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rust/compiler/rustc_codegen_ssa
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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 Use constant eval to do strict validity checks 2022-07-14 22:55:17 +01:00
README.md

README.md

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