Closure support at CallExpr

Closures's need to generate their specific function and setup their
argument passing based on the signiture specified in libcore. We can get
this information based on the specified bound on the closure.

Addresses #195

1 files changed, 272 insertions, 8 deletions

diff --git a/gcc/rust/backend/rust-compile-expr.cc b/gcc/rust/backend/rust-compile-expr.cc
index d66aa5d..738c7b1 100644
--- a/gcc/rust/backend/rust-compile-expr.cc
+++ b/gcc/rust/backend/rust-compile-expr.cc
@@ -1589,9 +1589,7 @@ CompileExpr::visit (HIR::CallExpr &expr)
     }
 
   // must be a tuple constructor
-  bool is_fn = tyty->get_kind () == TyTy::TypeKind::FNDEF
-	       || tyty->get_kind () == TyTy::TypeKind::FNPTR;
-  bool is_adt_ctor = !is_fn;
+  bool is_adt_ctor = tyty->get_kind () == TyTy::TypeKind::ADT;
   if (is_adt_ctor)
     {
       rust_assert (tyty->get_kind () == TyTy::TypeKind::ADT);
@@ -1692,6 +1690,57 @@ CompileExpr::visit (HIR::CallExpr &expr)
     return true;
   };
 
+  auto fn_address = CompileExpr::Compile (expr.get_fnexpr (), ctx);
+
+  // is this a closure call?
+  if (RS_CLOSURE_TYPE_P (TREE_TYPE (fn_address)))
+    {
+      rust_assert (tyty->get_kind () == TyTy::TypeKind::CLOSURE);
+      TyTy::ClosureType *closure = static_cast<TyTy::ClosureType *> (tyty);
+
+      std::vector<tree> tuple_arg_vals;
+      for (auto &argument : expr.get_arguments ())
+	{
+	  auto rvalue = CompileExpr::Compile (argument.get (), ctx);
+	  tuple_arg_vals.push_back (rvalue);
+	}
+
+      tree tuple_args_tyty
+	= TyTyResolveCompile::compile (ctx, &closure->get_parameters ());
+      tree tuple_args
+	= ctx->get_backend ()->constructor_expression (tuple_args_tyty, false,
+						       tuple_arg_vals, -1,
+						       expr.get_locus ());
+
+      // need to apply any autoderef's to the self argument
+      HirId autoderef_mappings_id = expr.get_mappings ().get_hirid ();
+      std::vector<Resolver::Adjustment> *adjustments = nullptr;
+      bool ok
+	= ctx->get_tyctx ()->lookup_autoderef_mappings (autoderef_mappings_id,
+							&adjustments);
+      rust_assert (ok);
+
+      // apply adjustments for the fn call
+      tree self
+	= resolve_adjustements (*adjustments, fn_address, expr.get_locus ());
+
+      // args are always self, and the tuple of the args we are passing where
+      // self is the path of the call-expr in this case the fn_address
+      std::vector<tree> args;
+      args.push_back (self);
+      args.push_back (tuple_args);
+
+      // get the fn call address
+      tree closure_call_site = ctx->lookup_closure_decl (closure);
+      tree closure_call_address
+	= address_expression (closure_call_site, expr.get_locus ());
+      translated
+	= ctx->get_backend ()->call_expression (closure_call_address, args,
+						nullptr /* static chain ?*/,
+						expr.get_locus ());
+      return;
+    }
+
   bool is_varadic = false;
   if (tyty->get_kind () == TyTy::TypeKind::FNDEF)
     {
@@ -1699,13 +1748,13 @@ CompileExpr::visit (HIR::CallExpr &expr)
       is_varadic = fn->is_varadic ();
     }
 
-  size_t required_num_args;
+  size_t required_num_args = expr.get_arguments ().size ();
   if (tyty->get_kind () == TyTy::TypeKind::FNDEF)
     {
       const TyTy::FnType *fn = static_cast<const TyTy::FnType *> (tyty);
       required_num_args = fn->num_params ();
     }
-  else
+  else if (tyty->get_kind () == TyTy::TypeKind::FNPTR)
     {
       const TyTy::FnPtr *fn = static_cast<const TyTy::FnPtr *> (tyty);
       required_num_args = fn->num_params ();
@@ -1746,8 +1795,7 @@ CompileExpr::visit (HIR::CallExpr &expr)
       args.push_back (rvalue);
     }
 
