Re: [PATCH] combine: Fix PR80233

[Jakub Jelinek <jakub@redhat.com>]

On Wed, Mar 29, 2017 at 02:35:32PM -0600, Jeff Law wrote:
> On 03/29/2017 12:23 PM, Segher Boessenkool wrote:
> > If combine has added an unconditional trap there will be a new basic
> > block as well.  It will then end up considering the NOTE_INSN_BASIC_BLOCK
> > as the last_combined_insn, but then it tries to take the DF_INSN_LUID
> > of that and that dereferences a NULL pointer (since such a note is not
> > an INSN_P).
> > 
> > This fixes it by not taking non-insns as last_combined_insn.
> > 
> > Bootstrapped and tested on powerpc64-linux {-m32,-m64}.
> > 
> > 
> > Segher
> > 
> > 
> > 2017-03-29  Segher Boessenkool  <segher@kernel.crashing.org>
> > 
> > 	PR rtl-optimization/80233
> > 	* combine.c (combine_instructions): Only take NONDEBUG_INSN_P insns
> > 	as last_combined_insn.  Do not test for BARRIER_P separately.
> > 
> > gcc/testsuite/
> > 	PR rtl-optimization/80233
> > 	* gcc.c-torture/compile/pr80233.c: New testcase.
> No strong opinions on this vs Jakub's patch.  I guess yours may walk more
> objects on the chain, but in doing so is more likely to find a useful
> LAST_COMBINED_INSN.  Jakub's stops earlier, but is less likely to have
> stopped on something useful.
> 
> Your call Segher.

I like Segher's latest patch.  But it is his call anyway ;)

	Jakub