On Thu, Mar 24, 2022 at 2:43 AM Alexandre Oliva via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
>
> If we harden a compare at the end of a block with an edge to the
> abnormal dispatch block, it won't have a single successor. Arrange to
> split the block at its final stmt so as to have a single succ.
>
> Regstrapped on x86_64-linux-gnu. Ok to install?
OK.
>
> for gcc/ChangeLog
>
> PR middle-end/104975
> * gimple-harden-conditionals.cc
> (pass_harden_compares::execute): Force split in case of
> multiple edges.
>
> for gcc/testsuite/ChangeLog
>
> PR middle-end/104975
> * gcc.dg/pr104975.c: New.
> ---
> gcc/gimple-harden-conditionals.cc | 12 +++++++++---
> gcc/testsuite/gcc.dg/pr104975.c | 20 ++++++++++++++++++++
> 2 files changed, 29 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/pr104975.c
>
> diff --git a/gcc/gimple-harden-conditionals.cc
> b/gcc/gimple-harden-conditionals.cc
> index 6a5fc3fb9e1a2..be01f3ea8c44a 100644
> --- a/gcc/gimple-harden-conditionals.cc
> +++ b/gcc/gimple-harden-conditionals.cc
> @@ -509,10 +509,16 @@ pass_harden_compares::execute (function *fun)
> gsi_insert_before (&gsi_split, asgnck, GSI_SAME_STMT);
>
> /* We wish to insert a cond_expr after the compare, so arrange
> - for it to be at the end of a block if it isn't. */
> - if (!gsi_end_p (gsi_split))
> + for it to be at the end of a block if it isn't, and for it
> + to have a single successor in case there's more than
> + one, as in PR104975. */
> + if (!gsi_end_p (gsi_split)
> + || !single_succ_p (gsi_bb (gsi_split)))
> {
> - gsi_prev (&gsi_split);
> + if (!gsi_end_p (gsi_split))
> + gsi_prev (&gsi_split);
> + else
> + gsi_split = gsi_last_bb (gsi_bb (gsi_split));
> basic_block obb = gsi_bb (gsi_split);
> basic_block nbb = split_block (obb, gsi_stmt (gsi_split))->dest;
> gsi_next (&gsi_split);
> diff --git a/gcc/testsuite/gcc.dg/pr104975.c b/gcc/testsuite/gcc.dg/pr104975.c
> new file mode 100644
> index 0000000000000..04532fc444340
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr104975.c
> @@ -0,0 +1,20 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fharden-compares -fno-inline -fno-ipa-pure-const" } */
> +
> +__attribute__ ((pure, returns_twice)) int
> +bar (int);
> +
> +int
> +quux (void)
> +{
> + return 0;
> +}
> +
> +int
> +foo (short int x)
> +{
> + x = !x;
> + bar (quux ());
> +
> + return x;
> +}
>
>
> --
> 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>
