On Fri, May 24, 2024 at 8:56 AM Richard Biener
<richard.guent...@gmail.com> wrote:
>
> On Fri, May 24, 2024 at 8:37 AM Li, Pan2 <pan2...@intel.com> wrote:
> >
> > Thanks Jeff and Richard for suggestion and reviewing.
> >
> > Have another try in phiopt to do the convert from PHI to stmt = cond ? a :
> > b.
> > It can perform the convert from PHI to stmt = cond ? a : b successfully,
> > and then
> > the widen-mul is able to do the recog to .SAT_ADD.
> >
> > For now, to limit the risck, the above convert from PHI to stmt = cond ? a
> > : b only be performed when matched,
> > as well as the backend support the usadd standard name. Unfortunately, I am
> > stuck in the case that when the lhs
> > is not matched, we need to clean up something like created stmt in
> > previous, or we will have ICE for missing definition.
> >
> > sat_add.c: In function ‘sat_add_u_3_uint8_t’:
> > sat_add.c:69:1: error: missing definition
> > 69 | SAT_ADD_U_3(uint8_t);
> > | ^~~~~~~~~~~
> > for SSA_NAME: _6 in statement:
> > # VUSE <.MEM_14(D)>
> > return _6;
> > during GIMPLE pass: phiopt
> > dump file: sat_add.c.046t.phiopt1
> > sat_add.c:69:1: internal compiler error: verify_ssa failed
> > 0x1db41ba verify_ssa(bool, bool
> > /home/pli/gcc/555/riscv-gnu-toolchain/gcc/__RISCV_BUILD__/../gcc/tree-ssa.cc:1203
> > 0x18e3075 execute_function_todo
> >
> > /home/pli/gcc/555/riscv-gnu-toolchain/gcc/__RISCV_BUILD__/../gcc/passes.cc:2096
> > 0x18e1c52 do_per_function
> >
> > /home/pli/gcc/555/riscv-gnu-toolchain/gcc/__RISCV_BUILD__/../gcc/passes.cc:1688
> > 0x18e3222 execute_todo
> >
> > I bet the reason is that we created new stmt like stmt_cond and stmt_val
> > but we don't insert it.
> > Thus, there will be orphan nodes somewhere and we need something like
> > rollback to recover the
> > gimple up to a point. I tried sorts of release_xx or likewise but seems not
> > working.
> >
> > So is there any suggest to take care of such gimple rollback or another
> > solution for this? Below are
> > The function to perform the convert from PHI to stmt = cond ? a : b for
> > reference, thanks a lot.
> >
> > Pan
> >
> > diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
> > index 918cf50b589..7982b65bac4 100644
> > --- a/gcc/tree-ssa-phiopt.cc
> > +++ b/gcc/tree-ssa-phiopt.cc
> > @@ -486,6 +486,88 @@ phiopt_early_allow (gimple_seq &seq, gimple_match_op
> > &op)
> > }
> > }
> >
> > +extern bool gimple_unsigned_integer_sat_add (tree, tree*, tree (*)(tree));
> > +
> > +/* Try to match the phi expr to the gimple cond. Return true if we can
> > + perform the convert or return false. There will be some restrictions
> > + or such kind of conversion, aka:
> > +
> > + 1. Only selected pattern will try this convert.
> > + 2. The generated gassign matched the selected IFN pattern.
> > + 3. The backend has implement the standard name.
> > +
> > + From:
> > + <bb 2> :
> > + _1 = x_3(D) + y_4(D);
> > + if (_1 >= x_3(D))
> > + goto <bb 3>; [INV]
> > + else
> > + goto <bb 4>; [INV]
> > +
> > + <bb 3> :
> > +
> > + <bb 4> :
> > + # _2 = PHI <255(2), _1(3)>
> > +
> > + To:
> > + <bb 2> :
> > + _1 = x_3(D) + y_4(D);
> > + phi_cond_6 = _1 >= x_3(D);
> > + _2 = phi_cond_6 ? _1 : 255; */
> > +
> > +static bool
> > +match_phi_to_gimple_cond (basic_block cond_bb, gphi *phi, tree arg0, tree
> > arg1)
>
> You should do this in widen-mult and/or ISEL and if necessary for
> vectorization
> in tree-if-conv.cc, though eventually what if-convert creates might be
> good enough
> to match during pattern recognition.
>
> > +{
> > + gcond *cond = as_a <gcond *> (*gsi_last_bb (cond_bb));
> > +
> > + if (!cond)
> > + return false;
> > +
> > + enum tree_code code = gimple_cond_code (cond);
> > + tree phi_result = gimple_phi_result (phi);
> > + tree cond_tree = make_temp_ssa_name (boolean_type_node, NULL,
> > "phi_cond");
> > + tree cmp_tree = build2 (code, boolean_type_node, gimple_cond_lhs (cond),
> > + gimple_cond_rhs (cond));
> > + tree rhs = build3 (COND_EXPR, TREE_TYPE (phi_result), cond_tree, arg0,
> > arg1);
>
> phiopt directly uses cmp_tree, so you could do that as well and avoid
> stmt_cond.
