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[PATCH 5/N] Add new *_atomic counter update function, (-fprofile-update=atomic)
Hello.
This patch is follow-up of the series where I introduce a set of counter update
function that are thread-safe. I originally thought that majority of profile corruptions are
caused by non-atomic updated of CFG (-fprofile-arc). But there are multiple counters that compare
it's count to a number of execution of a basic block:
blake2s.cpp:150:40: error: corrupted value profile: value profile counter (11301120 out of 11314388) inconsistent with basic-block count (11555117)
memcpy( S->buf + left, in, fill ); // Fill buffer
This can be seen for unrar binary: PR58306. I'm also adding a simple test-case which reveals the inconsistency: val-profiler-threads-1.c.
I've been running regression tests, ready to install after it finishes?
Thanks,
Martin
From a55681992f572b0591a24e82715ddc01330230e0 Mon Sep 17 00:00:00 2001
From: marxin <mliska@suse.cz>
Date: Mon, 8 Aug 2016 15:44:28 +0200
Subject: [PATCH 5/5] Add new *_atomic counter update function
(-fprofile-update=atomic)
libgcc/ChangeLog:
2016-08-08 Martin Liska <mliska@suse.cz>
PR gcov-profile/58306
* Makefile.in: New functions (modules) are added.
* libgcov-profiler.c (__gcov_interval_profiler_atomic): New
function.
(__gcov_pow2_profiler_atomic): New function.
(__gcov_one_value_profiler_body): New argument is instroduced.
(__gcov_one_value_profiler): Call with the new argument.
(__gcov_one_value_profiler_atomic): Likewise.
(__gcov_indirect_call_profiler_v2): Likewise.
(__gcov_time_profiler_atomic): New function.
(__gcov_average_profiler_atomic): Likewise.
(__gcov_ior_profiler_atomic): Likewise.
* libgcov.h: Declare the aforementioned functions.
gcc/testsuite/ChangeLog:
2016-08-08 Martin Liska <mliska@suse.cz>
PR gcov-profile/58306
* gcc.dg/tree-prof/val-profiler-threads-1.c: New test.
gcc/ChangeLog:
2016-08-08 Martin Liska <mliska@suse.cz>
PR gcov-profile/58306
* tree-profile.c (gimple_init_edge_profiler): Create conditionally
atomic variants of profile update functions.
---
.../gcc.dg/tree-prof/val-profiler-threads-1.c | 41 +++++++++
gcc/tree-profile.c | 36 ++++----
libgcc/Makefile.in | 15 +++-
libgcc/libgcov-profiler.c | 97 ++++++++++++++++++++--
libgcc/libgcov.h | 10 +++
5 files changed, 173 insertions(+), 26 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-prof/val-profiler-threads-1.c
diff --git a/gcc/testsuite/gcc.dg/tree-prof/val-profiler-threads-1.c b/gcc/testsuite/gcc.dg/tree-prof/val-profiler-threads-1.c
new file mode 100644
index 0000000..0f7477e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-prof/val-profiler-threads-1.c
@@ -0,0 +1,41 @@
+/* { dg-options "-O0 -pthread -fprofile-update=atomic" } */
+#include <pthread.h>
+
+#define NUM_THREADS 8
+#define SIZE 1024
+#define ITERATIONS (1000 * 1000)
+
+char buffer[SIZE];
+char buffer2[SIZE];
+
+void *copy_memory(char *dst, char *src, unsigned size)
+{
+ for (unsigned i = 0; i < ITERATIONS; i++)
+ {
+ dst[size % 10] = src[size % 20];
+ }
+}
+
+void *foo(void *d)
+{
+ copy_memory (buffer, buffer2, SIZE);
+}
+
+int main(int argc, char *argv[])
+{
+ pthread_t threads[NUM_THREADS];
+ int rc;
+ long t;
+ for(t=0;t<NUM_THREADS;t++){
+ rc = pthread_create(&threads[t], NULL, foo, 0);
+ if (rc){
+ return 1;
