Rollup merge of rust-lang#96587 - bjorn3:refactor_backend_write, r=michaelwoerister

Refactor the WriteBackendMethods and ExtraBackendMethods traits

The new interface is slightly less confusing and is easier to implement for non-LLVM backends.

Author: JohnTitor

compiler/rustc_codegen_gcc/src/lib.rs

@@ -139,14 +139,12 @@ impl CodegenBackend for GccCodegenBackend {
 }
 
 impl ExtraBackendMethods for GccCodegenBackend {
-    fn new_metadata<'tcx>(&self, _tcx: TyCtxt<'tcx>, _mod_name: &str) -> Self::Module {
-        GccContext {
+    fn codegen_allocator<'tcx>(&self, tcx: TyCtxt<'tcx>, module_name: &str, kind: AllocatorKind, has_alloc_error_handler: bool) -> Self::Module {
+        let mut mods = GccContext {
             context: Context::default(),
-        }
-    }
-
-    fn codegen_allocator<'tcx>(&self, tcx: TyCtxt<'tcx>, mods: &mut Self::Module, module_name: &str, kind: AllocatorKind, has_alloc_error_handler: bool) {
-        unsafe { allocator::codegen(tcx, mods, module_name, kind, has_alloc_error_handler) }
+        };
+        unsafe { allocator::codegen(tcx, &mut mods, module_name, kind, has_alloc_error_handler); }
+        mods
     }
 
     fn compile_codegen_unit<'tcx>(&self, tcx: TyCtxt<'tcx>, cgu_name: Symbol) -> (ModuleCodegen<Self::Module>, u64) {
@@ -213,7 +211,7 @@ impl WriteBackendMethods for GccCodegenBackend {
                     unimplemented!();
                 }
             };
-        Ok(LtoModuleCodegen::Fat { module: Some(module), _serialized_bitcode: vec![] })
+        Ok(LtoModuleCodegen::Fat { module, _serialized_bitcode: vec![] })
     }
 
     fn run_thin_lto(_cgcx: &CodegenContext<Self>, _modules: Vec<(String, Self::ThinBuffer)>, _cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>) -> Result<(Vec<LtoModuleCodegen<Self>>, Vec<WorkProduct>), FatalError> {
@@ -229,7 +227,12 @@ impl WriteBackendMethods for GccCodegenBackend {
         Ok(())
     }
 
-    unsafe fn optimize_thin(_cgcx: &CodegenContext<Self>, _thin: &mut ThinModule<Self>) -> Result<ModuleCodegen<Self::Module>, FatalError> {
+    fn optimize_fat(_cgcx: &CodegenContext<Self>, _module: &mut ModuleCodegen<Self::Module>) -> Result<(), FatalError> {
+        // TODO(antoyo)
+        Ok(())
+    }
+
+    unsafe fn optimize_thin(_cgcx: &CodegenContext<Self>, _thin: ThinModule<Self>) -> Result<ModuleCodegen<Self::Module>, FatalError> {
         unimplemented!();
     }
 
@@ -245,11 +248,6 @@ impl WriteBackendMethods for GccCodegenBackend {
         unimplemented!();
     }
 
-    fn run_lto_pass_manager(_cgcx: &CodegenContext<Self>, _module: &ModuleCodegen<Self::Module>, _config: &ModuleConfig, _thin: bool) -> Result<(), FatalError> {
-        // TODO(antoyo)
-        Ok(())
-    }
-
     fn run_link(cgcx: &CodegenContext<Self>, diag_handler: &Handler, modules: Vec<ModuleCodegen<Self::Module>>) -> Result<ModuleCodegen<Self::Module>, FatalError> {
         back::write::link(cgcx, diag_handler, modules)
     }

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -6,9 +6,7 @@ use crate::llvm::{self, build_string, False, True};
 use crate::{llvm_util, LlvmCodegenBackend, ModuleLlvm};
 use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule, ThinShared};
 use rustc_codegen_ssa::back::symbol_export;
-use rustc_codegen_ssa::back::write::{
-    CodegenContext, FatLTOInput, ModuleConfig, TargetMachineFactoryConfig,
-};
+use rustc_codegen_ssa::back::write::{CodegenContext, FatLTOInput, TargetMachineFactoryConfig};
 use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{looks_like_rust_object_file, ModuleCodegen, ModuleKind};
 use rustc_data_structures::fx::FxHashMap;
@@ -353,7 +351,7 @@ fn fat_lto(
         }
     }
 
-    Ok(LtoModuleCodegen::Fat { module: Some(module), _serialized_bitcode: serialized_bitcode })
+    Ok(LtoModuleCodegen::Fat { module, _serialized_bitcode: serialized_bitcode })
 }
 
 crate struct Linker<'a>(&'a mut llvm::Linker<'a>);
@@ -578,11 +576,11 @@ fn thin_lto(
 pub(crate) fn run_pass_manager(
     cgcx: &CodegenContext<LlvmCodegenBackend>,
     diag_handler: &Handler,
-    module: &ModuleCodegen<ModuleLlvm>,
-    config: &ModuleConfig,
+    module: &mut ModuleCodegen<ModuleLlvm>,
     thin: bool,
 ) -> Result<(), FatalError> {
     let _timer = cgcx.prof.extra_verbose_generic_activity("LLVM_lto_optimize", &*module.name);
+    let config = cgcx.config(module.kind);
 
