This all started with Stuart Hastings' original decloning patch way back
in 2002:
http://gcc.gnu.org/ml/gcc-patches/2002-08/msg00354.html
Bill Maddox tried to revive it in 2007:
http://gcc.gnu.org/ml/gcc-patches/2007-11/msg01147.html
I'm embarrassed that it has taken so long to get this in. The main
source of concern in the past was ABI issues. But now that we have
COMDAT groups and precedent for putting multiple [cd]tors into the same
group for aliasing, I see a solution: make the unified 'tor internal to
the comdat, so the ABI of the comdat is no different from the cloned case.
I had to change various things in cgraph/ipa in order to support the
notion of a comdat-local symbol which can only be referenced from within
that comdat, which is what I'm looking for feedback/approval for. The
change to can_refer_decl_in_current_unit_p is not actually necessary,
but seemed worth adding for possible future use of this functionality.
When decloning is turned on it is done regardless of the size of the
'tor; we don't need to consider the size because the inliner will clean
everything up for us. If the unified function is small enough to inline
into the thunks, it will do so and then the thunks can themselves be
inlined into their callers; otherwise, inlining of the thunks is prevented.
The patch enables decloning with -Os, or in the rare case when cloning
breaks semantics (i.e. in the presence of the GNU label address
extension, as in the testcase).
OK for trunk?
commit 631d568491a3f4581e7067885a07a6096d06bf02
Author: Jason Merrill <ja...@redhat.com>
Date: Thu Jan 12 14:04:42 2012 -0500
PR c++/41090
Add -fdeclone-ctor-dtor.
gcc/cp/
* optimize.c (can_alias_cdtor, populate_clone_array): Split out
from maybe_clone_body.
(maybe_thunk_body): New function.
(maybe_clone_body): Call it.
* mangle.c (write_mangled_name): Remove code to suppress
writing of mangled name for cloned constructor or destructor.
(write_special_name_constructor): Handle decloned constructor.
(write_special_name_destructor): Handle decloned destructor.
* method.c (trivial_fn_p): Handle decloning.
* semantics.c (expand_or_defer_fn_1): Clone after setting linkage.
gcc/c-family/
* c-common.c, c-common.h (flag_declone_ctor_dtor): New variable.
* c.opt: Add -fdeclone-ctor-dtor.
* c-opts.c (c_common_handle_option): Likewise.
(c_common_post_options): Default to on iff -Os.
gcc/
* cgraph.h (comdat_local_p): New.
* cgraph.c (verify_cgraph_node): Make sure we don't call a
comdat-local function from outside its comdat.
* gimple-fold.c (can_refer_decl_in_current_unit_p): Check
references to comdat-local symbols.
* ipa-cp.c (decide_about_value): Don't clone comdat-local fns.
* ipa-inline.c (calls_comdat_local_p): New.
(can_inline_edge_p): Check it.
* ipa.c (symtab_remove_unreachable_nodes): Ignore comdat-local
symbols when marking everything in the group as reachable.
(function_and_variable_visibility): Handle comdat-local fns.
include/
* demangle.h (enum gnu_v3_ctor_kinds):
Added literal gnu_v3_unified_ctor.
(enum gnu_v3_ctor_kinds):
Added literal gnu_v3_unified_dtor.
libiberty/
* cp-demangle.c (cplus_demangle_fill_ctor,cplus_demangle_fill_dtor):
Handle unified ctor/dtor.
(d_ctor_dtor_name): Handle unified ctor/dtor.
