Thanks Richard.
>> + (convert (widen_mult:c@3 (convert@4 (convert @0))
>> So I added 2 times convert to match above sematics. Do you indicate that we
>> only need one convert here?
> Yes, the above extra widening looks odd to me.
Remove the inner convert of (convert @0)) will make the pattern fail to match.
The after_dom_children will meet MUL_EXPR first and then the
convert_mult_to_widen
will introduce the convert, as well as wide_mult.
The 220t.fab1 doesn't have wide_mult, so I think we need to move the sat_mul
before widening_mul pass to get ride of the
Inner convert up to a point.
20 │ _1 = (__int128 unsigned) a_8(D);
21 │ _2 = (__int128 unsigned) b_9(D);
22 │ x_10 = _1 * _2;
23 │ _3 = x_10 >> 16;
24 │ hi_11 = (uint16_t) _3;
25 │ _4 = hi_11 != 0;
26 │ _14 = (signed short) _4;
27 │ _5 = -_14;
28 │ lo.0_6 = (signed short) x_10;
29 │ _7 = _5 | lo.0_6;
30 │ _12 = (uint16_t) _7;
The 2 times covert will be present from 272t.optmized two.
Pan
-----Original Message-----
From: Richard Biener <richard.guent...@gmail.com>
Sent: Tuesday, September 2, 2025 10:01 PM
To: Li, Pan2 <pan2...@intel.com>
Cc: gcc-patches@gcc.gnu.org; juzhe.zh...@rivai.ai; kito.ch...@gmail.com;
jeffreya...@gmail.com; rdapp....@gmail.com; Chen, Ken <ken.c...@intel.com>;
Liu, Hongtao <hongtao....@intel.com>
Subject: Re: [PATCH v1 1/2] Match: Add form 5 of unsigned SAT_MUL for widen-mul
On Tue, Sep 2, 2025 at 3:35 PM Li, Pan2 <pan2...@intel.com> wrote:
>
> Thanks Richard for comments.
>
> > Are the inner (convert ..) around @0 and @1 necessary? The whole
> > thing as written seems to match (long)(short)x * (long)(unsigned int)y
> > for 'char' x and y?
>
> The gimple after wide-mul has 2 times convert similar as below.
>
> 21 <bb 2> [local count: 1073741824]:
> 22 _1 = (__int128 unsigned) a_8(D);
> 23 _2 = (__int128 unsigned) b_9(D);
> 24 _34 = (unsigned long) _1;
> 25 _33 = (unsigned long) _2;
> 26 x_10 = _34 w* _33;
> 27 _3 = x_10 >> 64;
> 28 hi_11 = (uint64_t) _3;
> 29 lo_12 = (uint64_t) x_10;
>
> + (convert (widen_mult:c@3 (convert@4 (convert @0))
>
> So I added 2 times convert to match above sematics. Do you indicate that we
> only need one convert here?
Yes, the above extra widening looks odd to me.
> > I also wonder if there isn't any TYPE_UNSIGNED check
> > missing below given the comment mentions unsigned WT.
>
> The outer checked the type with TYPE_UNSIGNED, and inner checked the
> types_match (type, @0, @1)).
> So I think this ensure it only works for unsigned.
Ah, OK.
> 3184 /* Saturation add for unsigned integer. */
> 3185 (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type))
>
> Pan
>
> -----Original Message-----
> From: Richard Biener <richard.guent...@gmail.com>
> Sent: Tuesday, September 2, 2025 8:31 PM
> To: Li, Pan2 <pan2...@intel.com>
> Cc: gcc-patches@gcc.gnu.org; juzhe.zh...@rivai.ai; kito.ch...@gmail.com;
> jeffreya...@gmail.com; rdapp....@gmail.com; Chen, Ken <ken.c...@intel.com>;
> Liu, Hongtao <hongtao....@intel.com>
> Subject: Re: [PATCH v1 1/2] Match: Add form 5 of unsigned SAT_MUL for
> widen-mul
>
> On Mon, Sep 1, 2025 at 6:57 AM <pan2...@intel.com> wrote:
> >
> > From: Pan Li <pan2...@intel.com>
> >
> > This patch would like to try to match the the unsigned
> > SAT_MUL form 4, aka below:
> >
> > #define DEF_SAT_U_MUL_FMT_5(NT, WT) \
> > NT __attribute__((noinline)) \
> > sat_u_mul_##NT##_from_##WT##_fmt_5 (NT a, NT b) \
> > { \
> > WT x = (WT)a * (WT)b; \
> > NT hi = x >> (sizeof(NT) * 8); \
> > NT lo = (NT)x; \
> > return lo | -!!hi; \
> > }
> >
> > while WT is uint128_t, T is uint8_t, uint16_t, uint32_t or uint64_t.
