Re: [PATCH v2] IPA: Provide a mechanism to register static DTORs via cxa_atexit.
> sheesh … EWRONGREVISEDPATCH > > > On 5 Nov 2021, at 13:08, Iain Sandoe wrote: > > > > I tried enabling this on x86-64-linux (just for interest) and it seems to > > work > > OK there too - but that testing revealed a thinko that didn’t show with a > > a normal regstrap. > > … now with the correct patch. > > [PATCH v2] IPA: Provide a mechanism to register static DTORs via > cxa_atexit. > > For at least one target (Darwin) the platform convention is to > register static destructors (i.e. __attribute__((destructor))) > with __cxa_atexit rather than placing them into a list that is > run by some other mechanism. > > This patch provides a target hook that allows a target to opt > into this and handling for the process in ipa_cdtor_merge (). > > When the mode is enabled (dtors_from_cxa_atexit is set) we: > > * Generate new CTORs to register static destructors with >__cxa_atexit and add them to the existing list of CTORs; >we then process the revised CTORs list. > > * We sort the DTORs into priority and then TU order, this >means that they are registered in that order with >__cxa_atexit () and therefore will be run in the reverse >order. > > * Likewise, CTORs are sorted into priority and then TU order, >which means that they will run in that order. > > This matches the behavior of using init/fini (or > mod_init_func/mod_term_func) sections. > > Signed-off-by: Iain Sandoe > > gcc/ChangeLog: > > * config/darwin.h (TARGET_DTORS_FROM_CXA_ATEXIT): New. > * doc/tm.texi: Regenerated. > * doc/tm.texi.in: Add TARGET_DTORS_FROM_CXA_ATEXIT hook. > * ipa.c (ipa_discover_variable_flags): > (cgraph_build_static_cdtor_1): Return the built function > decl. > (build_cxa_atexit_decl): New. > (build_dso_handle_decl): New. > (build_cxa_dtor_registrations): New. > (compare_cdtor_tu_order): New. > (build_cxa_atexit_fns): New. > (ipa_cdtor_merge): If dtors_from_cxa_atexit is set, > process the DTORs/CTORs accordingly. > (pass_ipa_cdtor_merge::gate): Also run if > dtors_from_cxa_atexit is set. > * target.def (dtors_from_cxa_atexit): New hook. OK, thanks! Honza
Re: [PATCH v2] IPA: Provide a mechanism to register static DTORs via cxa_atexit.
sheesh … EWRONGREVISEDPATCH
> On 5 Nov 2021, at 13:08, Iain Sandoe wrote:
>
> I tried enabling this on x86-64-linux (just for interest) and it seems to work
> OK there too - but that testing revealed a thinko that didn’t show with a
> a normal regstrap.
… now with the correct patch.
[PATCH v2] IPA: Provide a mechanism to register static DTORs via
cxa_atexit.
For at least one target (Darwin) the platform convention is to
register static destructors (i.e. __attribute__((destructor)))
with __cxa_atexit rather than placing them into a list that is
run by some other mechanism.
This patch provides a target hook that allows a target to opt
into this and handling for the process in ipa_cdtor_merge ().
When the mode is enabled (dtors_from_cxa_atexit is set) we:
* Generate new CTORs to register static destructors with
__cxa_atexit and add them to the existing list of CTORs;
we then process the revised CTORs list.
* We sort the DTORs into priority and then TU order, this
means that they are registered in that order with
__cxa_atexit () and therefore will be run in the reverse
order.
* Likewise, CTORs are sorted into priority and then TU order,
which means that they will run in that order.
This matches the behavior of using init/fini (or
mod_init_func/mod_term_func) sections.
Signed-off-by: Iain Sandoe
gcc/ChangeLog:
* config/darwin.h (TARGET_DTORS_FROM_CXA_ATEXIT): New.
* doc/tm.texi: Regenerated.
* doc/tm.texi.in: Add TARGET_DTORS_FROM_CXA_ATEXIT hook.
* ipa.c (ipa_discover_variable_flags):
(cgraph_build_static_cdtor_1): Return the built function
decl.
(build_cxa_atexit_decl): New.
(build_dso_handle_decl): New.
(build_cxa_dtor_registrations): New.
(compare_cdtor_tu_order): New.
(build_cxa_atexit_fns): New.
