1 /* Global, SSA-based optimizations using mathematical identities.
2 Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by the
8 Free Software Foundation; either version 3, or (at your option) any
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /* Currently, the only mini-pass in this file tries to CSE reciprocal
21 operations. These are common in sequences such as this one:
23 modulus = sqrt(x*x + y*y + z*z);
28 that can be optimized to
30 modulus = sqrt(x*x + y*y + z*z);
31 rmodulus = 1.0 / modulus;
36 We do this for loop invariant divisors, and with this pass whenever
37 we notice that a division has the same divisor multiple times.
39 Of course, like in PRE, we don't insert a division if a dominator
40 already has one. However, this cannot be done as an extension of
41 PRE for several reasons.
43 First of all, with some experiments it was found out that the
44 transformation is not always useful if there are only two divisions
45 hy the same divisor. This is probably because modern processors
46 can pipeline the divisions; on older, in-order processors it should
47 still be effective to optimize two divisions by the same number.
48 We make this a param, and it shall be called N in the remainder of
51 Second, if trapping math is active, we have less freedom on where
52 to insert divisions: we can only do so in basic blocks that already
53 contain one. (If divisions don't trap, instead, we can insert
54 divisions elsewhere, which will be in blocks that are common dominators
55 of those that have the division).
57 We really don't want to compute the reciprocal unless a division will
58 be found. To do this, we won't insert the division in a basic block
59 that has less than N divisions *post-dominating* it.
61 The algorithm constructs a subset of the dominator tree, holding the
62 blocks containing the divisions and the common dominators to them,
63 and walk it twice. The first walk is in post-order, and it annotates
64 each block with the number of divisions that post-dominate it: this
65 gives information on where divisions can be inserted profitably.
66 The second walk is in pre-order, and it inserts divisions as explained
67 above, and replaces divisions by multiplications.
69 In the best case, the cost of the pass is O(n_statements). In the
70 worst-case, the cost is due to creating the dominator tree subset,
71 with a cost of O(n_basic_blocks ^ 2); however this can only happen
72 for n_statements / n_basic_blocks statements. So, the amortized cost
73 of creating the dominator tree subset is O(n_basic_blocks) and the
74 worst-case cost of the pass is O(n_statements * n_basic_blocks).
76 More practically, the cost will be small because there are few
77 divisions, and they tend to be in the same basic block, so insert_bb
78 is called very few times.
80 If we did this using domwalk.c, an efficient implementation would have
81 to work on all the variables in a single pass, because we could not
82 work on just a subset of the dominator tree, as we do now, and the
83 cost would also be something like O(n_statements * n_basic_blocks).
84 The data structures would be more complex in order to work on all the
85 variables in a single pass. */
89 #include "coretypes.h"
93 #include "tree-flow.h"
96 #include "tree-pass.h"
97 #include "alloc-pool.h"
98 #include "basic-block.h"
102 /* This structure represents one basic block that either computes a
103 division, or is a common dominator for basic block that compute a
106 /* The basic block represented by this structure. */
109 /* If non-NULL, the SSA_NAME holding the definition for a reciprocal
113 /* If non-NULL, the GIMPLE_ASSIGN for a reciprocal computation that
114 was inserted in BB. */
115 gimple recip_def_stmt;
117 /* Pointer to a list of "struct occurrence"s for blocks dominated
119 struct occurrence *children;
121 /* Pointer to the next "struct occurrence"s in the list of blocks
122 sharing a common dominator. */
123 struct occurrence *next;
125 /* The number of divisions that are in BB before compute_merit. The
126 number of divisions that are in BB or post-dominate it after
130 /* True if the basic block has a division, false if it is a common
131 dominator for basic blocks that do. If it is false and trapping
132 math is active, BB is not a candidate for inserting a reciprocal. */
133 bool bb_has_division;
137 /* The instance of "struct occurrence" representing the highest
138 interesting block in the dominator tree. */
139 static struct occurrence *occ_head;
141 /* Allocation pool for getting instances of "struct occurrence". */
142 static alloc_pool occ_pool;
146 /* Allocate and return a new struct occurrence for basic block BB, and
147 whose children list is headed by CHILDREN. */
148 static struct occurrence *
149 occ_new (basic_block bb, struct occurrence *children)
151 struct occurrence *occ;
153 bb->aux = occ = (struct occurrence *) pool_alloc (occ_pool);
154 memset (occ, 0, sizeof (struct occurrence));
157 occ->children = children;
162 /* Insert NEW_OCC into our subset of the dominator tree. P_HEAD points to a
163 list of "struct occurrence"s, one per basic block, having IDOM as
164 their common dominator.
