[compiler-rt] Fix entry count for __llvm_prf_data on i386 Darwin

[vsk]

Summary

Compiler-rt miscalculates the number of entries in the __llvm_prf_data section on i386 Darwin. This results in a number of test failures (which we started catching after r261344).

The fix we attempted earlier is insufficient (r261683). It caused some tests to start passing again, but that hid the fact that we drop data entries.

This patch should fix the real problem. It fixes the way we compute DataSize by taking into account the way the Darwin linker lays out __llvm_prf_data.

[davidxl]

lib/profile/InstrProfilingBuffer.c

31

Probably just

EndI = (llvm_profile_data *) ((intptr_t)End + sizeof(llvm_profile_data) -1);
return EndI - Begin;

[vsk]

• Simplify according to David's comment, but prefer not to do arithmetic on unaligned pointers.

[davidxl]

lgtm

lib/profile/InstrProfiling.h

 void __llvm_profile_initialize_file(void);
 
 /*! \brief Get the magic token for the file format. */
 uint64_t __llvm_profile_get_magic(void);
 
 /*! \brief Get the version of the file format. */
 uint64_t __llvm_profile_get_version(void);
 
+/*! \brief Get the number of entries in the profile data section. */
+uint64_t __llvm_profile_get_data_size(const __llvm_profile_data *Begin,
+                                      const __llvm_profile_data *End);
+
 #endif /* PROFILE_INSTRPROFILING_H_ */

lib/profile/InstrProfilingBuffer.c

uint64_t __llvm_profile_get_size_for_buffer(void) {
   const uint64_t *CountersEnd = __llvm_profile_end_counters();
   const char *NamesBegin = __llvm_profile_begin_names();
   const char *NamesEnd = __llvm_profile_end_names();
 
   return __llvm_profile_get_size_for_buffer_internal(
       DataBegin, DataEnd, CountersBegin, CountersEnd, NamesBegin, NamesEnd);
 }
 
-#define PROFILE_RANGE_SIZE(Range) (Range##End - Range##Begin)
+COMPILER_RT_VISIBILITY
+uint64_t __llvm_profile_get_data_size(const __llvm_profile_data *Begin,
+                                      const __llvm_profile_data *End) {
+  intptr_t BeginI = (intptr_t)Begin, EndI = (intptr_t)End;
+  return ((EndI + sizeof(__llvm_profile_data) - 1) - BeginI) /
+         sizeof(__llvm_profile_data);
+}
 
 COMPILER_RT_VISIBILITY
 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) {
   /* Match logic in __llvm_profile_write_buffer(). */
-  const uint64_t NamesSize = PROFILE_RANGE_SIZE(Names) * sizeof(char);
+  const uint64_t NamesSize = (NamesEnd - NamesBegin) * sizeof(char);
   const uint8_t Padding = __llvm_profile_get_num_padding_bytes(NamesSize);
   return sizeof(__llvm_profile_header) +
-         PROFILE_RANGE_SIZE(Data) * sizeof(__llvm_profile_data) +
-         PROFILE_RANGE_SIZE(Counters) * sizeof(uint64_t) + NamesSize + Padding;
+         (__llvm_profile_get_data_size(DataBegin, DataEnd) *
+          sizeof(__llvm_profile_data)) +
+         (CountersEnd - CountersBegin) * sizeof(uint64_t) + NamesSize + Padding;
 }
 
 COMPILER_RT_VISIBILITY int __llvm_profile_write_buffer(char *Buffer) {
   return llvmWriteProfData(llvmBufferWriter, Buffer, 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) {
   return llvmWriteProfDataImpl(llvmBufferWriter, Buffer, DataBegin, DataEnd,
                                CountersBegin, CountersEnd, 0, 0, NamesBegin,
                                NamesEnd);
 }

lib/profile/InstrProfilingValue.c

   ValueProfData **ValueDataArray;
 
   const __llvm_profile_data *DataEnd = __llvm_profile_end_data();
   const __llvm_profile_data *DataBegin = __llvm_profile_begin_data();
 
   if (!ValueDataSize)
     return NULL;
 
-  ValueDataArray =
-      (ValueProfData **)calloc(DataEnd - DataBegin, sizeof(void *));
+  ValueDataArray = (ValueProfData **)calloc(
+      __llvm_profile_get_data_size(DataBegin, DataEnd), sizeof(void *));
   if (!ValueDataArray)
     PROF_OOM_RETURN("Failed to write value profile data ");
 
   /*
    * Compute the total Size of the buffer to hold ValueProfData
    * structures for functions with value profile data.
    */
   for (I = (__llvm_profile_data *)DataBegin; I < DataEnd; ++I) {

lib/profile/InstrProfilingWriter.c

 COMPILER_RT_VISIBILITY int llvmWriteProfDataImpl(
     WriterCallback Writer, void *WriterCtx,
     const __llvm_profile_data *DataBegin, const __llvm_profile_data *DataEnd,
     const uint64_t *CountersBegin, const uint64_t *CountersEnd,
     ValueProfData **ValueDataBegin, const uint64_t ValueDataSize,
     const char *NamesBegin, const char *NamesEnd) {
 
   /* Calculate size of sections. */
-  const uint64_t DataSize = DataEnd - DataBegin;
+  const uint64_t DataSize = __llvm_profile_get_data_size(DataBegin, DataEnd);
   const uint64_t CountersSize = CountersEnd - CountersBegin;
   const uint64_t NamesSize = NamesEnd - NamesBegin;
   const uint64_t Padding = __llvm_profile_get_num_padding_bytes(NamesSize);
 
   /* Enough zeroes for padding. */
   const char Zeroes[sizeof(uint64_t)] = {0};
 
   /* Create the header. */