Merge #684

684: Initial Dynamic dispatch support r=philberty a=philberty

This rebases my branch for dynamic dispatch (dyn bound) support it supports
the HIR::TraitObjectOneBound for now but can be easily extended. The computation
of the addresses of the methods only supports impl items and does not support
optional trait methods yet but the change set was already 10 commits and this seems like
a good initial stab at support here.

Please see the git commits for more detail information on each change.

Fixes #197 

Co-authored-by: Philip Herron <philip.herron@embecosm.com>

1 files changed, 62 insertions, 8 deletions

diff --git a/gcc/rust/backend/rust-compile-context.h b/gcc/rust/backend/rust-compile-context.h
index 3a92c32..7a4344e 100644
--- a/gcc/rust/backend/rust-compile-context.h
+++ b/gcc/rust/backend/rust-compile-context.h
@@ -343,9 +343,10 @@ private:
 class TyTyResolveCompile : public TyTy::TyVisitor
 {
 public:
-  static ::Btype *compile (Context *ctx, TyTy::BaseType *ty)
+  static ::Btype *compile (Context *ctx, TyTy::BaseType *ty,
+			   bool trait_object_mode = false)
   {
-    TyTyResolveCompile compiler (ctx);
+    TyTyResolveCompile compiler (ctx, trait_object_mode);
     ty->accept_vis (compiler);
     return compiler.translated;
   }
@@ -378,7 +379,8 @@ public:
     if (!type.get_return_type ()->is_unit ())
       {
 	auto hir_type = type.get_return_type ();
-	auto ret = TyTyResolveCompile::compile (ctx, hir_type);
+	auto ret
+	  = TyTyResolveCompile::compile (ctx, hir_type, trait_object_mode);
 	results.push_back (Backend::Btyped_identifier (
 	  "_", ret,
 	  ctx->get_mappings ()->lookup_location (hir_type->get_ref ())));
@@ -388,7 +390,7 @@ public:
       {
 	auto param_tyty = param_pair.second;
 	auto compiled_param_type
-	  = TyTyResolveCompile::compile (ctx, param_tyty);
+	  = TyTyResolveCompile::compile (ctx, param_tyty, trait_object_mode);
 
 	auto compiled_param = Backend::Btyped_identifier (
 	  param_pair.first->as_string (), compiled_param_type,
@@ -429,7 +431,6 @@ public:
     if (ctx->lookup_compiled_types (type.get_ty_ref (), &translated, &type))
       return;
 
-    // create implicit struct
     std::vector<Backend::Btyped_identifier> fields;
     for (size_t i = 0; i < type.num_fields (); i++)
       {
@@ -570,7 +571,7 @@ public:
   void visit (TyTy::ReferenceType &type) override
   {
     Btype *base_compiled_type
-      = TyTyResolveCompile::compile (ctx, type.get_base ());
+      = TyTyResolveCompile::compile (ctx, type.get_base (), trait_object_mode);
     if (type.is_mutable ())
       {
 	translated = ctx->get_backend ()->reference_type (base_compiled_type);
@@ -585,7 +586,7 @@ public:
   void visit (TyTy::PointerType &type) override
   {
     Btype *base_compiled_type
-      = TyTyResolveCompile::compile (ctx, type.get_base ());
+      = TyTyResolveCompile::compile (ctx, type.get_base (), trait_object_mode);
     if (type.is_mutable ())
       {
 	translated = ctx->get_backend ()->pointer_type (base_compiled_type);
@@ -610,10 +611,63 @@ public:
     translated = ctx->get_backend ()->unit_type ();
   }
 
+  void visit (TyTy::DynamicObjectType &type) override
+  {
+    if (trait_object_mode)
+      {
+	translated = ctx->get_backend ()->integer_type (
+	  true, ctx->get_backend ()->get_pointer_size ());
+	return;
+      }
+
+    if (ctx->lookup_compiled_types (type.get_ty_ref (), &translated, &type))
+      return;
+
+    // create implicit struct
+    auto items = type.get_object_items ();
+    std::vector<Backend::Btyped_identifier> fields;
+
+    Btype *uint = ctx->get_backend ()->integer_type (
+      true, ctx->get_backend ()->get_pointer_size ());
+    Btype *uintptr_ty = ctx->get_backend ()->pointer_type (uint);
+
+    Backend::Btyped_identifier f ("__receiver_trait_obj_ptr", uintptr_ty,
+				  ctx->get_mappings ()->lookup_location (
+				    type.get_ty_ref ()));
+    fields.push_back (std::move (f));
+
+    for (size_t i = 0; i < items.size (); i++)
+      {
+	// mrustc seems to make a vtable consisting of uintptr's
+	Btype *uint = ctx->get_backend ()->integer_type (
+	  true, ctx->get_backend ()->get_pointer_size ());
+	Btype *uintptr_ty = ctx->get_backend ()->pointer_type (uint);
+
+	Backend::Btyped_identifier f ("__" + std::to_string (i), uintptr_ty,
+				      ctx->get_mappings ()->lookup_location (
+					type.get_ty_ref ()));
+	fields.push_back (std::move (f));
+      }
+
+    Btype *type_record = ctx->get_backend ()->struct_type (fields);
+    Btype *named_struct
+      = ctx->get_backend ()->named_type (type.get_name (), type_record,
+					 ctx->get_mappings ()->lookup_location (
+					   type.get_ty_ref ()));
+
+    ctx->push_type (named_struct);
+    translated = named_struct;
+
+    ctx->insert_compiled_type (type.get_ty_ref (), named_struct, &type);
+  }
+
 private:
-  TyTyResolveCompile (Context *ctx) : ctx (ctx), translated (nullptr) {}
+  TyTyResolveCompile (Context *ctx, bool trait_object_mode)
+    : ctx (ctx), trait_object_mode (trait_object_mode), translated (nullptr)
+  {}
 
   Context *ctx;
+  bool trait_object_mode;
   ::Btype *translated;
 };