On Wed, Feb 23, 2022 at 11:44 PM Alexandre Oliva via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
>
> When we duplicate a throwing compare for hardening, the EH edge from
> the original compare gets duplicated for the inverted compare, but we
> failed to adjust any PHI nodes in the EH block. This patch adds the
> needed adjustment, copying the PHI args from those of the preexisting
> edge.
>
> Regstrapped on x86_64-linux-gnu. Ok to install?
OK.
>
> for gcc/ChangeLog
>
> PR tree-optimization/103856
> * gimple-harden-conditionals.cc (non_eh_succ_edge): Enable the
> eh edge to be requested through an extra parameter.
> (pass_harden_compares::execute): Copy PHI args in the EH dest
> block for the new EH edge added for the inverted compare.
>
> for gcc/testsuite/ChangeLog
>
> PR tree-optimization/103856
> * g++.dg/pr103856.C: New.
> ---
> gcc/gimple-harden-conditionals.cc | 31 ++++++++++++++++++++++++++++---
> gcc/testsuite/g++.dg/pr103856.C | 17 +++++++++++++++++
> 2 files changed, 45 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/pr103856.C
>
> diff --git a/gcc/gimple-harden-conditionals.cc
> b/gcc/gimple-harden-conditionals.cc
> index 9418194cb20c2..6a5fc3fb9e1a2 100644
> --- a/gcc/gimple-harden-conditionals.cc
> +++ b/gcc/gimple-harden-conditionals.cc
> @@ -361,9 +361,9 @@ make_pass_harden_conditional_branches (gcc::context *ctxt)
> }
>
> /* Return the fallthru edge of a block whose other edge is an EH
> - edge. */
> + edge. If EHP is not NULL, store the EH edge in it. */
> static inline edge
> -non_eh_succ_edge (basic_block bb)
> +non_eh_succ_edge (basic_block bb, edge *ehp = NULL)
> {
> gcc_checking_assert (EDGE_COUNT (bb->succs) == 2);
>
> @@ -375,6 +375,9 @@ non_eh_succ_edge (basic_block bb)
> gcc_checking_assert (!(ret->flags & EDGE_EH)
> && (eh->flags & EDGE_EH));
>
> + if (ehp)
> + *ehp = eh;
> +
> return ret;
> }
>
> @@ -538,8 +541,9 @@ pass_harden_compares::execute (function *fun)
> add_stmt_to_eh_lp (asgnck, lookup_stmt_eh_lp (asgn));
> make_eh_edges (asgnck);
>
> + edge ckeh;
> basic_block nbb = split_edge (non_eh_succ_edge
> - (gimple_bb (asgnck)));
> + (gimple_bb (asgnck), &ckeh));
> gsi_split = gsi_start_bb (nbb);
>
> if (dump_file)
> @@ -547,6 +551,27 @@ pass_harden_compares::execute (function *fun)
> "Splitting non-EH edge from block %i into %i after"
> " the newly-inserted reversed throwing compare\n",
> gimple_bb (asgnck)->index, nbb->index);
> +
> + if (!gimple_seq_empty_p (phi_nodes (ckeh->dest)))
> + {
> + edge aseh;
> + non_eh_succ_edge (gimple_bb (asgn), &aseh);
> +
> + gcc_checking_assert (aseh->dest == ckeh->dest);
> +
> + for (gphi_iterator psi = gsi_start_phis (ckeh->dest);
> + !gsi_end_p (psi); gsi_next (&psi))
> + {
> + gphi *phi = psi.phi ();
> + add_phi_arg (phi, PHI_ARG_DEF_FROM_EDGE (phi, aseh), ckeh,
> + gimple_phi_arg_location_from_edge (phi,
> aseh));
> + }
> +
> + if (dump_file)
> + fprintf (dump_file,
> + "Copying PHI args in EH block %i from %i to %i\n",
> + aseh->dest->index, aseh->src->index,
> ckeh->src->index);
> + }
> }
>
> gcc_checking_assert (single_succ_p (gsi_bb (gsi_split)));
> diff --git a/gcc/testsuite/g++.dg/pr103856.C b/gcc/testsuite/g++.dg/pr103856.C
> new file mode 100644
> index 0000000000000..26c7d8750255a
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/pr103856.C
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-Og -fnon-call-exceptions -fsignaling-nans
> -fharden-compares" } */
> +
> +struct S {
> + S(float);
> + S();
> + operator float();
> + ~S() {}
> +};
> +
> +int
> +main() {
> + S s_arr[] = {2};
> + S var1;
> + if (var1)
> + ;
> +}
>
>
> --
> Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/
> Free Software Activist GNU Toolchain Engineer
> Disinformation flourishes because many people care deeply about injustice
> but very few check the facts. Ask me about <https://stallmansupport.org>