166 We try to insert NEW_OCC as deep as possible in the tree, and we also
167 insert any other block that is a common dominator for BB and one
168 block already in the tree. */
171 insert_bb (struct occurrence *new_occ, basic_block idom,
172 struct occurrence **p_head)
174 struct occurrence *occ, **p_occ;
176 for (p_occ = p_head; (occ = *p_occ) != NULL; )
178 basic_block bb = new_occ->bb, occ_bb = occ->bb;
179 basic_block dom = nearest_common_dominator (CDI_DOMINATORS, occ_bb, bb);
182 /* BB dominates OCC_BB. OCC becomes NEW_OCC's child: remove OCC
185 occ->next = new_occ->children;
186 new_occ->children = occ;
188 /* Try the next block (it may as well be dominated by BB). */
191 else if (dom == occ_bb)
193 /* OCC_BB dominates BB. Tail recurse to look deeper. */
194 insert_bb (new_occ, dom, &occ->children);
198 else if (dom != idom)
200 gcc_assert (!dom->aux);
202 /* There is a dominator between IDOM and BB, add it and make
203 two children out of NEW_OCC and OCC. First, remove OCC from
209 /* None of the previous blocks has DOM as a dominator: if we tail
210 recursed, we would reexamine them uselessly. Just switch BB with
211 DOM, and go on looking for blocks dominated by DOM. */
212 new_occ = occ_new (dom, new_occ);
217 /* Nothing special, go on with the next element. */
222 /* No place was found as a child of IDOM. Make BB a sibling of IDOM. */
223 new_occ->next = *p_head;
227 /* Register that we found a division in BB. */
230 register_division_in (basic_block bb)
232 struct occurrence *occ;
234 occ = (struct occurrence *) bb->aux;
237 occ = occ_new (bb, NULL);
238 insert_bb (occ, ENTRY_BLOCK_PTR, &occ_head);
241 occ->bb_has_division = true;
242 occ->num_divisions++;
246 /* Compute the number of divisions that postdominate each block in OCC and
250 compute_merit (struct occurrence *occ)
252 struct occurrence *occ_child;
253 basic_block dom = occ->bb;
255 for (occ_child = occ->children; occ_child; occ_child = occ_child->next)
258 if (occ_child->children)
259 compute_merit (occ_child);
262 bb = single_noncomplex_succ (dom);
266 if (dominated_by_p (CDI_POST_DOMINATORS, bb, occ_child->bb))
267 occ->num_divisions += occ_child->num_divisions;
272 /* Return whether USE_STMT is a floating-point division by DEF. */
274 is_division_by (gimple use_stmt, tree def)
276 return is_gimple_assign (use_stmt)
277 && gimple_assign_rhs_code (use_stmt) == RDIV_EXPR
278 && gimple_assign_rhs2 (use_stmt) == def
279 /* Do not recognize x / x as valid division, as we are getting
280 confused later by replacing all immediate uses x in such
282 && gimple_assign_rhs1 (use_stmt) != def;
285 /* Walk the subset of the dominator tree rooted at OCC, setting the
286 RECIP_DEF field to a definition of 1.0 / DEF that can be used in
287 the given basic block. The field may be left NULL, of course,
288 if it is not possible or profitable to do the optimization.
