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Re: other/7114: ICE building strcoll.op from glibc-2.2.5
- From: Alan Modra <amodra at bigpond dot net dot au>
- To: Geoff Keating <geoffk at redhat dot com>
- Cc: d dot mueller at elsoft dot ch, gcc-gnats at gcc dot gnu dot org, gcc-patches at gcc dot gnu dot org, dje at watson dot ibm dot com
- Date: Tue, 16 Jul 2002 09:20:27 +0930
- Subject: Re: other/7114: ICE building strcoll.op from glibc-2.2.5
- References: <20020625081846.10430.qmail@sources.redhat.com> <20020715092603.GS30362@bubble.sa.bigpond.net.au> <200207151943.g6FJh2r26360@desire.geoffk.org>
On Mon, Jul 15, 2002 at 12:43:02PM -0700, Geoff Keating wrote:
> > Date: Mon, 15 Jul 2002 18:56:03 +0930
> > From: Alan Modra <amodra@bigpond.net.au>
>
> > This patch cures the testcase. The !using_store_multiple code tests
> > whether regs are live before saving. We need to do something similar
> > for using_store_multiple, in case all regs need not be saved.
>
> Those registers are actually saved, whether they need to be or not,
> correct?
>
> So the RTL generated is an accurate representation of the instruction,
> and the bug must be elsewhere.
The testcase saves r30 and r31, but both are marked unused (don't
appear in regs_ever_live). Later rtl analysis decides that the
save instruction can be eliminated, thus the ICE. The real bug is
that r30 is not marked used when current_function_needs_context.
This is also the reason for PR5967.
The code that I copied from the !using_store_multiple case just
papers over this bug. So the above patch merely makes -mmultiple
and -mno-multiple consistently wrong.
--
Alan Modra
IBM OzLabs - Linux Technology Centre