-  // must be a call to a function
-  auto fn_address = CompileExpr::Compile (expr.get_fnexpr (), ctx);
+  // must be a regular call to a function
   translated = ctx->get_backend ()->call_expression (fn_address, args, nullptr,
 						     expr.get_locus ());
 }
@@ -2801,7 +2849,223 @@ CompileExpr::visit (HIR::ArrayIndexExpr &expr)
 void
 CompileExpr::visit (HIR::ClosureExpr &expr)
 {
-  gcc_unreachable ();
+  TyTy::BaseType *closure_expr_ty = nullptr;
+  if (!ctx->get_tyctx ()->lookup_type (expr.get_mappings ().get_hirid (),
+				       &closure_expr_ty))
+    {
+      rust_fatal_error (expr.get_locus (),
+			"did not resolve type for this ClosureExpr");
+      return;
+    }
+  rust_assert (closure_expr_ty->get_kind () == TyTy::TypeKind::CLOSURE);
+  TyTy::ClosureType *closure_tyty
+    = static_cast<TyTy::ClosureType *> (closure_expr_ty);
+  tree compiled_closure_tyty = TyTyResolveCompile::compile (ctx, closure_tyty);
+
+  // generate closure function
+  generate_closure_function (expr, *closure_tyty, compiled_closure_tyty);
+
+  // lets ignore state capture for now we need to instantiate the struct anyway
+  // then generate the function
+
+  std::vector<tree> vals;
+  // TODO
+  // setup argument captures based on the mode?
+
+  translated
+    = ctx->get_backend ()->constructor_expression (compiled_closure_tyty, false,
+						   vals, -1, expr.get_locus ());
+}
+
+tree
+CompileExpr::generate_closure_function (HIR::ClosureExpr &expr,
+					TyTy::ClosureType &closure_tyty,
+					tree compiled_closure_tyty)
+{
+  TyTy::FnType *fn_tyty = nullptr;
+  tree compiled_fn_type
+    = generate_closure_fntype (expr, closure_tyty, compiled_closure_tyty,
+			       &fn_tyty);
+  if (compiled_fn_type == error_mark_node)
+    return error_mark_node;
+
+  const Resolver::CanonicalPath &parent_canonical_path
+    = closure_tyty.get_ident ().path;
+  Resolver::CanonicalPath path = parent_canonical_path.append (
+    Resolver::CanonicalPath::new_seg (UNKNOWN_NODEID, "{{closure}}"));
+
+  std::string ir_symbol_name = path.get ();
+  std::string asm_name = ctx->mangle_item (&closure_tyty, path);
+
+  unsigned int flags = 0;
+  tree fndecl
+    = ctx->get_backend ()->function (compiled_fn_type, ir_symbol_name, asm_name,
+				     flags, expr.get_locus ());
+
+  // insert into the context
+  ctx->insert_function_decl (fn_tyty, fndecl);
+  ctx->insert_closure_decl (&closure_tyty, fndecl);
+
+  // setup the parameters
+  std::vector<Bvariable *> param_vars;
+
+  // closure self
+  Bvariable *self_param
+    = ctx->get_backend ()->parameter_variable (fndecl, "$closure",
+					       compiled_closure_tyty,
+					       expr.get_locus ());
+  DECL_ARTIFICIAL (self_param->get_decl ()) = 1;
+  param_vars.push_back (self_param);
+
+  // setup the implicit argument captures
+  // TODO
+
+  // args tuple
+  tree args_type
+    = TyTyResolveCompile::compile (ctx, &closure_tyty.get_parameters ());
+  Bvariable *args_param
+    = ctx->get_backend ()->parameter_variable (fndecl, "args", args_type,
+					       expr.get_locus ());
+  param_vars.push_back (args_param);
+
+  // setup the implicit mappings for the arguments. Since argument passing to
+  // closure functions is done via passing a tuple but the closure body expects
+  // just normal arguments this means we need to destructure them similar to
+  // what we do in MatchExpr's. This means when we have a closure-param of a we
+  // actually setup the destructure to take from the args tuple
+
+  tree args_param_expr = args_param->get_tree (expr.get_locus ());
+  size_t i = 0;
+  for (auto &closure_param : expr.get_params ())
+    {
+      tree compiled_param_var = ctx->get_backend ()->struct_field_expression (
+	args_param_expr, i, closure_param.get_locus ());
+
+      const HIR::Pattern &param_pattern = *closure_param.get_pattern ();
+      ctx->insert_pattern_binding (
+	param_pattern.get_pattern_mappings ().get_hirid (), compiled_param_var);
+      i++;
+    }
+
