1 /* Analysis Utilities for Loop Vectorization.
2 Copyright (C) 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
3 Contributed by Dorit Nuzman <dorit@il.ibm.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
28 #include "basic-block.h"
29 #include "diagnostic.h"
30 #include "tree-flow.h"
31 #include "tree-dump.h"
36 #include "tree-data-ref.h"
37 #include "tree-vectorizer.h"
41 /* Function prototypes */
42 static void vect_pattern_recog_1
43 (gimple (* ) (gimple, tree *, tree *), gimple_stmt_iterator);
44 static bool widened_name_p (tree, gimple, tree *, gimple *);
46 /* Pattern recognition functions */
47 static gimple vect_recog_widen_sum_pattern (gimple, tree *, tree *);
48 static gimple vect_recog_widen_mult_pattern (gimple, tree *, tree *);
49 static gimple vect_recog_dot_prod_pattern (gimple, tree *, tree *);
50 static gimple vect_recog_pow_pattern (gimple, tree *, tree *);
51 static vect_recog_func_ptr vect_vect_recog_func_ptrs[NUM_PATTERNS] = {
52 vect_recog_widen_mult_pattern,
53 vect_recog_widen_sum_pattern,
54 vect_recog_dot_prod_pattern,
55 vect_recog_pow_pattern};
58 /* Function widened_name_p
60 Check whether NAME, an ssa-name used in USE_STMT,
61 is a result of a type-promotion, such that:
62 DEF_STMT: NAME = NOP (name0)
63 where the type of name0 (HALF_TYPE) is smaller than the type of NAME.
67 widened_name_p (tree name, gimple use_stmt, tree *half_type, gimple *def_stmt)
71 loop_vec_info loop_vinfo;
72 stmt_vec_info stmt_vinfo;
73 tree type = TREE_TYPE (name);
75 enum vect_def_type dt;
78 stmt_vinfo = vinfo_for_stmt (use_stmt);
79 loop_vinfo = STMT_VINFO_LOOP_VINFO (stmt_vinfo);
81 if (!vect_is_simple_use (name, loop_vinfo, NULL, def_stmt, &def, &dt))
84 if (dt != vect_internal_def
85 && dt != vect_external_def && dt != vect_constant_def)
91 if (!is_gimple_assign (*def_stmt))
94 if (gimple_assign_rhs_code (*def_stmt) != NOP_EXPR)
97 oprnd0 = gimple_assign_rhs1 (*def_stmt);
99 *half_type = TREE_TYPE (oprnd0);
100 if (!INTEGRAL_TYPE_P (type) || !INTEGRAL_TYPE_P (*half_type)
101 || (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (*half_type))
102 || (TYPE_PRECISION (type) < (TYPE_PRECISION (*half_type) * 2)))
105 if (!vect_is_simple_use (oprnd0, loop_vinfo, NULL, &dummy_gimple, &dummy,
112 /* Helper to return a new temporary for pattern of TYPE for STMT. If STMT
113 is NULL, the caller must set SSA_NAME_DEF_STMT for the returned SSA var. */
116 vect_recog_temp_ssa_var (tree type, gimple stmt)
118 tree var = create_tmp_var (type, "patt");
120 add_referenced_var (var);
121 var = make_ssa_name (var, stmt);
125 /* Function vect_recog_dot_prod_pattern
127 Try to find the following pattern:
133 sum_0 = phi <init, sum_1>
136 S3 x_T = (TYPE1) x_t;
137 S4 y_T = (TYPE1) y_t;
139 [S6 prod = (TYPE2) prod; #optional]
140 S7 sum_1 = prod + sum_0;
142 where 'TYPE1' is exactly double the size of type 'type', and 'TYPE2' is the
143 same size of 'TYPE1' or bigger. This is a special case of a reduction
148 * LAST_STMT: A stmt from which the pattern search begins. In the example,
149 when this function is called with S7, the pattern {S3,S4,S5,S6,S7} will be
154 * TYPE_IN: The type of the input arguments to the pattern.