>
> > +
> > + gassign *stmt_cond = gimple_build_assign (cond_tree, cmp_tree);
> > + gassign *stmt_val = gimple_build_assign (phi_result, rhs);
> > +
> > + tree ops[2];
> > + tree lhs = gimple_assign_lhs (stmt_val);
> > + bool matched_p = (gimple_unsigned_integer_sat_add (lhs, ops, NULL)
> > + && direct_internal_fn_supported_p (IFN_SAT_ADD, TREE_TYPE (lhs),
> > + OPTIMIZE_FOR_BOTH));
> > +
> > + if (matched_p)
> > + {
> > + gimple_stmt_iterator gsi = gsi_last_bb (cond_bb);
> > + gimple_stmt_iterator psi = gsi_for_stmt (phi);
> > +
> > + gsi_insert_before (&gsi, stmt_cond, GSI_SAME_STMT);
> > + gsi_insert_before (&gsi, stmt_val, GSI_SAME_STMT);
> > + remove_phi_node (&psi, false);
>
> You only matched but you do not insert the actual .SAT_ADD here and that's
> the definition that's missing. You probably shouldn't need to add the
> cond-stmt?
>
> > + }
> > + else
> > + {
> > + // Clean up the stmt created, but non of blow works well.
> > + // gsi = gsi_for_stmt (stmt_val);
> > + // gsi_remove (&gsi, true);
> > + // release_defs (stmt_val);
> > + // ggc_free (stmt_val);
> > +
> > + // gsi = gsi_for_stmt (stmt_cond);
> > + // gsi_remove (&gsi, true);
> > + // release_defs (stmt_cond);
> > + // ggc_free (stmt_cond);
> > +
> > + // release_defs (stmt_cond);
> > + // release_defs (stmt_val);
> > + release_ssa_name (cond_tree);
>
> As you don't insert the stmts you should be able to simply
> only release the SSA names and ggc_free the stmt. You can also
> look at maybe_fold_comparisons_from_match_pd in gimple-fold.cc
> for more "ugly" ways to do this.
>
> Building a helper in one place to match a PHI def as COND_EXPR
> might be nice. As said, avoiding all the mess by providing native
> support from genmatch would be even better, but I'm not asking you
> to do that.For reference the attached outlines where/what to do if you are curious. Richard. > > Richard. > > > + } > > + > > + return matched_p; > > +} > > + > > /* gimple_simplify_phiopt is like gimple_simplify but designed for PHIOPT. > > Return NULL if nothing can be simplified or the resulting simplified > > value > > with parts pushed if EARLY_P was true. Also rejects non allowed tree > > code > > @@ -826,6 +908,9 @@ match_simplify_replacement (basic_block cond_bb, > > basic_block middle_bb, > > So, given the condition COND, and the two PHI arguments, match and > > simplify > > can happen on (COND) ? arg0 : arg1. */ > > > > + if (match_phi_to_gimple_cond (cond_bb, phi, arg0, arg1)) > > + return true; > > + > > stmt = last_nondebug_stmt (cond_bb); > > > > /* We need to know which is the true edge and which is the false > > > > > > -----Original Message----- > > From: Jeff Law <jeffreya...@gmail.com> > > Sent: Thursday, May 23, 2024 10:59 PM > > To: Richard Biener <richard.guent...@gmail.com>; Li, Pan2 > > <pan2...@intel.com> > > Cc: gcc-patches@gcc.gnu.org; juzhe.zh...@rivai.ai; kito.ch...@gmail.com; > > tamar.christ...@arm.com; pins...@gmail.com > > Subject: Re: [PATCH v2] Match: Support __builtin_add_overflow branch form > > for unsigned SAT_ADD > > > > > > > > On 5/23/24 6:14 AM, Richard Biener wrote: > > > On Thu, May 23, 2024 at 1:08 PM Li, Pan2 <pan2...@intel.com> wrote: > > >> > > >> I have a try to convert the PHI from Part-A to Part-B, aka PHI to _2 = > > >> phi_cond ? _1 : 255. > > >> And then we can do the matching on COND_EXPR in the underlying widen-mul > > >> pass. > > >> > > >> Unfortunately, meet some ICE when verify_gimple_phi in sccopy1 pass => > > >> sat_add.c:66:1: internal compiler error: tree check: expected class > > >> ‘type’, have ‘exceptional’ (error_mark) in useless_type_conversion_p, at > > >> gimple-expr.cc:86 > > > > > > Likely you have released _2, more comments below on your previous mail. > > You can be sure by calling debug_tree () on the SSA_NAME node in > > question. If it reports "in-free-list", then that's definitive that the > > SSA_NAME was released back to the SSA_NAME manager. If that SSA_NAME is > > still in the IL, then that's very bad. > > > > jeff > >
p
Description: Binary data