     // Now we have one massive module inside of llmod. Time to run the
     // LTO-specific optimization passes that LLVM provides.
@@ -726,7 +724,7 @@ impl Drop for ThinBuffer {
 }
 
 pub unsafe fn optimize_thin_module(
-    thin_module: &mut ThinModule<LlvmCodegenBackend>,
+    thin_module: ThinModule<LlvmCodegenBackend>,
     cgcx: &CodegenContext<LlvmCodegenBackend>,
 ) -> Result<ModuleCodegen<ModuleLlvm>, FatalError> {
     let diag_handler = cgcx.create_diag_handler();
@@ -743,7 +741,7 @@ pub unsafe 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(), &diag_handler)? as *const _;
-    let module = ModuleCodegen {
+    let mut module = ModuleCodegen {
         module_llvm: ModuleLlvm { llmod_raw, llcx, tm },
         name: thin_module.name().to_string(),
         kind: ModuleKind::Regular,
@@ -859,8 +857,7 @@ pub unsafe fn optimize_thin_module(
         // little differently.
         {
             info!("running thin lto passes over {}", module.name);
-            let config = cgcx.config(module.kind);
-            run_pass_manager(cgcx, &diag_handler, &module, config, true)?;
+            run_pass_manager(cgcx, &diag_handler, &mut module, true)?;
             save_temp_bitcode(cgcx, &module, "thin-lto-after-pm");
         }
     }

compiler/rustc_codegen_llvm/src/lib.rs

@@ -104,19 +104,18 @@ impl Drop for TimeTraceProfiler {
 }
 
 impl ExtraBackendMethods for LlvmCodegenBackend {
-    fn new_metadata(&self, tcx: TyCtxt<'_>, mod_name: &str) -> ModuleLlvm {
-        ModuleLlvm::new_metadata(tcx, mod_name)
-    }
-
     fn codegen_allocator<'tcx>(
         &self,
         tcx: TyCtxt<'tcx>,
-        module_llvm: &mut ModuleLlvm,
         module_name: &str,
         kind: AllocatorKind,
         has_alloc_error_handler: bool,
-    ) {
-        unsafe { allocator::codegen(tcx, module_llvm, module_name, kind, has_alloc_error_handler) }
+    ) -> ModuleLlvm {
+        let mut module_llvm = ModuleLlvm::new_metadata(tcx, module_name);
+        unsafe {
+            allocator::codegen(tcx, &mut module_llvm, module_name, kind, has_alloc_error_handler);
+        }
+        module_llvm
     }
     fn compile_codegen_unit(
         &self,
@@ -210,9 +209,16 @@ impl WriteBackendMethods for LlvmCodegenBackend {
     ) -> Result<(), FatalError> {
         back::write::optimize(cgcx, diag_handler, module, config)
     }
+    fn optimize_fat(
+        cgcx: &CodegenContext<Self>,
+        module: &mut ModuleCodegen<Self::Module>,
+    ) -> Result<(), FatalError> {
+        let diag_handler = cgcx.create_diag_handler();
+        back::lto::run_pass_manager(cgcx, &diag_handler, module, false)
+    }
     unsafe fn optimize_thin(
         cgcx: &CodegenContext<Self>,
-        thin: &mut ThinModule<Self>,
+        thin: ThinModule<Self>,
     ) -> Result<ModuleCodegen<Self::Module>, FatalError> {
         back::lto::optimize_thin_module(thin, cgcx)
     }
@@ -230,15 +236,6 @@ impl WriteBackendMethods for LlvmCodegenBackend {
     fn serialize_module(module: ModuleCodegen<Self::Module>) -> (String, Self::ModuleBuffer) {
         (module.name, back::lto::ModuleBuffer::new(module.module_llvm.llmod()))
     }
-    fn run_lto_pass_manager(
-        cgcx: &CodegenContext<Self>,
-        module: &ModuleCodegen<Self::Module>,
-        config: &ModuleConfig,
-        thin: bool,
-    ) -> Result<(), FatalError> {
-        let diag_handler = cgcx.create_diag_handler();
-        back::lto::run_pass_manager(cgcx, &diag_handler, module, config, thin)
-    }
 }
 
 unsafe impl Send for LlvmCodegenBackend {} // Llvm is on a per-thread basis

compiler/rustc_codegen_ssa/src/back/lto.rs

@@ -42,7 +42,7 @@ pub struct ThinShared<B: WriteBackendMethods> {
 
 pub enum LtoModuleCodegen<B: WriteBackendMethods> {
     Fat {
-        module: Option<ModuleCodegen<B::Module>>,
+        module: ModuleCodegen<B::Module>,
         _serialized_bitcode: Vec<SerializedModule<B::ModuleBuffer>>,
     },
 