+ }
+ }
+
+ int retval;
+ for(t=0;t<NUM_THREADS;t++)
+ pthread_join (threads[t], (void**)&retval);
+
+ return buffer[10];
+}
diff --git a/gcc/tree-profile.c b/gcc/tree-profile.c
index 740f7ab..0b29e72 100644
--- a/gcc/tree-profile.c
+++ b/gcc/tree-profile.c
@@ -128,9 +128,13 @@ gimple_init_edge_profiler (void)
tree average_profiler_fn_type;
tree time_profiler_fn_type;
const char *profiler_fn_name;
+ const char *fn_name;
if (!gcov_type_node)
{
+ const char *fn_suffix
+ = flag_profile_update == PROFILE_UPDATE_ATOMIC ? "_atomic" : "";
+
gcov_type_node = get_gcov_type ();
gcov_type_ptr = build_pointer_type (gcov_type_node);
@@ -140,9 +144,9 @@ gimple_init_edge_profiler (void)
gcov_type_ptr, gcov_type_node,
integer_type_node,
unsigned_type_node, NULL_TREE);
- tree_interval_profiler_fn
- = build_fn_decl ("__gcov_interval_profiler",
- interval_profiler_fn_type);
+ fn_name = concat ("__gcov_interval_profiler", fn_suffix, NULL);
+ tree_interval_profiler_fn = build_fn_decl (fn_name,
+ interval_profiler_fn_type);
TREE_NOTHROW (tree_interval_profiler_fn) = 1;
DECL_ATTRIBUTES (tree_interval_profiler_fn)
= tree_cons (get_identifier ("leaf"), NULL,
@@ -153,8 +157,8 @@ gimple_init_edge_profiler (void)
= build_function_type_list (void_type_node,
gcov_type_ptr, gcov_type_node,
NULL_TREE);
- tree_pow2_profiler_fn = build_fn_decl ("__gcov_pow2_profiler",
- pow2_profiler_fn_type);
+ fn_name = concat ("__gcov_pow2_profiler", fn_suffix, NULL);
+ tree_pow2_profiler_fn = build_fn_decl (fn_name, pow2_profiler_fn_type);
TREE_NOTHROW (tree_pow2_profiler_fn) = 1;
DECL_ATTRIBUTES (tree_pow2_profiler_fn)
= tree_cons (get_identifier ("leaf"), NULL,
@@ -165,9 +169,9 @@ gimple_init_edge_profiler (void)
= build_function_type_list (void_type_node,
gcov_type_ptr, gcov_type_node,
NULL_TREE);
- tree_one_value_profiler_fn
- = build_fn_decl ("__gcov_one_value_profiler",
- one_value_profiler_fn_type);
+ fn_name = concat ("__gcov_one_value_profiler", fn_suffix, NULL);
+ tree_one_value_profiler_fn = build_fn_decl (fn_name,
+ one_value_profiler_fn_type);
TREE_NOTHROW (tree_one_value_profiler_fn) = 1;
DECL_ATTRIBUTES (tree_one_value_profiler_fn)
= tree_cons (get_identifier ("leaf"), NULL,
@@ -197,9 +201,8 @@ gimple_init_edge_profiler (void)
time_profiler_fn_type
= build_function_type_list (void_type_node,
gcov_type_ptr, NULL_TREE);
- tree_time_profiler_fn
- = build_fn_decl ("__gcov_time_profiler",
- time_profiler_fn_type);
+ fn_name = concat ("__gcov_time_profiler", fn_suffix, NULL);
+ tree_time_profiler_fn = build_fn_decl (fn_name, time_profiler_fn_type);
TREE_NOTHROW (tree_time_profiler_fn) = 1;
DECL_ATTRIBUTES (tree_time_profiler_fn)
= tree_cons (get_identifier ("leaf"), NULL,
@@ -209,16 +212,15 @@ gimple_init_edge_profiler (void)
average_profiler_fn_type
= build_function_type_list (void_type_node,
gcov_type_ptr, gcov_type_node, NULL_TREE);
- tree_average_profiler_fn
- = build_fn_decl ("__gcov_average_profiler",
- average_profiler_fn_type);
+ fn_name = concat ("__gcov_average_profiler", fn_suffix, NULL);
+ tree_average_profiler_fn = build_fn_decl (fn_name,
+ average_profiler_fn_type);
TREE_NOTHROW (tree_average_profiler_fn) = 1;
DECL_ATTRIBUTES (tree_average_profiler_fn)
= tree_cons (get_identifier ("leaf"), NULL,
DECL_ATTRIBUTES (tree_average_profiler_fn));
- tree_ior_profiler_fn
