On Wed, Aug 6, 2025 at 7:30 PM Andrew Pinski <quic_apin...@quicinc.com> wrote:
>
> In the testcase provided, currently we lose the landing pad for the exception
> that could
> throw from the aggregate load as we remove one copy and the second statement
> where load
> happens was not marked as throwable before so the landing pad for that
> internal throw is
> now gone.
>
> The fix is to ignore statements that could throw (internally or externally).
OK.
Thanks,
Richard.
> PR tree-optimization/120599
>
> gcc/ChangeLog:
>
> * tree-ssa-forwprop.cc (optimize_agr_copyprop): Don't try to copy
> from statements that throw.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/torture/noncall-eh-1.C: New test.
>
> Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> ---
> gcc/testsuite/g++.dg/torture/noncall-eh-1.C | 26 +++++++++++++++++++++
> gcc/tree-ssa-forwprop.cc | 4 ++++
> 2 files changed, 30 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/torture/noncall-eh-1.C
>
> diff --git a/gcc/testsuite/g++.dg/torture/noncall-eh-1.C
> b/gcc/testsuite/g++.dg/torture/noncall-eh-1.C
> new file mode 100644
> index 00000000000..ea8fd7953f5
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/torture/noncall-eh-1.C
> @@ -0,0 +1,26 @@
> +// { dg-do compile }
> +// For slim LTO there's no optimized dump
> +// { dg-skip-if "" { *-*-* } { "-flto" } { "" } }
> +// { dg-additional-options "-fnon-call-exceptions -fexceptions
> -fdump-tree-optimized-eh" }
> +
> +// PR tree-optimization/120599
> +// Copying prop for aggregates should not touch `a = *__val` since that
> statement
> +// can throw (internally) so we need to be able to keep the landing pad.
> +
> +struct RefitOption {
> + char subtype;
> + int string;
> +} n;
> +void h(RefitOption) __attribute__((nothrow));
> +void k(RefitOption *__val, RefitOption a)
> +{
> + try {
> + a = *__val;
> + RefitOption __trans_tmp_2 = a;
> + h(__trans_tmp_2);
> + }
> + catch(...){}
> +}
> +
> +// Make sure There is a landing pad for the non-call exception from the
> aggregate load.
> +// { dg-final { scan-tree-dump "LP " "optimized" } }
> diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc
> index 156ea322867..3d38d88844b 100644
> --- a/gcc/tree-ssa-forwprop.cc
> +++ b/gcc/tree-ssa-forwprop.cc
> @@ -1417,6 +1417,10 @@ optimize_agr_copyprop (gimple_stmt_iterator *gsip)
> if (gimple_has_volatile_ops (stmt))
> return false;
>
> + /* Can't prop if the statement could throw. */
> + if (stmt_could_throw_p (cfun, stmt))
> + return false;
> +
> tree dest = gimple_assign_lhs (stmt);
> tree src = gimple_assign_rhs1 (stmt);
> /* If the statement is `src = src;` then ignore it. */
> --
> 2.43.0
>
