https://gcc.gnu.org/g:86512292270860bbe1dd33cef1ebe041d597462c
commit r15-2730-g86512292270860bbe1dd33cef1ebe041d597462c
Author: Iain Sandoe <i...@sandoe.co.uk>
Date: Wed Jul 31 23:05:49 2024 +0100
c++, coroutines: Simplify separation of the user function body and ramp.
We need to separate the original user-authored function body from the
definition of the ramp function (which is what is called instead).
The function body tree is either in DECL_SAVED_TREE or the first operand
of current_eh_spec_block (for functions with an EH spec).
This version simplifies the process by extracting the second case directly
instead of inspecting the DECL_SAVED_TREE trees to discover it.
gcc/cp/ChangeLog:
* coroutines.cc (split_coroutine_body_from_ramp): New.
(morph_fn_to_coro): Use split_coroutine_body_from_ramp().
* cp-tree.h (use_eh_spec_block): New.
* decl.cc (use_eh_spec_block): Make non-static.
Signed-off-by: Iain Sandoe <i...@sandoe.co.uk>
Diff:
---
gcc/cp/coroutines.cc | 90 ++++++++++++++++++++++++++--------------------------
gcc/cp/cp-tree.h | 1 +
gcc/cp/decl.cc | 2 +-
3 files changed, 47 insertions(+), 46 deletions(-)
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 742f0e505976..145ec4b1d16b 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -4547,6 +4547,43 @@ coro_rewrite_function_body (location_t fn_start, tree
fnbody, tree orig,
return update_body;
}
+/* Extract the body of the function we are going to outline, leaving
+ to original function decl ready to build the ramp. */
+
+static tree
+split_coroutine_body_from_ramp (tree fndecl)
+{
+ tree body;
+ /* Once we've tied off the original user-authored body in fn_body.
+ Start the replacement synthesized ramp body. */
+
+ if (use_eh_spec_block (fndecl))
+ {
+ body = pop_stmt_list (TREE_OPERAND (current_eh_spec_block, 0));
+ TREE_OPERAND (current_eh_spec_block, 0) = push_stmt_list ();
+ }
+ else
+ {
+ body = pop_stmt_list (DECL_SAVED_TREE (fndecl));
+ DECL_SAVED_TREE (fndecl) = push_stmt_list ();
+ }
+
+ /* We can't validly get here with an empty statement list, since there's no
+ way for the FE to decide it's a coroutine in the absence of any code. */
+ gcc_checking_assert (body != NULL_TREE);
+
+ /* If we have an empty or erroneous function body, do not try to transform it
+ since that would potentially wrap errors. */
+ tree body_start = expr_first (body);
+ if (body_start == NULL_TREE || body_start == error_mark_node)
+ {
+ /* Restore the original state. */
+ add_stmt (body);
+ return NULL_TREE;
+ }
+ return body;
+}
+
/* Here we:
a) Check that the function and promise type are valid for a
coroutine.
@@ -4593,57 +4630,22 @@ morph_fn_to_coro (tree orig, tree *resumer, tree
*destroyer)
/* Discard the body, we can't process it further. */
pop_stmt_list (DECL_SAVED_TREE (orig));
DECL_SAVED_TREE (orig) = push_stmt_list ();
+ /* Match the expected nesting when an eh block is in use. */
+ if (use_eh_spec_block (orig))
+ current_eh_spec_block = begin_eh_spec_block ();
return false;
}
- /* We can't validly get here with an empty statement list, since there's no
- way for the FE to decide it's a coroutine in the absence of any code. */
- tree fnbody = pop_stmt_list (DECL_SAVED_TREE (orig));
- gcc_checking_assert (fnbody != NULL_TREE);
-
/* We don't have the locus of the opening brace - it's filled in later (and
there doesn't really seem to be any easy way to get at it).
The closing brace is assumed to be input_location. */
location_t fn_start = DECL_SOURCE_LOCATION (orig);
- gcc_rich_location fn_start_loc (fn_start);
-
- /* Initial processing of the function-body.
- If we have no expressions or just an error then punt. */
- tree body_start = expr_first (fnbody);
- if (body_start == NULL_TREE || body_start == error_mark_node)
- {
- DECL_SAVED_TREE (orig) = push_stmt_list ();
- append_to_statement_list (fnbody, &DECL_SAVED_TREE (orig));
- /* Suppress warnings about the missing return value. */
- suppress_warning (orig, OPT_Wreturn_type);
- return false;
- }
-
- /* So, we've tied off the original user-authored body in fn_body.
-
- Start the replacement synthesized ramp body as newbody.
- If we encounter a fatal error we might return a now-empty body.
-
- Note, the returned ramp body is not 'popped', to be compatible with
- the way that decl.cc handles regular functions, the scope pop is done
- in the caller. */
- tree newbody = push_stmt_list ();
- DECL_SAVED_TREE (orig) = newbody;
-
- /* If our original body is noexcept, then that's what we apply to our
- generated ramp, transfer any MUST_NOT_THOW_EXPR to that. */
- bool is_noexcept = TREE_CODE (body_start) == MUST_NOT_THROW_EXPR;
- if (is_noexcept)
- {
- /* The function body we will continue with is the single operand to
- the must-not-throw. */
- fnbody = TREE_OPERAND (body_start, 0);
- /* Transfer the must-not-throw to the ramp body. */
- add_stmt (body_start);
- /* Re-start the ramp as must-not-throw. */
- TREE_OPERAND (body_start, 0) = push_stmt_list ();
- }
+ /* FIXME: This has the hidden side-effect of preparing the current function
+ to be the ramp. */
+ tree fnbody = split_coroutine_body_from_ramp (orig);
+ if (!fnbody)
+ return false;
/* If the original function has a return value with a non-trivial DTOR
and the body contains a var with a DTOR that might throw, the decl is
@@ -5169,7 +5171,6 @@ morph_fn_to_coro (tree orig, tree *resumer, tree
*destroyer)
if (get_ro == error_mark_node)
{
BIND_EXPR_BODY (ramp_bind) = pop_stmt_list (ramp_body);
- DECL_SAVED_TREE (orig) = newbody;
/* Suppress warnings about the missing return value. */
suppress_warning (orig, OPT_Wreturn_type);
return false;
@@ -5396,7 +5397,6 @@ morph_fn_to_coro (tree orig, tree *resumer, tree
*destroyer)
pop_deferring_access_checks ();
- DECL_SAVED_TREE (orig) = newbody;
/* Link our new functions into the list. */
TREE_CHAIN (destroy) = TREE_CHAIN (orig);
TREE_CHAIN (actor) = destroy;
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 238d786b0674..911d1d7924cc 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7097,6 +7097,7 @@ extern bool check_array_designated_initializer
(constructor_elt *,
unsigned HOST_WIDE_INT);
extern bool check_for_uninitialized_const_var (tree, bool, tsubst_flags_t);
extern tree build_explicit_specifier (tree, tsubst_flags_t);
+extern bool use_eh_spec_block (tree);
extern void do_push_parm_decls (tree, tree, tree *);
extern tree do_aggregate_paren_init (tree, tree);
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 687ae6937f53..641d44b21ea0 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -18303,7 +18303,7 @@ start_function (cp_decl_specifier_seq *declspecs,
/* Returns true iff an EH_SPEC_BLOCK should be created in the body of
FN. */
-static bool
+bool
use_eh_spec_block (tree fn)
{
return (flag_exceptions && flag_enforce_eh_specs
