both
targets I mentioned.
2022-05-10 22:48:19 -04:00
..
src Fix e_flags for 32-bit MIPS targets in generated object file 2022-05-10 22:48:19 -04:00
Cargo.toml Fix e_flags for 32-bit MIPS targets in generated object file 2022-05-10 22:48:19 -04:00
README.md mv compiler to compiler/ 2020-08-30 18:45:07 +03:00

Please read the rustc-dev-guide chapter on Backend Agnostic Codegen.