Performance improvement.
Using fwrite and fread was very *very* slow. The resulting code was multiple
times slower than GCC's implementation of gcov. Replace the fwrite/fread system
with an mmap() version.
If the `.gcda' file doesn't exist, we (re)allocate a buffer that we write
into. That gets written to the `.gcda' file in one chunk. If the `.gcda' file
already exists, we simply mmap() the file, modify the mapped data, and use
msync() to write the contents out to disk. It's much easier than implementing
our own buffering scheme, and we don't have to use fwrite's and fread's
buffering.
For those who are numbers-oriented, here are some timings:
GCC Verison
-----------
`.gcda' files don't exist: 23s
`.gcda' files do exist: 14s
LLVM Version (before this change)
---------------------------------
`.gcda' files don't exist: 28s
`.gcda' files do exist: 28s
LLVM Version (with this change)
-------------------------------
`.gcda' files don't exist: 18s
`.gcda' files do exist: 4s
It's a win-win-win-win-lose-win-win scenario!
<rdar://problem/13466086>
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@182563 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/SDKs/linux/usr/include/stdio.h b/SDKs/linux/usr/include/stdio.h
index 0ca10fa..fba5936 100644
--- a/SDKs/linux/usr/include/stdio.h
+++ b/SDKs/linux/usr/include/stdio.h
@@ -33,11 +33,11 @@
extern int fclose(FILE *);
extern int fflush(FILE *);
extern FILE *fopen(const char * restrict, const char * restrict);
+extern FILE *fdopen(int, const char * restrict);
extern int fprintf(FILE * restrict, const char * restrict, ...);
extern size_t fwrite(const void * restrict, size_t, size_t, FILE * restrict);
extern size_t fread(void * restrict, size_t, size_t, FILE * restrict);
extern long ftell(FILE *);
extern int fseek(FILE *, long, int);
-extern void setbuf(FILE * restrict, char * restrict);
#endif /* __STDIO_H__ */