1 /* Tail call optimization on trees.
2 Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GCC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
23 #include "coretypes.h"
28 #include "hard-reg-set.h"
29 #include "basic-block.h"
31 #include "tree-flow.h"
32 #include "tree-dump.h"
33 #include "diagnostic.h"
35 #include "tree-pass.h"
37 #include "langhooks.h"
39 /* The file implements the tail recursion elimination. It is also used to
40 analyze the tail calls in general, passing the results to the rtl level
41 where they are used for sibcall optimization.
43 In addition to the standard tail recursion elimination, we handle the most
44 trivial cases of making the call tail recursive by creating accumulators.
45 For example the following function
50 return n + sum (n - 1);
67 To do this, we maintain two accumulators (a_acc and m_acc) that indicate
68 when we reach the return x statement, we should return a_acc + x * m_acc
69 instead. They are initially initialized to 0 and 1, respectively,
70 so the semantics of the function is obviously preserved. If we are
71 guaranteed that the value of the accumulator never change, we
74 There are three cases how the function may exit. The first one is
75 handled in adjust_return_value, the other two in adjust_accumulator_values
76 (the second case is actually a special case of the third one and we
77 present it separately just for clarity):
79 1) Just return x, where x is not in any of the remaining special shapes.
80 We rewrite this to a gimple equivalent of return m_acc * x + a_acc.
82 2) return f (...), where f is the current function, is rewritten in a
83 classical tail-recursion elimination way, into assignment of arguments
84 and jump to the start of the function. Values of the accumulators
87 3) return a + m * f(...), where a and m do not depend on call to f.
88 To preserve the semantics described before we want this to be rewritten
89 in such a way that we finally return
91 a_acc + (a + m * f(...)) * m_acc = (a_acc + a * m_acc) + (m * m_acc) * f(...).
93 I.e. we increase a_acc by a * m_acc, multiply m_acc by m and
94 eliminate the tail call to f. Special cases when the value is just
95 added or just multiplied are obtained by setting a = 0 or m = 1.
97 TODO -- it is possible to do similar tricks for other operations. */
99 /* A structure that describes the tailcall. */
103 /* The block in that the call occur. */
104 basic_block call_block
;
106 /* The iterator pointing to the call statement. */
107 block_stmt_iterator call_bsi
;
109 /* True if it is a call to the current function. */
112 /* The return value of the caller is mult * f + add, where f is the return
113 value of the call. */
116 /* Next tailcall in the chain. */
117 struct tailcall
*next
;
120 /* The variables holding the value of multiplicative and additive
122 static tree m_acc
, a_acc
;
124 static bool suitable_for_tail_opt_p (void);
125 static bool optimize_tail_call (struct tailcall
*, bool);
126 static void eliminate_tail_call (struct tailcall
*);
127 static void find_tail_calls (basic_block
, struct tailcall
**);
129 /* Returns false when the function is not suitable for tail call optimization
130 from some reason (e.g. if it takes variable number of arguments). */
133 suitable_for_tail_opt_p (void)
137 if (current_function_stdarg
)
140 /* No local variable nor structure field should be call-clobbered. We
141 ignore any kind of memory tag, as these are not real variables. */
142 for (i
= 0; i
< (int) VARRAY_ACTIVE_SIZE (referenced_vars
); i
++)
144 tree var
= VARRAY_TREE (referenced_vars
, i
);
146 if (!(TREE_STATIC (var
) || DECL_EXTERNAL (var
))
147 && (var_ann (var
)->mem_tag_kind
== NOT_A_TAG
148 || var_ann (var
)->mem_tag_kind
== STRUCT_FIELD
)
149 && is_call_clobbered (var
))
155 /* Returns false when the function is not suitable for tail call optimization
156 from some reason (e.g. if it takes variable number of arguments).
