gcov: Add __gcov_info_to_gdca()

Add __gcov_info_to_gcda() to libgcov to get the gcda data for a gcda info in a
freestanding 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 (use "gcc -coverage -fprofile-info-section -lgcov test.c" to compile
it):

  #include <gcov.h>
  #include <stdio.h>
  #include <stdlib.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 = d;

    for (unsigned i = 0; i < n; ++i)
      printf ("%02x", c[i]);
  }

  static void *
  allocate (unsigned length, void *arg)
  {
    return malloc (length);
  }

  int main()
  {
    __asm__ volatile (".set my_info, .LPBX2");
    __gcov_info_to_gcda (my_info, filename, dump, allocate, NULL);
    return 0;
  }

With this patch, <stdint.h> is included in libgcov-driver.c even if
inhibit_libc is defined.  This header file should be also available for
freestanding environments.  If this is not the case, then we have to define
intptr_t somehow.

The patch removes one use of memset() which makes the <string.h> include
superfluous.

gcc/

	* gcov-io.h (gcov_write): Declare.
	* gcov-io.c (gcov_write): New.
	(gcov_write_counter): Remove.
	(gcov_write_tag_length): Likewise.
	(gcov_write_summary): Replace gcov_write_tag_length() with calls to
	gcov_write_unsigned().
	* doc/invoke.texi (fprofile-info-section): Mention
	__gcov_info_to_gdca().

gcc/testsuite/

	* gcc.dg/gcov-info-to-gcda.c: New test.

libgcc/

	* Makefile.in (LIBGCOV_DRIVER): Add _gcov_info_to_gcda.
	* gcov.h (gcov_info): Declare.
	(__gcov_info_to_gdca): Likewise.
	* libgcov.h (gcov_write_counter): Remove.
	(gcov_write_tag_length): Likewise.
	* libgcov-driver.c (#include <stdint.h>): New.
	(#include <string.h>): Remove.
	(NEED_L_GCOV): Conditionally define.
	(NEED_L_GCOV_INFO_TO_GCDA): Likewise.
	(are_all_counters_zero): New.
	(gcov_dump_handler): Likewise.
	(gcov_allocate_handler): Likewise.
	(dump_unsigned): Likewise.
	(dump_counter): Likewise.
	(write_topn_counters): Add dump_fn, allocate_fn, and arg parameters.
	Use dump_unsigned() and dump_counter().
	(write_one_data): Add dump_fn, allocate_fn, and arg parameters.  Use
	dump_unsigned(), dump_counter(), and are_all_counters_zero().
	(__gcov_info_to_gcda): New.

4 files changed, 141 insertions, 36 deletions

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 4efc8b7..a64cec5 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -14801,17 +14801,17 @@ 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      :
@@ -14822,6 +14822,64 @@ 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>
+#include <stdlib.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 *
+allocate (unsigned length, void *arg)
+@{
+  return malloc (length);
+@}
+
+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" (info));
+
+  while (info != end)
+  @{
+    void *arg = NULL;
+    __gcov_info_to_gcda (*info, filename, dump, allocate, arg);
+    putchar ('\n');
+    ++info;
+  @}
+@}
+
+int
+main()
+@{
+  dump_gcov_info();
+  return 0;
+@}
+@end smallexample
+
 @item -fprofile-note=@var{path}
 @opindex fprofile-note
 
diff --git a/gcc/gcov-io.c b/gcc/gcov-io.c
index 7819593..d3e56af 100644
--- a/gcc/gcov-io.c
+++ b/gcc/gcov-io.c
@@ -229,30 +229,25 @@ gcov_magic (gcov_unsigned_t magic, gcov_unsigned_t expected)
 #endif
 
 #if !IN_GCOV
-/* Write unsigned VALUE to coverage file.  */
+/* Write DATA of LENGTH characters to coverage file.  */
 
 GCOV_LINKAGE void
-gcov_write_unsigned (gcov_unsigned_t value)
+gcov_write (const void *data, unsigned length)
 {
-  gcov_unsigned_t r = fwrite (&value, sizeof (value), 1, gcov_var.file);
+  gcov_unsigned_t r = fwrite (data, length, 1, gcov_var.file);
   if (r != 1)
     gcov_var.error = 1;
 }
 
-/* Write counter VALUE to coverage file.  Sets error flag
-   appropriately.  */
+/* Write unsigned VALUE to coverage file.  */
 
