When r12-4038 introduced the global auto_vec save_opt_decoded_options,
it broke compilers configured with --enable-gather-detailed-mem-stats,
due to the memory descriptors getting discarded before the auto_vec was
destroyed. Attached below are two approaches to making this work,
either by using the init_priority attribute, or turning vec_mem_desc
into a singleton function. I prefer the first one, primarily because it
doesn't require auto_vec variables to force immediate allocation. It
relies on a G++ extension, but I figure that's OK for code that is only
exercised with a debugging configure flag.
Thoughts? Either one OK for trunk?
From b12018cb7842a0bab1f5bcf259f73ec17186f4ad Mon Sep 17 00:00:00 2001
From: Jason Merrill <ja...@redhat.com>
Date: Sat, 2 Oct 2021 05:45:02 -0400
Subject: [PATCH 1/2] vec: Fix --enable-gather-detailed-mem-stats
To: gcc-patches@gcc.gnu.org
When r12-4038 introduced the global auto_vec save_opt_decoded_options, it
broke compilers configured with --enable-gather-detailed-mem-stats due to
the memory descriptors getting discarded before the auto_vec was destroyed.
We can fix the ordering of construction/destruction using the init_priority
attribute.
gcc/ChangeLog:
* vec.c (vec_mem_desc): Add init_priority attribute.
---
gcc/vec.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/gcc/vec.c b/gcc/vec.c
index 6d767cc12c1..715460397c6 100644
--- a/gcc/vec.c
+++ b/gcc/vec.c
@@ -111,6 +111,11 @@ public:
};
/* Vector memory description. */
+#if GATHER_STATISTICS
+/* With --enable-gather-detailed-mem-stats, this needs to be constructed before
+ any auto_vec variables. The number 237 is entirely arbitrary. */
+[[gnu::init_priority (237)]]
+#endif
static mem_alloc_description <vec_usage> vec_mem_desc;
/* Account the overhead. */
--
2.27.0
From 7641bceec2cb53e76c57bd70c38f390610bb82b6 Mon Sep 17 00:00:00 2001
From: Jason Merrill <ja...@redhat.com>
Date: Fri, 1 Oct 2021 16:09:57 -0400
Subject: [PATCH 2/2] vec: make vec_mem_desc a singleton function
To: gcc-patches@gcc.gnu.org
When r12-4038 introduced the global auto_vec save_opt_decoded_options, it
broke compilers configured with --enable-gather-detailed-mem-stats due to
the memory descriptors getting discarded before the auto_vec was destroyed.
We can fix the ordering of construction/destruction by turning vec_mem_desc
into a singleton function.
For this to work, the construction of save_opt_decoded_options needs to
allocate immediately, so that allocation calls vec_mem_desc.
gcc/ChangeLog:
* vec.c (vec_mem_desc): Change to function.
(vec_prefix::register_overhead): Adjust.
(vec_prefix::release_overhead): Adjust.
(dump_vec_loc_statistics): Adjust.
* toplev.c (save_opt_decoded_options): Allocate.
---
gcc/toplev.c | 7 ++++++-
gcc/vec.c | 28 +++++++++++++++-------------
2 files changed, 21 insertions(+), 14 deletions(-)
diff --git a/gcc/toplev.c b/gcc/toplev.c
index ec9f998a49b..727a9972dd0 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -122,7 +122,12 @@ struct cl_decoded_option *save_decoded_options;
unsigned int save_decoded_options_count;
/* Vector of saved Optimization decoded command line options. */
-auto_vec<cl_decoded_option> save_opt_decoded_options;
+auto_vec<cl_decoded_option> save_opt_decoded_options
+#if GATHER_STATISTICS
+/* Force allocation so vec_mem_desc is called. */
+(1)
+#endif
+;
/* Used to enable -fvar-tracking, -fweb and -frename-registers according
to optimize in process_options (). */
diff --git a/gcc/vec.c b/gcc/vec.c
index 715460397c6..4858753223c 100644
--- a/gcc/vec.c
+++ b/gcc/vec.c
@@ -110,13 +110,15 @@ public:
size_t m_element_size;
};
-/* Vector memory description. */
-#if GATHER_STATISTICS
-/* With --enable-gather-detailed-mem-stats, this needs to be constructed before
- any auto_vec variables. The number 237 is entirely arbitrary. */
-[[gnu::init_priority (237)]]
-#endif
-static mem_alloc_description <vec_usage> vec_mem_desc;
+/* Vector memory description. This is a singleton function rather than a
+ variable so that the object's [cd]tor are properly ordered relative to any
+ auto_vec variables. */
+static mem_alloc_description <vec_usage> &
+vec_mem_desc ()
+{
+ static mem_alloc_description<vec_usage> m;
+ return m;
+}
/* Account the overhead. */
@@ -124,10 +126,10 @@ void
vec_prefix::register_overhead (void *ptr, size_t elements,
size_t element_size MEM_STAT_DECL)
{
- vec_mem_desc.register_descriptor (ptr, VEC_ORIGIN, false
+ vec_mem_desc ().register_descriptor (ptr, VEC_ORIGIN, false
FINAL_PASS_MEM_STAT);
vec_usage *usage
- = vec_mem_desc.register_instance_overhead (elements * element_size, ptr);
+ = vec_mem_desc ().register_instance_overhead (elements * element_size, ptr);
usage->m_element_size = element_size;
usage->m_items += elements;
if (usage->m_items_peak < usage->m_items)
@@ -140,10 +142,10 @@ void
vec_prefix::release_overhead (void *ptr, size_t size, size_t elements,
bool in_dtor MEM_STAT_DECL)
{
- if (!vec_mem_desc.contains_descriptor_for_instance (ptr))
- vec_mem_desc.register_descriptor (ptr, VEC_ORIGIN,
+ if (!vec_mem_desc ().contains_descriptor_for_instance (ptr))
+ vec_mem_desc ().register_descriptor (ptr, VEC_ORIGIN,
false FINAL_PASS_MEM_STAT);
- vec_usage *usage = vec_mem_desc.release_instance_overhead (ptr, size,
+ vec_usage *usage = vec_mem_desc ().release_instance_overhead (ptr, size,
in_dtor);
usage->m_items -= elements;
}
@@ -178,7 +180,7 @@ vec_prefix::calculate_allocation_1 (unsigned alloc, unsigned desired)
void
dump_vec_loc_statistics (void)
{
- vec_mem_desc.dump (VEC_ORIGIN);
+ vec_mem_desc ().dump (VEC_ORIGIN);
}
#if CHECKING_P
--
2.27.0
