5af6385f9f
Add support for RISC-V relax target feature
This adds `relax` as an allowed RISC-V target feature. The relax feature in LLVM enables [linker relaxation](https://www.sifive.com/blog/all-aboard-part-3-linker-relaxation-in-riscv-toolchain), an optimization specific to RISC-V that allows global variable accesses to be resolved by the linker by using the global pointer (`gp`) register (rather than constructing the addresses from scratch for each access). Enabling `relax` will cause LLVM to emit relocations in the object file that support this. The feature can be enabled in rustc with `-C target-feature=+relax`.
Currently this feature is disabled by default, but maybe it should be enabled by default since it is an easy performance improvement (but requires the `gp` register to be set up properly). GCC/Clang enable this feature by default (for both hosted/bare-metal targets), and include the `-mno-relax` flag to disable it (see [here](
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| back | ||
| coverageinfo | ||
| debuginfo | ||
| mir | ||
| traits | ||
| base.rs | ||
| codegen_attrs.rs | ||
| common.rs | ||
| errors.rs | ||
| glue.rs | ||
| lib.rs | ||
| meth.rs | ||
| mono_item.rs | ||
| target_features.rs | ||