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 97f33c1..ab0fca0 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -259,6 +259,12 @@ enum cxx_dialect cxx_dialect = cxx98;
int max_tinst_depth = 900;
+/* For positive value, generate thunks to share a common constructor or
+ destructor body. Otherwise, the code is replicated in the complete and
+ base-class variants of the ctor/dtor. */
+
+int flag_declone_ctor_dtor = -1;
+
/* The elements of `ridpointers' are identifier nodes for the reserved
type names and storage classes. It is indexed by a RID_... value. */
tree *ridpointers;
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 664e928..6721146 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -666,6 +666,12 @@ extern int c_inhibit_evaluation_warnings;
extern bool done_lexing;
+/* For nonzero value, generate thunks to share a common constructor or
+ destructor body. Otherwise, the code is replicated in the complete and
+ base-class variants of the ctor/dtor. */
+
+extern int flag_declone_ctor_dtor;
+
/* C types are partitioned into three subsets: object, function, and
incomplete types. */
#define C_TYPE_OBJECT_P(type) \
diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c
index f368cab..3e3b609 100644
--- a/gcc/c-family/c-opts.c
+++ b/gcc/c-family/c-opts.c
@@ -496,6 +496,10 @@ c_common_handle_option (size_t scode, const char *arg, int value,
constant_string_class_name = arg;
break;
+ case OPT_fdeclone_ctor_dtor:
+ flag_declone_ctor_dtor = value;
+ break;
+
case OPT_fextended_identifiers:
cpp_opts->extended_identifiers = value;
break;
@@ -899,6 +903,10 @@ c_common_post_options (const char **pfilename)
if (warn_implicit_function_declaration == -1)
warn_implicit_function_declaration = flag_isoc99;
+ /* Declone C++ 'structors if -Os. */
+ if (flag_declone_ctor_dtor == -1)
+ flag_declone_ctor_dtor = optimize_size;
+
if (cxx_dialect >= cxx11)
{
/* If we're allowing C++0x constructs, don't warn about C++98
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index ac67885..0154312 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -891,6 +891,10 @@ fdeduce-init-list
C++ ObjC++ Var(flag_deduce_init_list) Init(0)
-fdeduce-init-list enable deduction of std::initializer_list for a template type parameter from a brace-enclosed initializer-list
+fdeclone-ctor-dtor
+C++ ObjC++ UInteger
+Factor complex constructors and destructors to favor space over speed
+
fdefault-inline
C++ ObjC++ Ignore
Does nothing. Preserved for backward compatibility.
diff --git a/gcc/cgraph.c b/gcc/cgraph.c
index 009a165..0854b95 100644
--- a/gcc/cgraph.c
+++ b/gcc/cgraph.c
@@ -2664,10 +2664,20 @@ verify_cgraph_node (struct cgraph_node *node)
error_found = true;
}
}
+ tree required_group = NULL_TREE;
+ if (comdat_local_p (node))
+ required_group = DECL_COMDAT_GROUP (node->decl);
for (e = node->callers; e; e = e->next_caller)
{
if (verify_edge_count_and_frequency (e))
error_found = true;
+ if (required_group
+ && DECL_COMDAT_GROUP (e->caller->decl) != required_group)
+ {
+ error ("comdat-local function called by %s outside its comdat",
+ identifier_to_locale (e->caller->name ()));
+ error_found = true;
+ }
if (!e->inline_failed)
{
if (node->global.inlined_to
diff --git a/gcc/cgraph.h b/gcc/cgraph.h
index 15719fb..b791811 100644
--- a/gcc/cgraph.h
+++ b/gcc/cgraph.h
@@ -1390,4 +1390,14 @@ symtab_can_be_discarded (symtab_node *node)
&& node->resolution != LDPR_PREVAILING_DEF_IRONLY
&& node->resolution != LDPR_PREVAILING_DEF_IRONLY_EXP));
}
+
+/* Return true if NODE is local to a particular COMDAT group, and must not
+ be named from outside the COMDAT. This is used for C++ decloned
+ constructors. */
+
+static inline bool
+comdat_local_p (symtab_node *node)
+{
+ return (node->same_comdat_group && !TREE_PUBLIC (node->decl));
+}
#endif /* GCC_CGRAPH_H */
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 500c81f..cc1f8c3 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -10154,7 +10154,9 @@ grokdeclarator (const cp_declarator *declarator,
/* The TYPE_DECL is "abstract" because there will be
clones of this constructor/destructor, and there will
be copies of this TYPE_DECL generated in those
- clones. */
+ clones. The decloning optimization (for space) may
+ revert this subsequently if it determines that
+ the clones should share a common implementation. */
DECL_ABSTRACT (decl) = 1;
}
else if (current_class_type
diff --git a/gcc/cp/mangle.c b/gcc/cp/mangle.c
index 8a24d6c..d99062d 100644
--- a/gcc/cp/mangle.c
+++ b/gcc/cp/mangle.c
@@ -689,13 +689,6 @@ write_mangled_name (const tree decl, bool top_level)
mangled_name:;
write_string ("_Z");
write_encoding (decl);
- if (DECL_LANG_SPECIFIC (decl)
- && (DECL_MAYBE_IN_CHARGE_DESTRUCTOR_P (decl)
- || DECL_MAYBE_IN_CHARGE_CONSTRUCTOR_P (decl)))
- /* We need a distinct mangled name for these entities, but
- we should never actually output it. So, we append some
- characters the assembler won't like. */
- write_string (" *INTERNAL* ");
}
}
@@ -1653,25 +1646,21 @@ write_identifier (const char *identifier)
::= C2 # base object constructor
::= C3 # complete object allocating constructor
- Currently, allocating constructors are never used.