> >
> > gcc/ChangeLog:
> >
> > * match.pd: Add pattern for SAT_MUL form 5.
> > * tree-ssa-math-opts.cc (math_opts_dom_walker::after_dom_children):
> > Try match pattern for IOR.
> >
> > Signed-off-by: Pan Li <pan2...@intel.com>
> > ---
> > gcc/match.pd | 25 +++++++++++++++++++++++++
> > gcc/tree-ssa-math-opts.cc | 1 +
> > 2 files changed, 26 insertions(+)
> >
> > diff --git a/gcc/match.pd b/gcc/match.pd
> > index b1d7a3a1b73..4a3587017d1 100644
> > --- a/gcc/match.pd
> > +++ b/gcc/match.pd
> > @@ -3660,6 +3660,31 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> > bool c2_is_type_precision_p = c2 == prec;
> > }
> > (if (widen_prec > prec && c2_is_type_precision_p && c4_is_max_p)))))
> > + (match (unsigned_integer_sat_mul @0 @1)
> > + /* SAT_U_MUL (X, Y) = {
> > + WT x = (WT)a * (WT)b;
> > + NT hi = x >> (sizeof(NT) * 8);
> > + NT lo = (NT)x;
> > + return lo | -!!hi;
> > + } while WT is uint128_t, T is uint8_t, uint16_t, uint32_t or
> > uint64_t. */
> > + (convert1?
> > + (bit_ior (convert? (negate (convert (ne (convert (rshift @3
> > INTEGER_CST@2))
> > + integer_zerop))))
> > + (convert (widen_mult:c@3 (convert@4 (convert @0))
> > + (convert@5 (convert @1))))))
>
> Are the inner (convert ..) around @0 and @1 necessary? The whole
> thing as written seems to match (long)(short)x * (long)(unsigned int)y
> for 'char' x and y? I also wonder if there isn't any TYPE_UNSIGNED check
> missing below given the comment mentions unsigned WT.
>
> > + (if (types_match (type, @0, @1))
> > + (with
> > + {
> > + unsigned widen_prec = TYPE_PRECISION (TREE_TYPE (@3));
> > + unsigned cvt4_prec = TYPE_PRECISION (TREE_TYPE (@4));
> > + unsigned cvt5_prec = TYPE_PRECISION (TREE_TYPE (@5));
> > + bool widen_mult_p = cvt4_prec == cvt5_prec && widen_prec ==
> > cvt5_prec * 2;
> > +
> > + unsigned c2 = tree_to_uhwi (@2);
> > + unsigned prec = TYPE_PRECISION (type);
> > + bool c2_is_type_precision_p = c2 == prec;
> > + }
> > + (if (widen_mult_p && c2_is_type_precision_p)))))
> > )
> >
> > /* The boundary condition for case 10: IMM = 1:
> > diff --git a/gcc/tree-ssa-math-opts.cc b/gcc/tree-ssa-math-opts.cc
> > index bfad4cf5c99..fcbb752a5e3 100644
> > --- a/gcc/tree-ssa-math-opts.cc
> > +++ b/gcc/tree-ssa-math-opts.cc
> > @@ -6509,6 +6509,7 @@ math_opts_dom_walker::after_dom_children (basic_block
> > bb)
> > break;
> >
> > case BIT_IOR_EXPR:
> > + match_unsigned_saturation_mul (&gsi, as_a<gassign *> (stmt));
> > match_saturation_add_with_assign (&gsi, as_a<gassign *>
> > (stmt));
> > match_unsigned_saturation_trunc (&gsi, as_a<gassign *>
> > (stmt));
> > /* fall-through */
> > --
> > 2.43.0
> >