@@ -64,19 +64,15 @@ impl<B: WriteBackendMethods> LtoModuleCodegen<B> {
     /// It's intended that the module returned is immediately code generated and
     /// dropped, and then this LTO module is dropped.
     pub unsafe fn optimize(
-        &mut self,
+        self,
         cgcx: &CodegenContext<B>,
     ) -> Result<ModuleCodegen<B::Module>, FatalError> {
-        match *self {
-            LtoModuleCodegen::Fat { ref mut module, .. } => {
-                let module = module.take().unwrap();
-                {
-                    let config = cgcx.config(module.kind);
-                    B::run_lto_pass_manager(cgcx, &module, config, false)?;
-                }
+        match self {
+            LtoModuleCodegen::Fat { mut module, .. } => {
+                B::optimize_fat(cgcx, &mut module)?;
                 Ok(module)
             }
-            LtoModuleCodegen::Thin(ref mut thin) => B::optimize_thin(cgcx, thin),
+            LtoModuleCodegen::Thin(thin) => B::optimize_thin(cgcx, thin),
         }
     }
 

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -889,7 +889,7 @@ fn execute_copy_from_cache_work_item<B: ExtraBackendMethods>(
 
 fn execute_lto_work_item<B: ExtraBackendMethods>(
     cgcx: &CodegenContext<B>,
-    mut module: lto::LtoModuleCodegen<B>,
+    module: lto::LtoModuleCodegen<B>,
     module_config: &ModuleConfig,
 ) -> Result<WorkItemResult<B>, FatalError> {
     let module = unsafe { module.optimize(cgcx)? };

compiler/rustc_codegen_ssa/src/base.rs

@@ -575,15 +575,8 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
     } else if let Some(kind) = tcx.allocator_kind(()) {
         let llmod_id =
             cgu_name_builder.build_cgu_name(LOCAL_CRATE, &["crate"], Some("allocator")).to_string();
-        let mut module_llvm = backend.new_metadata(tcx, &llmod_id);
-        tcx.sess.time("write_allocator_module", || {
-            backend.codegen_allocator(
-                tcx,
-                &mut module_llvm,
-                &llmod_id,
-                kind,
-                tcx.lang_items().oom().is_some(),
-            )
+        let module_llvm = tcx.sess.time("write_allocator_module", || {
+            backend.codegen_allocator(tcx, &llmod_id, kind, tcx.lang_items().oom().is_some())
         });
 
         Some(ModuleCodegen { name: llmod_id, module_llvm, kind: ModuleKind::Allocator })

compiler/rustc_codegen_ssa/src/traits/backend.rs

@@ -114,15 +114,13 @@ pub trait CodegenBackend {
 }
 
 pub trait ExtraBackendMethods: CodegenBackend + WriteBackendMethods + Sized + Send + Sync {
-    fn new_metadata(&self, sess: TyCtxt<'_>, mod_name: &str) -> Self::Module;
     fn codegen_allocator<'tcx>(
         &self,
         tcx: TyCtxt<'tcx>,
-        module_llvm: &mut Self::Module,
         module_name: &str,
         kind: AllocatorKind,
         has_alloc_error_handler: bool,
-    );
+    ) -> Self::Module;
     /// This generates the codegen unit and returns it along with
     /// a `u64` giving an estimate of the unit's processing cost.
     fn compile_codegen_unit(

compiler/rustc_codegen_ssa/src/traits/write.rs

@@ -41,9 +41,13 @@ pub trait WriteBackendMethods: 'static + Sized + Clone {
         module: &ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
     ) -> Result<(), FatalError>;
+    fn optimize_fat(
+        cgcx: &CodegenContext<Self>,
+        llmod: &mut ModuleCodegen<Self::Module>,
+    ) -> Result<(), FatalError>;
     unsafe fn optimize_thin(
         cgcx: &CodegenContext<Self>,
-        thin: &mut ThinModule<Self>,
+        thin: ThinModule<Self>,
     ) -> Result<ModuleCodegen<Self::Module>, FatalError>;
     unsafe fn codegen(
         cgcx: &CodegenContext<Self>,
@@ -53,12 +57,6 @@ pub trait WriteBackendMethods: 'static + Sized + Clone {
     ) -> Result<CompiledModule, FatalError>;
     fn prepare_thin(module: ModuleCodegen<Self::Module>) -> (String, Self::ThinBuffer);
     fn serialize_module(module: ModuleCodegen<Self::Module>) -> (String, Self::ModuleBuffer);
-    fn run_lto_pass_manager(
-        cgcx: &CodegenContext<Self>,
-        llmod: &ModuleCodegen<Self::Module>,
-        config: &ModuleConfig,
-        thin: bool,
-    ) -> Result<(), FatalError>;
 }
 
 pub trait ThinBufferMethods: Send + Sync {