gcov: Add __gcov_filename_to_gcfn()

gcc/

	* doc/invoke.texi (fprofile-info-section): Mention
	__gcov_filename_to_gcfn().  Use "freestanding" to match with C11
	standard language.  Fix minor example code issues.
	* gcov-io.h (GCOV_FILENAME_MAGIC): Define and document.

gcc/testsuite/

	* gcc.dg/gcov-info-to-gcda.c: Test __gcov_filename_to_gcfn().

libgcc/

	* gcov.h (__gcov_info_to_gcda): Mention __gcov_filename_to_gcfn().
	(__gcov_filename_to_gcfn): Declare and document.
	* libgcov-driver.c (dump_string): New.
	(__gcov_filename_to_gcfn): Likewise.
	(__gcov_info_to_gcda): Adjust comment to match C11 standard language.

gcc/doc/invoke.texi

@@ -15462,7 +15462,7 @@ 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
+used in hosted environments such as GNU/Linux.  It targets freestanding
 environments (for example embedded systems) with limited resources which do not
 support constructors/destructors or the C library file I/O.
 
@@ -15487,14 +15487,8 @@ for example like this:
 #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);
-@}
+extern const struct gcov_info *const __gcov_info_start[];
+extern const struct gcov_info *const __gcov_info_end[];
 
 static void
 dump (const void *d, unsigned n, void *arg)
@@ -15505,6 +15499,12 @@ dump (const void *d, unsigned n, void *arg)
     printf ("%02x", c[i]);
 @}
 
+static void
+filename (const char *f, void *arg)
+@{
+  __gcov_filename_to_gcfn (f, dump, arg );
+@}
+
 static void *
 allocate (unsigned length, void *arg)
 @{
@@ -15514,8 +15514,8 @@ allocate (unsigned length, void *arg)
 static void
 dump_gcov_info (void)
 @{
-  const struct gcov_info **info = __gcov_info_start;
-  const struct gcov_info **end = __gcov_info_end;
+  const struct gcov_info *const *info = __gcov_info_start;
+  const struct gcov_info *const *end = __gcov_info_end;
 
   /* Obfuscate variable to prevent compiler optimizations.  */
   __asm__ ("" : "+r" (info));
@@ -15530,9 +15530,9 @@ dump_gcov_info (void)
 @}
 
 int
-main()
+main (void)
 @{
-  dump_gcov_info();
+  dump_gcov_info ();
   return 0;
 @}
 @end smallexample

gcc/gcov-io.h

@@ -60,14 +60,21 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 
    	file : int32:magic int32:version int32:stamp record*
 
-   The magic ident is different for the notes and the data files.  The
-   magic ident is used to determine the endianness of the file, when
-   reading.  The version is the same for both files and is derived
-   from gcc's version number. The stamp value is used to synchronize
-   note and data files and to synchronize merging within a data
-   file. It need not be an absolute time stamp, merely a ticker that
-   increments fast enough and cycles slow enough to distinguish
-   different compile/run/compile cycles.
+   A filename header may be used to provide a filename for the data in
+   a stream of data to support gcov in freestanding environments.  This
+   header is used by the merge-stream subcommand of the gcov-tool.  The
+   format of the filename header is
+
+	filename-header : int32:magic int32:version string
+
+   The magic ident is different for the notes and the data files as
+   well as the filename header.  The magic ident is used to determine
+   the endianness of the file, when reading.  The version is the same
+   for both files and is derived from gcc's version number. The stamp
+   value is used to synchronize note and data files and to synchronize
+   merging within a data file. It need not be an absolute time stamp,
+   merely a ticker that increments fast enough and cycles slow enough
+   to distinguish different compile/run/compile cycles.
 
    Although the ident and version are formally 32 bit numbers, they
    are derived from 4 character ASCII strings.  The version number
@@ -228,6 +235,7 @@ typedef uint64_t gcov_type_unsigned;
 /* File magic. Must not be palindromes.  */
 #define GCOV_DATA_MAGIC ((gcov_unsigned_t)0x67636461) /* "gcda" */
 #define GCOV_NOTE_MAGIC ((gcov_unsigned_t)0x67636e6f) /* "gcno" */
+#define GCOV_FILENAME_MAGIC ((gcov_unsigned_t)0x6763666e) /* "gcfn" */
 
 #include "version.h"
 

gcc/testsuite/gcc.dg/gcov-info-to-gcda.c

@@ -17,16 +17,20 @@ __gcov_info_to_gcda (const struct gcov_info *__info,
 		     void *(*__allocate_fn) (unsigned, void *),
 		     void *__arg);
 
