Use unbuffered I/O. This reduces the runtime by about half. Our implementation is now only about 5 times slower than gcc's.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@180980 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/profile/GCDAProfiling.c b/lib/profile/GCDAProfiling.c
index 653f641f7..3e0fff25f 100644
--- a/lib/profile/GCDAProfiling.c
+++ b/lib/profile/GCDAProfiling.c
@@ -194,6 +194,9 @@ void llvm_gcda_start_file(const char *orig_filename, const char version[4]) {
     }
   }
 
+  /* Make the file I/O unbuffered. */
+  setbuf(output_file, (char*)NULL);
+
   /* gcda file, version, stamp LLVM. */
   fwrite("adcg", 4, 1, output_file);
   fwrite(version, 4, 1, output_file);