157 This test must pass in addition to suitable_for_tail_opt_p in order to make
158 tail call discovery happen. */
161 suitable_for_tail_call_opt_p (void)
165 /* alloca (until we have stack slot life analysis) inhibits
166 sibling call optimizations, but not tail recursion. */
167 if (current_function_calls_alloca
)
170 /* If we are using sjlj exceptions, we may need to add a call to
171 _Unwind_SjLj_Unregister at exit of the function. Which means
172 that we cannot do any sibcall transformations. */
173 if (USING_SJLJ_EXCEPTIONS
&& current_function_has_exception_handlers ())
176 /* Any function that calls setjmp might have longjmp called from
177 any called function. ??? We really should represent this
178 properly in the CFG so that this needn't be special cased. */
179 if (current_function_calls_setjmp
)
182 /* ??? It is OK if the argument of a function is taken in some cases,
183 but not in all cases. See PR15387 and PR19616. Revisit for 4.1. */
184 for (param
= DECL_ARGUMENTS (current_function_decl
);
186 param
= TREE_CHAIN (param
))
187 if (TREE_ADDRESSABLE (param
))
193 /* Checks whether the expression EXPR in stmt AT is independent of the
194 statement pointed by BSI (in a sense that we already know EXPR's value
195 at BSI). We use the fact that we are only called from the chain of
196 basic blocks that have only single successor. Returns the expression
197 containing the value of EXPR at BSI. */
200 independent_of_stmt_p (tree expr
, tree at
, block_stmt_iterator bsi
)
202 basic_block bb
, call_bb
, at_bb
;
206 if (is_gimple_min_invariant (expr
))
209 if (TREE_CODE (expr
) != SSA_NAME
)
212 /* Mark the blocks in the chain leading to the end. */
213 at_bb
= bb_for_stmt (at
);
214 call_bb
= bb_for_stmt (bsi_stmt (bsi
));
215 for (bb
= call_bb
; bb
!= at_bb
; bb
= single_succ (bb
))
221 at
= SSA_NAME_DEF_STMT (expr
);
222 bb
= bb_for_stmt (at
);
224 /* The default definition or defined before the chain. */
230 for (; !bsi_end_p (bsi
); bsi_next (&bsi
))
231 if (bsi_stmt (bsi
) == at
)
234 if (!bsi_end_p (bsi
))
239 if (TREE_CODE (at
) != PHI_NODE
)
245 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
250 expr
= PHI_ARG_DEF_FROM_EDGE (at
, e
);
251 if (TREE_CODE (expr
) != SSA_NAME
)
253 /* The value is a constant. */
258 /* Unmark the blocks. */
259 for (bb
= call_bb
; bb
!= at_bb
; bb
= single_succ (bb
))
266 /* Simulates the effect of an assignment of ASS in STMT on the return value
267 of the tail recursive CALL passed in ASS_VAR. M and A are the
268 multiplicative and the additive factor for the real return value. */
271 process_assignment (tree ass
, tree stmt
, block_stmt_iterator call
, tree
*m
,
272 tree
*a
, tree
*ass_var
)
274 tree op0
, op1
, non_ass_var
;
275 tree dest
= TREE_OPERAND (ass
, 0);
276 tree src
= TREE_OPERAND (ass
, 1);
277 enum tree_code code
= TREE_CODE (src
);
280 /* See if this is a simple copy operation of an SSA name to the function
281 result. In that case we may have a simple tail call. Ignore type
282 conversions that can never produce extra code between the function
283 call and the function return. */
284 STRIP_NOPS (src_var
);
285 if (TREE_CODE (src_var
) == SSA_NAME
)
287 if (src_var
!= *ass_var
)
294 if (TREE_CODE_CLASS (code
) != tcc_binary
)
297 /* Accumulator optimizations will reverse the order of operations.
