MSVC10 optimization bug

msvc10optbug.cpp

// cl 16.00.40219.01 for 80x86
// Compile with /O2:
// pData - slcControlFlags = 48
// Assertion failed: (pData - slcControlFlags) == sizeof(slcControlFlags), file msvc10optbug.cpp, line 46
#include <stdint.h>
#include <assert.h>
#include <string.h>
#include <stdio.h>

const size_t kSlcSizeWithoutBoneArray = 96;
struct Locator { char data[16]; };

__declspec(noinline)
void WriteFlagsAt(uint8_t (&slcControlFlags)[kSlcSizeWithoutBoneArray], int controlSlot, const Locator& locator)
{
       // create working handle
       uint8_t* pData = slcControlFlags;

       // locator
       for ( int i = 0; i < 4; ++i )
       {
              if (i == controlSlot)
              {
                     memcpy(pData, &locator, sizeof(locator));
              }
              pData += sizeof(locator);
       }

       // masks
       for (int i = 0; i < 4; ++i)
       {
              if (i == controlSlot)
              {
                       *((uint32_t*)pData) = 0;
              }
              pData += sizeof(uint32_t);
       }

       // indices
       for (int i = 0; i < 4; ++i)
       {
              if (i == controlSlot)
              {
                     *((uint32_t*)pData) = 0;
              }
              pData += sizeof(uint32_t);
       }

        printf("pData - slcControlFlags = %d\n", (int)(pData - slcControlFlags));
       assert( (pData - slcControlFlags) == sizeof(slcControlFlags) );
}

int main()
{
    uint8_t dest[kSlcSizeWithoutBoneArray];
    WriteFlagsAt(dest, 1, Locator());
}