diff options
Diffstat (limited to 'compiler/rustc_codegen_gcc/src/callee.rs')
| -rw-r--r-- | compiler/rustc_codegen_gcc/src/callee.rs | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_gcc/src/callee.rs b/compiler/rustc_codegen_gcc/src/callee.rs new file mode 100644 index 00000000000..9fc77627b1b --- /dev/null +++ b/compiler/rustc_codegen_gcc/src/callee.rs @@ -0,0 +1,174 @@ +#[cfg(feature="master")] +use gccjit::{FnAttribute, Visibility}; +use gccjit::{FunctionType, Function}; +use rustc_middle::ty::{self, Instance, TypeVisitableExt}; +use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt}; + +use crate::attributes; +use crate::context::CodegenCx; + +/// Codegens a reference to a fn/method item, monomorphizing and +/// inlining as it goes. +/// +/// # Parameters +/// +/// - `cx`: the crate context +/// - `instance`: the instance to be instantiated +pub fn get_fn<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, instance: Instance<'tcx>) -> Function<'gcc> { + let tcx = cx.tcx(); + + assert!(!instance.args.has_infer()); + assert!(!instance.args.has_escaping_bound_vars()); + + let sym = tcx.symbol_name(instance).name; + + if let Some(&func) = cx.function_instances.borrow().get(&instance) { + return func; + } + + let fn_abi = cx.fn_abi_of_instance(instance, ty::List::empty()); + + let func = + if let Some(_func) = cx.get_declared_value(&sym) { + // FIXME(antoyo): we never reach this because get_declared_value only returns global variables + // and here we try to get a function. + unreachable!(); + /* + // Create a fn pointer with the new signature. + let ptrty = fn_abi.ptr_to_gcc_type(cx); + + // This is subtle and surprising, but sometimes we have to bitcast + // the resulting fn pointer. The reason has to do with external + // functions. If you have two crates that both bind the same C + // library, they may not use precisely the same types: for + // example, they will probably each declare their own structs, + // which are distinct types from LLVM's point of view (nominal + // types). + // + // Now, if those two crates are linked into an application, and + // they contain inlined code, you can wind up with a situation + // where both of those functions wind up being loaded into this + // application simultaneously. In that case, the same function + // (from LLVM's point of view) requires two types. But of course + // LLVM won't allow one function to have two types. + // + // What we currently do, therefore, is declare the function with + // one of the two types (whichever happens to come first) and then + // bitcast as needed when the function is referenced to make sure + // it has the type we expect. + // + // This can occur on either a crate-local or crate-external + // reference. It also occurs when testing libcore and in some + // other weird situations. Annoying. + if cx.val_ty(func) != ptrty { + // TODO(antoyo): cast the pointer. + func + } + else { + func + }*/ + } + else { + cx.linkage.set(FunctionType::Extern); + let func = cx.declare_fn(&sym, &fn_abi); + + attributes::from_fn_attrs(cx, func, instance); + + let instance_def_id = instance.def_id(); + + // TODO(antoyo): set linkage and attributes. + + // Apply an appropriate linkage/visibility value to our item that we + // just declared. + // + // This is sort of subtle. Inside our codegen unit we started off + // compilation by predefining all our own `MonoItem` instances. That + // is, everything we're codegenning ourselves is already defined. That + // means that anything we're actually codegenning in this codegen unit + // will have hit the above branch in `get_declared_value`. As a result, + // we're guaranteed here that we're declaring a symbol that won't get + // defined, or in other words we're referencing a value from another + // codegen unit or even another crate. + // + // So because this is a foreign value we blanket apply an external + // linkage directive because it's coming from a different object file. + // The visibility here is where it gets tricky. This symbol could be + // referencing some foreign crate or foreign library (an `extern` + // block) in which case we want to leave the default visibility. We may + // also, though, have multiple codegen units. It could be a + // monomorphization, in which case its expected visibility depends on + // whether we are sharing generics or not. The important thing here is + // that the visibility we apply to the declaration is the same one that + // has been applied to the definition (wherever that definition may be). + let is_generic = instance.args.non_erasable_generics(tcx, instance.def_id()).next().is_some(); + + if is_generic { + // This is a monomorphization. Its expected visibility depends + // on whether we are in share-generics mode. + + if cx.tcx.sess.opts.share_generics() { + // We are in share_generics mode. + + if let Some(instance_def_id) = instance_def_id.as_local() { + // This is a definition from the current crate. If the + // definition is unreachable for downstream crates or + // the current crate does not re-export generics, the + // definition of the instance will have been declared + // as `hidden`. + if cx.tcx.is_unreachable_local_definition(instance_def_id) + || !cx.tcx.local_crate_exports_generics() + { + #[cfg(feature="master")] + func.add_attribute(FnAttribute::Visibility(Visibility::Hidden)); + } + } else { + // This is a monomorphization of a generic function + // defined in an upstream crate. + if instance.upstream_monomorphization(tcx).is_some() { + // This is instantiated in another crate. It cannot + // be `hidden`. + } else { + // This is a local instantiation of an upstream definition. + // If the current crate does not re-export it + // (because it is a C library or an executable), it + // will have been declared `hidden`. + if !cx.tcx.local_crate_exports_generics() { + #[cfg(feature="master")] + func.add_attribute(FnAttribute::Visibility(Visibility::Hidden)); + } + } + } + } else { + // When not sharing generics, all instances are in the same + // crate and have hidden visibility + #[cfg(feature="master")] + func.add_attribute(FnAttribute::Visibility(Visibility::Hidden)); + } + } else { + // This is a non-generic function + if cx.tcx.is_codegened_item(instance_def_id) { + // This is a function that is instantiated in the local crate + + if instance_def_id.is_local() { + // This is function that is defined in the local crate. + // If it is not reachable, it is hidden. + if !cx.tcx.is_reachable_non_generic(instance_def_id) { + #[cfg(feature="master")] + func.add_attribute(FnAttribute::Visibility(Visibility::Hidden)); + } + } else { + // This is a function from an upstream crate that has + // been instantiated here. These are always hidden. + #[cfg(feature="master")] + func.add_attribute(FnAttribute::Visibility(Visibility::Hidden)); + } + } + } + + func + }; + + cx.function_instances.borrow_mut().insert(instance, func); + + func +} |