rust/compiler/rustc_codegen_llvm
bors 74f600b990 Auto merge of #98162 - nextsilicon:support_lto_embed_bitcode, r=davidtwco
Allow to disable thinLTO buffer to support lto-embed-bitcode lld feature

Hello
This change is to fix issue (https://github.com/rust-lang/rust/issues/84395) in which passing "-lto-embed-bitcode=optimized" to lld when linking rust code via linker-plugin-lto doesn't produce the expected result.

Instead of emitting a single unified module into a llvmbc section of the linked elf, it emits multiple submodules.
This is caused because rustc emits the BC modules after running llvm `createWriteThinLTOBitcodePass` pass.
Which in turn triggers a thinLTO linkage and causes the said issue.

This patch allows via compiler flag (-Cemit-thin-lto=<bool>) to select between running `createWriteThinLTOBitcodePass` and `createBitcodeWriterPass`.
Note this pattern of selecting between those 2 passes is common inside of LLVM code.
The default is to match the old behavior.
2022-07-21 10:13:59 +00:00
..
src Auto merge of #98162 - nextsilicon:support_lto_embed_bitcode, r=davidtwco 2022-07-21 10:13:59 +00:00
Cargo.toml Update smallvec to 1.8.1. 2022-06-27 08:48:55 +10:00
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.