[GCC, ARM] Backport trunk fix to 4.8 branch to properly handle rtx of ARM PLD instruction

[Terry Guo]

> -----Original Message-----
> From: Richard Earnshaw
> Sent: Wednesday, January 15, 2014 10:30 PM
> To: Terry Guo
> Cc: gcc-patches@gcc.gnu.org
> Subject: Re: [GCC, ARM] Backport trunk fix to 4.8 branch to properly
handle
> rtx of ARM PLD instruction
> 
> On 15/01/14 12:37, Terry Guo wrote:
> >
> >
> >> -----Original Message-----
> >> From: Terry Guo [mailto:terry.guo@arm.com]
> >> Sent: Wednesday, January 15, 2014 8:21 PM
> >> To: Richard Earnshaw
> >> Cc: gcc-patches@gcc.gnu.org
> >> Subject: RE: [GCC, ARM] Backport trunk fix to 4.8 branch to properly
> > handle
> >> rtx of ARM PLD instruction
> >>
> >>>
> >>> Preferably, particularly since you haven't supplied a testcase.
> >>>
> >>> R.
> >>
> >> Bug is reported at http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59826.
> >> I
> > shall
> >> update the patch to include the test case.
> >>
> >> BR,
> >> Terry
> >
> > Here is updated patch along with test case. Is it OK?
> >
> 
> I'm rather concerned about the complexity of this patch as a backport.
> Furthermore, part of the problem is that the preload insn is misclassified
as
> an alu_reg operation, which it clearly isn't.
> 
> Instead of doing this, please could you try a simpler patch that simply
> reclassifies the "type" of preload as "load1".  This would break the
> alu->load/store dependency and thereby avoid the trigger of the problem
> 
> R.

Thanks Richard and you are right. What you said should be the root cause for
this issue. I will implement another patch for trunk to correctly classify
the preload instruction into load1, and then back port to 4.8 branch.
Therefore please consider my request in this thread discarded.

BR,
Terry