-
- We also need to provide mangled names for the maybe-in-charge
- constructor, so we treat it here too. mangle_decl_string will
- append *INTERNAL* to that, to make sure we never emit it. */
+ Currently, allocating constructors are never used. */
static void
write_special_name_constructor (const tree ctor)
{
if (DECL_BASE_CONSTRUCTOR_P (ctor))
write_string ("C2");
+ /* This is the old-style "[unified]" constructor.
+ In some cases, we may emit this function and call
+ it from the clones in order to share code and save space. */
+ else if (DECL_MAYBE_IN_CHARGE_CONSTRUCTOR_P (ctor))
+ write_string ("C4");
else
{
- gcc_assert (DECL_COMPLETE_CONSTRUCTOR_P (ctor)
- /* Even though we don't ever emit a definition of
- the old-style destructor, we still have to
- consider entities (like static variables) nested
- inside it. */
- || DECL_MAYBE_IN_CHARGE_CONSTRUCTOR_P (ctor));
+ gcc_assert (DECL_COMPLETE_CONSTRUCTOR_P (ctor));
write_string ("C1");
}
}
@@ -1681,11 +1670,7 @@ write_special_name_constructor (const tree ctor)
<special-name> ::= D0 # deleting (in-charge) destructor
::= D1 # complete object (in-charge) destructor
- ::= D2 # base object (not-in-charge) destructor
-
- We also need to provide mangled names for the maybe-incharge
- destructor, so we treat it here too. mangle_decl_string will
- append *INTERNAL* to that, to make sure we never emit it. */
+ ::= D2 # base object (not-in-charge) destructor */
static void
write_special_name_destructor (const tree dtor)
@@ -1694,14 +1679,14 @@ write_special_name_destructor (const tree dtor)
write_string ("D0");
else if (DECL_BASE_DESTRUCTOR_P (dtor))
write_string ("D2");
+ else if (DECL_MAYBE_IN_CHARGE_DESTRUCTOR_P (dtor))
+ /* This is the old-style "[unified]" destructor.
+ In some cases, we may emit this function and call
+ it from the clones in order to share code and save space. */
+ write_string ("D4");
else
{
- gcc_assert (DECL_COMPLETE_DESTRUCTOR_P (dtor)
- /* Even though we don't ever emit a definition of
- the old-style destructor, we still have to
- consider entities (like static variables) nested
- inside it. */
- || DECL_MAYBE_IN_CHARGE_DESTRUCTOR_P (dtor));
+ gcc_assert (DECL_COMPLETE_DESTRUCTOR_P (dtor));
write_string ("D1");
}
}
diff --git a/gcc/cp/method.c b/gcc/cp/method.c
index 7405365..e79a922 100644
--- a/gcc/cp/method.c
+++ b/gcc/cp/method.c
@@ -477,7 +477,8 @@ trivial_fn_p (tree fn)
return false;
/* If fn is a clone, get the primary variant. */
- fn = DECL_ORIGIN (fn);
+ if (tree prim = DECL_CLONED_FUNCTION (fn))
+ fn = prim;
return type_has_trivial_fn (DECL_CONTEXT (fn), special_function_p (fn));
}
diff --git a/gcc/cp/optimize.c b/gcc/cp/optimize.c
index b8df134..c7480ef 100644
--- a/gcc/cp/optimize.c
+++ b/gcc/cp/optimize.c
@@ -193,30 +193,40 @@ cdtor_comdat_group (tree complete, tree base)
return get_identifier (grp_name);
}
-/* FN is a function that has a complete body. Clone the body as
- necessary. Returns nonzero if there's no longer any need to
- process the main body. */
+/* Returns true iff we can make the base and complete [cd]tor aliases of
+ the same symbol rather than separate functions. */
-bool
-maybe_clone_body (tree fn)
+static bool
+can_alias_cdtor (tree fn)
+{
+#ifndef ASM_OUTPUT_DEF
+ /* If aliases aren't supported by the assembler, fail. */
+ return false;
+#endif
+ /* We can't use an alias if there are virtual bases. */
+ if (CLASSTYPE_VBASECLASSES (DECL_CONTEXT (fn)))
+ return false;
+ /* ??? Why not use aliases with -frepo? */
+ if (flag_use_repository)
+ return false;
+ gcc_assert (DECL_MAYBE_IN_CHARGE_CONSTRUCTOR_P (fn)