156 * TYPE_OUT: The type of the output of this pattern.
158 * Return value: A new stmt that will be used to replace the sequence of
159 stmts that constitute the pattern. In this case it will be:
160 WIDEN_DOT_PRODUCT <x_t, y_t, sum_0>
162 Note: The dot-prod idiom is a widening reduction pattern that is
163 vectorized without preserving all the intermediate results. It
164 produces only N/2 (widened) results (by summing up pairs of
165 intermediate results) rather than all N results. Therefore, we
166 cannot allow this pattern when we want to get all the results and in
167 the correct order (as is the case when this computation is in an
168 inner-loop nested in an outer-loop that us being vectorized). */
171 vect_recog_dot_prod_pattern (gimple last_stmt, tree *type_in, tree *type_out)
175 tree oprnd00, oprnd01;
176 stmt_vec_info stmt_vinfo = vinfo_for_stmt (last_stmt);
177 tree type, half_type;
180 loop_vec_info loop_info = STMT_VINFO_LOOP_VINFO (stmt_vinfo);
181 struct loop *loop = LOOP_VINFO_LOOP (loop_info);
184 if (!is_gimple_assign (last_stmt))
187 type = gimple_expr_type (last_stmt);
189 /* Look for the following pattern
193 DDPROD = (TYPE2) DPROD;
194 sum_1 = DDPROD + sum_0;
196 - DX is double the size of X
197 - DY is double the size of Y
198 - DX, DY, DPROD all have the same type
199 - sum is the same size of DPROD or bigger
200 - sum has been recognized as a reduction variable.
202 This is equivalent to:
203 DPROD = X w* Y; #widen mult
204 sum_1 = DPROD w+ sum_0; #widen summation
206 DPROD = X w* Y; #widen mult
207 sum_1 = DPROD + sum_0; #summation
210 /* Starting from LAST_STMT, follow the defs of its uses in search
211 of the above pattern. */
213 if (gimple_assign_rhs_code (last_stmt) != PLUS_EXPR)
216 if (STMT_VINFO_IN_PATTERN_P (stmt_vinfo))
218 /* Has been detected as widening-summation? */
220 stmt = STMT_VINFO_RELATED_STMT (stmt_vinfo);
221 type = gimple_expr_type (stmt);
222 if (gimple_assign_rhs_code (stmt) != WIDEN_SUM_EXPR)
224 oprnd0 = gimple_assign_rhs1 (stmt);
225 oprnd1 = gimple_assign_rhs2 (stmt);
226 half_type = TREE_TYPE (oprnd0);
232 if (STMT_VINFO_DEF_TYPE (stmt_vinfo) != vect_reduction_def)
234 oprnd0 = gimple_assign_rhs1 (last_stmt);
235 oprnd1 = gimple_assign_rhs2 (last_stmt);
236 if (TYPE_MAIN_VARIANT (TREE_TYPE (oprnd0)) != TYPE_MAIN_VARIANT (type)
237 || TYPE_MAIN_VARIANT (TREE_TYPE (oprnd1)) != TYPE_MAIN_VARIANT (type))
241 if (widened_name_p (oprnd0, stmt, &half_type, &def_stmt))
244 oprnd0 = gimple_assign_rhs1 (stmt);
250 /* So far so good. Since last_stmt was detected as a (summation) reduction,
251 we know that oprnd1 is the reduction variable (defined by a loop-header
252 phi), and oprnd0 is an ssa-name defined by a stmt in the loop body.
