vect: Add costing_for_scalar parameter to init_cost hook

rs6000 port function rs6000_density_test wants to differentiate the
current cost model is for the scalar version of a loop or block, or
the vector version.  As Richi suggested, this patch introduces one
new parameter costing_for_scalar to init_cost hook to pass down this
information explicitly.

gcc/ChangeLog:

	* doc/tm.texi: Regenerated.
	* target.def (init_cost): Add new parameter costing_for_scalar.
	* targhooks.c (default_init_cost): Adjust for new parameter.
	* targhooks.h (default_init_cost): Likewise.
	* tree-vect-loop.c (_loop_vec_info::_loop_vec_info): Likewise.
	(vect_compute_single_scalar_iteration_cost): Likewise.
	(vect_analyze_loop_2): Likewise.
	* tree-vect-slp.c (_bb_vec_info::_bb_vec_info): Likewise.
	(vect_bb_vectorization_profitable_p): Likewise.
	* tree-vectorizer.h (init_cost): Likewise.
	* config/aarch64/aarch64.c (aarch64_init_cost): Likewise.
	* config/i386/i386.c (ix86_init_cost): Likewise.
	* config/rs6000/rs6000.c (rs6000_init_cost): Likewise.

gcc/config/aarch64/aarch64.c

@@ -14388,7 +14388,7 @@ struct aarch64_vector_costs
 
 /* Implement TARGET_VECTORIZE_INIT_COST.  */
 void *
-aarch64_init_cost (class loop *)
+aarch64_init_cost (class loop *, bool)
 {
   return new aarch64_vector_costs;
 }

gcc/config/i386/i386.c

@@ -22289,7 +22289,7 @@ ix86_noce_conversion_profitable_p (rtx_insn *seq, struct noce_if_info *if_info)
 /* Implement targetm.vectorize.init_cost.  */
 
 static void *
-ix86_init_cost (class loop *)
+ix86_init_cost (class loop *, bool)
 {
   unsigned *cost = XNEWVEC (unsigned, 3);
   cost[vect_prologue] = cost[vect_body] = cost[vect_epilogue] = 0;

gcc/config/rs6000/rs6000.c

@@ -5296,7 +5296,7 @@ rs6000_density_test (rs6000_cost_data *data)
 /* Implement targetm.vectorize.init_cost.  */
 
 static void *
-rs6000_init_cost (struct loop *loop_info)
+rs6000_init_cost (struct loop *loop_info, bool)
 {
   rs6000_cost_data *data = XNEW (struct _rs6000_cost_data);
   data->loop_info = loop_info;

gcc/doc/tm.texi

@@ -6120,8 +6120,8 @@ type @code{internal_fn}) should be considered expensive when the mask is
 all zeros.  GCC can then try to branch around the instruction instead.
 @end deftypefn
 
-@deftypefn {Target Hook} {void *} TARGET_VECTORIZE_INIT_COST (class loop *@var{loop_info})
-This hook should initialize target-specific data structures in preparation for modeling the costs of vectorizing a loop or basic block.  The default allocates three unsigned integers for accumulating costs for the prologue, body, and epilogue of the loop or basic block.  If @var{loop_info} is non-NULL, it identifies the loop being vectorized; otherwise a single block is being vectorized.
+@deftypefn {Target Hook} {void *} TARGET_VECTORIZE_INIT_COST (class loop *@var{loop_info}, bool @var{costing_for_scalar})
+This hook should initialize target-specific data structures in preparation for modeling the costs of vectorizing a loop or basic block.  The default allocates three unsigned integers for accumulating costs for the prologue, body, and epilogue of the loop or basic block.  If @var{loop_info} is non-NULL, it identifies the loop being vectorized; otherwise a single block is being vectorized.  If @var{costing_for_scalar} is true, it indicates the current cost model is for the scalar version of a loop or block; otherwise it is for the vector version.
 @end deftypefn
 
 @deftypefn {Target Hook} unsigned TARGET_VECTORIZE_ADD_STMT_COST (class vec_info *@var{}, void *@var{data}, int @var{count}, enum vect_cost_for_stmt @var{kind}, class _stmt_vec_info *@var{stmt_info}, tree @var{vectype}, int @var{misalign}, enum vect_cost_model_location @var{where})

gcc/target.def

@@ -2004,9 +2004,11 @@ DEFHOOK
  "allocates three unsigned integers for accumulating costs for the prologue, "
  "body, and epilogue of the loop or basic block.  If @var{loop_info} is "
  "non-NULL, it identifies the loop being vectorized; otherwise a single block "
- "is being vectorized.",
+ "is being vectorized.  If @var{costing_for_scalar} is true, it indicates the "
+ "current cost model is for the scalar version of a loop or block; otherwise "
+ "it is for the vector version.",
  void *,
- (class loop *loop_info),
+ (class loop *loop_info, bool costing_for_scalar),
  default_init_cost)
 
