Re: [PATCH] Fix ICE in rewrite_expr_tree_parallel

[Richard Biener <richard.guenther@gmail.com>]

On Wed, May 31, 2023 at 3:35 AM Cui, Lili <lili.cui@intel.com> wrote:
>
> Hi,
>
> This patch is to fix ICE in rewrite_expr_tree_parallel.
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110038
>
> Bootstrapped and regtested. Ok for trunk?

OK.

> Regards
> Lili.
>
> 1. Limit the value of tree-reassoc-width to IntegerRange(0, 256).
> 2. Add width limit in rewrite_expr_tree_parallel.
>
> gcc/ChangeLog:
>
>         PR tree-optimization/110038
>         * params.opt: Add a limit on tree-reassoc-width.
>         * tree-ssa-reassoc.cc
>         (rewrite_expr_tree_parallel): Add width limit.
>
> gcc/testsuite/ChangeLog:
>
>         PR tree-optimization/110038
>         * gcc.dg/pr110038.c: New test.
> ---
>  gcc/params.opt                  |  2 +-
>  gcc/testsuite/gcc.dg/pr110038.c | 10 ++++++++++
>  gcc/tree-ssa-reassoc.cc         |  3 +++
>  3 files changed, 14 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.dg/pr110038.c
>
> diff --git a/gcc/params.opt b/gcc/params.opt
> index 66f1c99036a..70cfb495e3a 100644
> --- a/gcc/params.opt
> +++ b/gcc/params.opt
> @@ -1091,7 +1091,7 @@ Common Joined UInteger Var(param_tracer_min_branch_ratio) Init(10) IntegerRange(
>  Stop reverse growth if the reverse probability of best edge is less than this threshold (in percent).
>
>  -param=tree-reassoc-width=
> -Common Joined UInteger Var(param_tree_reassoc_width) Param Optimization
> +Common Joined UInteger Var(param_tree_reassoc_width) IntegerRange(0, 256) Param Optimization
>  Set the maximum number of instructions executed in parallel in reassociated tree.  If 0, use the target dependent heuristic.
>
>  -param=tsan-distinguish-volatile=
> diff --git a/gcc/testsuite/gcc.dg/pr110038.c b/gcc/testsuite/gcc.dg/pr110038.c
> new file mode 100644
> index 00000000000..0f578b182ca
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr110038.c
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O --param=tree-reassoc-width=256" } */
> +
> +unsigned a, b;
> +
> +void
> +foo (unsigned c)
> +{
> +  a += b + c + 1;
> +}
> diff --git a/gcc/tree-ssa-reassoc.cc b/gcc/tree-ssa-reassoc.cc
> index ad2f528ff07..f8055d59d57 100644
> --- a/gcc/tree-ssa-reassoc.cc
> +++ b/gcc/tree-ssa-reassoc.cc
> @@ -5510,6 +5510,9 @@ rewrite_expr_tree_parallel (gassign *stmt, int width, bool has_fma,
>    for (i = stmt_num - 2; i >= 0; i--)
>      stmts[i] = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (stmts[i+1]));
>
> +   /* Width should not be larger than op_num/2.  */
> +   width = width <= op_num / 2 ? width : op_num / 2;
> +
>    /* Build parallel dependency chain according to width.  */
>    for (i = 0; i < width; i++)
>      {
> --
> 2.25.1
>