290 DEF_BSI is an iterator pointing at the statement defining DEF.
291 If RECIP_DEF is set, a dominator already has a computation that can
295 insert_reciprocals (gimple_stmt_iterator *def_gsi, struct occurrence *occ,
296 tree def, tree recip_def, int threshold)
300 gimple_stmt_iterator gsi;
301 struct occurrence *occ_child;
304 && (occ->bb_has_division || !flag_trapping_math)
305 && occ->num_divisions >= threshold)
307 /* Make a variable with the replacement and substitute it. */
308 type = TREE_TYPE (def);
309 recip_def = make_rename_temp (type, "reciptmp");
310 new_stmt = gimple_build_assign_with_ops (RDIV_EXPR, recip_def,
311 build_one_cst (type), def);
313 if (occ->bb_has_division)
315 /* Case 1: insert before an existing division. */
316 gsi = gsi_after_labels (occ->bb);
317 while (!gsi_end_p (gsi) && !is_division_by (gsi_stmt (gsi), def))
320 gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
322 else if (def_gsi && occ->bb == def_gsi->bb)
324 /* Case 2: insert right after the definition. Note that this will
325 never happen if the definition statement can throw, because in
326 that case the sole successor of the statement's basic block will
327 dominate all the uses as well. */
328 gsi_insert_after (def_gsi, new_stmt, GSI_NEW_STMT);
332 /* Case 3: insert in a basic block not containing defs/uses. */
333 gsi = gsi_after_labels (occ->bb);
334 gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
337 occ->recip_def_stmt = new_stmt;
340 occ->recip_def = recip_def;
341 for (occ_child = occ->children; occ_child; occ_child = occ_child->next)
342 insert_reciprocals (def_gsi, occ_child, def, recip_def, threshold);
346 /* Replace the division at USE_P with a multiplication by the reciprocal, if
350 replace_reciprocal (use_operand_p use_p)
352 gimple use_stmt = USE_STMT (use_p);
353 basic_block bb = gimple_bb (use_stmt);
354 struct occurrence *occ = (struct occurrence *) bb->aux;
356 if (occ->recip_def && use_stmt != occ->recip_def_stmt)
358 gimple_assign_set_rhs_code (use_stmt, MULT_EXPR);
359 SET_USE (use_p, occ->recip_def);
360 fold_stmt_inplace (use_stmt);
361 update_stmt (use_stmt);
366 /* Free OCC and return one more "struct occurrence" to be freed. */
368 static struct occurrence *
369 free_bb (struct occurrence *occ)
371 struct occurrence *child, *next;
373 /* First get the two pointers hanging off OCC. */
375 child = occ->children;
377 pool_free (occ_pool, occ);
379 /* Now ensure that we don't recurse unless it is necessary. */
385 next = free_bb (next);
392 /* Look for floating-point divisions among DEF's uses, and try to
393 replace them by multiplications with the reciprocal. Add
394 as many statements computing the reciprocal as needed.
396 DEF must be a GIMPLE register of a floating-point type. */
399 execute_cse_reciprocals_1 (gimple_stmt_iterator *def_gsi, tree def)
402 imm_use_iterator use_iter;
403 struct occurrence *occ;
404 int count = 0, threshold;
406 gcc_assert (FLOAT_TYPE_P (TREE_TYPE (def)) && is_gimple_reg (def));
408 FOR_EACH_IMM_USE_FAST (use_p, use_iter, def)
410 gimple use_stmt = USE_STMT (use_p);
411 if (is_division_by (use_stmt, def))
413 register_division_in (gimple_bb (use_stmt));
418 /* Do the expensive part only if we can hope to optimize something. */
419 threshold = targetm.min_divisions_for_recip_mul (TYPE_MODE (TREE_TYPE (def)));
420 if (count >= threshold)
423 for (occ = occ_head; occ; occ = occ->next)
426 insert_reciprocals (def_gsi, occ, def, NULL, threshold);
429 FOR_EACH_IMM_USE_STMT (use_stmt, use_iter, def)
431 if (is_division_by (use_stmt, def))
433 FOR_EACH_IMM_USE_ON_STMT (use_p, use_iter)
434 replace_reciprocal (use_p);
439 for (occ = occ_head; occ; )