298 We can only do that for floating-point types if we're assuming
299 that addition and multiplication are associative. */
300 if (!flag_unsafe_math_optimizations
)
301 if (FLOAT_TYPE_P (TREE_TYPE (DECL_RESULT (current_function_decl
))))
304 /* We only handle the code like
311 TODO -- Extend it for cases where the linear transformation of the output
312 is expressed in a more complicated way. */
314 op0
= TREE_OPERAND (src
, 0);
315 op1
= TREE_OPERAND (src
, 1);
318 && (non_ass_var
= independent_of_stmt_p (op1
, stmt
, call
)))
320 else if (op1
== *ass_var
321 && (non_ass_var
= independent_of_stmt_p (op0
, stmt
, call
)))
329 /* There should be no previous addition. TODO -- it should be fairly
330 straightforward to lift this restriction -- just allow storing
331 more complicated expressions in *A, and gimplify it in
332 adjust_accumulator_values. */
340 /* Similar remark applies here. Handling multiplication after addition
341 is just slightly more complicated -- we need to multiply both *A and
349 /* TODO -- Handle other codes (NEGATE_EXPR, MINUS_EXPR). */
356 /* Propagate VAR through phis on edge E. */
359 propagate_through_phis (tree var
, edge e
)
361 basic_block dest
= e
->dest
;
364 for (phi
= phi_nodes (dest
); phi
; phi
= PHI_CHAIN (phi
))
365 if (PHI_ARG_DEF_FROM_EDGE (phi
, e
) == var
)
366 return PHI_RESULT (phi
);
371 /* Finds tailcalls falling into basic block BB. The list of found tailcalls is
372 added to the start of RET. */
375 find_tail_calls (basic_block bb
, struct tailcall
**ret
)
377 tree ass_var
, ret_var
, stmt
, func
, param
, args
, call
= NULL_TREE
;
378 block_stmt_iterator bsi
, absi
;
386 if (!single_succ_p (bb
))
389 for (bsi
= bsi_last (bb
); !bsi_end_p (bsi
); bsi_prev (&bsi
))
391 stmt
= bsi_stmt (bsi
);
394 if (TREE_CODE (stmt
) == LABEL_EXPR
)
397 /* Check for a call. */
398 if (TREE_CODE (stmt
) == MODIFY_EXPR
)
400 ass_var
= TREE_OPERAND (stmt
, 0);
401 call
= TREE_OPERAND (stmt
, 1);
402 if (TREE_CODE (call
) == WITH_SIZE_EXPR
)
403 call
= TREE_OPERAND (call
, 0);
411 if (TREE_CODE (call
) == CALL_EXPR
)
414 /* If the statement has virtual or volatile operands, fail. */
415 ann
= stmt_ann (stmt
);
416 if (NUM_V_MAY_DEFS (V_MAY_DEF_OPS (ann
))
417 || NUM_V_MUST_DEFS (V_MUST_DEF_OPS (ann
))
418 || NUM_VUSES (VUSE_OPS (ann
))
419 || ann
->has_volatile_ops
)
426 /* Recurse to the predecessors. */
427 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
428 find_tail_calls (e
->src
, ret
);
433 /* We found the call, check whether it is suitable. */
434 tail_recursion
= false;
435 func
= get_callee_fndecl (call
);
436 if (func
== current_function_decl
)
438 for (param
= DECL_ARGUMENTS (func
), args
= TREE_OPERAND (call
, 1);
440 param
= TREE_CHAIN (param
), args
= TREE_CHAIN (args
))
442 tree arg
= TREE_VALUE (args
);
445 /* Make sure there are no problems with copying. The parameter
446 have a copyable type and the two arguments must have reasonably
447 equivalent types. The latter requirement could be relaxed if
448 we emitted a suitable type conversion statement. */
449 if (!is_gimple_reg_type (TREE_TYPE (param
))
450 || !lang_hooks
.types_compatible_p (TREE_TYPE (param
),
