[PATCH] gcov: Add __gcov_info_to_gdca()
Sebastian Huber
sebastian.huber@embedded-brains.de
Tue Nov 17 09:57:41 GMT 2020
This is a proposal to get the gcda data for a gcda info in a free-standing
environment. It is intended to be used with the -fprofile-info-section option.
A crude test program which doesn't use a linker script is:
#include <gcov.h>
#include <stdio.h>
extern const struct gcov_info *my_info;
static void
filename(const char *f, void *arg)
{
printf("filename: %s\n", f);
}
static void
dump(const void *d, unsigned n, void *arg)
{
const unsigned char *c;
unsigned i;
c = d;
for (i = 0; i < n; ++i) {
printf("%02x", c[i]);
}
}
int main()
{
__asm__ volatile (".set my_info, .LPBX2");
__gcov_info_to_gcda(my_info, filename, dump, NULL);
return 0;
}
gcc/
* doc/invoke.texi (fprofile-info-section): Mention
__gcov_info_to_gdca().
libgcc/
Makefile.in (LIBGCOV_DRIVER): Add _gcov_info_to_gcda.
gcov.h (gcov_info): Declare.
(__gcov_info_to_gdca): Likewise.
libgcov-driver.c (gcov_are_all_counters_zero): New.
(write_one_data): Use gcov_are_all_counters_zero().
(gcov_fn_info_to_gcda): New.
(__gcov_info_to_gcda): Likewise.
---
gcc/doc/invoke.texi | 73 ++++++++++++++++++++----
libgcc/Makefile.in | 2 +-
libgcc/gcov.h | 15 +++++
libgcc/libgcov-driver.c | 120 ++++++++++++++++++++++++++++++++++++----
4 files changed, 188 insertions(+), 22 deletions(-)
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 3510a54c6c4..09cb4922f5e 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -14248,17 +14248,17 @@ To optimize the program based on the collected profile information, use
Register the profile information in the specified section instead of using a
constructor/destructor. The section name is @var{name} if it is specified,
otherwise the section name defaults to @code{.gcov_info}. A pointer to the
-profile information generated by @option{-fprofile-arcs} or
-@option{-ftest-coverage} is placed in the specified section for each
-translation unit. This option disables the profile information registration
-through a constructor and it disables the profile information processing
-through a destructor. This option is not intended to be used in hosted
-environments such as GNU/Linux. It targets systems with limited resources
-which do not support constructors and destructors. The linker could collect
-the input sections in a continuous memory block and define start and end
-symbols. The runtime support could dump the profiling information registered
-in this linker set during program termination to a serial line for example. A
-GNU linker script example which defines a linker output section follows:
+profile information generated by @option{-fprofile-arcs} is placed in the
+specified section for each translation unit. This option disables the profile
+information registration through a constructor and it disables the profile
+information processing through a destructor. This option is not intended to be
+used in hosted environments such as GNU/Linux. It targets free-standing
+environments (for example embedded systems) with limited resources which do not
+support constructors/destructors or the C library file I/O.