253 Left to check that oprnd0 is defined by a (widen_)mult_expr */
255 prod_type = half_type;
256 stmt = SSA_NAME_DEF_STMT (oprnd0);
257 /* FORNOW. Can continue analyzing the def-use chain when this stmt in a phi
258 inside the loop (in case we are analyzing an outer-loop). */
259 if (!is_gimple_assign (stmt))
261 stmt_vinfo = vinfo_for_stmt (stmt);
262 gcc_assert (stmt_vinfo);
263 if (STMT_VINFO_DEF_TYPE (stmt_vinfo) != vect_internal_def)
265 if (gimple_assign_rhs_code (stmt) != MULT_EXPR)
267 if (STMT_VINFO_IN_PATTERN_P (stmt_vinfo))
269 /* Has been detected as a widening multiplication? */
271 stmt = STMT_VINFO_RELATED_STMT (stmt_vinfo);
272 if (gimple_assign_rhs_code (stmt) != WIDEN_MULT_EXPR)
274 stmt_vinfo = vinfo_for_stmt (stmt);
275 gcc_assert (stmt_vinfo);
276 gcc_assert (STMT_VINFO_DEF_TYPE (stmt_vinfo) == vect_internal_def);
277 oprnd00 = gimple_assign_rhs1 (stmt);
278 oprnd01 = gimple_assign_rhs2 (stmt);
282 tree half_type0, half_type1;
286 oprnd0 = gimple_assign_rhs1 (stmt);
287 oprnd1 = gimple_assign_rhs2 (stmt);
288 if (TYPE_MAIN_VARIANT (TREE_TYPE (oprnd0))
289 != TYPE_MAIN_VARIANT (prod_type)
290 || TYPE_MAIN_VARIANT (TREE_TYPE (oprnd1))
291 != TYPE_MAIN_VARIANT (prod_type))
293 if (!widened_name_p (oprnd0, stmt, &half_type0, &def_stmt))
295 oprnd00 = gimple_assign_rhs1 (def_stmt);
296 if (!widened_name_p (oprnd1, stmt, &half_type1, &def_stmt))
298 oprnd01 = gimple_assign_rhs1 (def_stmt);
299 if (TYPE_MAIN_VARIANT (half_type0) != TYPE_MAIN_VARIANT (half_type1))
301 if (TYPE_PRECISION (prod_type) != TYPE_PRECISION (half_type0) * 2)
305 half_type = TREE_TYPE (oprnd00);
306 *type_in = half_type;
309 /* Pattern detected. Create a stmt to be used to replace the pattern: */
310 var = vect_recog_temp_ssa_var (type, NULL);
311 rhs = build3 (DOT_PROD_EXPR, type, oprnd00, oprnd01, oprnd1),
312 pattern_stmt = gimple_build_assign (var, rhs);
314 if (vect_print_dump_info (REPORT_DETAILS))
316 fprintf (vect_dump, "vect_recog_dot_prod_pattern: detected: ");
317 print_gimple_stmt (vect_dump, pattern_stmt, 0, TDF_SLIM);
320 /* We don't allow changing the order of the computation in the inner-loop
321 when doing outer-loop vectorization. */
322 if (nested_in_vect_loop_p (loop, last_stmt))
324 if (vect_print_dump_info (REPORT_DETAILS))
325 fprintf (vect_dump, "vect_recog_dot_prod_pattern: not allowed.");
332 /* Function vect_recog_widen_mult_pattern
334 Try to find the following pattern:
337 TYPE a_T, b_T, prod_T;
343 S5 prod_T = a_T * b_T;
345 where type 'TYPE' is at least double the size of type 'type'.
349 * LAST_STMT: A stmt from which the pattern search begins. In the example,
350 when this function is called with S5, the pattern {S3,S4,S5} is be detected.
354 * TYPE_IN: The type of the input arguments to the pattern.
356 * TYPE_OUT: The type of the output of this pattern.