(ipa_cdtor_merge): If dtors_from_cxa_atexit is set,
process the DTORs/CTORs accordingly.
(pass_ipa_cdtor_merge::gate): Also run if
dtors_from_cxa_atexit is set.
* target.def (dtors_from_cxa_atexit): New hook.
---
gcc/config/darwin.h | 7 +-
gcc/doc/tm.texi | 8 ++
gcc/doc/tm.texi.in | 2 +
gcc/ipa.c | 200 +++-
gcc/target.def | 10 +++
5 files changed, 222 insertions(+), 5 deletions(-)
diff --git a/gcc/config/darwin.h b/gcc/config/darwin.h
index 27cb3e4bb30..2b19fb7c085 100644
--- a/gcc/config/darwin.h
+++ b/gcc/config/darwin.h
@@ -54,6 +54,11 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If
not, see
#define DO_GLOBAL_DTORS_BODY
+/* Register static destructors to run from __cxa_atexit instead of putting
+ them into a .mod_term_funcs section. */
+
+#define TARGET_DTORS_FROM_CXA_ATEXIT true
+
/* The string value for __SIZE_TYPE__. */
#ifndef SIZE_TYPE
@@ -1160,7 +1165,7 @@ extern void darwin_driver_init (unsigned int *,struct
cl_decoded_option **);
/* The Apple assembler and linker do not support constructor priorities. */
#undef SUPPORTS_INIT_PRIORITY
-#define SUPPORTS_INIT_PRIORITY 0
+#define SUPPORTS_INIT_PRIORITY 1
#undef STACK_CHECK_STATIC_BUILTIN
#define STACK_CHECK_STATIC_BUILTIN 1
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 990152f5b15..0a4df18b825 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -9233,6 +9233,14 @@ collecting constructors and destructors to be run at
startup and exit.
It is false if we must use @command{collect2}.
@end deftypevr
+@deftypevr {Target Hook} bool TARGET_DTORS_FROM_CXA_ATEXIT
+This value is true if the target wants destructors to be queued to be
+run from __cxa_atexit. If this is the case then, for each priority level,
+a new constructor will be entered that registers the destructors for that
+level with __cxa_atexit (and there will be no destructors emitted).
+It is false the method implied by @code{have_ctors_dtors} is used.
+@end deftypevr
+
@deftypefn {Target Hook} void TARGET_ASM_CONSTRUCTOR (rtx @var{symbol}, int
@var{priority})
If defined, a function that outputs assembler code to arrange to call
the function referenced by @var{symbol} at initialization time.
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 193c9bdd853..c733f356fe4 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -6021,6 +6021,8 @@ encountering an @code{init_priority} attribute.
@hook TARGET_HAVE_CTORS_DTORS
+@hook TARGET_DTORS_FROM_CXA_ATEXIT
+
@hook TARGET_ASM_CONSTRUCTOR
@hook TARGET_ASM_DESTRUCTOR
diff --git a/gcc/ipa.c b/gcc/ipa.c
index 4f62ac183ee..325b658b55e 100644
--- a/gcc/ipa.c
+++ b/gcc/ipa.c
@@ -837,7 +837,7 @@ ipa_discover_variable_flags (void)
FINAL specify whether the externally visible name for collect2 should
be produced. */
-static void
+static tree
cgraph_build_static_cdtor_1 (char which, tree body, int priority, bool final,
tree optimization,
tree target)
@
[PATCH v2] IPA: Provide a mechanism to register static DTORs via cxa_atexit.
I tried enabling this on x86-64-linux (just for interest) and it seems to work
OK there too - but that testing revealed a thinko that didn’t show with a
a normal regstrap.
Changes from original post:
1. amended a comment
2. fixed a thinko where I was not allowing for functions declared as
*both* CTOR and DTOR.
For at least one target (Darwin) the platform convention is to
register static destructors (i.e. __attribute__((destructor)))
with __cxa_atexit rather than placing them into a list that is
run by some other mechanism.
This patch provides a target hook that allows a target to opt
into this and handling for the process in ipa_cdtor_merge ().
When the mode is enabled (dtors_from_cxa_atexit is set) we:
* Generate new CTORs to register static destructors with
__cxa_atexit and add them to the existing list of CTORs;
we then process the revised CTORs list.
