Add parallelism support to gcov for MinGW platforms

If you attempt a profiled bootstrap on the MinGW platforms with -jN, N > 1,
it miserably fails because of profile mismatches all over the place, the
reason being that gcov has no support for parallelism on these platforms.

libgcc/
	* libgcov.h: For the target, define GCOV_LOCKED_WITH_LOCKING
	if __MSVCRT__ and, for the host, define it if HOST_HAS_LK_LOCK.
	* libgcov-driver.c: Add directives if GCOV_LOCKED_WITH_LOCKING.
gcc/
	* configure.ac: Check for the presence of sys/locking.h header and
	for whether _LK_LOCK is supported by _locking.
	* configure: Regenerate.
	* config.in: Likewise.
	* gcov-io.h: Define GCOV_LOCKED_WITH_LOCKING if HOST_HAS_LK_LOCK.
	* gcov-io.c (gcov_open): Add support for GCOV_LOCKED_WITH_LOCKING.
	* system.h: Include <sys/locking.h> if HAVE_SYS_LOCKING_H.

1 files changed, 30 insertions, 0 deletions

diff --git a/gcc/gcov-io.c b/gcc/gcov-io.c
index 80c9082..21ca394 100644
--- a/gcc/gcov-io.c
+++ b/gcc/gcov-io.c
@@ -137,6 +137,8 @@ gcov_open (const char *name, int mode)
   s_flock.l_start = 0;
   s_flock.l_len = 0; /* Until EOF.  */
   s_flock.l_pid = getpid ();
+#elif GCOV_LOCKED_WITH_LOCKING
+  int fd;
 #endif
 
   gcov_nonruntime_assert (!gcov_var.file);
@@ -175,6 +177,34 @@ gcov_open (const char *name, int mode)
       close (fd);
       return 0;
     }
+#elif GCOV_LOCKED_WITH_LOCKING
+  if (mode > 0)
+    {
+      /* pass mode (ignored) for compatibility */
+      fd = open (name, O_RDONLY | O_BINARY, S_IRUSR | S_IWUSR);
+    }
+  else
+     {
+       /* Truncate if force new mode.  */
+       fd = open (name, O_RDWR | O_BINARY | O_CREAT | (mode < 0 ? O_TRUNC : 0),
+		  0666);
+    }
+  if (fd < 0)
+    return 0;
+
+  if (_locking (fd, _LK_LOCK, LONG_MAX) < 0)
+    {
+      close (fd);
+      return 0;
+    }
+
+  gcov_var.file = fdopen (fd, (mode > 0) ? "rb" : "r+b");
+
+  if (!gcov_var.file)
+    {
+      close (fd);
+      return 0;
+    }
 #else
   if (mode >= 0)
     /* Open an existing file.  */