- = build_fn_decl ("__gcov_ior_profiler",
- average_profiler_fn_type);
+ fn_name = concat ("__gcov_ior_profiler", fn_suffix, NULL);
+ tree_ior_profiler_fn = build_fn_decl (fn_name, average_profiler_fn_type);
TREE_NOTHROW (tree_ior_profiler_fn) = 1;
DECL_ATTRIBUTES (tree_ior_profiler_fn)
= tree_cons (get_identifier ("leaf"), NULL,
diff --git a/libgcc/Makefile.in b/libgcc/Makefile.in
index efaf7f7..f0cbc92 100644
--- a/libgcc/Makefile.in
+++ b/libgcc/Makefile.in
@@ -858,10 +858,19 @@ include $(iterator)
LIBGCOV_MERGE = _gcov_merge_add _gcov_merge_single _gcov_merge_delta \
_gcov_merge_ior _gcov_merge_time_profile _gcov_merge_icall_topn
-LIBGCOV_PROFILER = _gcov_interval_profiler _gcov_pow2_profiler \
+LIBGCOV_PROFILER = _gcov_interval_profiler \
+ _gcov_interval_profiler_atomic \
+ _gcov_pow2_profiler \
+ _gcov_pow2_profiler_atomic \
_gcov_one_value_profiler \
- _gcov_average_profiler _gcov_ior_profiler \
- _gcov_indirect_call_profiler_v2 _gcov_time_profiler \
+ _gcov_one_value_profiler_atomic \
+ _gcov_average_profiler \
+ _gcov_average_profiler_atomic \
+ _gcov_ior_profiler \
+ _gcov_ior_profiler_atomic \
+ _gcov_indirect_call_profiler_v2 \
+ _gcov_time_profiler \
+ _gcov_time_profiler_atomic \
_gcov_indirect_call_topn_profiler
LIBGCOV_INTERFACE = _gcov_dump _gcov_flush _gcov_fork \
_gcov_execl _gcov_execlp \
diff --git a/libgcc/libgcov-profiler.c b/libgcc/libgcov-profiler.c
index 6b4557a..0837ea1 100644
--- a/libgcc/libgcov-profiler.c
+++ b/libgcc/libgcov-profiler.c
@@ -46,6 +46,26 @@ __gcov_interval_profiler (gcov_type *counters, gcov_type value,
}
#endif
+#ifdef L_gcov_interval_profiler_atomic
+/* If VALUE is in interval <START, START + STEPS - 1>, then increases the
+ corresponding counter in COUNTERS. If the VALUE is above or below
+ the interval, COUNTERS[STEPS] or COUNTERS[STEPS + 1] is increased
+ instead. Function is thread-safe. */
+
+void
+__gcov_interval_profiler_atomic (gcov_type *counters, gcov_type value,
+ int start, unsigned steps)
+{
+ gcov_type delta = value - start;
+ if (delta < 0)
+ __atomic_fetch_add (&counters[steps + 1], 1, MEMMODEL_RELAXED);
+ else if (delta >= steps)
+ __atomic_fetch_add (&counters[steps], 1, MEMMODEL_RELAXED);
+ else
+ __atomic_fetch_add (&counters[delta], 1, MEMMODEL_RELAXED);
+}
+#endif
+
#ifdef L_gcov_pow2_profiler
/* If VALUE is a power of two, COUNTERS[1] is incremented. Otherwise
COUNTERS[0] is incremented. */
@@ -60,6 +80,21 @@ __gcov_pow2_profiler (gcov_type *counters, gcov_type value)
}
#endif
+#ifdef L_gcov_pow2_profiler_atomic
+/* If VALUE is a power of two, COUNTERS[1] is incremented. Otherwise
+ COUNTERS[0] is incremented. Function is thread-safe. */
+
+void
+__gcov_pow2_profiler_atomic (gcov_type *counters, gcov_type value)
+{
+ if (value & (value - 1))
+ __atomic_fetch_add (&counters[0], 1, MEMMODEL_RELAXED);
+ else
+ __atomic_fetch_add (&counters[1], 1, MEMMODEL_RELAXED);
+}
+#endif
+
+
/* Tries to determine the most common value among its inputs. Checks if the
value stored in COUNTERS[0] matches VALUE. If this is the case, COUNTERS[1]
is incremented. If this is not the case and COUNTERS[1] is not zero,
@@ -68,10 +103,12 @@ __gcov_pow2_profiler (gcov_type *counters, gcov_type value)
function is called more than 50% of the time with one value, this value
will be in COUNTERS[0] in the end.
