[profile] Delete unused __llvm_profile_write_buffer_internal

[MaskRay]

Summary

Unused since D14692 (2015).

[davidxl]

not sure if one is used by downstream users -- on the other hand if is used, the name of the API should be changed.

[vsk]

The API isn't unused. We have low-level projects at Apple (xnu, various bits of firmware) that rely on it.

[vsk]

The API is missing test coverage. I sent a patch adding some here: https://reviews.llvm.org/D97697

compiler-rt/lib/profile/InstrProfilingBuffer.c

void initBufferWriter(ProfDataWriter *BufferWriter, char *Buffer) {
   BufferWriter->WriterCtx = Buffer;
 }
 
 COMPILER_RT_VISIBILITY int __llvm_profile_write_buffer(char *Buffer) {
   ProfDataWriter BufferWriter;
   initBufferWriter(&BufferWriter, Buffer);
   return lprofWriteData(&BufferWriter, 0, 0);
 }
-
-COMPILER_RT_VISIBILITY int __llvm_profile_write_buffer_internal(
-    char *Buffer, const __llvm_profile_data *DataBegin,
-    const __llvm_profile_data *DataEnd, const uint64_t *CountersBegin,
-    const uint64_t *CountersEnd, const char *NamesBegin, const char *NamesEnd) {
-  ProfDataWriter BufferWriter;
-  initBufferWriter(&BufferWriter, Buffer);
-  return lprofWriteDataImpl(&BufferWriter, DataBegin, DataEnd, CountersBegin,
-                            CountersEnd, 0, NamesBegin, NamesEnd, 0);
-}

compiler-rt/lib/profile/InstrProfilingInternal.h

  * your program has a custom memory layout.
  */
 uint64_t __llvm_profile_get_size_for_buffer_internal(
     const __llvm_profile_data *DataBegin, const __llvm_profile_data *DataEnd,
     const uint64_t *CountersBegin, const uint64_t *CountersEnd,
     const char *NamesBegin, const char *NamesEnd);
 
 /*!
- * \brief Write instrumentation data to the given buffer, given explicit
- * pointers to the live data in memory.  This function is probably not what you
- * want.  Use __llvm_profile_write_buffer instead.  Use this function if your
- * program has a custom memory layout.
- *
- * \pre \c Buffer is the start of a buffer at least as big as \a
- * __llvm_profile_get_size_for_buffer_internal().
- */
-int __llvm_profile_write_buffer_internal(
-    char *Buffer, const __llvm_profile_data *DataBegin,
-    const __llvm_profile_data *DataEnd, const uint64_t *CountersBegin,
-    const uint64_t *CountersEnd, const char *NamesBegin, const char *NamesEnd);
-
-/*!
  * The data structure describing the data to be written by the
  * low level writer callback function.
  *
  * If \ref ProfDataIOVec.Data is null, and \ref ProfDataIOVec.UseZeroPadding is
  * 0, the write is skipped (the writer simply advances ElmSize*NumElm bytes).
  *
  * If \ref ProfDataIOVec.Data is null, and \ref ProfDataIOVec.UseZeroPadding is
  * nonzero, ElmSize*NumElm zero bytes are written.