454 /* The parameter should be a real operand, so that phi node
455 created for it at the start of the function has the meaning
456 of copying the value. This test implies is_gimple_reg_type
457 from the previous condition, however this one could be
458 relaxed by being more careful with copying the new value
459 of the parameter (emitting appropriate MODIFY_EXPR and
460 updating the virtual operands). */
461 if (!is_gimple_reg (param
))
466 tail_recursion
= true;
469 /* Now check the statements after the call. None of them has virtual
470 operands, so they may only depend on the call through its return
471 value. The return value should also be dependent on each of them,
472 since we are running after dce. */
482 while (bsi_end_p (absi
))
484 ass_var
= propagate_through_phis (ass_var
, single_succ_edge (abb
));
485 abb
= single_succ (abb
);
486 absi
= bsi_start (abb
);
489 stmt
= bsi_stmt (absi
);
491 if (TREE_CODE (stmt
) == LABEL_EXPR
)
494 if (TREE_CODE (stmt
) == RETURN_EXPR
)
497 if (TREE_CODE (stmt
) != MODIFY_EXPR
)
500 if (!process_assignment (stmt
, stmt
, bsi
, &m
, &a
, &ass_var
))
504 /* See if this is a tail call we can handle. */
505 ret_var
= TREE_OPERAND (stmt
, 0);
507 && TREE_CODE (ret_var
) == MODIFY_EXPR
)
509 tree ret_op
= TREE_OPERAND (ret_var
, 1);
512 && TREE_CODE (ret_op
) != SSA_NAME
)
515 if (!process_assignment (ret_var
, stmt
, bsi
, &m
, &a
, &ass_var
))
517 ret_var
= TREE_OPERAND (ret_var
, 0);
520 /* We may proceed if there either is no return value, or the return value
521 is identical to the call's return. */
523 && (ret_var
!= ass_var
))
526 /* If this is not a tail recursive call, we cannot handle addends or
528 if (!tail_recursion
&& (m
|| a
))
531 nw
= xmalloc (sizeof (struct tailcall
));
536 nw
->tail_recursion
= tail_recursion
;
545 /* Adjust the accumulator values according to A and M after BSI, and update
546 the phi nodes on edge BACK. */
549 adjust_accumulator_values (block_stmt_iterator bsi
, tree m
, tree a
, edge back
)
551 tree stmt
, var
, phi
, tmp
;
552 tree ret_type
= TREE_TYPE (DECL_RESULT (current_function_decl
));
553 tree a_acc_arg
= a_acc
, m_acc_arg
= m_acc
;
559 if (integer_onep (a
))
563 stmt
= build (MODIFY_EXPR
, ret_type
, NULL_TREE
,
564 build (MULT_EXPR
, ret_type
, m_acc
, a
));
566 tmp
= create_tmp_var (ret_type
, "acc_tmp");
567 add_referenced_tmp_var (tmp
);
569 var
= make_ssa_name (tmp
, stmt
);
570 TREE_OPERAND (stmt
, 0) = var
;
571 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
577 stmt
= build (MODIFY_EXPR
, ret_type
, NULL_TREE
,
578 build (PLUS_EXPR
, ret_type
, a_acc
, var
));
579 var
= make_ssa_name (SSA_NAME_VAR (a_acc
), stmt
);
580 TREE_OPERAND (stmt
, 0) = var
;
581 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
587 stmt
= build (MODIFY_EXPR
, ret_type
, NULL_TREE
,
588 build (MULT_EXPR
, ret_type
, m_acc
, m
));
589 var
= make_ssa_name (SSA_NAME_VAR (m_acc
), stmt
);
590 TREE_OPERAND (stmt
, 0) = var
;
591 bsi_insert_after (&bsi
, stmt
, BSI_NEW_STMT
);
597 for (phi
= phi_nodes (back
->dest
); phi
; phi
= PHI_CHAIN (phi
))
598 if (PHI_RESULT (phi
) == a_acc
)
601 add_phi_arg (phi
, a_acc_arg
, back
);
606 for (phi
= phi_nodes (back
->dest
); phi
; phi
= PHI_CHAIN (phi
