rust/compiler/rustc_codegen_ssa
Seth Junot 329e099400 Support explicit 32-bit MIPS ABI for the synthetic object
PR #95604 introduced a "synthetic object file to ensure all exported and
used symbols participate in the linking". One constraint on this file is
that for MIPS-based targets, its architecture-specific ELF flags must be
the same as all other object files passed to the linker. That's enforced
by LLD, here:
https://github.com/llvm/llvm-project/blob/llvmorg-16.0.6/lld/ELF/Arch/MipsArchTree.cpp#L77

The current approach to determining e_flags for 32-bit was implemented
in PR #96930, which links to this issue that summarizes the problem well:
https://github.com/ayrtonm/psx-sdk-rs/issues/9

> ... the temporary object file is created with an e_flags which is
> invalid for 32-bit MIPS targets. The main issue is that it omits the ABI
> bits (EF_MIPS_ABI_O32) which implies it uses the N64 ABI.

To enable the N32 MIPS ABI (which succeeded O32), this patch enables
setting the synthetic object's ABI based on the target "llvm-abiname"
field, if it's given; otherwise, the O32 ABI is assumed for 32-bit MIPS
targets.

More information about the N32 ABI can be found here:
https://web.archive.org/web/20160121005457/http://techpubs.sgi.com/library/manuals/2000/007-2816-005/pdf/007-2816-005.pdf
2023-07-09 11:17:37 -07:00
..
src Support explicit 32-bit MIPS ABI for the synthetic object 2023-07-09 11:17:37 -07:00
Cargo.toml Support rust metadata for AIX. 2023-05-23 16:23:59 +08:00
messages.ftl Add rustc option to output LLVM optimization remarks to YAML files 2023-07-02 13:41:36 +02:00
README.md

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