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rustc_codegen_llvm: add support for writing summary bitcode Typical uses of ThinLTO don't have any use for this as a standalone file, but distributed ThinLTO uses this to make the linker phase more efficient. With clang you'd do something like `clang -flto=thin -fthin-link-bitcode=foo.indexing.o -c foo.c` and then get both foo.o (full of bitcode) and foo.indexing.o (just the summary or index part of the bitcode). That's then usable by a two-stage linking process that's more friendly to distributed build systems like bazel, which is why I'm working on this area. I talked some to `@teresajohnson` about naming in this area, as things seem to be a little confused between various blog posts and build systems. "bitcode index" and "bitcode summary" tend to be a little too ambiguous, and she tends to use "thin link bitcode" and "minimized bitcode" (which matches the descriptions in LLVM). Since the clang option is thin-link-bitcode, I went with that to try and not add a new spelling in the world. Per `@dtolnay,` you can work around the lack of this by using `lld --thinlto-index-only` to do the indexing on regular .o files of bitcode, but that is a bit wasteful on actions when we already have all the information in rustc and could just write out the matching minimized bitcode. I didn't test that at all in our infrastructure, because by the time I learned that I already had this patch largely written. |
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| .. | ||
| abi | ||
| debuginfo | ||
| driver | ||
| intrinsics | ||
| optimize | ||
| allocator.rs | ||
| analyze.rs | ||
| archive.rs | ||
| base.rs | ||
| cast.rs | ||
| codegen_i128.rs | ||
| common.rs | ||
| compiler_builtins.rs | ||
| concurrency_limiter.rs | ||
| config.rs | ||
| constant.rs | ||
| discriminant.rs | ||
| global_asm.rs | ||
| inline_asm.rs | ||
| lib.rs | ||
| linkage.rs | ||
| main_shim.rs | ||
| num.rs | ||
| pointer.rs | ||
| pretty_clif.rs | ||
| toolchain.rs | ||
| trap.rs | ||
| unsize.rs | ||
| value_and_place.rs | ||
| vtable.rs | ||