On Fri, Aug 1, 2025 at 10:38 AM <pan2...@intel.com> wrote:
>
> From: Pan Li <pan2...@intel.com>
>
> For mul_overflow api, we will have PHI node similar as below:
>
> _6 = .MUL_OVERFLOW (a_4(D), b_5(D));
> _2 = IMAGPART_EXPR <_6>;
> if (_2 != 0)
> goto <bb 4>; [35.00%]
> else
> goto <bb 3>; [65.00%]
>
> <bb 3> [local count: 697932184]:
> _1 = REALPART_EXPR <_6>;
>
> <bb 4> [local count: 1073741824]:
> # _3 = PHI <18446744073709551615(2), _1(3)>
>
> Based on the help of match.pd pattern match, the widening-mul will
> try to convert it to below:
>
> _3 = .SAT_MUL (a_4(D), b_5(D));
OK
> gcc/ChangeLog:
>
> * tree-ssa-math-opts.cc (match_saturation_mul): Add new func
> to emit IFN_SAT_MUL if matched.
> (math_opts_dom_walker::after_dom_children): Try to match
> the phi node for SAT_MUL.
>
> Signed-off-by: Pan Li <pan2...@intel.com>
> ---
> gcc/tree-ssa-math-opts.cc | 36 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/tree-ssa-math-opts.cc b/gcc/tree-ssa-math-opts.cc
> index ca98205d58f..591ecd387a6 100644
> --- a/gcc/tree-ssa-math-opts.cc
> +++ b/gcc/tree-ssa-math-opts.cc
> @@ -4241,6 +4241,39 @@ match_unsigned_saturation_mul (gimple_stmt_iterator
> *gsi, gassign *stmt)
> ops[0], ops[1]);
> }
>
> +/* Try to match saturation unsigned mul, aka:
> + _6 = .MUL_OVERFLOW (a_4(D), b_5(D));
> + _2 = IMAGPART_EXPR <_6>;
> + if (_2 != 0)
> + goto <bb 4>; [35.00%]
> + else
> + goto <bb 3>; [65.00%]
> +
> + <bb 3> [local count: 697932184]:
> + _1 = REALPART_EXPR <_6>;
> +
> + <bb 4> [local count: 1073741824]:
> + # _3 = PHI <18446744073709551615(2), _1(3)>
> + =>
> + _3 = .SAT_MUL (a_4(D), b_5(D)); */
> +
> +static bool
> +match_saturation_mul (gimple_stmt_iterator *gsi, gphi *phi)
> +{
> + if (gimple_phi_num_args (phi) != 2)
> + return false;
> +
> + tree ops[2];
> + tree phi_result = gimple_phi_result (phi);
> +
> + if (!gimple_unsigned_integer_sat_mul (phi_result, ops, NULL))
> + return false;
> +
> + return build_saturation_binary_arith_call_and_insert (gsi, IFN_SAT_MUL,
> + phi_result, ops[0],
> + ops[1]);
> +}
> +
> /*
> * Try to match saturation unsigned sub.
> * <bb 2> [local count: 1073741824]:
> @@ -6417,7 +6450,8 @@ math_opts_dom_walker::after_dom_children (basic_block
> bb)
>
> if (match_saturation_add (&gsi, phi)
> || match_saturation_sub (&gsi, phi)
> - || match_saturation_trunc (&gsi, phi))
> + || match_saturation_trunc (&gsi, phi)
> + || match_saturation_mul (&gsi, phi))
> remove_phi_node (&psi, /* release_lhs_p */ false);
> }
>
> --
> 2.43.0
>