))
607 if (PHI_RESULT (phi
) == m_acc
)
610 add_phi_arg (phi
, m_acc_arg
, back
);
614 /* Adjust value of the return at the end of BB according to M and A
618 adjust_return_value (basic_block bb
, tree m
, tree a
)
620 tree ret_stmt
= last_stmt (bb
), ret_var
, var
, stmt
, tmp
;
621 tree ret_type
= TREE_TYPE (DECL_RESULT (current_function_decl
));
622 block_stmt_iterator bsi
= bsi_last (bb
);
624 gcc_assert (TREE_CODE (ret_stmt
) == RETURN_EXPR
);
626 ret_var
= TREE_OPERAND (ret_stmt
, 0);
630 if (TREE_CODE (ret_var
) == MODIFY_EXPR
)
632 ret_var
->common
.ann
= (tree_ann_t
) stmt_ann (ret_stmt
);
633 bsi_replace (&bsi
, ret_var
, true);
634 SSA_NAME_DEF_STMT (TREE_OPERAND (ret_var
, 0)) = ret_var
;
635 ret_var
= TREE_OPERAND (ret_var
, 0);
636 ret_stmt
= build1 (RETURN_EXPR
, TREE_TYPE (ret_stmt
), ret_var
);
637 bsi_insert_after (&bsi
, ret_stmt
, BSI_NEW_STMT
);
642 stmt
= build (MODIFY_EXPR
, ret_type
, NULL_TREE
,
643 build (MULT_EXPR
, ret_type
, m_acc
, ret_var
));
645 tmp
= create_tmp_var (ret_type
, "acc_tmp");
646 add_referenced_tmp_var (tmp
);
648 var
= make_ssa_name (tmp
, stmt
);
649 TREE_OPERAND (stmt
, 0) = var
;
650 bsi_insert_before (&bsi
, stmt
, BSI_SAME_STMT
);
657 stmt
= build (MODIFY_EXPR
, ret_type
, NULL_TREE
,
658 build (PLUS_EXPR
, ret_type
, a_acc
, var
));
660 tmp
= create_tmp_var (ret_type
, "acc_tmp");
661 add_referenced_tmp_var (tmp
);
663 var
= make_ssa_name (tmp
, stmt
);
664 TREE_OPERAND (stmt
, 0) = var
;
665 bsi_insert_before (&bsi
, stmt
, BSI_SAME_STMT
);
668 TREE_OPERAND (ret_stmt
, 0) = var
;
669 update_stmt (ret_stmt
);
672 /* Eliminates tail call described by T. TMP_VARS is a list of
673 temporary variables used to copy the function arguments. */
676 eliminate_tail_call (struct tailcall
*t
)
678 tree param
, stmt
, args
, rslt
, call
;
679 basic_block bb
, first
;
683 v_may_def_optype v_may_defs
;
685 block_stmt_iterator bsi
;
687 stmt
= bsi_stmt (t
->call_bsi
);
688 ann
= stmt_ann (stmt
);
691 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
693 fprintf (dump_file
, "Eliminated tail recursion in bb %d : ",
695 print_generic_stmt (dump_file
, stmt
, TDF_SLIM
);
696 fprintf (dump_file
, "\n");
699 if (TREE_CODE (stmt
) == MODIFY_EXPR
)
700 stmt
= TREE_OPERAND (stmt
, 1);
702 first
= single_succ (ENTRY_BLOCK_PTR
);
704 /* Remove the code after call_bsi that will become unreachable. The
705 possibly unreachable code in other blocks is removed later in
709 while (!bsi_end_p (bsi
))
711 tree t
= bsi_stmt (bsi
);
712 /* Do not remove the return statement, so that redirect_edge_and_branch
713 sees how the block ends. */
714 if (TREE_CODE (t
) == RETURN_EXPR
)
721 /* Replace the call by a jump to the start of function. */
722 e
= redirect_edge_and_branch (single_succ_edge (t
->call_block
), first
);
724 PENDING_STMT (e
) = NULL_TREE
;
726 /* Add phi node entries for arguments. Not every PHI node corresponds to
727 a function argument (there may be PHI nodes for virtual definitions of the
728 eliminated calls), so we search for a PHI corresponding to each argument
729 rather than searching for which argument a PHI node corresponds to. */
731 for (param
= DECL_ARGUMENTS (current_function_decl
),
