other/7114: ICE building strcoll.op from glibc-2.2.5

[Alan Modra]

The following reply was made to PR other/7114; it has been noted by GNATS.

From: Alan Modra <amodra@bigpond.net.au>
To: Geoff Keating <geoffk@redhat.com>
Cc: d.mueller@elsoft.ch, gcc-gnats@gcc.gnu.org, gcc-patches@gcc.gnu.org,
  dje@watson.ibm.com
Subject: Re: other/7114: ICE building strcoll.op from glibc-2.2.5
Date: Tue, 16 Jul 2002 09:20:27 +0930

 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