358 * Return value: A new stmt that will be used to replace the sequence of
359 stmts that constitute the pattern. In this case it will be:
360 WIDEN_MULT <a_t, b_t>
364 vect_recog_widen_mult_pattern (gimple last_stmt,
368 gimple def_stmt0, def_stmt1;
370 tree type, half_type0, half_type1;
375 enum tree_code dummy_code;
377 VEC (tree, heap) *dummy_vec;
379 if (!is_gimple_assign (last_stmt))
382 type = gimple_expr_type (last_stmt);
384 /* Starting from LAST_STMT, follow the defs of its uses in search
385 of the above pattern. */
387 if (gimple_assign_rhs_code (last_stmt) != MULT_EXPR)
390 oprnd0 = gimple_assign_rhs1 (last_stmt);
391 oprnd1 = gimple_assign_rhs2 (last_stmt);
392 if (TYPE_MAIN_VARIANT (TREE_TYPE (oprnd0)) != TYPE_MAIN_VARIANT (type)
393 || TYPE_MAIN_VARIANT (TREE_TYPE (oprnd1)) != TYPE_MAIN_VARIANT (type))
396 /* Check argument 0 */
397 if (!widened_name_p (oprnd0, last_stmt, &half_type0, &def_stmt0))
399 oprnd0 = gimple_assign_rhs1 (def_stmt0);
401 /* Check argument 1 */
402 if (!widened_name_p (oprnd1, last_stmt, &half_type1, &def_stmt1))
404 oprnd1 = gimple_assign_rhs1 (def_stmt1);
406 if (TYPE_MAIN_VARIANT (half_type0) != TYPE_MAIN_VARIANT (half_type1))
409 /* Pattern detected. */
410 if (vect_print_dump_info (REPORT_DETAILS))
411 fprintf (vect_dump, "vect_recog_widen_mult_pattern: detected: ");
413 /* Check target support */
414 vectype = get_vectype_for_scalar_type (half_type0);
416 || !supportable_widening_operation (WIDEN_MULT_EXPR, last_stmt, vectype,
417 &dummy, &dummy, &dummy_code,
418 &dummy_code, &dummy_int, &dummy_vec))
422 *type_out = NULL_TREE;
424 /* Pattern supported. Create a stmt to be used to replace the pattern: */
425 var = vect_recog_temp_ssa_var (type, NULL);
426 pattern_stmt = gimple_build_assign_with_ops (WIDEN_MULT_EXPR, var, oprnd0,
428 SSA_NAME_DEF_STMT (var) = pattern_stmt;
430 if (vect_print_dump_info (REPORT_DETAILS))
431 print_gimple_stmt (vect_dump, pattern_stmt, 0, TDF_SLIM);
437 /* Function vect_recog_pow_pattern
439 Try to find the following pattern:
443 with POW being one of pow, powf, powi, powif and N being
448 * LAST_STMT: A stmt from which the pattern search begins.
452 * TYPE_IN: The type of the input arguments to the pattern.
454 * TYPE_OUT: The type of the output of this pattern.
456 * Return value: A new stmt that will be used to replace the sequence of
457 stmts that constitute the pattern. In this case it will be:
464 vect_recog_pow_pattern (gimple last_stmt, tree *type_in, tree *type_out)
467 tree fn, base, exp = NULL;
471 if (!is_gimple_call (last_stmt) || gimple_call_lhs (last_stmt) == NULL)
474 type = gimple_expr_type (last_stmt);
476 fn = gimple_call_fndecl (last_stmt);
477 switch (DECL_FUNCTION_CODE (fn))
483 base = gimple_call_arg (last_stmt, 0);
484 exp = gimple_call_arg (last_stmt, 1);
485 if (TREE_CODE (exp) != REAL_CST
486 && TREE_CODE (exp) != INTEGER_CST)
494 /* We now have a pow or powi builtin function call with a constant
497 *type_out = NULL_TREE;
499 /* Catch squaring. */
500 if ((host_integerp (exp, 0)
501 && tree_low_cst (exp, 0) == 2)
502 || (TREE_CODE (exp) == REAL_CST
503 && REAL_VALUES_EQUAL (TREE_REAL_CST (exp), dconst2)))
505 *type_in = TREE_TYPE (base);
507 var = vect_recog_temp_ssa_var (TREE_TYPE (base), NULL);
508 stmt = gimple_build_assign_with_ops (MULT_EXPR, var, base, base);
509 SSA_NAME_DEF_STMT (var) = stmt;
513 /* Catch square root. */
514 if (TREE_CODE (exp) == REAL_CST
515 && REAL_VALUES_EQUAL (TREE_REAL_CST (exp), dconsthalf))
517 tree newfn = mathfn_built_in (TREE_TYPE (base), BUILT_IN_SQRT);
518 *type_in = get_vectype_for_scalar_type (TREE_TYPE (base));
521 gimple stmt = gimple_build_call (newfn, 1, base);
522 if (vectorizable_function (stmt, *type_in, *type_in)
525 var = vect_recog_temp_ssa_var (TREE_TYPE (base), stmt);
526 gimple_call_set_lhs (stmt, var);
536 /* Function vect_recog_widen_sum_pattern
538 Try to find the following pattern:
541 TYPE x_T, sum = init;
543 sum_0 = phi <init, sum_1>
546 S3 sum_1 = x_T + sum_0;
548 where type 'TYPE' is at least double the size of type 'type', i.e - we're
549 summing elements of type 'type' into an accumulator of type 'TYPE'. This is
550 a special case of a reduction computation.