+
+The linker could collect the input sections in a continuous memory block and
+define start and end symbols. A GNU linker script example which defines a
+linker output section follows:
@smallexample
.gcov_info :
@@ -14269,6 +14269,57 @@ GNU linker script example which defines a linker output section follows:
@}
@end smallexample
+The program could dump the profiling information registered in this linker set
+for example like this:
+
+@smallexample
+#include <gcov.h>
+#include <stdio.h>
+
+extern const struct gcov_info *__gcov_info_start[];
+extern const struct gcov_info *__gcov_info_end[];
+
+static void
+filename (const char *f, void *arg)
+@{
+ puts (f);
+@}
+
+static void
+dump (const void *d, unsigned n, void *arg)
+@{
+ const unsigned char *c = d;
+
+ for (unsigned i = 0; i < n; ++i)
+ printf ("%02x", c[i]);
+@}
+
+static void
+dump_gcov_info (void)
+@{
+ const struct gcov_info **info = __gcov_info_start;
+ const struct gcov_info **end = __gcov_info_end;
+
+ /* Obfuscate variable to prevent compiler optimizations. */
+ __asm__ ("" : "+r" (end));
+
+ while (info != end)
+ @{
+ void *arg = NULL;
+ __gcov_info_to_gcda (*info, filename, dump, arg);
+ putchar ('\n');
+ ++info;
+ @}
+@}
+
+int
+main()
+@{
+ dump_gcov_info();
+ return 0;
+@}
+@end smallexample
+
@item -fprofile-note=@var{path}
@opindex fprofile-note
diff --git a/libgcc/Makefile.in b/libgcc/Makefile.in
index d6075d32bd4..c22413d768c 100644
--- a/libgcc/Makefile.in
+++ b/libgcc/Makefile.in
@@ -908,7 +908,7 @@ LIBGCOV_INTERFACE = _gcov_dump _gcov_fork \
_gcov_execl _gcov_execlp \
_gcov_execle _gcov_execv _gcov_execvp _gcov_execve _gcov_reset \
_gcov_lock_unlock
-LIBGCOV_DRIVER = _gcov
+LIBGCOV_DRIVER = _gcov _gcov_info_to_gcda
libgcov-merge-objects = $(patsubst %,%$(objext),$(LIBGCOV_MERGE))
libgcov-profiler-objects = $(patsubst %,%$(objext),$(LIBGCOV_PROFILER))
diff --git a/libgcc/gcov.h b/libgcc/gcov.h
index 0e3eed31032..371ee6feb11 100644
--- a/libgcc/gcov.h
+++ b/libgcc/gcov.h
@@ -25,6 +25,8 @@
#ifndef GCC_GCOV_H
#define GCC_GCOV_H
+struct gcov_info;
+
/* Set all counters to zero. */
extern void __gcov_reset (void);
@@ -33,4 +35,17 @@ extern void __gcov_reset (void);
extern void __gcov_dump (void);
+/* Convert the gcov information to a gcda data stream. The first callback is
+ called exactly once with the filename associated with the gcov information.
+ The filename may be NULL. Afterwards, the second callback is subsequently
+ called with chunks (the begin and length of the chunk are passed as the
+ first two arguments) of the gcda data stream. The fourth parameter is a
+ user-provided argument passed as the last argument to the callback
+ functions. */
+
+extern void __gcov_info_to_gcda (const struct gcov_info *,
+ void (*) (const char *, void *),
+ void (*) (const void *, unsigned, void *),
+ void *);
+
#endif /* GCC_GCOV_H */
diff --git a/libgcc/libgcov-driver.c b/libgcc/libgcov-driver.c
index e53e4dc392a..4191b89a6f7 100644
--- a/libgcc/libgcov-driver.c
+++ b/libgcc/libgcov-driver.c
@@ -26,6 +26,18 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
#include "libgcov.h"
#include "gcov-io.h"
+/* Return 1, if all counter values are zero, otherwise 0. */
+
+static inline int
+gcov_are_all_counters_zero (const struct gcov_ctr_info *ci_ptr)
+{
+ for (unsigned i = 0; i < ci_ptr->num; i++)
+ if (ci_ptr->values[i] != 0)
+ return 0;
+
+ return 1;
+}
+
#if defined(inhibit_libc)