+ || DECL_MAYBE_IN_CHARGE_DESTRUCTOR_P (fn));
+ /* Don't use aliases for weak/linkonce definitions unless we can put both
+ symbols in the same COMDAT group. */
+ return (DECL_INTERFACE_KNOWN (fn)
+ && (SUPPORTS_ONE_ONLY || !DECL_WEAK (fn))
+ && (!DECL_ONE_ONLY (fn)
+ || (HAVE_COMDAT_GROUP && DECL_WEAK (fn))));
+}
+
+/* FN is a [cd]tor, fns is a pointer to an array of length 3. Fill fns
+ with pointers to the base, complete, and deleting variants. */
+
+static void
+populate_clone_array (tree fn, tree *fns)
{
- tree comdat_group = NULL_TREE;
tree clone;
- tree fns[3];
- bool first = true;
- bool in_charge_parm_used;
- int idx;
- bool need_alias = false;
- /* We only clone constructors and destructors. */
- if (!DECL_MAYBE_IN_CHARGE_CONSTRUCTOR_P (fn)
- && !DECL_MAYBE_IN_CHARGE_DESTRUCTOR_P (fn))
- return 0;
-
- /* Emit the DWARF1 abstract instance. */
- (*debug_hooks->deferred_inline_function) (fn);
-
- in_charge_parm_used = CLASSTYPE_VBASECLASSES (DECL_CONTEXT (fn)) != NULL;
fns[0] = NULL_TREE;
fns[1] = NULL_TREE;
fns[2] = NULL_TREE;
@@ -234,6 +244,206 @@ maybe_clone_body (tree fn)
fns[2] = clone;
else
gcc_unreachable ();
+}
+
+/* FN is a constructor or destructor, and there are FUNCTION_DECLs
+ cloned from it nearby. Instead of cloning this body, leave it
+ alone and create tiny one-call bodies for the cloned
+ FUNCTION_DECLs. These clones are sibcall candidates, and their
+ resulting code will be very thunk-esque. */
+
+static bool
+maybe_thunk_body (tree fn, bool force)
+{
+ tree bind, block, call, clone, clone_result, fn_parm, fn_parm_typelist;
+ tree last_arg, modify, *args;
+ int parmno, vtt_parmno, max_parms;
+ tree fns[3];
+
+ if (!force && !flag_declone_ctor_dtor)
+ return 0;
+
+ /* If function accepts variable arguments, give up. */
+ last_arg = tree_last (TYPE_ARG_TYPES (TREE_TYPE (fn)));
+ if (last_arg != void_list_node)
+ return 0;
+
+ /* If we got this far, we've decided to turn the clones into thunks. */
+
+ /* We're going to generate code for fn, so it is no longer "abstract."
+ Also make the unified ctor/dtor private to either the translation unit
+ (for non-vague linkage ctors) or the COMDAT group (otherwise). */
+
+ populate_clone_array (fn, fns);
+ DECL_ABSTRACT (fn) = false;
+ if (!DECL_WEAK (fn))
+ {
+ TREE_PUBLIC (fn) = false;
+ DECL_EXTERNAL (fn) = false;
+ DECL_INTERFACE_KNOWN (fn) = true;
+ }
+ else if (HAVE_COMDAT_GROUP)
+ {
+ tree comdat_group = cdtor_comdat_group (fns[1], fns[0]);
+ DECL_COMDAT_GROUP (fns[0]) = comdat_group;
+ symtab_add_to_same_comdat_group (cgraph_get_create_node (fns[1]),
+ cgraph_get_create_node (fns[0]));
+ symtab_add_to_same_comdat_group (symtab_get_node (fn),
+ symtab_get_node (fns[0]));
+ if (fns[2])
+ /* If *[CD][12]* dtors go into the *[CD]5* comdat group and dtor is
+ virtual, it goes into the same comdat group as well. */
+ symtab_add_to_same_comdat_group (cgraph_get_create_node (fns[2]),
+ symtab_get_node (fns[0]));
+ TREE_PUBLIC (fn) = false;
+ DECL_EXTERNAL (fn) = false;
+ DECL_INTERFACE_KNOWN (fn) = true;
+ /* function_and_variable_visibility doesn't want !PUBLIC decls to
+ have these flags set. */
+ DECL_WEAK (fn) = false;
+ DECL_COMDAT (fn) = false;
+ }
+
+ /* Find the vtt_parm, if present. */
+ for (vtt_parmno = -1, parmno = 0, fn_parm = DECL_ARGUMENTS (fn);
+ fn_parm;
+ ++parmno, fn_parm = TREE_CHAIN (fn_parm))
+ {
+ if (DECL_ARTIFICIAL (fn_parm)
+ && DECL_NAME (fn_parm) == vtt_parm_identifier)
+ {
+ /* Compensate for removed in_charge parameter. */
+ vtt_parmno = parmno;
+ break;
+ }
+ }
+
+ /* Allocate an argument buffer for build_cxx_call().
