On Wed, Apr 23, 2025 at 6:00 AM Andrew Pinski <quic_apin...@quicinc.com> wrote:
>
> Since match and simplify will simplify `bool_var != 0` to just `bool_var` and
> this is inside a GIMPLE_COND, fold_stmt will return true but nothing has
> changed.
> So let's just reject the replacement if we are replacing with the same
> simplification
> inside replace_stmt_with_simplification. This can speed up things slightly
> because
> now fold_stmt won't return true on all GIMPLE_COND with `bool_var != 0` in it.
OK. Note the same should happen for code == INTEGER_CST where we should
return false if the cond is already gimple_cond_false/true_p (but we
should still
canonicalize, thus make_true/false there or more literally just avoid
returning true
for the exact same form generated).
Richard.
> gcc/ChangeLog:
>
> * gimple-fold.cc (replace_stmt_with_simplification): Return false
> if replacing `bool_var != 0` with `bool_var` in GIMPLE_COND.
>
> Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> ---
> gcc/gimple-fold.cc | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
> index 2381a82d2b1..de1f1a44aa3 100644
> --- a/gcc/gimple-fold.cc
> +++ b/gcc/gimple-fold.cc
> @@ -6246,8 +6246,16 @@ replace_stmt_with_simplification (gimple_stmt_iterator
> *gsi,
> false, NULL_TREE)))
> gimple_cond_set_condition (cond_stmt, code, ops[0], ops[1]);
> else if (code == SSA_NAME)
> - gimple_cond_set_condition (cond_stmt, NE_EXPR, ops[0],
> - build_zero_cst (TREE_TYPE (ops[0])));
> + {
> + /* If setting the gimple cond to the same thing,
> + return false as nothing changed. */
> + if (gimple_cond_code (cond_stmt) == NE_EXPR
> + && operand_equal_p (gimple_cond_lhs (cond_stmt), ops[0])
> + && integer_zerop (gimple_cond_rhs (cond_stmt)))
> + return false;
> + gimple_cond_set_condition (cond_stmt, NE_EXPR, ops[0],
> + build_zero_cst (TREE_TYPE (ops[0])));
> + }
> else if (code == INTEGER_CST)
> {
> if (integer_zerop (ops[0]))
> --
> 2.43.0
>
