Auto merge of #53356 - michaelwoerister:itlto, r=alexcrichton

Preliminary work for incremental ThinLTO (CGU name edition)

Bring back the first half of #52266 but hopefully without the performance regression.

3 files changed, 6 insertions, 15 deletions

diff --git a/src/librustc_codegen_llvm/back/link.rs b/src/librustc_codegen_llvm/back/link.rs
index bbe1ccf3696..37c99932f56 100644
--- a/src/librustc_codegen_llvm/back/link.rs
+++ b/src/librustc_codegen_llvm/back/link.rs
@@ -46,13 +46,6 @@ use std::process::{Output, Stdio};
 use std::str;
 use syntax::attr;
 
-/// The LLVM module name containing crate-metadata. This includes a `.` on
-/// purpose, so it cannot clash with the name of a user-defined module.
-pub const METADATA_MODULE_NAME: &'static str = "crate.metadata";
-
-// same as for metadata above, but for allocator shim
-pub const ALLOCATOR_MODULE_NAME: &'static str = "crate.allocator";
-
 pub use rustc_codegen_utils::link::{find_crate_name, filename_for_input, default_output_for_target,
                                   invalid_output_for_target, build_link_meta, out_filename,
                                   check_file_is_writeable};
diff --git a/src/librustc_codegen_llvm/back/lto.rs b/src/librustc_codegen_llvm/back/lto.rs
index d7741230327..56858a31efd 100644
--- a/src/librustc_codegen_llvm/back/lto.rs
+++ b/src/librustc_codegen_llvm/back/lto.rs
@@ -242,7 +242,7 @@ fn fat_lto(cgcx: &CodegenContext,
             let llvm = module.llvm().expect("can't lto pre-codegened modules");
             (&llvm.llcx, llvm.llmod())
         };
-        info!("using {:?} as a base module", module.llmod_id);
+        info!("using {:?} as a base module", module.name);
 
         // The linking steps below may produce errors and diagnostics within LLVM
         // which we'd like to handle and print, so set up our diagnostic handlers
@@ -257,7 +257,7 @@ fn fat_lto(cgcx: &CodegenContext,
         for module in modules {
             let llvm = module.llvm().expect("can't lto pre-codegened modules");
             let buffer = ModuleBuffer::new(llvm.llmod());
-            let llmod_id = CString::new(&module.llmod_id[..]).unwrap();
+            let llmod_id = CString::new(&module.name[..]).unwrap();
             serialized_modules.push((SerializedModule::Local(buffer), llmod_id));
         }
 
@@ -384,9 +384,9 @@ fn thin_lto(diag_handler: &Handler,
         //        the most expensive portion of this small bit of global
         //        analysis!
         for (i, module) in modules.iter().enumerate() {
-            info!("local module: {} - {}", i, module.llmod_id);
+            info!("local module: {} - {}", i, module.name);
             let llvm = module.llvm().expect("can't lto precodegened module");
-            let name = CString::new(module.llmod_id.clone()).unwrap();
+            let name = CString::new(module.name.clone()).unwrap();
             let buffer = ThinBuffer::new(llvm.llmod());
             thin_modules.push(llvm::ThinLTOModule {
                 identifier: name.as_ptr(),
@@ -395,7 +395,7 @@ fn thin_lto(diag_handler: &Handler,
             });
             thin_buffers.push(buffer);
             module_names.push(name);
-            timeline.record(&module.llmod_id);
+            timeline.record(&module.name);
         }
 
         // FIXME: All upstream crates are deserialized internally in the
@@ -668,7 +668,6 @@ impl ThinModule {
                 llcx,
                 tm,
             }),
-            llmod_id: self.name().to_string(),
             name: self.name().to_string(),
             kind: ModuleKind::Regular,
         };
diff --git a/src/librustc_codegen_llvm/back/write.rs b/src/librustc_codegen_llvm/back/write.rs
index d60983d7697..b62836ec255 100644
--- a/src/librustc_codegen_llvm/back/write.rs
+++ b/src/librustc_codegen_llvm/back/write.rs
@@ -728,7 +728,7 @@ unsafe fn codegen(cgcx: &CodegenContext,
 
             if config.emit_bc_compressed {
                 let dst = bc_out.with_extension(RLIB_BYTECODE_EXTENSION);
-                let data = bytecode::encode(&module.llmod_id, data);
+                let data = bytecode::encode(&module.name, data);
                 if let Err(e) = fs::write(&dst, data) {
                     diag_handler.err(&format!("failed to write bytecode: {}", e));
                 }
@@ -1338,7 +1338,6 @@ fn execute_work_item(cgcx: &CodegenContext,
         assert_eq!(bytecode_compressed.is_some(), config.emit_bc_compressed);
 
         Ok(WorkItemResult::Compiled(CompiledModule {
-            llmod_id: module.llmod_id.clone(),
             name: module_name,
             kind: ModuleKind::Regular,
             pre_existing: true,