x86 backend details

[Henry Cejtin]

It  still  might  be worth while using a register to point to the base of the
pseudo-register block in memory.  At the very least it  will  make  the  code
smaller  (3 bytes for a load relative to a register vs. 5 bytes when you have
to provide an absolute address) which means less I-cache pressure.   I  would
have  thought  it  would  also be faster, but it isn't much.  (About 3% by my
test.)  I guess it all depends on how good the register allocator is.  If  it
is  good  enough  that it can figure other useful things to keep in registers
(and it isn't like there are very many registers) then it isn't worth it, but
otherwise you might as well use a register for this.