InstrProf: Write the __llvm_profile_write_buffer()

Write __llvm_profile_write_buffer(), which uses the same logic as
__llvm_profile_write_file(), but writes directly to a provided `char*`
buffer instead.

<rdar://problem/15943240>

llvm-svn: 204499

compiler-rt/lib/profile/InstrProfilingBuffer.c

@@ -10,5 +10,48 @@
 #include "InstrProfiling.h"
 #include <string.h>
 
-/* TODO: uint64_t __llvm_profile_get_size_for_buffer(void) */
-/* TODO: int __llvm_profile_write_buffer(char *Buffer) */
+uint64_t __llvm_profile_get_size_for_buffer(void) {
+  return sizeof(uint64_t) * 7 +
+     PROFILE_RANGE_SIZE(data) * sizeof(__llvm_profile_data) +
+     PROFILE_RANGE_SIZE(counters) * sizeof(uint64_t) +
+     PROFILE_RANGE_SIZE(names) * sizeof(char);
+}
+
+int __llvm_profile_write_buffer(char *Buffer) {
+  const __llvm_profile_data *DataBegin = __llvm_profile_data_begin();
+  const __llvm_profile_data *DataEnd = __llvm_profile_data_end();
+  const uint64_t *CountersBegin = __llvm_profile_counters_begin();
+  const uint64_t *CountersEnd   = __llvm_profile_counters_end();
+  const char *NamesBegin = __llvm_profile_names_begin();
+  const char *NamesEnd   = __llvm_profile_names_end();
+
+  /* Calculate size of sections. */
+  const uint64_t DataSize = DataEnd - DataBegin;
+  const uint64_t CountersSize = CountersEnd - CountersBegin;
+  const uint64_t NamesSize = NamesEnd - NamesBegin;
+
+  /* Create the header. */
+  uint64_t Header[] = {
+    __llvm_profile_get_magic(),
+    __llvm_profile_get_version(),
+    DataSize,
+    CountersSize,
+    NamesSize,
+    (uint64_t)CountersBegin,
+    (uint64_t)NamesBegin
+  };
+
+  /* Write the data. */
+#define UPDATE_memcpy(Data, Size) \
+  do {                            \
+    memcpy(Buffer, Data, Size);   \
+    Buffer += Size;               \
+  } while (0)
+  UPDATE_memcpy(Header,        sizeof(Header));
+  UPDATE_memcpy(DataBegin,     DataSize     * sizeof(__llvm_profile_data));
+  UPDATE_memcpy(CountersBegin, CountersSize * sizeof(uint64_t));
+  UPDATE_memcpy(NamesBegin,    NamesSize    * sizeof(char));
+#undef UPDATE_memcpy
+
+  return 0;
+}