554 * LAST_STMT: A stmt from which the pattern search begins. In the example,
555 when this function is called with S3, the pattern {S2,S3} will be detected.
559 * TYPE_IN: The type of the input arguments to the pattern.
561 * TYPE_OUT: The type of the output of this pattern.
563 * Return value: A new stmt that will be used to replace the sequence of
564 stmts that constitute the pattern. In this case it will be:
565 WIDEN_SUM <x_t, sum_0>
567 Note: The widening-sum idiom is a widening reduction pattern that is
568 vectorized without preserving all the intermediate results. It
569 produces only N/2 (widened) results (by summing up pairs of
570 intermediate results) rather than all N results. Therefore, we
571 cannot allow this pattern when we want to get all the results and in
572 the correct order (as is the case when this computation is in an
573 inner-loop nested in an outer-loop that us being vectorized). */
576 vect_recog_widen_sum_pattern (gimple last_stmt, tree *type_in, tree *type_out)
580 stmt_vec_info stmt_vinfo = vinfo_for_stmt (last_stmt);
581 tree type, half_type;
583 loop_vec_info loop_info = STMT_VINFO_LOOP_VINFO (stmt_vinfo);
584 struct loop *loop = LOOP_VINFO_LOOP (loop_info);
587 if (!is_gimple_assign (last_stmt))
590 type = gimple_expr_type (last_stmt);
592 /* Look for the following pattern
595 In which DX is at least double the size of X, and sum_1 has been
596 recognized as a reduction variable.
599 /* Starting from LAST_STMT, follow the defs of its uses in search
600 of the above pattern. */
602 if (gimple_assign_rhs_code (last_stmt) != PLUS_EXPR)
605 if (STMT_VINFO_DEF_TYPE (stmt_vinfo) != vect_reduction_def)
608 oprnd0 = gimple_assign_rhs1 (last_stmt);
609 oprnd1 = gimple_assign_rhs2 (last_stmt);
610 if (TYPE_MAIN_VARIANT (TREE_TYPE (oprnd0)) != TYPE_MAIN_VARIANT (type)
611 || TYPE_MAIN_VARIANT (TREE_TYPE (oprnd1)) != TYPE_MAIN_VARIANT (type))
614 /* So far so good. Since last_stmt was detected as a (summation) reduction,
615 we know that oprnd1 is the reduction variable (defined by a loop-header
616 phi), and oprnd0 is an ssa-name defined by a stmt in the loop body.
617 Left to check that oprnd0 is defined by a cast from type 'type' to type
620 if (!widened_name_p (oprnd0, last_stmt, &half_type, &stmt))
623 oprnd0 = gimple_assign_rhs1 (stmt);
624 *type_in = half_type;
627 /* Pattern detected. Create a stmt to be used to replace the pattern: */
628 var = vect_recog_temp_ssa_var (type, NULL);
629 pattern_stmt = gimple_build_assign_with_ops (WIDEN_SUM_EXPR, var,
631 SSA_NAME_DEF_STMT (var) = pattern_stmt;
633 if (vect_print_dump_info (REPORT_DETAILS))
635 fprintf (vect_dump, "vect_recog_widen_sum_pattern: detected: ");
636 print_gimple_stmt (vect_dump, pattern_stmt, 0, TDF_SLIM);
639 /* We don't allow changing the order of the computation in the inner-loop
640 when doing outer-loop vectorization. */
641 if (nested_in_vect_loop_p (loop, last_stmt))
643 if (vect_print_dump_info (REPORT_DETAILS))
644 fprintf (vect_dump, "vect_recog_widen_sum_pattern: not allowed.");