+  if (!ctx->get_backend ()->function_set_parameters (fndecl, param_vars))
+    return error_mark_node;
+
+  // lookup locals
+  HIR::Expr *function_body = expr.get_expr ().get ();
+  auto body_mappings = function_body->get_mappings ();
+  Resolver::Rib *rib = nullptr;
+  bool ok
+    = ctx->get_resolver ()->find_name_rib (body_mappings.get_nodeid (), &rib);
+  rust_assert (ok);
+
+  std::vector<Bvariable *> locals
+    = compile_locals_for_block (ctx, *rib, fndecl);
+
+  tree enclosing_scope = NULL_TREE;
+  Location start_location = function_body->get_locus ();
+  Location end_location = function_body->get_locus ();
+  bool is_block_expr
+    = function_body->get_expression_type () == HIR::Expr::ExprType::Block;
+  if (is_block_expr)
+    {
+      HIR::BlockExpr *body = static_cast<HIR::BlockExpr *> (function_body);
+      start_location = body->get_locus ();
+      end_location = body->get_end_locus ();
+    }
+
+  tree code_block = ctx->get_backend ()->block (fndecl, enclosing_scope, locals,
+						start_location, end_location);
+  ctx->push_block (code_block);
+
+  TyTy::BaseType *tyret = &closure_tyty.get_result_type ();
+  bool function_has_return = !closure_tyty.get_result_type ().is_unit ();
+  Bvariable *return_address = nullptr;
+  if (function_has_return)
+    {
+      tree return_type = TyTyResolveCompile::compile (ctx, tyret);
+
+      bool address_is_taken = false;
+      tree ret_var_stmt = NULL_TREE;
+
+      return_address = ctx->get_backend ()->temporary_variable (
+	fndecl, code_block, return_type, NULL, address_is_taken,
+	expr.get_locus (), &ret_var_stmt);
+
+      ctx->add_statement (ret_var_stmt);
+    }
+
+  ctx->push_fn (fndecl, return_address);
+
+  if (is_block_expr)
+    {
+      HIR::BlockExpr *body = static_cast<HIR::BlockExpr *> (function_body);
+      compile_function_body (ctx, fndecl, *body, true);
+    }
+  else
+    {
+      tree value = CompileExpr::Compile (function_body, ctx);
+      tree return_expr
+	= ctx->get_backend ()->return_statement (fndecl, {value},
+						 function_body->get_locus ());
+      ctx->add_statement (return_expr);
+    }
+
+  tree bind_tree = ctx->pop_block ();
+
+  gcc_assert (TREE_CODE (bind_tree) == BIND_EXPR);
+  DECL_SAVED_TREE (fndecl) = bind_tree;
+
+  ctx->pop_fn ();
+  ctx->push_function (fndecl);
+
+  return fndecl;
+}
+
+tree
+CompileExpr::generate_closure_fntype (HIR::ClosureExpr &expr,
+				      const TyTy::ClosureType &closure_tyty,
+				      tree compiled_closure_tyty,
+				      TyTy::FnType **fn_tyty)
+{
+  // grab the specified_bound
+  rust_assert (closure_tyty.num_specified_bounds () == 1);
+  const TyTy::TypeBoundPredicate &predicate
+    = *closure_tyty.get_specified_bounds ().begin ();
+
+  // ensure the fn_once_output associated type is set
+  closure_tyty.setup_fn_once_output ();
+
+  // the function signature is based on the trait bound that the closure
+  // implements which is determined at the type resolution time
+  //
+  // https://github.com/rust-lang/rust/blob/7807a694c2f079fd3f395821bcc357eee8650071/library/core/src/ops/function.rs#L54-L71
+
+  TyTy::TypeBoundPredicateItem item = TyTy::TypeBoundPredicateItem::error ();
+  if (predicate.get_name ().compare ("FnOnce") == 0)
+    {
+      item = predicate.lookup_associated_item ("call_once");
+    }
+  else if (predicate.get_name ().compare ("FnMut") == 0)
+    {
+      item = predicate.lookup_associated_item ("call_mut");
+    }
+  else if (predicate.get_name ().compare ("Fn") == 0)
+    {
+      item = predicate.lookup_associated_item ("call");
+    }
+  else
+    {
+      // FIXME error message?
+      gcc_unreachable ();
+      return error_mark_node;
+    }
+
+  rust_assert (!item.is_error ());
+
+  TyTy::BaseType *item_tyty = item.get_tyty_for_receiver (&closure_tyty);
+  rust_assert (item_tyty->get_kind () == TyTy::TypeKind::FNDEF);
+  *fn_tyty = static_cast<TyTy::FnType *> (item_tyty);
+  return TyTyResolveCompile::compile (ctx, item_tyty);
 }
 
 } // namespace Compile