Fix to do LTO when requested

Author: antoyo

src/back/lto.rs

@@ -40,7 +40,7 @@ use tempfile::{TempDir, tempdir};
 
 use crate::back::write::save_temp_bitcode;
 use crate::errors::{DynamicLinkingWithLTO, LtoBitcodeFromRlib, LtoDisallowed, LtoDylib};
-use crate::{GccCodegenBackend, GccContext, SyncContext, to_gcc_opt_level};
+use crate::{GccCodegenBackend, GccContext, LtoMode, SyncContext, to_gcc_opt_level};
 
 pub fn crate_type_allows_lto(crate_type: CrateType) -> bool {
     match crate_type {
@@ -302,7 +302,7 @@ fn fat_lto(
             info!("linking {:?}", name);
             match bc_decoded {
                 SerializedModule::Local(ref module_buffer) => {
-                    module.module_llvm.should_combine_object_files = true;
+                    module.module_llvm.lto_mode = LtoMode::Fat;
                     module
                         .module_llvm
                         .context
@@ -610,7 +610,7 @@ pub fn optimize_thin_module(
     // that LLVM Context and Module.
     //let llcx = llvm::LLVMRustContextCreate(cgcx.fewer_names);
     //let llmod_raw = parse_module(llcx, module_name, thin_module.data(), &dcx)? as *const _;
-    let mut should_combine_object_files = false;
+    let mut lto_mode = LtoMode::None;
     let context = match thin_module.shared.thin_buffers.get(thin_module.idx) {
         Some(thin_buffer) => Arc::clone(&thin_buffer.context),
         None => {
@@ -621,7 +621,7 @@ pub fn optimize_thin_module(
                 SerializedModule::Local(ref module_buffer) => {
                     let path = module_buffer.0.to_str().expect("path");
                     context.add_driver_option(path);
-                    should_combine_object_files = true;
+                    lto_mode = LtoMode::Thin;
                     /*module.module_llvm.should_combine_object_files = true;
                     module
                         .module_llvm
@@ -640,7 +640,7 @@ pub fn optimize_thin_module(
         thin_module.name().to_string(),
         GccContext {
             context,
-            should_combine_object_files,
+            lto_mode,
             // TODO(antoyo): use the correct relocation model here.
             relocation_model: RelocModel::Pic,
             temp_dir: None,

src/back/write.rs

@@ -12,7 +12,7 @@ use rustc_target::spec::SplitDebuginfo;
 
 use crate::base::add_pic_option;
 use crate::errors::CopyBitcode;
-use crate::{GccCodegenBackend, GccContext};
+use crate::{GccCodegenBackend, GccContext, LtoMode};
 
 pub(crate) fn codegen(
     cgcx: &CodegenContext<GccCodegenBackend>,
@@ -24,7 +24,7 @@ pub(crate) fn codegen(
     {
         let context = &module.module_llvm.context;
 
-        let should_combine_object_files = module.module_llvm.should_combine_object_files;
+        let lto_mode = module.module_llvm.lto_mode;
 
         let bc_out = cgcx.output_filenames.temp_path_for_cgu(
             OutputType::Bitcode,
@@ -124,8 +124,8 @@ pub(crate) fn codegen(
                     context.set_debug_info(true);
                     context.dump_to_file(path, true);
                 }
-                if should_combine_object_files {
-                    let fat_lto = config.emit_obj == EmitObj::ObjectCode(BitcodeSection::Full);
+                if lto_mode != LtoMode::None {
+                    let fat_lto = lto_mode == LtoMode::Fat;
                     // We need to check if we're doing LTO since this code is also used for the
                     // dummy ThinLTO implementation to combine the object files.
                     if fat_lto {

src/base.rs

@@ -21,7 +21,7 @@ use rustc_target::spec::{PanicStrategy, RelocModel};
 
 use crate::builder::Builder;
 use crate::context::CodegenCx;
-use crate::{GccContext, LockedTargetInfo, SyncContext, gcc_util, new_context};
+use crate::{GccContext, LockedTargetInfo, LtoMode, SyncContext, gcc_util, new_context};
 
 #[cfg(feature = "master")]
 pub fn visibility_to_gcc(visibility: Visibility) -> gccjit::Visibility {
@@ -242,7 +242,7 @@ pub fn compile_codegen_unit(
             GccContext {
                 context: Arc::new(SyncContext::new(context)),
                 relocation_model: tcx.sess.relocation_model(),
-                should_combine_object_files: false,
+                lto_mode: LtoMode::None,
                 temp_dir: None,
             },
         )

src/lib.rs

@@ -297,7 +297,7 @@ impl ExtraBackendMethods for GccCodegenBackend {
         let mut mods = GccContext {
             context: Arc::new(SyncContext::new(new_context(tcx))),
             relocation_model: tcx.sess.relocation_model(),
-            should_combine_object_files: false,
+            lto_mode: LtoMode::None,
             temp_dir: None,
         };
 
@@ -326,12 +326,19 @@ impl ExtraBackendMethods for GccCodegenBackend {
     }
 }
 
+#[derive(Clone, Copy, PartialEq)]
+pub enum LtoMode {
+    None,
+    Thin,
+    Fat,
+}
+
 pub struct GccContext {
     context: Arc<SyncContext>,
     /// This field is needed in order to be able to set the flag -fPIC when necessary when doing
     /// LTO.
     relocation_model: RelocModel,
-    should_combine_object_files: bool,
+    lto_mode: LtoMode,
     // Temporary directory used by LTO. We keep it here so that it's not removed before linking.
     temp_dir: Option<TempDir>,
 }