convert_move does not know how to zero-extend a constant integer to the
target mode -- simply because it does not know the source mode.  As a
result, 32-bit SImode with the high bit set would be effectively sign-
extended instead of zero-extended.

This patch fixes it.


	PR target/68865
	PR target/68879
	* config/rs6000/rs6000.md (cstore_si_as_di): Force all operands
	into registers.

From-SVN: r231621