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Re: PR 13722 candidate fix
On Thu, 2004-01-22 at 23:43, Zack Weinberg wrote:
> Under what circumstances should REG_INC notes be tagged onto the insns
> emitted here? It's currently done only for POST_MODIFYs, but this
> patch will generate POST_INC and POST_DEC as well.
I believe the answer is that we need it for all auto-inc addresses. The
REG_INC note indicates that the instruction has another side-effect
besides the sets and clobbers. Any routines that care about instruction
side-effects aren't going to notice the auto-inc address unless the
REG_INC note is there.
The fact that we only do this after reload reduces the chances of a
problem, but the rtlanal.c reg_set_p function needs it, and it is likely
that there is already some code somewhere after reload that directly or
indirectly calls reg_set_p. Thus the REG_INC notes should be added to
be safe.
--
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com