1 /* GIMPLE lowering pass. Converts High GIMPLE into Low GIMPLE.
3 Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
24 #include "coretypes.h"
28 #include "tree-iterator.h"
29 #include "tree-inline.h"
30 #include "tree-flow.h"
33 #include "diagnostic-core.h"
34 #include "tree-pass.h"
35 #include "langhooks.h"
37 /* The differences between High GIMPLE and Low GIMPLE are the
40 1- Lexical scopes are removed (i.e., GIMPLE_BIND disappears).
42 2- GIMPLE_TRY and GIMPLE_CATCH are converted to abnormal control
43 flow and exception regions are built as an on-the-side region
44 hierarchy (See tree-eh.c:lower_eh_constructs).
46 3- Multiple identical return statements are grouped into a single
47 return and gotos to the unique return site. */
49 /* Match a return statement with a label. During lowering, we identify
50 identical return statements and replace duplicates with a jump to
51 the corresponding label. */
52 struct return_statements_t
57 typedef struct return_statements_t return_statements_t;
59 DEF_VEC_O(return_statements_t);
60 DEF_VEC_ALLOC_O(return_statements_t,heap);
64 /* Block the current statement belongs to. */
67 /* A vector of label and return statements to be moved to the end
69 VEC(return_statements_t,heap) *return_statements;
71 /* True if the current statement cannot fall through. */
74 /* True if the function calls __builtin_setjmp. */
75 bool calls_builtin_setjmp;
78 static void lower_stmt (gimple_stmt_iterator *, struct lower_data *);
79 static void lower_gimple_bind (gimple_stmt_iterator *, struct lower_data *);
80 static void lower_gimple_return (gimple_stmt_iterator *, struct lower_data *);
81 static void lower_builtin_setjmp (gimple_stmt_iterator *);
84 /* Lower the body of current_function_decl from High GIMPLE into Low
88 lower_function_body (void)
90 struct lower_data data;
91 gimple_seq body = gimple_body (current_function_decl);
92 gimple_seq lowered_body;
93 gimple_stmt_iterator i;
98 /* The gimplifier should've left a body of exactly one statement,
99 namely a GIMPLE_BIND. */
100 gcc_assert (gimple_seq_first (body) == gimple_seq_last (body)
101 && gimple_code (gimple_seq_first_stmt (body)) == GIMPLE_BIND);
103 memset (&data, 0, sizeof (data));
104 data.block = DECL_INITIAL (current_function_decl);
105 BLOCK_SUBBLOCKS (data.block) = NULL_TREE;
106 BLOCK_CHAIN (data.block) = NULL_TREE;
107 TREE_ASM_WRITTEN (data.block) = 1;
108 data.return_statements = VEC_alloc (return_statements_t, heap, 8);
110 bind = gimple_seq_first_stmt (body);
112 gimple_seq_add_stmt (&lowered_body, bind);
113 i = gsi_start (lowered_body);
114 lower_gimple_bind (&i, &data);
116 /* Once the old body has been lowered, replace it with the new
118 gimple_set_body (current_function_decl, lowered_body);
120 i = gsi_last (lowered_body);
122 /* If the function falls off the end, we need a null return statement.
123 If we've already got one in the return_statements vector, we don't
124 need to do anything special. Otherwise build one by hand. */
125 if (gimple_seq_may_fallthru (lowered_body)
126 && (VEC_empty (return_statements_t, data.return_statements)
127 || gimple_return_retval (VEC_last (return_statements_t,
128 data.return_statements)->stmt) != NULL))
130 x = gimple_build_return (NULL);
131 gimple_set_location (x, cfun->function_end_locus);
132 gimple_set_block (x, DECL_INITIAL (current_function_decl));
133 gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
136 /* If we lowered any return statements, emit the representative
137 at the end of the function. */
138 while (!VEC_empty (return_statements_t, data.return_statements))
140 return_statements_t t;
142 /* Unfortunately, we can't use VEC_pop because it returns void for
