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Re: [PATCH] Fix ICE with __builtin_unreachable() as only statement in a function.


On Tue, Jun 16, 2009 at 11:18 AM, David Daney<ddaney@caviumnetworks.com> wrote:
> This patch fixed an ICE I found doing additional __builtin_unreachable()
> ?testing.
>
> If __builtin_unreachable() is the only statement in a function, the
> resulting barrier will be the first non-note insn when doing barrier
> cleanup. ?This causes SIGSEGV in cleanup_barriers. ?The fix is to check for
> NULL before dereferencing.
>
> Tested on x86_64-pc-linux-gnu all default languages. ?No regressions found.
>

Is this the same as

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40445

If yes, you should include PR in ChangeLog.


H.J.
> OK to commit?
>
> gcc/
> 2009-06-16 ?David Daney ?<ddaney@caviumnetworks.com>
>
> ? ? ? ?* jump.c (cleanup_barriers): Handle case of no insns before a
> ? ? ? ?barrier.
>
> gcc/testsuite/
> 2009-06-16 ?David Daney ?<ddaney@caviumnetworks.com>
>
> ? ? ? ?* gcc.dg/builtin-unreachable-3.c: New test.
>
> Index: gcc/testsuite/gcc.dg/builtin-unreachable-3.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/builtin-unreachable-3.c ? ? ? ?(revision 0)
> +++ gcc/testsuite/gcc.dg/builtin-unreachable-3.c ? ? ? ?(revision 0)
> @@ -0,0 +1,9 @@
> +/* Check that a function containing only __builtin_unreachable()
> + ? doesn't ICE. ?*/
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */
> +const char *
> +f (void)
> +{
> + ?__builtin_unreachable ();
> +}
> Index: gcc/jump.c
> ===================================================================
> --- gcc/jump.c ?(revision 148409)
> +++ gcc/jump.c ?(working copy)
> @@ -113,6 +113,11 @@ cleanup_barriers (void)
> ? ? ? if (BARRIER_P (insn))
> ? ? ? ?{
> ? ? ? ? ?prev = prev_nonnote_insn (insn);
> + ? ? ? ? /* A function that contains only __builtin_unreachable() may
> + ? ? ? ? ? ?start with a barrier. ?In this case PREV will be
> + ? ? ? ? ? ?NULL. ?*/
> + ? ? ? ? if (!prev)
> + ? ? ? ? ? continue;
> ? ? ? ? ?if (BARRIER_P (prev))
> ? ? ? ? ? ?delete_insn (insn);
> ? ? ? ? ?else if (prev != PREV_INSN (insn))
>
>



-- 
H.J.


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