[PR middle-end/20491] combine generates bad subregs

[Alexandre Oliva]

On Mar 29, 2005, Alexandre Oliva <aoliva@redhat.com> wrote:

> On Mar 28, 2005, Richard Henderson <rth@gcc.gnu.org> wrote:
>> On Thu, Mar 24, 2005 at 07:45:44AM -0300, Alexandre Oliva wrote:
>>> * combine.c (subst): Make sure we don't create invalid subregs.

>> Ok.

> As it turned out, the bug seems to have been fixed by some other
> patch, because I no longer get the error in mainline or in the 4.0
> branch.

Or perhaps it never actually failed on x86_64-linux-gnu, which is
where I was trying to trigger it again.  Not even with -m32.  A build
on i686-pc-linux-gnu was enough to trigger it.  Yay me! :-)

So, the patch posted in my previous e-mail still stands, but if you,
like me, find that it's working too hard to avoid such subregs, here's
an alternative patch that also fixes the problem, at least as long as
the X-constrained asm operand is not actually used in the asm output
pattern.

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-- 
Alexandre Oliva             http://www.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}