On Fri, May 9, 2025 at 5:00 AM Andrew Pinski <quic_apin...@quicinc.com> wrote:
>
> This removes the ability to follow statements that can throw internally.
> This was suggested in bug report as a way to solve the issue here.
> The overhead is not that high since without non-call exceptions turned
> on, there is an early exit for non-calls.
So - the testcase doesn't ICE for me any longer. I know I suggested this
as a possible solution but I don't like it very much - one reason is because
stmt_can_throw_internal asserts on cfun != nullptr and conservative handling
would mean we can't do any get_def () from IPA w/o switching it a function.
The other reason is that we do get_def() a lot (yeah, it's very much quite
unoptimized in genmatch generated code). So there's work to do there
(we also often valueize twice).
It seems we can defer this now? The bug was closed at least.
Richard.
> PR tree-optimization/119903
>
> gcc/ChangeLog:
>
> * gimple-match-head.cc (get_def): Reject statements that can throw
> internally.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/tree-ssa/pr119903-1.C: New test.
>
> Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> ---
> gcc/gimple-match-head.cc | 5 ++++-
> gcc/testsuite/g++.dg/tree-ssa/pr119903-1.C | 24 ++++++++++++++++++++++
> 2 files changed, 28 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/g++.dg/tree-ssa/pr119903-1.C
>
> diff --git a/gcc/gimple-match-head.cc b/gcc/gimple-match-head.cc
> index 6b3c5febbea..62ff8e57fbb 100644
> --- a/gcc/gimple-match-head.cc
> +++ b/gcc/gimple-match-head.cc
> @@ -63,7 +63,10 @@ get_def (tree (*valueize)(tree), tree name)
> {
> if (valueize && ! valueize (name))
> return NULL;
> - return SSA_NAME_DEF_STMT (name);
> + gimple *t = SSA_NAME_DEF_STMT (name);
> + if (stmt_can_throw_internal (cfun, t))
> + return nullptr;
> + return t;
> }
>
> /* Routine to determine if the types T1 and T2 are effectively
> diff --git a/gcc/testsuite/g++.dg/tree-ssa/pr119903-1.C
> b/gcc/testsuite/g++.dg/tree-ssa/pr119903-1.C
> new file mode 100644
> index 00000000000..605f989a2eb
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/tree-ssa/pr119903-1.C
> @@ -0,0 +1,24 @@
> +// { dg-do compile { target c++11 } }
> +// { dg-options "-O2 -fnon-call-exceptions -ftrapping-math
> -fdump-tree-optimized-eh" }
> +
> +// PR tree-optimization/119903
> +// match and simplify would cause the internal throwable fp comparison
> +// to become only external throwable and lose the landing pad.
> +
> +int f() noexcept;
> +int g() noexcept;
> +
> +int m(double a)
> +{
> + try {
> + if (a < 1.0)
> + return f();
> + return g();
> + }catch(...)
> + {
> + return -1;
> + }
> +}
> +
> +// Make sure There is a landing pad for the non-call exception from the
> comparison.
> +// { dg-final { scan-tree-dump "LP " "optimized" } }
> --
> 2.43.0
>
