zero extend pointer converstions to unsigned long long

[Mike Stump <mrs at apple dot com>]

The below patch preserves TREE_UNSIGNED on pointers during conversions 
to int instead of ignoring it.? The outcome of this is to zero extend a 
pointer instead of sign extend it when converting to a size larger than 
the pointer.? There is code in layout_type that does:

? ? case POINTER_TYPE:
? ? case REFERENCE_TYPE:
? ? ? {

? ? ? ? enum machine_mode mode = ((TREE_CODE (type) == REFERENCE_TYPE
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? && reference_types_internal)
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Pmode : TYPE_MODE (type));

? ? ? ? int nbits = GET_MODE_BITSIZE (mode);

? ? ? ? TYPE_SIZE (type) = bitsize_int (nbits);
? ? ? ? TYPE_SIZE_UNIT (type) = size_int (GET_MODE_SIZE (mode));
? ? ? ? TYPE_UNSIGNED (type) = 1;
? ? ? ? TYPE_PRECISION (type) = nbits;
? ? ? }

thus making pointers unsigned.? My patch merely follows that desire.? 
This patch enables a certain style of kernel programming where the 
kernel uses unsigned long long values to store user land Pmode values 
and have all the math come out right.

Ok?

Attachment: conv.diffs.txt
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