+extern void
+__gcov_filename_to_gcfn (const char *__filename,
+			 void (*__dump_fn) (const void *, 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 unsigned counter_after_filename;
+
+static int check_zero;
+
+static int check_after_filename;
 
 static void
 dump (const void *d, unsigned n, void *arg)
@@ -35,14 +39,30 @@ dump (const void *d, unsigned n, void *arg)
   assert (arg == &counter);
 
   if (*m == 0)
+  {
+    const unsigned *u = d;
+    assert (*u == 0x6763666e);
+    check_zero = 1;
+  }
+  else if (*m == counter_after_filename)
   {
     const unsigned *u = d;
     assert (*u == 0x67636461);
+    check_after_filename = 1;
   }
 
   *m += n;
 }
 
+static void
+filename (const char *f, void *arg)
+{
+  assert (arg == &counter);
+  assert (__builtin_strstr (f, "gcov-info-to-gcda.c") == 0);
+  __gcov_filename_to_gcfn (f, dump, arg);
+  counter_after_filename = counter;
+}
+
 static void *
 allocate (unsigned length, void *arg)
 {
@@ -54,6 +74,8 @@ int main()
 {
   __asm__ volatile (".set my_info, .LPBX2");
   __gcov_info_to_gcda (my_info, filename, dump, allocate, &counter);
-  assert (counter > 4);
+  assert (counter > 8);
+  assert (check_zero);
+  assert (check_after_filename);
   return 0;
 }

libgcc/gcov.h

@@ -43,7 +43,8 @@ extern void __gcov_dump (void);
    stream.  The ALLOCATE_FN callback shall allocate memory with a size in
    characters specified by the first callback parameter.  The ARG parameter is
    a user-provided argument passed as the last argument to the callback
-   functions.  */
+   functions.  It is recommended to use the __gcov_filename_to_gcfn()
+   in the filename callback function.  */
 
 extern void
 __gcov_info_to_gcda (const struct gcov_info *__info,
@@ -52,4 +53,18 @@ __gcov_info_to_gcda (const struct gcov_info *__info,
 		     void *(*__allocate_fn) (unsigned, void *),
 		     void *__arg);
 
+/* Convert the FILENAME to a gcfn data stream.  The DUMP_FN callback is
+   subsequently called with chunks (the begin and length of the chunk are
+   passed as the first two callback parameters) of the gcfn data stream.
+   The ARG parameter is a user-provided argument passed as the last
+   argument to the DUMP_FN callback function.  This function is intended
+   to be used by the filename callback of __gcov_info_to_gcda().  The gcfn
+   data stream is used by the merge-stream subcommand of the gcov-tool to
+   get the filename associated with a gcda data stream.  */
+
+extern void
+__gcov_filename_to_gcfn (const char *__filename,
+			 void (*__dump_fn) (const void *, unsigned, void *),
+			 void *__arg);
+
 #endif /* GCC_GCOV_H */

libgcc/libgcov-driver.c

@@ -410,6 +410,23 @@ dump_counter (gcov_type counter,
     dump_unsigned (0, dump_fn, arg);
 }
 
+/* Dump the STRING using the DUMP handler called with ARG.  */
+
+static inline void
+dump_string (const char *string,
+	     void (*dump_fn) (const void *, unsigned, void *),
+	     void *arg)
+{
+  unsigned length = 0;
+
+  if (string)
+    length = strlen (string) + 1;
+
+  dump_unsigned (length, dump_fn, arg);
+  if (string)
+    (*dump_fn) (string, length, arg);
+}
+
 #define MAX(X,Y) ((X) > (Y) ? (X) : (Y))
 
 /* Store all TOP N counters where each has a dynamic length.  */
@@ -768,7 +785,7 @@ __gcov_init (struct gcov_info *info)
 
 #ifdef NEED_L_GCOV_INFO_TO_GCDA
 /* Convert the gcov info to a gcda data stream.  It is intended for
-   free-standing environments which do not support the C library file I/O.  */
+   freestanding environments which do not support the C library file I/O.  */
 
 void
 __gcov_info_to_gcda (const struct gcov_info *gi_ptr,
@@ -780,4 +797,17 @@ __gcov_info_to_gcda (const struct gcov_info *gi_ptr,
   (*filename_fn) (gi_ptr->filename, arg);
   write_one_data (gi_ptr, NULL, dump_fn, allocate_fn, arg);
 }
+
+/* Convert the filename to a gcfn data stream.  It is intended for
+   freestanding environments which do not support the C library file I/O.  */
+
+void
+__gcov_filename_to_gcfn (const char *filename,
+			 void (*dump_fn) (const void *, unsigned, void *),
+			 void *arg)
+{
+  dump_unsigned (GCOV_FILENAME_MAGIC, dump_fn, arg);
+  dump_unsigned (GCOV_VERSION, dump_fn, arg);
+  dump_string (filename, dump_fn, arg);
+}
 #endif /* NEED_L_GCOV_INFO_TO_GCDA */