https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105989
--- Comment #4 from Michal Jankovič <michal.jankovic59 at gmail dot com> --- Comment on attachment 53273 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53273 Experimental patch implementing the proposed transformation diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc index edb3b706ddc..ed1ac4decaf 100644 --- a/gcc/cp/coroutines.cc +++ b/gcc/cp/coroutines.cc @@ -1997,6 +1997,7 @@ struct local_var_info bool is_static; bool has_value_expr_p; location_t def_loc; + vec<tree, va_gc> *field_access_path; }; /* For figuring out what local variable usage we have. */ @@ -2009,6 +2010,26 @@ struct local_vars_transform hash_map<tree, local_var_info> *local_var_uses; }; +/* Build a COMPONENT_REF chain for accessing a nested variable in the coroutine + frame. */ +static tree +build_local_var_frame_access_expr (local_vars_transform *lvt, + local_var_info *local_var) +{ + tree access_expr = lvt->actor_frame; + + for (tree path_elem_id : *local_var->field_access_path) + { + tree path_elem_member = lookup_member ( + TREE_TYPE (access_expr), path_elem_id, 1, 0, tf_warning_or_error); + access_expr = build3_loc ( + lvt->loc, COMPONENT_REF, TREE_TYPE (path_elem_member), + access_expr, path_elem_member, NULL_TREE); + } + + return access_expr; +} + static tree transform_local_var_uses (tree *stmt, int *do_subtree, void *d) { @@ -2040,12 +2061,7 @@ transform_local_var_uses (tree *stmt, int *do_subtree, void *d) if (local_var.field_id == NULL_TREE) continue; /* Wasn't used. */ - tree fld_ref - = lookup_member (lvd->coro_frame_type, local_var.field_id, - /*protect=*/1, /*want_type=*/0, - tf_warning_or_error); - tree fld_idx = build3_loc (lvd->loc, COMPONENT_REF, TREE_TYPE (lvar), - lvd->actor_frame, fld_ref, NULL_TREE); + tree fld_idx = build_local_var_frame_access_expr (lvd, &local_var); local_var.field_idx = fld_idx; SET_DECL_VALUE_EXPR (lvar, fld_idx); DECL_HAS_VALUE_EXPR_P (lvar) = true; @@ -3873,14 +3889,24 @@ analyze_fn_parms (tree orig) /* Small helper for the repetitive task of adding a new field to the coro frame type. */ +static void +coro_make_frame_entry_id (tree *field_list, tree id, tree fld_type, + location_t loc) +{ + tree decl = build_decl (loc, FIELD_DECL, id, fld_type); + DECL_CHAIN (decl) = *field_list; + *field_list = decl; +} + +/* Same as coro_make_frame_entry_id, but creates an identifier from string. */ + static tree coro_make_frame_entry (tree *field_list, const char *name, tree fld_type, location_t loc) { tree id = get_identifier (name); - tree decl = build_decl (loc, FIELD_DECL, id, fld_type); - DECL_CHAIN (decl) = *field_list; - *field_list = decl; + coro_make_frame_entry_id (field_list, id, fld_type, loc); + return id; } @@ -3894,6 +3920,8 @@ struct local_vars_frame_data location_t loc; bool saw_capture; bool local_var_seen; + tree orig; + vec<tree, va_gc> *field_access_path; }; /* A tree-walk callback that processes one bind expression noting local @@ -3912,6 +3940,21 @@ register_local_var_uses (tree *stmt, int *do_subtree, void *d) if (TREE_CODE (*stmt) == BIND_EXPR) { + tree scope_field_id = NULL_TREE; + if (lvd->nest_depth != 0) + { + /* Create identifier under which fields for this bind-expression will + be accessed. */ + char *scope_field_name + = xasprintf ("_Scope%u_%u", lvd->nest_depth, lvd->bind_indx); + scope_field_id = get_identifier (scope_field_name); + free (scope_field_name); + + vec_safe_push (lvd->field_access_path, scope_field_id); + } + + tree scope_variables = NULL_TREE; + tree lvar; unsigned serial = 0; for (lvar = BIND_EXPR_VARS (*stmt); lvar != NULL; @@ -3980,17 +4023,99 @@ register_local_var_uses (tree *stmt, int *do_subtree, void *d) /* TODO: Figure out if we should build a local type that has any excess alignment or size from the original decl. */ - local_var.field_id = coro_make_frame_entry (lvd->field_list, buf, + + local_var.field_id = coro_make_frame_entry (&scope_variables, buf, lvtype, lvd->loc); free (buf); /* We don't walk any of the local var sub-trees, they won't contain any bind exprs. */ + + local_var.field_access_path = make_tree_vector_copy ( + lvd->field_access_path); + vec_safe_push (local_var.field_access_path, local_var.field_id); } + + unsigned bind_indx = lvd->bind_indx; + tree* parent_field_list = lvd->field_list; + + /* Collect the scope structs of child bind-expressions when recursing. */ + tree child_scopes = NULL_TREE; + lvd->field_list = &child_scopes; + + /* Create identifier under which fields for child bind-expressions will be + accessed. */ + char *child_scopes_field_name + = xasprintf ("_Scope_list%u_%u", lvd->nest_depth, bind_indx); + tree child_scopes_field_id = get_identifier (child_scopes_field_name); + free (child_scopes_field_name); + + /* Recurse to child bind expressions. */ lvd->bind_indx++; lvd->nest_depth++; + vec_safe_push (lvd->field_access_path, child_scopes_field_id); cp_walk_tree (&BIND_EXPR_BODY (*stmt), register_local_var_uses, d, NULL); *do_subtree = 0; /* We've done this. */ + lvd->field_access_path->pop (); lvd->nest_depth--; + + /* Restore the parent field