- In any case, COUNTERS[2] is incremented. */
+ In any case, COUNTERS[2] is incremented. If USE_ATOMIC is set to 1,
+ COUNTERS[2] is updated with an atomic instruction. */
static inline void
-__gcov_one_value_profiler_body (gcov_type *counters, gcov_type value)
+__gcov_one_value_profiler_body (gcov_type *counters, gcov_type value,
+ int use_atomic)
{
if (value == counters[0])
counters[1]++;
@@ -82,14 +119,26 @@ __gcov_one_value_profiler_body (gcov_type *counters, gcov_type value)
}
else
counters[1]--;
- counters[2]++;
+
+ if (use_atomic)
+ __atomic_fetch_add (&counters[2], 1, MEMMODEL_RELAXED);
+ else
+ counters[2]++;
}
#ifdef L_gcov_one_value_profiler
void
__gcov_one_value_profiler (gcov_type *counters, gcov_type value)
{
- __gcov_one_value_profiler_body (counters, value);
+ __gcov_one_value_profiler_body (counters, value, 0);
+}
+#endif
+
+#ifdef L_gcov_one_value_profiler_atomic
+void
+__gcov_one_value_profiler_atomic (gcov_type *counters, gcov_type value)
+{
+ __gcov_one_value_profiler_body (counters, value, 1);
}
#endif
@@ -265,14 +314,14 @@ __gcov_indirect_call_profiler_v2 (gcov_type value, void* cur_func)
if (cur_func == __gcov_indirect_call_callee
|| (__LIBGCC_VTABLE_USES_DESCRIPTORS__ && __gcov_indirect_call_callee
&& *(void **) cur_func == *(void **) __gcov_indirect_call_callee))
- __gcov_one_value_profiler_body (__gcov_indirect_call_counters, value);
+ __gcov_one_value_profiler_body (__gcov_indirect_call_counters, value, 0);
}
#endif
#ifdef L_gcov_time_profiler
/* Counter for first visit of each function. */
-static gcov_type function_counter;
+gcov_type function_counter;
/* Sets corresponding COUNTERS if there is no value. */
@@ -284,6 +333,19 @@ __gcov_time_profiler (gcov_type* counters)
}
#endif
+/* Sets corresponding COUNTERS if there is no value.
+ Function is thread-safe. */
+
+#ifdef L_gcov_time_profiler_atomic
+void
+__gcov_time_profiler_atomic (gcov_type* counters)
+{
+ if (!counters[0])
+ counters[0] = __atomic_add_fetch (&function_counter, 1, MEMMODEL_RELAXED);
+}
+#endif
+
+
#ifdef L_gcov_average_profiler
/* Increase corresponding COUNTER by VALUE. FIXME: Perhaps we want
to saturate up. */
@@ -296,6 +358,18 @@ __gcov_average_profiler (gcov_type *counters, gcov_type value)
}
#endif
+#ifdef L_gcov_average_profiler_atomic
+/* Increase corresponding COUNTER by VALUE. FIXME: Perhaps we want
+ to saturate up. Function is thread-safe. */
+
+void
+__gcov_average_profiler_atomic (gcov_type *counters, gcov_type value)
+{
+ __atomic_fetch_add (&counters[0], value, MEMMODEL_RELAXED);
+ __atomic_fetch_add (&counters[1], 1, MEMMODEL_RELAXED);
+}
+#endif
+
#ifdef L_gcov_ior_profiler
/* Bitwise-OR VALUE into COUNTER. */
@@ -306,4 +380,15 @@ __gcov_ior_profiler (gcov_type *counters, gcov_type value)
}
#endif
+#ifdef L_gcov_ior_profiler_atomic
+/* Bitwise-OR VALUE into COUNTER. Function is thread-safe. */
+
+void
+__gcov_ior_profiler_atomic (gcov_type *counters, gcov_type value)
+{
+ __atomic_fetch_or (&counters[0], value, MEMMODEL_RELAXED);
+}
+#endif
+
+
#endif /* inhibit_libc */
diff --git a/libgcc/libgcov.h b/libgcc/libgcov.h
index 80f13e2..82f620a 100644
--- a/libgcc/libgcov.h
+++ b/libgcc/libgcov.h
@@ -268,15 +268,25 @@ extern void __gcov_merge_icall_topn (gcov_type *, unsigned) ATTRIBUTE_HIDDEN;
/* The profiler functions. */
extern void __gcov_interval_profiler (gcov_type *, gcov_type, int, unsigned);
+extern void __gcov_interval_profiler_atomic (gcov_type *, gcov_type, int,
+ unsigned);
extern void __gcov_pow2_profiler (gcov_type *, gcov_type);
+extern void __gcov_pow2_profiler_atomic (gcov_type *, gcov_type);
extern void __gcov_one_value_profiler (gcov_type *, gcov_type);
+extern void __gcov_one_value_profiler_atomic (gcov_type *, gcov_type);
extern void __gcov_indirect_call_profiler_v2 (gcov_type, void *);
extern void __gcov_time_profiler (gcov_type *);
+extern void __gcov_time_profiler_atomic (gcov_type *);
extern void __gcov_average_profiler (gcov_type *, gcov_type);
+extern void __gcov_average_profiler_atomic (gcov_type *, gcov_type);
extern void __gcov_ior_profiler (gcov_type *, gcov_type);
+extern void __gcov_ior_profiler_atomic (gcov_type *, gcov_type);
extern void __gcov_indirect_call_topn_profiler (gcov_type, void *);
extern void gcov_sort_n_vals (gcov_type *, int);
+/* Counter for first visit of each function. */
+extern gcov_type function_counter;
+
#ifndef inhibit_libc
/* The wrappers around some library functions.. */
extern pid_t __gcov_fork (void) ATTRIBUTE_HIDDEN;
--
2.9.2