446 gate_cse_reciprocals (void)
448 return optimize && !optimize_size && flag_reciprocal_math;
451 /* Go through all the floating-point SSA_NAMEs, and call
452 execute_cse_reciprocals_1 on each of them. */
454 execute_cse_reciprocals (void)
459 occ_pool = create_alloc_pool ("dominators for recip",
460 sizeof (struct occurrence),
461 n_basic_blocks / 3 + 1);
463 calculate_dominance_info (CDI_DOMINATORS);
464 calculate_dominance_info (CDI_POST_DOMINATORS);
466 #ifdef ENABLE_CHECKING
468 gcc_assert (!bb->aux);
471 for (arg = DECL_ARGUMENTS (cfun->decl); arg; arg = TREE_CHAIN (arg))
472 if (gimple_default_def (cfun, arg)
473 && FLOAT_TYPE_P (TREE_TYPE (arg))
474 && is_gimple_reg (arg))
475 execute_cse_reciprocals_1 (NULL, gimple_default_def (cfun, arg));
479 gimple_stmt_iterator gsi;
483 for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
485 phi = gsi_stmt (gsi);
486 def = PHI_RESULT (phi);
487 if (FLOAT_TYPE_P (TREE_TYPE (def))
488 && is_gimple_reg (def))
489 execute_cse_reciprocals_1 (NULL, def);
492 for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); gsi_next (&gsi))
494 gimple stmt = gsi_stmt (gsi);
496 if (gimple_has_lhs (stmt)
497 && (def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF)) != NULL
498 && FLOAT_TYPE_P (TREE_TYPE (def))
499 && TREE_CODE (def) == SSA_NAME)
500 execute_cse_reciprocals_1 (&gsi, def);
503 /* Scan for a/func(b) and convert it to reciprocal a*rfunc(b). */
504 for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); gsi_next (&gsi))
506 gimple stmt = gsi_stmt (gsi);
509 if (is_gimple_assign (stmt)
510 && gimple_assign_rhs_code (stmt) == RDIV_EXPR)
512 tree arg1 = gimple_assign_rhs2 (stmt);
515 if (TREE_CODE (arg1) != SSA_NAME)
518 stmt1 = SSA_NAME_DEF_STMT (arg1);
520 if (is_gimple_call (stmt1)
521 && gimple_call_lhs (stmt1)
522 && (fndecl = gimple_call_fndecl (stmt1))
523 && (DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
524 || DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_MD))
526 enum built_in_function code;
529 code = DECL_FUNCTION_CODE (fndecl);
530 md_code = DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_MD;
532 fndecl = targetm.builtin_reciprocal (code, md_code, false);
536 gimple_call_set_fndecl (stmt1, fndecl);
539 gimple_assign_set_rhs_code (stmt, MULT_EXPR);
540 fold_stmt_inplace (stmt);
547 free_dominance_info (CDI_DOMINATORS);
548 free_dominance_info (CDI_POST_DOMINATORS);
549 free_alloc_pool (occ_pool);
553 struct gimple_opt_pass pass_cse_reciprocals =
558 gate_cse_reciprocals, /* gate */
559 execute_cse_reciprocals, /* execute */
562 0, /* static_pass_number */
564 PROP_ssa, /* properties_required */
565 0, /* properties_provided */
566 0, /* properties_destroyed */
567 0, /* todo_flags_start */
568 TODO_dump_func | TODO_update_ssa | TODO_verify_ssa
569 | TODO_verify_stmts /* todo_flags_finish */
573 /* Records an occurrence at statement USE_STMT in the vector of trees
574 STMTS if it is dominated by *TOP_BB or dominates it or this basic block
575 is not yet initialized. Returns true if the occurrence was pushed on
576 the vector. Adjusts *TOP_BB to be the basic block dominating all
577 statements in the vector. */
580 maybe_record_sincos (VEC(gimple, heap) **stmts,
581 basic_block *top_bb, gimple use_stmt)
583 basic_block use_bb = gimple_bb (use_stmt);
585 && (*top_bb == use_bb
586 || dominated_by_p (CDI_DOMINATORS, use_bb, *top_bb)))
587 VEC_safe_push (gimple, heap, *stmts, use_stmt);
589 || dominated_by_p (CDI_DOMINATORS, *top_bb, use_bb))
591 VEC_safe_push (gimple, heap, *stmts, use_stmt);
600 /* Look for sin, cos and cexpi calls with the same argument NAME and
601 create a single call to cexpi CSEing the result in this case.