+ Make sure it is large enough for any of the clones. */
+ max_parms = 0;
+ FOR_EACH_CLONE (clone, fn)
+ {
+ int length = list_length (DECL_ARGUMENTS (fn));
+ if (length > max_parms)
+ max_parms = length;
+ }
+ args = (tree *) alloca (max_parms * sizeof (tree));
+
+ /* We know that any clones immediately follow FN in TYPE_METHODS. */
+ FOR_EACH_CLONE (clone, fn)
+ {
+ tree clone_parm;
+
+ /* If we've already generated a body for this clone, avoid
+ duplicating it. (Is it possible for a clone-list to grow after we
+ first see it?) */
+ if (DECL_SAVED_TREE (clone) || TREE_ASM_WRITTEN (clone))
+ continue;
+
+ /* Start processing the function. */
+ start_preparsed_function (clone, NULL_TREE, SF_PRE_PARSED);
+
+ if (clone == fns[2])
+ {
+ for (clone_parm = DECL_ARGUMENTS (clone); clone_parm;
+ clone_parm = TREE_CHAIN (clone_parm))
+ DECL_ABSTRACT_ORIGIN (clone_parm) = NULL_TREE;
+ /* Build the delete destructor by calling complete destructor and
+ delete function. */
+ build_delete_destructor_body (clone, fns[1]);
+ }
+ else
+ {
+ /* Walk parameter lists together, creating parameter list for
+ call to original function. */
+ for (parmno = 0,
+ fn_parm = DECL_ARGUMENTS (fn),
+ fn_parm_typelist = TYPE_ARG_TYPES (TREE_TYPE (fn)),
+ clone_parm = DECL_ARGUMENTS (clone);
+ fn_parm;
+ ++parmno,
+ fn_parm = TREE_CHAIN (fn_parm))
+ {
+ if (parmno == vtt_parmno && ! DECL_HAS_VTT_PARM_P (clone))
+ {
+ gcc_assert (fn_parm_typelist);
+ /* Clobber argument with formal parameter type. */
+ args[parmno]
+ = convert (TREE_VALUE (fn_parm_typelist),
+ null_pointer_node);
+ }
+ else if (parmno == 1 && DECL_HAS_IN_CHARGE_PARM_P (fn))
+ {
+ tree in_charge
+ = copy_node (in_charge_arg_for_name (DECL_NAME (clone)));
+ args[parmno] = in_charge;
+ }
+ /* Map other parameters to their equivalents in the cloned
+ function. */
+ else
+ {
+ gcc_assert (clone_parm);
+ DECL_ABSTRACT_ORIGIN (clone_parm) = NULL;
+ args[parmno] = clone_parm;
+ clone_parm = TREE_CHAIN (clone_parm);
+ }
+ if (fn_parm_typelist)
+ fn_parm_typelist = TREE_CHAIN (fn_parm_typelist);
+ }
+
+ /* We built this list backwards; fix now. */
+ mark_used (fn);
+ call = build_cxx_call (fn, parmno, args, tf_warning_or_error);
+ /* Arguments passed to the thunk by invisible reference should
+ be transmitted to the callee unchanged. Do not create a
+ temporary and invoke the copy constructor. The thunking
+ transformation must not introduce any constructor calls. */
+ CALL_FROM_THUNK_P (call) = 1;
+ block = make_node (BLOCK);
+ if (targetm.cxx.cdtor_returns_this ())
+ {
+ clone_result = DECL_RESULT (clone);
+ modify = build2 (MODIFY_EXPR, TREE_TYPE (clone_result),
+ clone_result, call);
+ add_stmt (modify);
+ BLOCK_VARS (block) = clone_result;
+ }
+ else
+ {
+ add_stmt (call);
+ }
+ bind = c_build_bind_expr (DECL_SOURCE_LOCATION (clone),
+ block, cur_stmt_list);
+ DECL_SAVED_TREE (clone) = push_stmt_list ();
+ add_stmt (bind);
+ }
+
+ DECL_ABSTRACT_ORIGIN (clone) = NULL;
+ expand_or_defer_fn (finish_function (0));
+ }
+ return 1;
+}
+
+/* FN is a function that has a complete body. Clone the body as
+ necessary. Returns nonzero if there's no longer any need to
+ process the main body. */
+
+bool
+maybe_clone_body (tree fn)
+{
+ tree comdat_group = NULL_TREE;
+ tree clone;
+ tree fns[3];
+ bool first = true;
+ int idx;
+ bool need_alias = false;
+
+ /* We only clone constructors and destructors. */
+ if (!DECL_MAYBE_IN_CHARGE_CONSTRUCTOR_P (fn)
+ && !DECL_MAYBE_IN_CHARGE_DESTRUCTOR_P (fn))
+ return 0;
+
+ populate_clone_array (fn, fns);
/* Remember if we can't have multiple clones for some reason. We need to
