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LO_SUM memrefs offsettable ?
- To: egcs at cygnus dot com
- Subject: LO_SUM memrefs offsettable ?
- From: Michael Hayes <m dot hayes at elec dot canterbury dot ac dot nz>
- Date: Fri, 22 Jan 1999 00:10:21 +1300 (NZDT)
I've noticed from perusing some of the backends that there is
confusion over whether LO_SUM memrefs are offsettable.
Can anyone categorically state what the case is?
offsettable_address_p considers that LO_SUM memrefs are offsettable
yet operand_subword calls plus_constant instead of
plus_constant_for_output. This has the effect of generating
addresses of the form (PLUS (LO_SUM (REG) (SYMBOL_REF)) (CONST_INT)
instead of (LO_SUM (REG) (CONST (SYMBOL_REF) (CONST_INT))).
Now I can see that there is a problem when considering an offsettable
LO_SUM memref at the end of a data page, since the data page register
may require updating as well. Is this the main stumbling block with
the use of a LO_SUM/HIGH insn pair?
Michael.