Having the source operand of a pointer assignment available to later
instrctions can make for more efficient code as the value does not need to
be dereferenced later. For this purpose, pointer dereference dag nodes now
store the source operand as their value, and dagnode_match will match x=a.b
with *(a+b)=y so long as both a and b are the same in both nodes. x and y
are irrelevant to the match. The resulting code will be the equivalent of:
*(a+b) = y;
x = y;
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