 /* Target function to record N statements of the given kind using the

gcc/targhooks.c

@@ -1373,7 +1373,8 @@ default_empty_mask_is_expensive (unsigned ifn)
    array of three unsigned ints, set it to zero, and return its address.  */
 
 void *
-default_init_cost (class loop *loop_info ATTRIBUTE_UNUSED)
+default_init_cost (class loop *loop_info ATTRIBUTE_UNUSED,
+		   bool costing_for_scalar ATTRIBUTE_UNUSED)
 {
   unsigned *cost = XNEWVEC (unsigned, 3);
   cost[vect_prologue] = cost[vect_body] = cost[vect_epilogue] = 0;

gcc/targhooks.h

@@ -117,7 +117,7 @@ extern opt_machine_mode default_vectorize_related_mode (machine_mode,
 							poly_uint64);
 extern opt_machine_mode default_get_mask_mode (machine_mode);
 extern bool default_empty_mask_is_expensive (unsigned);
-extern void *default_init_cost (class loop *);
+extern void *default_init_cost (class loop *, bool);
 extern unsigned default_add_stmt_cost (class vec_info *, void *, int,
 				       enum vect_cost_for_stmt,
 				       class _stmt_vec_info *, tree, int,

gcc/tree-vect-loop.c

@@ -813,7 +813,7 @@ bb_in_loop_p (const_basic_block bb, const void *data)
    stmt_vec_info structs for all the stmts in LOOP_IN.  */
 
 _loop_vec_info::_loop_vec_info (class loop *loop_in, vec_info_shared *shared)
-  : vec_info (vec_info::loop, init_cost (loop_in), shared),
+  : vec_info (vec_info::loop, init_cost (loop_in, false), shared),
     loop (loop_in),
     bbs (XCNEWVEC (basic_block, loop->num_nodes)),
     num_itersm1 (NULL_TREE),
@@ -1284,7 +1284,7 @@ vect_compute_single_scalar_iteration_cost (loop_vec_info loop_vinfo)
     }
 
   /* Now accumulate cost.  */
-  void *target_cost_data = init_cost (loop);
+  void *target_cost_data = init_cost (loop, true);
   stmt_info_for_cost *si;
   int j;
   FOR_EACH_VEC_ELT (LOOP_VINFO_SCALAR_ITERATION_COST (loop_vinfo),
@@ -2723,7 +2723,7 @@ again:
   /* Reset target cost data.  */
   destroy_cost_data (LOOP_VINFO_TARGET_COST_DATA (loop_vinfo));
   LOOP_VINFO_TARGET_COST_DATA (loop_vinfo)
-    = init_cost (LOOP_VINFO_LOOP (loop_vinfo));
+    = init_cost (LOOP_VINFO_LOOP (loop_vinfo), false);
   /* Reset accumulated rgroup information.  */
   release_vec_loop_controls (&LOOP_VINFO_MASKS (loop_vinfo));
   release_vec_loop_controls (&LOOP_VINFO_LENS (loop_vinfo));

gcc/tree-vect-slp.c

@@ -3690,7 +3690,9 @@ vect_detect_hybrid_slp (loop_vec_info loop_vinfo)
 /* Initialize a bb_vec_info struct for the statements in BBS basic blocks.  */
 
 _bb_vec_info::_bb_vec_info (vec<basic_block> _bbs, vec_info_shared *shared)
-  : vec_info (vec_info::bb, init_cost (NULL), shared), bbs (_bbs), roots (vNULL)
+  : vec_info (vec_info::bb, init_cost (NULL, false), shared),
+    bbs (_bbs),
+    roots (vNULL)
 {
   for (unsigned i = 0; i < bbs.length (); ++i)
     {
@@ -4530,7 +4532,7 @@ vect_bb_vectorization_profitable_p (bb_vec_info bb_vinfo,
 	  continue;
 	}
 
-      void *scalar_target_cost_data = init_cost (NULL);
+      void *scalar_target_cost_data = init_cost (NULL, true);
       do
 	{
 	  add_stmt_cost (bb_vinfo, scalar_target_cost_data,
@@ -4544,7 +4546,7 @@ vect_bb_vectorization_profitable_p (bb_vec_info bb_vinfo,
       destroy_cost_data (scalar_target_cost_data);
 
       /* Complete the target-specific vector cost calculation.  */
-      void *vect_target_cost_data = init_cost (NULL);
+      void *vect_target_cost_data = init_cost (NULL, false);
       do
 	{
 	  add_stmt_cost (bb_vinfo, vect_target_cost_data,

gcc/tree-vectorizer.h

@@ -1455,9 +1455,9 @@ int vect_get_stmt_cost (enum vect_cost_for_stmt type_of_cost)
 /* Alias targetm.vectorize.init_cost.  */
 
 static inline void *
-init_cost (class loop *loop_info)
+init_cost (class loop *loop_info, bool costing_for_scalar)
 {
-  return targetm.vectorize.init_cost (loop_info);
+  return targetm.vectorize.init_cost (loop_info, costing_for_scalar);
 }
 
 extern void dump_stmt_cost (FILE *, void *, int, enum vect_cost_for_stmt,