Reduce PGO Instrumentation binary and profile data size (Patch-3)

[davidxl]

Summary

See patch-1 for descriptions

lib/profile/InstrProfiling.h

 int __llvm_profile_write_buffer(char *Buffer);
 
 const __llvm_profile_data *__llvm_profile_begin_data(void);
 const __llvm_profile_data *__llvm_profile_end_data(void);
 const char *__llvm_profile_begin_names(void);
 const char *__llvm_profile_end_names(void);
 uint64_t *__llvm_profile_begin_counters(void);
 uint64_t *__llvm_profile_end_counters(void);
+extern uint64_t __llvm_profile_magic;
+extern uint64_t __llvm_profile_version;
 
 /*!
  * \brief Write instrumentation data to the current file.
  *
  * Writes to the file with the last name given to \a __llvm_profile_set_filename(),
  * or if it hasn't been called, the \c LLVM_PROFILE_FILE environment variable,
  * or if that's not set, the last name given to
  * \a __llvm_profile_override_default_filename(), or if that's not set,

lib/profile/InstrProfiling.c

 /*===- InstrProfiling.c - Support library for PGO instrumentation ---------===*\
 |*
 |*                     The LLVM Compiler Infrastructure
 |*
 |* This file is distributed under the University of Illinois Open Source
 |* License. See LICENSE.TXT for details.
 |*
 \*===----------------------------------------------------------------------===*/
 
 #include "InstrProfiling.h"
 #include <string.h>
 
 __attribute__((visibility("hidden")))
 uint64_t __llvm_profile_get_magic(void) {
-  /* Magic number to detect file format and endianness.
-   *
-   * Use 255 at one end, since no UTF-8 file can use that character.  Avoid 0,
-   * so that utilities, like strings, don't grab it as a string.  129 is also
-   * invalid UTF-8, and high enough to be interesting.
-   *
-   * Use "lprofr" in the centre to stand for "LLVM Profile Raw", or "lprofR"
-   * for 32-bit platforms.
-   */
-  unsigned char R = sizeof(void *) == sizeof(uint64_t) ? 'r' : 'R';
-  return
-    (uint64_t)255 << 56 |
-    (uint64_t)'l' << 48 |
-    (uint64_t)'p' << 40 |
-    (uint64_t)'r' << 32 |
-    (uint64_t)'o' << 24 |
-    (uint64_t)'f' << 16 |
-    (uint64_t) R  <<  8 |
-    (uint64_t)129;
+  return __llvm_profile_magic;
 }
 
-__attribute__((visibility("hidden")))
-uint64_t __llvm_profile_get_version(void) {
-  /* This should be bumped any time the output format changes. */
-  return 1;
+__attribute__((visibility("hidden"))) uint64_t
+    __llvm_profile_get_version(void) {
+  return __llvm_profile_version;
 }
 
-__attribute__((visibility("hidden")))
-void __llvm_profile_reset_counters(void) {
+__attribute__((visibility("hidden"))) void __llvm_profile_reset_counters(void) {
   uint64_t *I = __llvm_profile_begin_counters();
   uint64_t *E = __llvm_profile_end_counters();
 
-  memset(I, 0, sizeof(uint64_t)*(E - I));
+  memset(I, 0, sizeof(uint64_t) * (E - I));
 }