[PATCH 1/5] Handle WORD_REGISTER_OPERATIONS when reloading (subreg(reg))

[Eric Botcazou]

> Agreed.  I don't think things like WORD_MODE_OPERATIONS should change
> rtl semantics, just optimisation decisions.  And using the smallest
> possible spill size is often good even for RISCy targets.

I don't think that's correct, WORD_MODE_OPERATIONS does change RTL semantics 
for SUBREGs smaller than a word since it can make all bits defined, even if 
only the lower part is assigned.  For example (SUBREG:SI (MEM:QI)) has the 
higher bits defined according to LOAD_EXTEND_OP if WORD_MODE_OPERATIONS.

LRA simply needs to preserve the semantics, just as reload does.

-- 
Eric Botcazou