GetAlignmentOf returns 4 on Sparc when T=word64

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We recently received access to the OpenCSW compile farm. The farm provides access to Solaris 9 through 11 on x86 and Sparc hardware. The machines make both GCC and SunCC available.

The cryptest.exe test program experienced a string of SIGBUS crashes. We kind of expected some trouble due to Issue 403. First it was SHA-384 (Issue 689), and then it was Tiger (Issue 690). Once Tiger was cleared VMAC crashed with a SIGBUS. It became obvious these were not one-offs.

We added code at Commit 0c0b68a4a28b to align the buffers in IteratedHashBase::HashMultipleBlocks() which should have avoided the SIGBUS:

if (noReverse)
{
   if (IsAligned<HashWordType>(input))
   {
      // Sparc bus error with non-aligned input.
      this->HashEndianCorrectedBlock(input);
   }
   else
   {
      std::memcpy(dataBuf, input, blockSize);
      this->HashEndianCorrectedBlock(dataBuf);
   }
}
else
{
   if (IsAligned<HashWordType>(input))
   {
      // Sparc bus error with non-aligned input.
      ByteReverse(dataBuf, input, blockSize);
      this->HashEndianCorrectedBlock(dataBuf);
   }
   else
   {
      std::memcpy(dataBuf, input, blockSize);
      ByteReverse(dataBuf, dataBuf, blockSize);
      this->HashEndianCorrectedBlock(dataBuf);
   }
}

We were still catching SIGBUSes after the change. Eventually the issue was tracked back to IsAligned<HashWordType>(), which uses GetAlignmentOf(). Notice there is no path for the SunCC compiler.

template <class T>
inline unsigned int GetAlignmentOf()
{
#if defined(CRYPTOPP_CXX11_ALIGNOF)
	return alignof(T);
#elif (_MSC_VER >= 1300)
	return __alignof(T);
#elif defined(__GNUC__)
	return __alignof__(T);
#elif CRYPTOPP_BOOL_SLOW_WORD64
	return UnsignedMin(4U, sizeof(T));
#else
# if __BIGGEST_ALIGNMENT__
	if (__BIGGEST_ALIGNMENT__ < sizeof(T))
		return __BIGGEST_ALIGNMENT__;
	else
# endif
	return sizeof(T);
#endif
}

With SunCC we landed in the UnsignedMin(4U, sizeof(T)) code path. Things worked fine with -xmemalign=4i but failed without it because alignment requirements of word64 is 8 without -xmemalign. Lack of -xmemalign is a good thing and means SunCC will generate a super-fast ldx machine instruction to load a 64-bit word (but it requires a 8-byte aligned load address).

The fix was simple. Add another code path for SunCC. The addition below was tested on the compile farm back to SunCC 5.8 on Solaris 9:

#elif defined(__GNUC__)
	return __alignof__(T);
#elif defined(__SUNPRO_CC)
	return __alignof__(T);

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Cleared at Commit d4f86d73209c.