144 t = *VEC_last (return_statements_t, data.return_statements);
145 VEC_truncate (return_statements_t,
146 data.return_statements,
147 VEC_length (return_statements_t,
148 data.return_statements) - 1);
150 x = gimple_build_label (t.label);
151 gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
152 gsi_insert_after (&i, t.stmt, GSI_CONTINUE_LINKING);
155 /* If the function calls __builtin_setjmp, we need to emit the computed
156 goto that will serve as the unique dispatcher for all the receivers. */
157 if (data.calls_builtin_setjmp)
159 tree disp_label, disp_var, arg;
161 /* Build 'DISP_LABEL:' and insert. */
162 disp_label = create_artificial_label (cfun->function_end_locus);
163 /* This mark will create forward edges from every call site. */
164 DECL_NONLOCAL (disp_label) = 1;
165 cfun->has_nonlocal_label = 1;
166 x = gimple_build_label (disp_label);
167 gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
169 /* Build 'DISP_VAR = __builtin_setjmp_dispatcher (DISP_LABEL);'
171 disp_var = create_tmp_var (ptr_type_node, "setjmpvar");
172 arg = build_addr (disp_label, current_function_decl);
173 t = builtin_decl_implicit (BUILT_IN_SETJMP_DISPATCHER);
174 x = gimple_build_call (t, 1, arg);
175 gimple_call_set_lhs (x, disp_var);
177 /* Build 'goto DISP_VAR;' and insert. */
178 gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
179 x = gimple_build_goto (disp_var);
180 gsi_insert_after (&i, x, GSI_CONTINUE_LINKING);
183 gcc_assert (data.block == DECL_INITIAL (current_function_decl));
184 BLOCK_SUBBLOCKS (data.block)
185 = blocks_nreverse (BLOCK_SUBBLOCKS (data.block));
187 clear_block_marks (data.block);
188 VEC_free(return_statements_t, heap, data.return_statements);
192 struct gimple_opt_pass pass_lower_cf =
198 lower_function_body, /* execute */
201 0, /* static_pass_number */
203 PROP_gimple_any, /* properties_required */
204 PROP_gimple_lcf, /* properties_provided */
205 0, /* properties_destroyed */
206 0, /* todo_flags_start */
207 0 /* todo_flags_finish */
213 /* Verify if the type of the argument matches that of the function
214 declaration. If we cannot verify this or there is a mismatch,
218 gimple_check_call_args (gimple stmt, tree fndecl)
221 unsigned int i, nargs;
223 /* Calls to internal functions always match their signature. */
224 if (gimple_call_internal_p (stmt))
227 nargs = gimple_call_num_args (stmt);
229 /* Get argument types for verification. */
231 parms = TYPE_ARG_TYPES (TREE_TYPE (fndecl));
233 parms = TYPE_ARG_TYPES (gimple_call_fntype (stmt));
235 /* Verify if the type of the argument matches that of the function
236 declaration. If we cannot verify this or there is a mismatch,
238 if (fndecl && DECL_ARGUMENTS (fndecl))
240 for (i = 0, p = DECL_ARGUMENTS (fndecl);
242 i++, p = DECL_CHAIN (p))
245 /* We cannot distinguish a varargs function from the case
246 of excess parameters, still deferring the inlining decision
247 to the callee is possible. */
250 arg = gimple_call_arg (stmt, i);
251 if (p == error_mark_node
252 || DECL_ARG_TYPE (p) == error_mark_node
253 || arg == error_mark_node
254 || (!types_compatible_p (DECL_ARG_TYPE (p), TREE_TYPE (arg))
255 && !fold_convertible_p (DECL_ARG_TYPE (p), arg)))
261 for (i = 0, p = parms; i < nargs; i++, p = TREE_CHAIN (p))
264 /* If this is a varargs function defer inlining decision
268 arg = gimple_call_arg (stmt, i);
269 if (TREE_VALUE (p) == error_mark_node
270 || arg == error_mark_node
271 || TREE_CODE (TREE_VALUE (p)) == VOID_TYPE
272 || (!types_compatible_p (TREE_VALUE (p), TREE_TYPE (arg))
273 && !fold_convertible_p (TREE_VALUE (p), arg)))
285 /* Verify if the type of the argument and lhs of CALL_STMT matches
286 that of the function declaration CALLEE.