check this before we remap local static initializers in clone_body. */
@@ -247,9 +457,6 @@ maybe_clone_body (tree fn)
{
tree parm;
tree clone_parm;
- int parmno;
- bool alias = false;
- struct pointer_map_t *decl_map;
clone = fns[idx];
if (!clone)
@@ -296,26 +503,44 @@ maybe_clone_body (tree fn)
parm = DECL_CHAIN (parm), clone_parm = DECL_CHAIN (clone_parm))
/* Update this parameter. */
update_cloned_parm (parm, clone_parm, first);
+ }
+
+ bool can_alias = can_alias_cdtor (fn);
+
+ /* If we decide to turn clones into thunks, they will branch to fn.
+ Must have original function available to call. */
+ if (!can_alias && maybe_thunk_body (fn, need_alias))
+ {
+ pop_from_top_level ();
+ /* We still need to emit the original function. */
+ return 0;
+ }
+
+ /* Emit the DWARF1 abstract instance. */
+ (*debug_hooks->deferred_inline_function) (fn);
+
+ /* We know that any clones immediately follow FN in the TYPE_METHODS list. */
+ for (idx = 0; idx < 3; idx++)
+ {
+ tree parm;
+ tree clone_parm;
+ int parmno;
+ struct pointer_map_t *decl_map;
+ bool alias = false;
+
+ clone = fns[idx];
+ if (!clone)
+ continue;
/* Start processing the function. */
start_preparsed_function (clone, NULL_TREE, SF_PRE_PARSED);
/* Tell cgraph if both ctors or both dtors are known to have
the same body. */
- if (!in_charge_parm_used
+ if (can_alias
&& fns[0]
&& idx == 1
- && !flag_use_repository
- && DECL_INTERFACE_KNOWN (fns[0])
- && (SUPPORTS_ONE_ONLY || !DECL_WEAK (fns[0]))
- && (!DECL_ONE_ONLY (fns[0])
- || (HAVE_COMDAT_GROUP
- && DECL_WEAK (fns[0])))
- && !flag_syntax_only
- /* Set linkage flags appropriately before
- cgraph_create_function_alias looks at them. */
- && expand_or_defer_fn_1 (clone)
- && cgraph_same_body_alias (cgraph_get_node (fns[0]),
+ && cgraph_same_body_alias (cgraph_get_create_node (fns[0]),
clone, fns[0]))
{
alias = true;
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 11f7812..56ea393 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -3901,20 +3901,6 @@ expand_or_defer_fn_1 (tree fn)
gcc_assert (DECL_SAVED_TREE (fn));
- /* If this is a constructor or destructor body, we have to clone
- it. */
- if (maybe_clone_body (fn))
- {
- /* We don't want to process FN again, so pretend we've written
- it out, even though we haven't. */
- TREE_ASM_WRITTEN (fn) = 1;
- /* If this is an instantiation of a constexpr function, keep
- DECL_SAVED_TREE for explain_invalid_constexpr_fn. */
- if (!is_instantiation_of_constexpr (fn))
- DECL_SAVED_TREE (fn) = NULL_TREE;
- return false;
- }
-
/* We make a decision about linkage for these functions at the end
of the compilation. Until that point, we do not want the back
end to output them -- but we do want it to see the bodies of
@@ -3962,6 +3948,20 @@ expand_or_defer_fn_1 (tree fn)
}
}
+ /* If this is a constructor or destructor body, we have to clone
+ it. */
+ if (maybe_clone_body (fn))
+ {
+ /* We don't want to process FN again, so pretend we've written
+ it out, even though we haven't. */
+ TREE_ASM_WRITTEN (fn) = 1;
+ /* If this is an instantiation of a constexpr function, keep
+ DECL_SAVED_TREE for explain_invalid_constexpr_fn. */
+ if (!is_instantiation_of_constexpr (fn))
+ DECL_SAVED_TREE (fn) = NULL_TREE;
+ return false;
+ }
+
/* There's no reason to do any of the work here if we're only doing
semantic analysis; this code just generates RTL. */
if (flag_syntax_only)
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 6fc56b9..675ad21 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -7265,6 +7265,18 @@ branch-less equivalents.
Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
+@item -fdeclone-ctor-dtor
+@opindex fdeclone-ctor-dtor
+The C++ ABI requires multiple entry points for constructors and
+destructors: one for a base subobject, one for a complete object, and
+one for a virtual destructor that calls operator delete afterwards.
+For a hierarchy with virtual bases, the base and complete variants are
+clones, which means two copies of the function. With this option, the
+base and complete variants are changed to be thunks that call a common
+implementation.
+
+Enabled by @option{-Os}.
+
@item -fdelete-null-pointer-checks
@opindex fdelete-null-pointer-checks
Assume that programs cannot safely dereference null pointers, and that
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index 91214bc..a57767e 100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -89,6 +89,12 @@ can_refer_decl_in_current_unit_p (tree decl, tree from_decl)
snode = symtab_get_node (decl);
if (!snode)
return false;
+ /* A decl local to a comdat group can only be referenced by other
+ decls in that group. */
+ if (comdat_local_p (snode)
+ && (!from_decl
+ || DECL_COMDAT_GROUP (from_decl) != DECL_COMDAT_GROUP (decl)))
+ return false;
node = dyn_cast <cgraph_node> (snode);
return !node || !node->global.inlined_to;
}
diff --git a/gcc/ipa-cp.c b/gcc/ipa-cp.c
index d0fa8db..96c889e 100644
--- a/gcc/ipa-cp.c
+++ b/gcc/ipa-cp.c
@@ -3318,6 +3318,10 @@ decide_about_value (struct cgraph_node *node, int index, HOST_WIDE_INT offset,
&caller_count))
return false;
+ /* Don't clone decls local to a comdat group. */
+ if (comdat_local_p (node))
+ return false;
+
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, " - considering value ");
diff --git a/gcc/ipa-inline.c b/gcc/ipa-inline.c
index fbb63da..aa49bfe 100644
--- a/gcc/ipa-inline.c
+++ b/gcc/ipa-inline.c
@@ -230,6 +230,25 @@ report_inline_failed_reason (struct cgraph_edge *e)
}
}
+/* True iff NODE calls another function which is local to its comdat
+ (i.e. C++ decloned constructor); in that case, calls to NODE cannot be
+ inlined, as that would cause a reference from outside the comdat to the
+ local symbol. If we inline the call from NODE to the local function,
+ then inlining NODE can succeed. */
+
+static bool
+calls_comdat_local_p (struct cgraph_node *node)
+{
+ if (!node->same_comdat_group)
+ return false;
+ for (struct cgraph_edge *e = node->callees; e; e = e->next_callee)
+ {
+ if (comdat_local_p (e->callee))
+ return true;
+ }
+ return false;
+}
+
/* Decide if we can inline the edge and possibly update
inline_failed reason.
We check whether inlining is possible at all and whether
@@ -237,7 +256,7 @@ report_inline_failed_reason (struct cgraph_edge *e)
if REPORT is true, output reason to the dump file.
