[PATCH] vect: Look through pattern stmt in fold_left_reduction.

[PATCH] vect: Look through pattern stmt in fold_left_reduction.

[Robin Dapp]

Hi,

more fallout from the COND_OP change was shown in PR112464.

It appears as if we "look through" a statement pattern in
vect_finish_replace_stmt but not before when we replace the newly
created vector statement's lhs.  Then the lhs is the statement pattern's
lhs while in vect_finish_replace_stmt we assert that it's from the
statement the pattern replaced.

This patch uses vect_orig_stmt on the scalar destination's definition
so the replaced statement is used everywhere.

Bootstrapped and regtested on x86 and aarch64, riscv testsuite
unchanged.

Regards
 Robin

gcc/ChangeLog:

	PR tree-optimization/112464

	* tree-vect-loop.cc (vectorize_fold_left_reduction): Use
        vect_orig_stmt on scalar_dest_def_info.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr112464.c: New test.
---
 gcc/testsuite/gcc.target/i386/pr112464.c | 10 ++++++++++
 gcc/tree-vect-loop.cc                    |  2 +-
 2 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr112464.c

diff --git a/gcc/testsuite/gcc.target/i386/pr112464.c b/gcc/testsuite/gcc.target/i386/pr112464.c
new file mode 100644
index 00000000000..2290c714986
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr112464.c
@@ -0,0 +1,10 @@
+/* { dg-do compile }  */
+/* { dg-options "-Ofast -mavx512dq -ftrapv" } */
+
+long *e;
+int n, i, err;
+void fn() {
+  for (; i < n; i++)
+    if (e[i])
+      err++;
+}
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 8abc1937d74..f61adad1ca3 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -7087,7 +7087,7 @@ vectorize_fold_left_reduction (loop_vec_info loop_vinfo,
 					 opmask, &vec_opmask);
     }
 
-  gimple *sdef = scalar_dest_def_info->stmt;
+  gimple *sdef = vect_orig_stmt (scalar_dest_def_info)->stmt;
   tree scalar_dest = gimple_get_lhs (sdef);
   tree scalar_type = TREE_TYPE (scalar_dest);
   tree reduc_var = gimple_phi_result (reduc_def_stmt);
-- 
2.41.0

Re: [PATCH] vect: Look through pattern stmt in fold_left_reduction.

[Richard Biener]

On Fri, Nov 10, 2023 at 10:06 AM Robin Dapp <rdapp.gcc@gmail.com> wrote:
>
> Hi,
>
> more fallout from the COND_OP change was shown in PR112464.
>
> It appears as if we "look through" a statement pattern in
> vect_finish_replace_stmt but not before when we replace the newly
> created vector statement's lhs.  Then the lhs is the statement pattern's
> lhs while in vect_finish_replace_stmt we assert that it's from the
> statement the pattern replaced.
>
> This patch uses vect_orig_stmt on the scalar destination's definition
> so the replaced statement is used everywhere.
>
> Bootstrapped and regtested on x86 and aarch64, riscv testsuite
> unchanged.

OK

> Regards
>  Robin
>
> gcc/ChangeLog:
>
>         PR tree-optimization/112464
>
>         * tree-vect-loop.cc (vectorize_fold_left_reduction): Use
>         vect_orig_stmt on scalar_dest_def_info.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/i386/pr112464.c: New test.
> ---
>  gcc/testsuite/gcc.target/i386/pr112464.c | 10 ++++++++++
>  gcc/tree-vect-loop.cc                    |  2 +-
>  2 files changed, 11 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr112464.c
>
> diff --git a/gcc/testsuite/gcc.target/i386/pr112464.c b/gcc/testsuite/gcc.target/i386/pr112464.c
> new file mode 100644
> index 00000000000..2290c714986
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr112464.c
> @@ -0,0 +1,10 @@
> +/* { dg-do compile }  */
> +/* { dg-options "-Ofast -mavx512dq -ftrapv" } */
> +
> +long *e;
> +int n, i, err;
> +void fn() {
> +  for (; i < n; i++)
> +    if (e[i])
> +      err++;
> +}
> diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> index 8abc1937d74..f61adad1ca3 100644
> --- a/gcc/tree-vect-loop.cc
> +++ b/gcc/tree-vect-loop.cc
> @@ -7087,7 +7087,7 @@ vectorize_fold_left_reduction (loop_vec_info loop_vinfo,
>                                          opmask, &vec_opmask);
>      }
>
> -  gimple *sdef = scalar_dest_def_info->stmt;
> +  gimple *sdef = vect_orig_stmt (scalar_dest_def_info)->stmt;
>    tree scalar_dest = gimple_get_lhs (sdef);
>    tree scalar_type = TREE_TYPE (scalar_dest);
>    tree reduc_var = gimple_phi_result (reduc_def_stmt);
> --
> 2.41.0