-#if IN_LIBGCOV
 GCOV_LINKAGE void
-gcov_write_counter (gcov_type value)
+gcov_write_unsigned (gcov_unsigned_t value)
 {
-  gcov_write_unsigned ((gcov_unsigned_t) value);
-  if (sizeof (value) > sizeof (gcov_unsigned_t))
-    gcov_write_unsigned ((gcov_unsigned_t) (value >> 32));
-  else
-    gcov_write_unsigned (0);
+  gcov_unsigned_t r = fwrite (&value, sizeof (value), 1, gcov_var.file);
+  if (r != 1)
+    gcov_var.error = 1;
 }
-#endif /* IN_LIBGCOV */
 
 #if !IN_LIBGCOV
 /* Write STRING to coverage file.  Sets error flag on file
@@ -349,22 +344,13 @@ gcov_write_length (gcov_position_t position)
 
 #else /* IN_LIBGCOV */
 
-/* Write a tag TAG and length LENGTH.  */
-
-GCOV_LINKAGE void
-gcov_write_tag_length (gcov_unsigned_t tag, gcov_unsigned_t length)
-{
-  gcov_write_unsigned (tag);
-  gcov_write_unsigned (length);
-}
-
-/* Write a summary structure to the gcov file.  Return nonzero on
-   overflow.  */
+/* Write a summary structure to the gcov file.  */
 
 GCOV_LINKAGE void
 gcov_write_summary (gcov_unsigned_t tag, const struct gcov_summary *summary)
 {
-  gcov_write_tag_length (tag, GCOV_TAG_SUMMARY_LENGTH);
+  gcov_write_unsigned (tag);
+  gcov_write_unsigned (GCOV_TAG_SUMMARY_LENGTH);
   gcov_write_unsigned (summary->runs);
   gcov_write_unsigned (summary->sum_max);
 }
diff --git a/gcc/gcov-io.h b/gcc/gcov-io.h
index 538bee8..99e1964 100644
--- a/gcc/gcov-io.h
+++ b/gcc/gcov-io.h
@@ -367,6 +367,7 @@ char *mangle_path (char const *base);
 
 #if !IN_GCOV
 /* Available outside gcov */
+GCOV_LINKAGE void gcov_write (const void *, unsigned) ATTRIBUTE_HIDDEN;
 GCOV_LINKAGE void gcov_write_unsigned (gcov_unsigned_t) ATTRIBUTE_HIDDEN;
 #endif
 
diff --git a/gcc/testsuite/gcc.dg/gcov-info-to-gcda.c b/gcc/testsuite/gcc.dg/gcov-info-to-gcda.c
new file mode 100644
index 0000000..a42a768
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gcov-info-to-gcda.c
@@ -0,0 +1,60 @@
+/* { dg-do run } */
+/* { dg-skip-if "profile-info-section" { powerpc-ibm-aix* } } */
+/* { dg-options "-fprofile-arcs -fprofile-info-section" } */
+
+#define assert(expr)                                            \
+  ((expr)                                                       \
+   ? (void)0                                                    \
+   : (__builtin_printf ("%s:%i: Assertion `%s' failed.\n",      \
+                        __FILE__, __LINE__, #expr),             \
+      __builtin_abort ()))
+
+struct gcov_info;
+
+extern void
+__gcov_info_to_gcda (const struct gcov_info *__info,
+		     void (*__filename_fn) (const char *, void *),
+		     void (*__dump_fn) (const void *, unsigned, void *),
+		     void *(*__allocate_fn) (unsigned, void *),
+		     void *__arg);
+
+extern const struct gcov_info *my_info;
+
+static unsigned counter;
+
+static void
+filename (const char *f, void *arg)
+{
+  assert (arg == &counter);
+  assert (__builtin_strstr (f, "gcov-info-to-gcda.c") == 0);
+}
+
+static void
+dump (const void *d, unsigned n, void *arg)
+{
+  unsigned *m = (unsigned *)arg;
+  assert (arg == &counter);
+
+  if (*m == 0)
+  {
+    const unsigned *u = d;
+    assert (*u == 0x67636461);
+  }
+
+  *m += n;
+}
+
+static void *
+allocate (unsigned length, void *arg)
+{
+  assert (arg == &counter);
+  return __builtin_malloc (length);
+}
+
+int main()
+{
+  __asm__ volatile (".set my_info, .LPBX2");
+  __gcov_info_to_gcda (my_info, filename, dump, allocate, &counter);
+  assert (counter > 4);
+  return 0;
+}