Re: [patch] h8300: Fix target/11805

[Roger Sayle <roger at eyesopen dot com>]

Kazu Hirata wrote:
> On h8300, the first insn does not set the overflow flag, but the
> second requires the overflow flag.  As a result, when the final wants
> to output the jump insn, it cannot find a test insn that gives
> appropriate condition flags.

Hi Kazu,

Sorry to ask, but are there any plans to upgrade the h8300 backend from
a cc0 target to a new style MODE_CC target?  The h8300 is clearly the
best maintained "cc0" backend and possibly the largest bottleneck
preventing GCC from ultimatelly deprecating cc0 ports for 3.5/3.6.  The
v850 port, for example, was unbuildable on mainline for over four months
and with that level of support is likely to be targeted for deprecation
before long, leaving even fewer (emulator) cc0 targets.

I know Alex Oliva is actively working on a new cc0 port(!?), but my
understanding is that we're trying to ease backends to a more consistent
way of handling condition codes [See Zack's GCC summit presentation].
PR target/11805 reveals that cc0 isn't a perfect model for the h8300's
condition codes, as clearly not all instructions set all of the flag
bits.


I certainly don't want this to hold up your patch, but I was just
wondering whether you had any long-term plans to transition to MODE_CC
or BImode condition codes?

Roger
--
Roger Sayle,                         E-mail: roger@eyesopen.com
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