[PATCH] Fix PR 102908: wrongly removing null pointer loads

[PATCH] Fix PR 102908: wrongly removing null pointer loads

[apinski]

From: Andrew Pinski <apinski@marvell.com>

Just like PR 100382, here we have a DCE removing a
null pointer load which is needed still.
In this case, execute_fixup_cfg removes a store (correctly)
and then removes the null load (incorrectly) due to
not checking stmt_unremovable_because_of_non_call_eh_p.
This patch adds the check in the similar way as the patch
to fix PR 100382 did.

gcc/ChangeLog:

	* tree-ssa-dce.c (simple_dce_from_worklist):
	Check stmt_unremovable_because_of_non_call_eh_p also
	before removing the statement.
---
 gcc/tree-ssa-dce.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index 372e0691ae6..1281e67489c 100644
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -1828,6 +1828,11 @@ simple_dce_from_worklist (bitmap worklist)
       if (gimple_has_side_effects (t))
 	continue;
 
+      /* Don't remove statements that are needed for non-call
+	 eh to work.  */
+      if (stmt_unremovable_because_of_non_call_eh_p (cfun, t))
+	continue;
+
       /* Add uses to the worklist.  */
       ssa_op_iter iter;
       use_operand_p use_p;
-- 
2.17.1

Re: [PATCH] Fix PR 102908: wrongly removing null pointer loads

[Richard Biener]

On Sun, Oct 24, 2021 at 11:28 AM apinski--- via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> From: Andrew Pinski <apinski@marvell.com>
>
> Just like PR 100382, here we have a DCE removing a
> null pointer load which is needed still.
> In this case, execute_fixup_cfg removes a store (correctly)
> and then removes the null load (incorrectly) due to
> not checking stmt_unremovable_because_of_non_call_eh_p.
> This patch adds the check in the similar way as the patch
> to fix PR 100382 did.

OK.

Thanks,
Richard.

> gcc/ChangeLog:
>
>         * tree-ssa-dce.c (simple_dce_from_worklist):
>         Check stmt_unremovable_because_of_non_call_eh_p also
>         before removing the statement.
> ---
>  gcc/tree-ssa-dce.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
> index 372e0691ae6..1281e67489c 100644
> --- a/gcc/tree-ssa-dce.c
> +++ b/gcc/tree-ssa-dce.c
> @@ -1828,6 +1828,11 @@ simple_dce_from_worklist (bitmap worklist)
>        if (gimple_has_side_effects (t))
>         continue;
>
> +      /* Don't remove statements that are needed for non-call
> +        eh to work.  */
> +      if (stmt_unremovable_because_of_non_call_eh_p (cfun, t))
> +       continue;
> +
>        /* Add uses to the worklist.  */
>        ssa_op_iter iter;
>        use_operand_p use_p;
> --
> 2.17.1
>