652 /* Function vect_pattern_recog_1
655 PATTERN_RECOG_FUNC: A pointer to a function that detects a certain
657 STMT: A stmt from which the pattern search should start.
659 If PATTERN_RECOG_FUNC successfully detected the pattern, it creates an
660 expression that computes the same functionality and can be used to
661 replace the sequence of stmts that are involved in the pattern.
664 This function checks if the expression returned by PATTERN_RECOG_FUNC is
665 supported in vector form by the target. We use 'TYPE_IN' to obtain the
666 relevant vector type. If 'TYPE_IN' is already a vector type, then this
667 indicates that target support had already been checked by PATTERN_RECOG_FUNC.
668 If 'TYPE_OUT' is also returned by PATTERN_RECOG_FUNC, we check that it fits
669 to the available target pattern.
671 This function also does some bookkeeping, as explained in the documentation
672 for vect_recog_pattern. */
675 vect_pattern_recog_1 (
676 gimple (* vect_recog_func) (gimple, tree *, tree *),
677 gimple_stmt_iterator si)
679 gimple stmt = gsi_stmt (si), pattern_stmt;
680 stmt_vec_info stmt_info = vinfo_for_stmt (stmt);
681 stmt_vec_info pattern_stmt_info;
682 loop_vec_info loop_vinfo = STMT_VINFO_LOOP_VINFO (stmt_info);
683 tree pattern_vectype;
684 tree type_in, type_out;
687 pattern_stmt = (* vect_recog_func) (stmt, &type_in, &type_out);
691 if (VECTOR_MODE_P (TYPE_MODE (type_in)))
693 /* No need to check target support (already checked by the pattern
694 recognition function). */
695 pattern_vectype = type_in;
699 enum machine_mode vec_mode;
700 enum insn_code icode;
703 /* Check target support */
704 pattern_vectype = get_vectype_for_scalar_type (type_in);
705 if (!pattern_vectype)
708 if (is_gimple_assign (pattern_stmt))
709 code = gimple_assign_rhs_code (pattern_stmt);
712 gcc_assert (is_gimple_call (pattern_stmt));
716 optab = optab_for_tree_code (code, pattern_vectype, optab_default);
717 vec_mode = TYPE_MODE (pattern_vectype);
719 || (icode = optab_handler (optab, vec_mode)->insn_code) ==
722 && (!get_vectype_for_scalar_type (type_out)
723 || (insn_data[icode].operand[0].mode !=
724 TYPE_MODE (get_vectype_for_scalar_type (type_out))))))
728 /* Found a vectorizable pattern. */
729 if (vect_print_dump_info (REPORT_DETAILS))
731 fprintf (vect_dump, "pattern recognized: ");
732 print_gimple_stmt (vect_dump, pattern_stmt, 0, TDF_SLIM);
735 /* Mark the stmts that are involved in the pattern. */
736 gsi_insert_before (&si, pattern_stmt, GSI_SAME_STMT);
737 set_vinfo_for_stmt (pattern_stmt,
738 new_stmt_vec_info (pattern_stmt, loop_vinfo, NULL));
739 pattern_stmt_info = vinfo_for_stmt (pattern_stmt);
741 STMT_VINFO_RELATED_STMT (pattern_stmt_info) = stmt;
742 STMT_VINFO_DEF_TYPE (pattern_stmt_info) = STMT_VINFO_DEF_TYPE (stmt_info);
743 STMT_VINFO_VECTYPE (pattern_stmt_info) = pattern_vectype;
744 STMT_VINFO_IN_PATTERN_P (stmt_info) = true;
745 STMT_VINFO_RELATED_STMT (stmt_info) = pattern_stmt;
751 /* Function vect_pattern_recog
754 LOOP_VINFO - a struct_loop_info of a loop in which we want to look for
757 Output - for each computation idiom that is detected we insert a new stmt
758 that provides the same functionality and that can be vectorized. We
759 also record some information in the struct_stmt_info of the relevant
760 stmts, as explained below:
762 At the entry to this function we have the following stmts, with the
763 following initial value in the STMT_VINFO fields:
765 stmt in_pattern_p related_stmt vec_stmt
767 S2: a_2 = ..use(a_i).. - - -
768 S3: a_1 = ..use(a_2).. - - -
769 S4: a_0 = ..use(a_1).. - - -
770 S5: ... = ..use(a_0).. - - -
772 Say the sequence {S1,S2,S3,S4} was detected as a pattern that can be
773 represented by a single stmt. We then:
774 - create a new stmt S6 that will replace the pattern.