list. */ + lvd->field_list = parent_field_list; + + if (child_scopes != NULL_TREE) + { + /* Create a union to house the child scopes, so that they are + overlapped in the coroutine frame. */ + char *child_scopes_union_name_suffix + = xasprintf ("Frame_scope_list%u_%u", lvd->nest_depth, bind_indx); + tree child_scopes_union_name = get_fn_local_identifier ( + lvd->orig, child_scopes_union_name_suffix); + free (child_scopes_union_name_suffix); + tree child_scopes_union + = xref_tag (union_type, child_scopes_union_name); + DECL_CONTEXT (TYPE_NAME (child_scopes_union)) = current_scope (); + child_scopes_union = begin_class_definition (child_scopes_union); + TYPE_FIELDS (child_scopes_union) = child_scopes; + TYPE_BINFO (child_scopes_union) = make_tree_binfo (0); + BINFO_OFFSET (TYPE_BINFO (child_scopes_union)) = size_zero_node; + BINFO_TYPE (TYPE_BINFO (child_scopes_union)) = child_scopes_union; + child_scopes_union = finish_struct (child_scopes_union, NULL_TREE); + + /* Add it to the current scope fields. */ + coro_make_frame_entry_id ( + &scope_variables, child_scopes_field_id, + child_scopes_union, lvd->loc); + } + + if (lvd->nest_depth == 0) + { + /* The outermost scope contains special variables, embed them directly + in the coroutine frame without nesting. */ + *lvd->field_list = scope_variables; + } else + { + /* Create a struct for housing the vars of this bind-expr + in the coroutine frame. */ + char *scope_struct_name_suffix + = xasprintf ("Frame_scope%u_%u", lvd->nest_depth, bind_indx); + tree scope_struct_name + = get_fn_local_identifier (lvd->orig, scope_struct_name_suffix); + free (scope_struct_name_suffix); + tree scope_struct = xref_tag (record_type, scope_struct_name); + DECL_CONTEXT (TYPE_NAME (scope_struct)) = current_scope (); + scope_struct = begin_class_definition (scope_struct); + TYPE_FIELDS (scope_struct) = scope_variables; + TYPE_BINFO (scope_struct) = make_tree_binfo (0); + BINFO_OFFSET (TYPE_BINFO (scope_struct)) = size_zero_node; + BINFO_TYPE (TYPE_BINFO (scope_struct)) = scope_struct; + scope_struct = finish_struct (scope_struct, NULL_TREE); + + /* Add the scope struct to the parent field list. */ + coro_make_frame_entry_id (parent_field_list, scope_field_id, + scope_struct, + lvd->loc); + + lvd->field_access_path->pop (); + } } return NULL_TREE; } @@ -4487,7 +4612,8 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer) would expect to delete unused entries later. */ hash_map<tree, local_var_info> local_var_uses; local_vars_frame_data local_vars_data - = {&field_list, &local_var_uses, 0, 0, fn_start, false, false}; + = {&field_list, &local_var_uses, 0, 0, fn_start, false, false, orig, + make_tree_vector ()}; cp_walk_tree (&fnbody, register_local_var_uses, &local_vars_data, NULL); /* Tie off the struct for now, so that we can build offsets to the diff --git a/gcc/testsuite/g++.dg/coroutines/pr105989.C b/gcc/testsuite/g++.dg/coroutines/pr105989.C new file mode 100644 index 00000000000..c8b9be634aa --- /dev/null +++ b/gcc/testsuite/g++.dg/coroutines/pr105989.C @@ -0,0 +1,124 @@ +// { dg-do run } + +#include <cstddef> + +#include "coro.h" + +struct promise; + +struct task +{ + coro::coroutine_handle<promise> handle; + + ~task () + { + if (handle) + { + handle.destroy (); + } + } +}; + +std::size_t frame_size = 0u; + +struct promise +{ + coro::coroutine_handle<> continuation = coro::noop_coroutine (); + + auto get_return_object () noexcept + { + return task{coro::coroutine_handle<promise>::from_promise (*this)}; + } + + void unhandled_exception () noexcept {} + + void return_void () {} + + auto initial_suspend () noexcept { return coro::suspend_always{}; } + + auto final_suspend () noexcept + { + struct awaiter_type : coro::suspend_always + { + auto await_suspend (coro::coroutine_handle <promise> handle) noexcept + { + return handle.promise ().continuation; + } + }; + + return awaiter_type{}; + } + + void * operator new (std::size_t size) + { + frame_size = size; + return new std::byte[size]; + } + + void operator delete (void *ptr, std::size_t size) + { + return delete[] static_cast<std::byte *>(ptr); + } +}; + +auto operator co_await (task &&t) +{ + struct awaiter_type : coro::suspend_always + { + coro::coroutine_handle<promise> handle; + + auto await_suspend (coro::coroutine_handle<promise> continuation) + { + handle.promise ().continuation = continuation; + return handle; + } + }; + + return awaiter_type{{}, t.handle}; +} + +template<typename... Args> +struct coro::coroutine_traits<task, Args...> +{ + using promise_type = promise; +}; + +auto coro_3 () -> task +{ + co_return; +} + +std::byte *arr_ptr = nullptr; + +task coro_2 () +{ + { + std::byte arr[256]; + co_await coro_3 (); + arr_ptr = arr; + } + { + std::byte arr[256]; + co_await coro_3 (); + arr_ptr = arr; + } +} + +task coro_1 () +{ + std::byte arr[256]; + co_await coro_3 (); + arr_ptr = arr; +} + +int main () +{ + coro_1 (); + auto first_frame_size = frame_size; + coro_2 (); + auto second_frame_size = frame_size; + + /* coro_1 frame should be the same size as coro_2 frame. */ + + return first_frame_size == second_frame_size ? 0 : 1; +}
