Alex Coplan <alex.cop...@arm.com> writes:
> As the PR shows, the fix in
> r14-6916-g057dc349021660c40699fb5c98fd9cac8e168653 was not complete.
> That fix was enough to stop us trying to move throwing accesses above
> nondebug insns, but due to this code in try_fuse_pair:
>
> // Placement strategy: push loads down and pull stores up, this should
> // help register pressure by reducing live ranges.
> if (load_p)
> range.first = range.last;
> else
> range.last = range.first;
>
> we would still try to move stores up above any debug insns that occurred
> immediately after the previous nondebug insn. This patch fixes that by
> narrowing the move range in the case that the second access is throwing
> to exactly the range of that insn.
>
> Note that we still need the fix to latest_hazard_before mentioned above
> so as to ensure we select a suitable base and reject pairs if it isn't
> viable to form the pair at the end of the BB.
>
> Bootstrapped/regtested on aarch64-linux-gnu, OK for trunk?
>
> Thanks,
> Alex
>
> gcc/ChangeLog:
>
> PR target/113217
> * config/aarch64/aarch64-ldp-fusion.cc
> (ldp_bb_info::try_fuse_pair): If the second access can throw,
> narrow the move range to exactly that insn.
>
> gcc/testsuite/ChangeLog:
>
> PR target/113217
> * g++.dg/pr113217.C: New test.
OK, thanks.
Richard
> diff --git a/gcc/config/aarch64/aarch64-ldp-fusion.cc
> b/gcc/config/aarch64/aarch64-ldp-fusion.cc
> index 25f9b2d01c5..2fe1b1d4d84 100644
> --- a/gcc/config/aarch64/aarch64-ldp-fusion.cc
> +++ b/gcc/config/aarch64/aarch64-ldp-fusion.cc
> @@ -2195,6 +2195,15 @@ ldp_bb_info::try_fuse_pair (bool load_p, unsigned
> access_size,
> if (base->hazards[0])
> range.last = base->hazards[0]->prev_nondebug_insn ();
>
> + // If the second insn can throw, narrow the move range to exactly that
> insn.
> + // This prevents us trying to move the second insn from the end of the BB.
> + if (cfun->can_throw_non_call_exceptions
> + && find_reg_note (insns[1]->rtl (), REG_EH_REGION, NULL_RTX))
> + {
> + gcc_assert (range.includes (insns[1]));
> + range = insn_range_info (insns[1]);
> + }
> +
> // Placement strategy: push loads down and pull stores up, this should
> // help register pressure by reducing live ranges.
> if (load_p)
> diff --git a/gcc/testsuite/g++.dg/pr113217.C b/gcc/testsuite/g++.dg/pr113217.C
> new file mode 100644
> index 00000000000..ec861543930
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/pr113217.C
> @@ -0,0 +1,15 @@
> +// { dg-do compile }
> +// { dg-options "-O -g -fnon-call-exceptions" }
> +struct _Vector_base {
> + int _M_end_of_storage;
> +};
> +struct vector : _Vector_base {
> + vector() : _Vector_base() {}
> + ~vector();
> +};
> +struct LoadGraph {
> + LoadGraph();
> + vector colors;
> + vector data_block;
> +};
> +LoadGraph::LoadGraph() {}