732 args
= TREE_OPERAND (stmt
, 1);
734 param
= TREE_CHAIN (param
),
735 args
= TREE_CHAIN (args
))
738 for (phi
= phi_nodes (first
); phi
; phi
= PHI_CHAIN (phi
))
739 if (param
== SSA_NAME_VAR (PHI_RESULT (phi
)))
742 /* The phi node indeed does not have to be there, in case the operand is
743 invariant in the function. */
747 add_phi_arg (phi
, TREE_VALUE (args
), e
);
750 /* Add phi nodes for the call clobbered variables. */
751 v_may_defs
= V_MAY_DEF_OPS (ann
);
752 for (i
= 0; i
< NUM_V_MAY_DEFS (v_may_defs
); i
++)
754 param
= SSA_NAME_VAR (V_MAY_DEF_RESULT (v_may_defs
, i
));
755 for (phi
= phi_nodes (first
); phi
; phi
= PHI_CHAIN (phi
))
756 if (param
== SSA_NAME_VAR (PHI_RESULT (phi
)))
761 tree name
= var_ann (param
)->default_def
;
766 /* It may happen that the tag does not have a default_def in case
767 when all uses of it are dominated by a MUST_DEF. This however
768 means that it is not necessary to add a phi node for this
772 new_name
= make_ssa_name (param
, SSA_NAME_DEF_STMT (name
));
774 var_ann (param
)->default_def
= new_name
;
775 phi
= create_phi_node (name
, first
);
776 SSA_NAME_DEF_STMT (name
) = phi
;
777 add_phi_arg (phi
, new_name
, single_succ_edge (ENTRY_BLOCK_PTR
));
779 /* For all calls the same set of variables should be clobbered. This
780 means that there always should be the appropriate phi node except
781 for the first time we eliminate the call. */
782 gcc_assert (EDGE_COUNT (first
->preds
) <= 2);
785 add_phi_arg (phi
, V_MAY_DEF_OP (v_may_defs
, i
), e
);
788 /* Update the values of accumulators. */
789 adjust_accumulator_values (t
->call_bsi
, t
->mult
, t
->add
, e
);
791 call
= bsi_stmt (t
->call_bsi
);
792 if (TREE_CODE (call
) == MODIFY_EXPR
)
794 rslt
= TREE_OPERAND (call
, 0);
796 /* Result of the call will no longer be defined. So adjust the
797 SSA_NAME_DEF_STMT accordingly. */
798 SSA_NAME_DEF_STMT (rslt
) = build_empty_stmt ();
801 bsi_remove (&t
->call_bsi
);
805 /* Optimizes the tailcall described by T. If OPT_TAILCALLS is true, also
806 mark the tailcalls for the sibcall optimization. */
809 optimize_tail_call (struct tailcall
*t
, bool opt_tailcalls
)
811 if (t
->tail_recursion
)
813 eliminate_tail_call (t
);
819 tree stmt
= bsi_stmt (t
->call_bsi
);
821 stmt
= get_call_expr_in (stmt
);
822 CALL_EXPR_TAILCALL (stmt
) = 1;
823 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
825 fprintf (dump_file
, "Found tail call ");
826 print_generic_expr (dump_file
, stmt
, dump_flags
);
827 fprintf (dump_file
, " in bb %i\n", t
->call_block
->index
);
834 /* Optimizes tail calls in the function, turning the tail recursion
838 tree_optimize_tail_calls_1 (bool opt_tailcalls
)
841 bool phis_constructed
= false;
842 struct tailcall
*tailcalls
= NULL
, *act
, *next
;
843 bool changed
= false;
844 basic_block first
= single_succ (ENTRY_BLOCK_PTR
);
845 tree stmt
, param
, ret_type
, tmp
, phi
;
848 if (!suitable_for_tail_opt_p ())
851 opt_tailcalls
= suitable_for_tail_call_opt_p ();
853 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
855 /* Only traverse the normal exits, i.e. those that end with return
857 stmt
= last_stmt (e
->src
);
860 && TREE_CODE (stmt
) == RETURN_EXPR
)
