tree-optimization/119960 - add validity checking to SLP scheduling

The following adds checks that when we search for a vector stmt
insert location we arrive at one where all required operand defs
are dominating the insert location.  At the moment any such
failure only blows up during SSA verification.

There's the long-standing issue that we do not verify there
exists a valid schedule of the SLP graph from BB vectorization
into the existing CFG.  We do not have the ability to insert
vector stmts on the dominance frontier "end", nor to insert
LC PHIs that would be eventually required.

This should be done all differently, computing the schedule
during analysis and failing if we can't schedule.

	PR tree-optimization/119960
	* tree-vect-slp.cc (vect_schedule_slp_node): Sanity
	check dominance check on operand defs.

diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index 19beeed8a3a980e226a115afdd61b755dc6b4015..b5a9604d074eab37be2557cf259d2fe068ebf879 100644 (file)
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -11161,9 +11161,14 @@ vect_schedule_slp_node (vec_info *vinfo,
                            == cycle_phi_info_type);
                gphi *phi = as_a <gphi *>
                              (vect_find_last_scalar_stmt_in_slp (child)->stmt);
-               if (!last_stmt
-                   || vect_stmt_dominates_stmt_p (last_stmt, phi))
+               if (!last_stmt)
                  last_stmt = phi;
+               else if (vect_stmt_dominates_stmt_p (last_stmt, phi))
+                 last_stmt = phi;
+               else if (vect_stmt_dominates_stmt_p (phi, last_stmt))
+                 ;
+               else
+                 gcc_unreachable ();
              }
            /* We are emitting all vectorized stmts in the same place and
               the last one is the last.
@@ -11174,9 +11179,14 @@ vect_schedule_slp_node (vec_info *vinfo,
            FOR_EACH_VEC_ELT (SLP_TREE_VEC_DEFS (child), j, vdef)
              {
                gimple *vstmt = SSA_NAME_DEF_STMT (vdef);
-               if (!last_stmt
-                   || vect_stmt_dominates_stmt_p (last_stmt, vstmt))
+               if (!last_stmt)
+                 last_stmt = vstmt;
+               else if (vect_stmt_dominates_stmt_p (last_stmt, vstmt))
                  last_stmt = vstmt;
+               else if (vect_stmt_dominates_stmt_p (vstmt, last_stmt))
+                 ;
+               else
+                 gcc_unreachable ();
              }
          }
        else if (!SLP_TREE_VECTYPE (child))
@@ -11189,9 +11199,14 @@ vect_schedule_slp_node (vec_info *vinfo,
                  && !SSA_NAME_IS_DEFAULT_DEF (def))
                {
                  gimple *stmt = SSA_NAME_DEF_STMT (def);
-                 if (!last_stmt
-                     || vect_stmt_dominates_stmt_p (last_stmt, stmt))
+                 if (!last_stmt)
+                   last_stmt = stmt;
+                 else if (vect_stmt_dominates_stmt_p (last_stmt, stmt))
                    last_stmt = stmt;
+                 else if (vect_stmt_dominates_stmt_p (stmt, last_stmt))
+                   ;
+                 else
+                   gcc_unreachable ();
                }
          }
        else
@@ -11212,9 +11227,14 @@ vect_schedule_slp_node (vec_info *vinfo,
                      && !SSA_NAME_IS_DEFAULT_DEF (vdef))
                    {
                      gimple *vstmt = SSA_NAME_DEF_STMT (vdef);
-                     if (!last_stmt
-                         || vect_stmt_dominates_stmt_p (last_stmt, vstmt))
+                     if (!last_stmt)
+                       last_stmt = vstmt;
+                     else if (vect_stmt_dominates_stmt_p (last_stmt, vstmt))
                        last_stmt = vstmt;
+                     else if (vect_stmt_dominates_stmt_p (vstmt, last_stmt))
+                       ;
+                     else
+                       gcc_unreachable ();
                    }
              }
          }