602 We first walk over all immediate uses of the argument collecting
603 statements that we can CSE in a vector and in a second pass replace
604 the statement rhs with a REALPART or IMAGPART expression on the
605 result of the cexpi call we insert before the use statement that
606 dominates all other candidates. */
609 execute_cse_sincos_1 (tree name)
611 gimple_stmt_iterator gsi;
612 imm_use_iterator use_iter;
613 tree fndecl, res, type;
614 gimple def_stmt, use_stmt, stmt;
615 int seen_cos = 0, seen_sin = 0, seen_cexpi = 0;
616 VEC(gimple, heap) *stmts = NULL;
617 basic_block top_bb = NULL;
620 type = TREE_TYPE (name);
621 FOR_EACH_IMM_USE_STMT (use_stmt, use_iter, name)
623 if (gimple_code (use_stmt) != GIMPLE_CALL
624 || !gimple_call_lhs (use_stmt)
625 || !(fndecl = gimple_call_fndecl (use_stmt))
626 || DECL_BUILT_IN_CLASS (fndecl) != BUILT_IN_NORMAL)
629 switch (DECL_FUNCTION_CODE (fndecl))
631 CASE_FLT_FN (BUILT_IN_COS):
632 seen_cos |= maybe_record_sincos (&stmts, &top_bb, use_stmt) ? 1 : 0;
635 CASE_FLT_FN (BUILT_IN_SIN):
636 seen_sin |= maybe_record_sincos (&stmts, &top_bb, use_stmt) ? 1 : 0;
639 CASE_FLT_FN (BUILT_IN_CEXPI):
640 seen_cexpi |= maybe_record_sincos (&stmts, &top_bb, use_stmt) ? 1 : 0;
647 if (seen_cos + seen_sin + seen_cexpi <= 1)
649 VEC_free(gimple, heap, stmts);
653 /* Simply insert cexpi at the beginning of top_bb but not earlier than
654 the name def statement. */
655 fndecl = mathfn_built_in (type, BUILT_IN_CEXPI);
658 res = make_rename_temp (TREE_TYPE (TREE_TYPE (fndecl)), "sincostmp");
659 stmt = gimple_build_call (fndecl, 1, name);
660 gimple_call_set_lhs (stmt, res);
662 def_stmt = SSA_NAME_DEF_STMT (name);
663 if (!SSA_NAME_IS_DEFAULT_DEF (name)
664 && gimple_code (def_stmt) != GIMPLE_PHI
665 && gimple_bb (def_stmt) == top_bb)
667 gsi = gsi_for_stmt (def_stmt);
668 gsi_insert_after (&gsi, stmt, GSI_SAME_STMT);
672 gsi = gsi_after_labels (top_bb);
673 gsi_insert_before (&gsi, stmt, GSI_SAME_STMT);
677 /* And adjust the recorded old call sites. */
678 for (i = 0; VEC_iterate(gimple, stmts, i, use_stmt); ++i)
681 fndecl = gimple_call_fndecl (use_stmt);
683 switch (DECL_FUNCTION_CODE (fndecl))
685 CASE_FLT_FN (BUILT_IN_COS):
686 rhs = fold_build1 (REALPART_EXPR, type, res);
689 CASE_FLT_FN (BUILT_IN_SIN):
690 rhs = fold_build1 (IMAGPART_EXPR, type, res);
693 CASE_FLT_FN (BUILT_IN_CEXPI):
701 /* Replace call with a copy. */
702 stmt = gimple_build_assign (gimple_call_lhs (use_stmt), rhs);
704 gsi = gsi_for_stmt (use_stmt);
705 gsi_insert_after (&gsi, stmt, GSI_SAME_STMT);
706 gsi_remove (&gsi, true);
709 VEC_free(gimple, heap, stmts);
712 /* Go through all calls to sin, cos and cexpi and call execute_cse_sincos_1
713 on the SSA_NAME argument of each of them. */
716 execute_cse_sincos (void)
720 calculate_dominance_info (CDI_DOMINATORS);