861 find_tail_calls (e
->src
, &tailcalls
);
864 /* Construct the phi nodes and accumulators if necessary. */
865 a_acc
= m_acc
= NULL_TREE
;
866 for (act
= tailcalls
; act
; act
= act
->next
)
868 if (!act
->tail_recursion
)
871 if (!phis_constructed
)
873 /* Ensure that there is only one predecessor of the block. */
874 if (!single_pred_p (first
))
875 first
= split_edge (single_succ_edge (ENTRY_BLOCK_PTR
));
877 /* Copy the args if needed. */
878 for (param
= DECL_ARGUMENTS (current_function_decl
);
880 param
= TREE_CHAIN (param
))
881 if (is_gimple_reg (param
)
883 /* Also parameters that are only defined but never used need not
885 && (var_ann (param
)->default_def
886 && TREE_CODE (var_ann (param
)->default_def
) == SSA_NAME
))
888 tree name
= var_ann (param
)->default_def
;
889 tree new_name
= make_ssa_name (param
, SSA_NAME_DEF_STMT (name
));
892 var_ann (param
)->default_def
= new_name
;
893 phi
= create_phi_node (name
, first
);
894 SSA_NAME_DEF_STMT (name
) = phi
;
895 add_phi_arg (phi
, new_name
, single_pred_edge (first
));
897 phis_constructed
= true;
900 if (act
->add
&& !a_acc
)
902 ret_type
= TREE_TYPE (DECL_RESULT (current_function_decl
));
904 tmp
= create_tmp_var (ret_type
, "add_acc");
905 add_referenced_tmp_var (tmp
);
907 phi
= create_phi_node (tmp
, first
);
909 /* RET_TYPE can be a float when -ffast-maths is
911 fold_convert (ret_type
, integer_zero_node
),
912 single_pred_edge (first
));
913 a_acc
= PHI_RESULT (phi
);
916 if (act
->mult
&& !m_acc
)
918 ret_type
= TREE_TYPE (DECL_RESULT (current_function_decl
));
920 tmp
= create_tmp_var (ret_type
, "mult_acc");
921 add_referenced_tmp_var (tmp
);
923 phi
= create_phi_node (tmp
, first
);
925 /* RET_TYPE can be a float when -ffast-maths is
927 fold_convert (ret_type
, integer_one_node
),
928 single_pred_edge (first
));
929 m_acc
= PHI_RESULT (phi
);
933 for (; tailcalls
; tailcalls
= next
)
935 next
= tailcalls
->next
;
936 changed
|= optimize_tail_call (tailcalls
, opt_tailcalls
);
942 /* Modify the remaining return statements. */
943 FOR_EACH_EDGE (e
, ei
, EXIT_BLOCK_PTR
->preds
)
945 stmt
= last_stmt (e
->src
);
948 && TREE_CODE (stmt
) == RETURN_EXPR
)
949 adjust_return_value (e
->src
, m_acc
, a_acc
);
955 free_dominance_info (CDI_DOMINATORS
);
961 execute_tail_recursion (void)
963 tree_optimize_tail_calls_1 (false);
967 gate_tail_calls (void)
969 return flag_optimize_sibling_calls
!= 0;
973 execute_tail_calls (void)
975 tree_optimize_tail_calls_1 (true);
978 struct tree_opt_pass pass_tail_recursion
=
982 execute_tail_recursion
, /* execute */
985 0, /* static_pass_number */
987 PROP_cfg
| PROP_ssa
| PROP_alias
, /* properties_required */
988 0, /* properties_provided */
989 0, /* properties_destroyed */
990 0, /* todo_flags_start */
991 TODO_dump_func
| TODO_verify_ssa
, /* todo_flags_finish */
995 struct tree_opt_pass pass_tail_calls
=
998 gate_tail_calls
, /* gate */
999 execute_tail_calls
, /* execute */
1002 0, /* static_pass_number */
1004 PROP_cfg
| PROP_ssa
| PROP_alias
, /* properties_required */
1005 0, /* properties_provided */
1006 0, /* properties_destroyed */
1007 0, /* todo_flags_start */
1008 TODO_dump_func
| TODO_verify_ssa
, /* todo_flags_finish */