On Sat, May 10, 2025 at 3:19 AM Andrew Pinski <quic_apin...@quicinc.com> wrote:
>
> with -ftrapping-math -fnon-call-exceptions and:
> ```
> tmp = FP0 CMP FP1;
>
> if (tmp != 0) ...
> ```
> a call fold_stmt on the GIMPLE_COND will replace the above with
> a new tmp each time and we even lose the eh informatin on the
> previous comparison too.
>
> gcc/ChangeLog:
>
> * gimple-fold.cc (replace_stmt_with_simplification): Reject for
> noncall exceptions replacing comparison with itself.
>
> Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> ---
> gcc/gimple-fold.cc | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
> index 7b3a3d30045..4ff5dbb8d50 100644
> --- a/gcc/gimple-fold.cc
> +++ b/gcc/gimple-fold.cc
> @@ -6276,6 +6276,32 @@ replace_stmt_with_simplification (gimple_stmt_iterator
> *gsi,
> }
> else if (!inplace)
> {
> + /* For throwing comparisons, see if the GIMPLE_COND is the same as
> + the comparison would be.
> + This can happen due to the match pattern for
> + `(ne (cmp @0 @1) integer_zerop)` which creates a new expression
> + for the comparison. */
> + if (TREE_CODE_CLASS (code) == tcc_comparison
> + && flag_exceptions
> + && cfun->can_throw_non_call_exceptions
I think you should allow !cfun here (aka treat it conservatively).
> + && operation_could_trap_p (code,
> + FLOAT_TYPE_P (TREE_TYPE (ops[0])),
> + false, NULL_TREE))
> + {
> + tree lhs = gimple_cond_lhs (cond_stmt);
> + if (gimple_cond_code (cond_stmt) == NE_EXPR
> + && TREE_CODE (lhs) == SSA_NAME
> + && TREE_CODE (TREE_TYPE (lhs)) == BOOLEAN_TYPE
Not sure about this - IIRC INTEGER_TYPE with appropriate precision
and sign is compatible. I'd just drop this.
Otherwise OK. I prefer this one over guarding the match.pd pattern.
Thanks,
Richard.
> + && integer_zerop (gimple_cond_rhs (cond_stmt)))
> + {
> + gimple *s = SSA_NAME_DEF_STMT (lhs);
> + if (is_gimple_assign (s)
> + && gimple_assign_rhs_code (s) == code
> + && operand_equal_p (gimple_assign_rhs1 (s), ops[0])
> + && operand_equal_p (gimple_assign_rhs2 (s), ops[1]))
> + return false;
> + }
> + }
> tree res = maybe_push_res_to_seq (res_op, seq);
> if (!res)
> return false;
> --
> 2.43.0
>