/* If libc and its header files are not available, provide dummy functions. */
@@ -428,16 +440,8 @@ write_one_data (const struct gcov_info *gi_ptr,
write_top_counters (ci_ptr, t_ix, n_counts);
else
{
- /* Do not stream when all counters are zero. */
- int all_zeros = 1;
- for (unsigned i = 0; i < n_counts; i++)
- if (ci_ptr->values[i] != 0)
- {
- all_zeros = 0;
- break;
- }
-
- if (all_zeros)
+ if (gcov_are_all_counters_zero (ci_ptr))
+ /* Do not stream when all counters are zero. */
gcov_write_tag_length (GCOV_TAG_FOR_COUNTER (t_ix),
GCOV_TAG_COUNTER_LENGTH (-n_counts));
else
@@ -637,3 +641,99 @@ __gcov_init (struct gcov_info *info)
#endif /* !IN_GCOV_TOOL */
#endif /* L_gcov */
#endif /* inhibit_libc */
+
+#if !IN_GCOV_TOOL
+#ifdef L_gcov_info_to_gcda
+static void
+gcov_fn_info_to_gcda (const struct gcov_info *gi_ptr,
+ const struct gcov_fn_info *gfi_ptr,
+ void (*dump) (const void *, unsigned, void *),
+ void *arg)
+{
+ const struct gcov_ctr_info *ci_ptr = gfi_ptr->ctrs;
+
+ for (unsigned t_ix = 0; t_ix < GCOV_COUNTERS; t_ix++)
+ {
+ if (!gi_ptr->merge[t_ix])
+ continue;
+
+ if (t_ix != GCOV_COUNTER_V_TOPN && t_ix != GCOV_COUNTER_V_INDIR)
+ {
+ gcov_unsigned_t word = GCOV_TAG_FOR_COUNTER (t_ix);
+ (*dump) (&word, sizeof (word), arg);
+ gcov_position_t n_counts = ci_ptr->num;
+
+ if (gcov_are_all_counters_zero (ci_ptr))
+ {
+ /* Do not stream when all counters are zero. */
+ word = GCOV_TAG_COUNTER_LENGTH (-n_counts);
+ (*dump) (&word, sizeof (word), arg);
+ }
+ else
+ {
+ word = GCOV_TAG_COUNTER_LENGTH (n_counts);
+ (*dump) (&word, sizeof (word), arg);
+
+ for (unsigned i = 0; i < n_counts; i++)
+ {
+ gcov_type value = ci_ptr->values[i];
+ word = (gcov_unsigned_t) value;
+ (*dump) (&word, sizeof (word), arg);
+
+ if (sizeof (value) > sizeof (word))
+ word = (gcov_unsigned_t) (value >> 32);
+ else
+ word = 0;
+
+ (*dump) (&word, sizeof (word), arg);
+ }
+ }
+ }
+
+ ci_ptr++;
+ }
+}
+
+/* Convert the gcov info to a gcda data stream. This function does not support
+ whole program statistics and top counters. It is intended for free-standing
+ environments which do not support the C library file I/O. For the data
+ format, see also write_one_data(). */
+
+void
+__gcov_info_to_gcda (const struct gcov_info *gi_ptr,
+ void (*filename) (const char *, void *),
+ void (*dump) (const void *, unsigned, void *),
+ void *arg)
+{
+ (*filename) (gi_ptr->filename, arg);
+ gcov_unsigned_t word = GCOV_DATA_MAGIC;
+ (*dump) (&word, sizeof (word), arg);
+ (*dump) (&gi_ptr->version, sizeof (gi_ptr->version), arg);
+ (*dump) (&gi_ptr->stamp, sizeof (gi_ptr->stamp), arg);
+
+ for (unsigned f_ix = 0; f_ix != gi_ptr->n_functions; f_ix++)
+ {
+ word = GCOV_TAG_FUNCTION;
+ (*dump) (&word, sizeof (word), arg);
+
+ const struct gcov_fn_info *gfi_ptr = gi_ptr->functions[f_ix];
+ if (gfi_ptr && gfi_ptr->key == gi_ptr)
+ word = GCOV_TAG_FUNCTION_LENGTH;
+ else
+ word = 0;
+ (*dump) (&word, sizeof (word), arg);
+ if (!word)
+ continue;
+
+ (*dump) (&gfi_ptr->ident, sizeof (gfi_ptr->ident), arg);
+ (*dump) (&gfi_ptr->lineno_checksum,
+ sizeof (gfi_ptr->lineno_checksum), arg);
+ (*dump) (&gfi_ptr->cfg_checksum, sizeof (gfi_ptr->cfg_checksum), arg);
+ gcov_fn_info_to_gcda (gi_ptr, gfi_ptr, dump, arg);
+ }
+
+ word = 0;
+ (*dump) (&word, sizeof (word), arg);
+}
+#endif /* L_gcov_info_to_gcda */
+#endif /* !IN_GCOV_TOOL */
--
2.26.2
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