diff options
Diffstat (limited to 'src/librustc_codegen_ssa/back/write.rs')
| -rw-r--r-- | src/librustc_codegen_ssa/back/write.rs | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/src/librustc_codegen_ssa/back/write.rs b/src/librustc_codegen_ssa/back/write.rs index 53dfe7cb749..f9ee7d8c5de 100644 --- a/src/librustc_codegen_ssa/back/write.rs +++ b/src/librustc_codegen_ssa/back/write.rs @@ -142,8 +142,22 @@ impl ModuleConfig { let emit_obj = if !should_emit_obj { EmitObj::None } else if sess.target.target.options.obj_is_bitcode - || sess.opts.cg.linker_plugin_lto.enabled() + || (sess.opts.cg.linker_plugin_lto.enabled() && !no_builtins) { + // This case is selected if the target uses objects as bitcode, or + // if linker plugin LTO is enabled. In the linker plugin LTO case + // the assumption is that the final link-step will read the bitcode + // and convert it to object code. This may be done by either the + // native linker or rustc itself. + // + // Note, however, that the linker-plugin-lto requested here is + // explicitly ignored for `#![no_builtins]` crates. These crates are + // specifically ignored by rustc's LTO passes and wouldn't work if + // loaded into the linker. These crates define symbols that LLVM + // lowers intrinsics to, and these symbol dependencies aren't known + // until after codegen. As a result any crate marked + // `#![no_builtins]` is assumed to not participate in LTO and + // instead goes on to generate object code. EmitObj::Bitcode } else if need_bitcode_in_object(sess) { EmitObj::ObjectCode(BitcodeSection::Full) |