Auto merge of #133250 - DianQK:embed-bitcode-pgo, r=nikic

The embedded bitcode should always be prepared for LTO/ThinLTO

Fixes #115344. Fixes #117220.

There are currently two methods for generating bitcode that used for LTO. One method involves using `-C linker-plugin-lto` to emit object files as bitcode, which is the typical setting used by cargo. The other method is through `-C embed-bitcode=yes`.

When using with `-C embed-bitcode=yes -C lto=no`, we run a complete non-LTO LLVM pipeline to obtain bitcode, then the bitcode is used for LTO. We run the Call Graph Profile Pass twice on the same module.

This PR is doing something similar to LLVM's `buildFatLTODefaultPipeline`, obtaining the bitcode for embedding after running `buildThinLTOPreLinkDefaultPipeline`.

r? nikic

1 files changed, 1 insertions, 1 deletions

diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index e9e1b644f18..c88372db491 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -194,7 +194,7 @@ impl WriteBackendMethods for LlvmCodegenBackend {
     unsafe fn optimize(
         cgcx: &CodegenContext<Self>,
         dcx: DiagCtxtHandle<'_>,
-        module: &ModuleCodegen<Self::Module>,
+        module: &mut ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
     ) -> Result<(), FatalError> {
         unsafe { back::write::optimize(cgcx, dcx, module, config) }