775 - insert the new stmt S6 before the last stmt in the pattern
776 - fill in the STMT_VINFO fields as follows:
778 in_pattern_p related_stmt vec_stmt
780 S2: a_2 = ..use(a_i).. - - -
781 S3: a_1 = ..use(a_2).. - - -
782 > S6: a_new = .... - S4 -
783 S4: a_0 = ..use(a_1).. true S6 -
784 S5: ... = ..use(a_0).. - - -
786 (the last stmt in the pattern (S4) and the new pattern stmt (S6) point
787 to each other through the RELATED_STMT field).
789 S6 will be marked as relevant in vect_mark_stmts_to_be_vectorized instead
790 of S4 because it will replace all its uses. Stmts {S1,S2,S3} will
791 remain irrelevant unless used by stmts other than S4.
793 If vectorization succeeds, vect_transform_stmt will skip over {S1,S2,S3}
794 (because they are marked as irrelevant). It will vectorize S6, and record
795 a pointer to the new vector stmt VS6 both from S6 (as usual), and also
796 from S4. We do that so that when we get to vectorizing stmts that use the
797 def of S4 (like S5 that uses a_0), we'll know where to take the relevant
798 vector-def from. S4 will be skipped, and S5 will be vectorized as usual:
800 in_pattern_p related_stmt vec_stmt
802 S2: a_2 = ..use(a_i).. - - -
803 S3: a_1 = ..use(a_2).. - - -
804 > VS6: va_new = .... - - -
805 S6: a_new = .... - S4 VS6
806 S4: a_0 = ..use(a_1).. true S6 VS6
807 > VS5: ... = ..vuse(va_new).. - - -
808 S5: ... = ..use(a_0).. - - -
810 DCE could then get rid of {S1,S2,S3,S4,S5,S6} (if their defs are not used
811 elsewhere), and we'll end up with:
814 VS5: ... = ..vuse(va_new)..
816 If vectorization does not succeed, DCE will clean S6 away (its def is
817 not used), and we'll end up with the original sequence.
821 vect_pattern_recog (loop_vec_info loop_vinfo)
823 struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
824 basic_block *bbs = LOOP_VINFO_BBS (loop_vinfo);
825 unsigned int nbbs = loop->num_nodes;
826 gimple_stmt_iterator si;
829 gimple (* vect_recog_func_ptr) (gimple, tree *, tree *);
831 if (vect_print_dump_info (REPORT_DETAILS))
832 fprintf (vect_dump, "=== vect_pattern_recog ===");
834 /* Scan through the loop stmts, applying the pattern recognition
835 functions starting at each stmt visited: */
836 for (i = 0; i < nbbs; i++)
838 basic_block bb = bbs[i];
839 for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
841 stmt = gsi_stmt (si);
843 /* Scan over all generic vect_recog_xxx_pattern functions. */
844 for (j = 0; j < NUM_PATTERNS; j++)
846 vect_recog_func_ptr = vect_vect_recog_func_ptrs[j];
847 vect_pattern_recog_1 (vect_recog_func_ptr, si);