- if DISREGARD_LIMITES is true, ignore size limits.*/
+ if DISREGARD_LIMITS is true, ignore size limits.*/
static bool
can_inline_edge_p (struct cgraph_edge *e, bool report,
@@ -267,6 +286,11 @@ can_inline_edge_p (struct cgraph_edge *e, bool report,
e->inline_failed = CIF_BODY_NOT_AVAILABLE;
inlinable = false;
}
+ else if (calls_comdat_local_p (callee))
+ {
+ e->inline_failed = CIF_FUNCTION_NOT_INLINABLE;
+ inlinable = false;
+ }
else if (!inline_summary (callee)->inlinable
|| (caller_cfun && fn_contains_cilk_spawn_p (caller_cfun)))
{
diff --git a/gcc/ipa.c b/gcc/ipa.c
index 3950d4e..ab55388 100644
--- a/gcc/ipa.c
+++ b/gcc/ipa.c
@@ -363,14 +363,17 @@ symtab_remove_unreachable_nodes (bool before_inlining_p, FILE *file)
enqueue_node (origin_node, &first, reachable);
}
/* If any symbol in a comdat group is reachable, force
- all other in the same comdat group to be also reachable. */
+ all externally visible symbols in the same comdat
+ group to be reachable as well. Comdat-local symbols
+ can be discarded if all uses were inlined. */
if (node->same_comdat_group)
{
symtab_node *next;
for (next = node->same_comdat_group;
next != node;
next = next->same_comdat_group)
- if (!pointer_set_insert (reachable, next))
+ if (!comdat_local_p (next)
+ && !pointer_set_insert (reachable, next))
enqueue_node (next, &first, reachable);
}
/* Mark references as reachable. */
@@ -949,6 +952,8 @@ function_and_variable_visibility (bool whole_program)
node->forced_by_abi = false;
}
if (!node->externally_visible
+ /* Don't mess with a function local to a comdat group. */
+ && !comdat_local_p (node)
&& node->definition && !node->weakref
&& !DECL_EXTERNAL (node->decl))
{
diff --git a/gcc/testsuite/g++.dg/ext/label13a.C b/gcc/testsuite/g++.dg/ext/label13a.C
new file mode 100644
index 0000000..3be8e31
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/label13a.C
@@ -0,0 +1,25 @@
+// PR c++/41090
+// { dg-do run }
+// { dg-options "-save-temps" }
+// { dg-final { scan-assembler "_ZN1CC4Ev" } }
+// { dg-final cleanup-saved-temps }
+
+int i;
+struct A { A() {} };
+struct C: virtual A
+{
+ C();
+};
+
+C::C()
+{
+ static void *labelref = &&label;
+ goto *labelref;
+ label: i = 1;
+}
+
+int main()
+{
+ C c;
+ return (i != 1);
+}
diff --git a/include/demangle.h b/include/demangle.h
index 58bf547..bbad71b 100644
--- a/include/demangle.h
+++ b/include/demangle.h
@@ -173,6 +173,10 @@ enum gnu_v3_ctor_kinds {
gnu_v3_complete_object_ctor = 1,
gnu_v3_base_object_ctor,
gnu_v3_complete_object_allocating_ctor,
+ /* These are not part of the V3 ABI. Unified constructors are generated
+ as a speed-for-space optimization when the -fdeclone-ctor-dtor option
+ is used, and are always internal symbols. */
+ gnu_v3_unified_ctor,
gnu_v3_object_ctor_group
};
@@ -188,6 +192,10 @@ enum gnu_v3_dtor_kinds {
gnu_v3_deleting_dtor = 1,
gnu_v3_complete_object_dtor,
gnu_v3_base_object_dtor,
+ /* These are not part of the V3 ABI. Unified destructors are generated
+ as a speed-for-space optimization when the -fdeclone-ctor-dtor option
+ is used, and are always internal symbols. */
+ gnu_v3_unified_dtor,
gnu_v3_object_dtor_group
};
diff --git a/libiberty/cp-demangle.c b/libiberty/cp-demangle.c
index cbe4d8c..8902dd8 100644
--- a/libiberty/cp-demangle.c
+++ b/libiberty/cp-demangle.c
@@ -2081,6 +2081,9 @@ d_ctor_dtor_name (struct d_info *di)
case '3':
kind = gnu_v3_complete_object_allocating_ctor;
break;
+ case '4':
+ kind = gnu_v3_unified_ctor;
+ break;
case '5':
kind = gnu_v3_object_ctor_group;
break;
@@ -2106,6 +2109,10 @@ d_ctor_dtor_name (struct d_info *di)
case '2':
kind = gnu_v3_base_object_dtor;
break;
+ /* digit '3' is not used */
+ case '4':
+ kind = gnu_v3_unified_dtor;
+ break;
case '5':
kind = gnu_v3_object_dtor_group;
break;