* We sort the DTORs into priority and then TU order, this
means that they are registered in that order with
__cxa_atexit () and therefore will be run in the reverse
order.
* Likewise, CTORs are sorted into priority and then TU order,
which means that they will run in that order.
This matches the behavior of using init/fini (or
mod_init_func/mod_term_func) sections.
Signed-off-by: Iain Sandoe
gcc/ChangeLog:
* config/darwin.h (TARGET_DTORS_FROM_CXA_ATEXIT): New.
* doc/tm.texi: Regenerated.
* doc/tm.texi.in: Add TARGET_DTORS_FROM_CXA_ATEXIT hook.
* ipa.c (ipa_discover_variable_flags):
(cgraph_build_static_cdtor_1): Return the built function
decl.
(build_cxa_atexit_decl): New.
(build_dso_handle_decl): New.
(build_cxa_dtor_registrations): New.
(compare_cdtor_tu_order): New.
(build_cxa_atexit_fns): New.
(ipa_cdtor_merge): If dtors_from_cxa_atexit is set,
process the DTORs/CTORs accordingly.
(pass_ipa_cdtor_merge::gate): Also run if
dtors_from_cxa_atexit is set.
* target.def (dtors_from_cxa_atexit): New hook.
---
gcc/config/darwin.h | 5 ++
gcc/doc/tm.texi | 8 ++
gcc/doc/tm.texi.in | 2 +
gcc/ipa.c | 201 +++-
gcc/target.def | 10 +++
5 files changed, 222 insertions(+), 4 deletions(-)
diff --git a/gcc/config/darwin.h b/gcc/config/darwin.h
index 27cb3e4bb30..5202903f5b2 100644
--- a/gcc/config/darwin.h
+++ b/gcc/config/darwin.h
@@ -54,6 +54,11 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If
not, see
#define DO_GLOBAL_DTORS_BODY
+/* Register static destructors to run from __cxa_atexit instead of putting
+ them into a .mod_term_funcs section. */
+
+#define TARGET_DTORS_FROM_CXA_ATEXIT true
+
/* The string value for __SIZE_TYPE__. */
#ifndef SIZE_TYPE
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 78a1af1ad4d..6ec1d50b3e4 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -9210,6 +9210,14 @@ collecting constructors and destructors to be run at
startup and exit.
It is false if we must use @command{collect2}.
@end deftypevr
+@deftypevr {Target Hook} bool TARGET_DTORS_FROM_CXA_ATEXIT
+This value is true if the target wants destructors to be queued to be
+run from __cxa_atexit. If this is the case then, for each priority level,
+a new constructor will be entered that registers the destructors for that
+level with __cxa_atexit (and there will be no destructors emitted).
+It is false the method implied by @code{have_ctors_dtors} is used.
+@end deftypevr
+
@deftypefn {Target Hook} void TARGET_ASM_CONSTRUCTOR (rtx @var{symbol}, int
@var{priority})
If defined, a function that outputs assembler code to arrange to call
the function referenced by @var{symbol} at initialization time.
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 4401550989e..2b9960b73d7 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -6015,6 +6015,8 @@ encountering an @code{init_priority} attribute.
@hook TARGET_HAVE_CTORS_DTORS
+@hook TARGET_DTORS_FROM_CXA_ATEXIT
+
@hook TARGET_ASM_CONSTRUCTOR
@hook TARGET_ASM_DESTRUCTOR
diff --git a/gcc/ipa.c b/gcc/ipa.c
index 4f62ac183ee..d234a69b9fe 100644
--- a/gcc/ipa.c
+++ b/gcc/ipa.c
@@ -837,7 +837,7 @@ ipa_discover_variable_flags (void)
FINAL specify whether the externally visible name for collect2 should
be produced. */
-static void
+static tree
cgraph_build_static_cdtor_1 (char which, tree body, int priority, bool final,
tree optimization,
tree target)
@@ -916,6 +916,7 @@ cgraph_build_static_cdtor_1 (char which, tree body, int
priority, bool final,
set_cfun (NULL);
current_function_decl = NULL;
+ return decl;
}
/* Generate and emit a static constructor or destructor. WHICH must
@@ -1022,6 +1023,128 @@ build_cdtor (bool ctor_p, const vec )
}
}
+/* Helper functions for build_cxa_dtor_registrations ().
+ Build a decl for __cxa_atexit (). */
+
+static