724 gimple_stmt_iterator gsi;
726 for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); gsi_next (&gsi))
728 gimple stmt = gsi_stmt (gsi);
731 if (is_gimple_call (stmt)
732 && gimple_call_lhs (stmt)
733 && (fndecl = gimple_call_fndecl (stmt))
734 && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
738 switch (DECL_FUNCTION_CODE (fndecl))
740 CASE_FLT_FN (BUILT_IN_COS):
741 CASE_FLT_FN (BUILT_IN_SIN):
742 CASE_FLT_FN (BUILT_IN_CEXPI):
743 arg = gimple_call_arg (stmt, 0);
744 if (TREE_CODE (arg) == SSA_NAME)
745 execute_cse_sincos_1 (arg);
754 free_dominance_info (CDI_DOMINATORS);
759 gate_cse_sincos (void)
761 /* Make sure we have either sincos or cexp. */
762 return (TARGET_HAS_SINCOS
763 || TARGET_C99_FUNCTIONS)
767 struct gimple_opt_pass pass_cse_sincos =
772 gate_cse_sincos, /* gate */
773 execute_cse_sincos, /* execute */
776 0, /* static_pass_number */
778 PROP_ssa, /* properties_required */
779 0, /* properties_provided */
780 0, /* properties_destroyed */
781 0, /* todo_flags_start */
782 TODO_dump_func | TODO_update_ssa | TODO_verify_ssa
783 | TODO_verify_stmts /* todo_flags_finish */
787 /* Find all expressions in the form of sqrt(a/b) and
788 convert them to rsqrt(b/a). */
791 execute_convert_to_rsqrt (void)
797 gimple_stmt_iterator gsi;
799 for (gsi = gsi_after_labels (bb); !gsi_end_p (gsi); gsi_next (&gsi))
801 gimple stmt = gsi_stmt (gsi);
804 if (is_gimple_call (stmt)
805 && gimple_call_lhs (stmt)
806 && (fndecl = gimple_call_fndecl (stmt))
807 && (DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
808 || DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_MD))
810 enum built_in_function code;
815 code = DECL_FUNCTION_CODE (fndecl);
816 md_code = DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_MD;
818 fndecl = targetm.builtin_reciprocal (code, md_code, true);
822 arg1 = gimple_call_arg (stmt, 0);
824 if (TREE_CODE (arg1) != SSA_NAME)
827 stmt1 = SSA_NAME_DEF_STMT (arg1);
829 if (is_gimple_assign (stmt1)
830 && gimple_assign_rhs_code (stmt1) == RDIV_EXPR)
834 arg10 = gimple_assign_rhs1 (stmt1);
835 arg11 = gimple_assign_rhs2 (stmt1);
837 /* Swap operands of RDIV_EXPR. */
838 gimple_assign_set_rhs1 (stmt1, arg11);
839 gimple_assign_set_rhs2 (stmt1, arg10);
840 fold_stmt_inplace (stmt1);
843 gimple_call_set_fndecl (stmt, fndecl);
854 gate_convert_to_rsqrt (void)
856 return flag_unsafe_math_optimizations && optimize;
859 struct gimple_opt_pass pass_convert_to_rsqrt =
864 gate_convert_to_rsqrt, /* gate */
865 execute_convert_to_rsqrt, /* execute */
868 0, /* static_pass_number */
870 PROP_ssa, /* properties_required */
871 0, /* properties_provided */
872 0, /* properties_destroyed */
873 0, /* todo_flags_start */
874 TODO_dump_func | TODO_update_ssa | TODO_verify_ssa
875 | TODO_verify_stmts /* todo_flags_finish */