287 If we cannot verify this or there is a mismatch, return false. */
290 gimple_check_call_matching_types (gimple call_stmt, tree callee)
294 if ((DECL_RESULT (callee)
295 && !DECL_BY_REFERENCE (DECL_RESULT (callee))
296 && (lhs = gimple_call_lhs (call_stmt)) != NULL_TREE
297 && !useless_type_conversion_p (TREE_TYPE (DECL_RESULT (callee)),
299 && !fold_convertible_p (TREE_TYPE (DECL_RESULT (callee)), lhs))
300 || !gimple_check_call_args (call_stmt, callee))
305 /* Lower sequence SEQ. Unlike gimplification the statements are not relowered
306 when they are changed -- if this has to be done, the lowering routine must
307 do it explicitly. DATA is passed through the recursion. */
310 lower_sequence (gimple_seq seq, struct lower_data *data)
312 gimple_stmt_iterator gsi;
314 for (gsi = gsi_start (seq); !gsi_end_p (gsi); )
315 lower_stmt (&gsi, data);
319 /* Lower the OpenMP directive statement pointed by GSI. DATA is
320 passed through the recursion. */
323 lower_omp_directive (gimple_stmt_iterator *gsi, struct lower_data *data)
327 stmt = gsi_stmt (*gsi);
329 lower_sequence (gimple_omp_body (stmt), data);
330 gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
331 gsi_insert_seq_before (gsi, gimple_omp_body (stmt), GSI_SAME_STMT);
332 gimple_omp_set_body (stmt, NULL);
333 gsi_remove (gsi, false);
337 /* Lower statement GSI. DATA is passed through the recursion. We try to
338 track the fallthruness of statements and get rid of unreachable return
339 statements in order to prevent the EH lowering pass from adding useless
340 edges that can cause bogus warnings to be issued later; this guess need
341 not be 100% accurate, simply be conservative and reset cannot_fallthru
342 to false if we don't know. */
345 lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
347 gimple stmt = gsi_stmt (*gsi);
349 gimple_set_block (stmt, data->block);
351 switch (gimple_code (stmt))
354 lower_gimple_bind (gsi, data);
355 /* Propagate fallthruness. */
361 data->cannot_fallthru = true;
366 if (data->cannot_fallthru)
368 gsi_remove (gsi, false);
369 /* Propagate fallthruness. */
373 lower_gimple_return (gsi, data);
374 data->cannot_fallthru = true;
380 bool try_cannot_fallthru;
381 lower_sequence (gimple_try_eval (stmt), data);
382 try_cannot_fallthru = data->cannot_fallthru;
383 data->cannot_fallthru = false;
384 lower_sequence (gimple_try_cleanup (stmt), data);
385 /* See gimple_stmt_may_fallthru for the rationale. */
386 if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY)
388 data->cannot_fallthru |= try_cannot_fallthru;
396 data->cannot_fallthru = false;
397 lower_sequence (gimple_catch_handler (stmt), data);
400 case GIMPLE_EH_FILTER:
401 data->cannot_fallthru = false;
402 lower_sequence (gimple_eh_filter_failure (stmt), data);
406 lower_sequence (gimple_eh_else_n_body (stmt), data);
407 lower_sequence (gimple_eh_else_e_body (stmt), data);
415 case GIMPLE_EH_MUST_NOT_THROW:
417 case GIMPLE_OMP_SECTIONS:
418 case GIMPLE_OMP_SECTIONS_SWITCH:
419 case GIMPLE_OMP_SECTION:
420 case GIMPLE_OMP_SINGLE:
421 case GIMPLE_OMP_MASTER:
422 case GIMPLE_OMP_ORDERED:
423 case GIMPLE_OMP_CRITICAL:
424 case GIMPLE_OMP_RETURN:
425 case GIMPLE_OMP_ATOMIC_LOAD:
426 case GIMPLE_OMP_ATOMIC_STORE:
427 case GIMPLE_OMP_CONTINUE:
432 tree decl = gimple_call_fndecl (stmt);
435 && DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL
436 && DECL_FUNCTION_CODE (decl) == BUILT_IN_SETJMP)
438 lower_builtin_setjmp (gsi);
439 data->cannot_fallthru = false;
440 data->calls_builtin_setjmp = true;
444 if (decl && (flags_from_decl_or_type (decl) & ECF_NORETURN))
446 data->cannot_fallthru = true;
453 case GIMPLE_OMP_PARALLEL:
454 case GIMPLE_OMP_TASK:
455 data->cannot_fallthru = false;
456 lower_omp_directive (gsi, data);
457 data->cannot_fallthru = false;
460 case GIMPLE_TRANSACTION:
461 lower_sequence (gimple_transaction_body (stmt), data);
468 data->cannot_fallthru = false;
472 /* Lower a bind_expr TSI. DATA is passed through the recursion. */
475 lower_gimple_bind (gimple_stmt_iterator *gsi, struct lower_data *data)
477 tree old_block = data->block;
478 gimple stmt = gsi_stmt (*gsi);
479 tree new_block = gimple_bind_block (stmt);
483 if (new_block == old_block)
485 /* The outermost block of the original function may not be the
486 outermost statement chain of the gimplified function. So we
487 may see the outermost block just inside the function. */
488 gcc_assert (new_block == DECL_INITIAL (current_function_decl));
493 /* We do not expect to handle duplicate blocks. */
494 gcc_assert (!TREE_ASM_WRITTEN (new_block));
495 TREE_ASM_WRITTEN (new_block) = 1;
497 /* Block tree may get clobbered by inlining. Normally this would
498 be fixed in rest_of_decl_compilation using block notes, but
499 since we are not going to emit them, it is up to us. */
500 BLOCK_CHAIN (new_block) = BLOCK_SUBBLOCKS (old_block);
501 BLOCK_SUBBLOCKS (old_block) = new_block;
502 BLOCK_SUBBLOCKS (new_block) = NULL_TREE;
503 BLOCK_SUPERCONTEXT (new_block) = old_block;
505 data->block = new_block;
509 record_vars (gimple_bind_vars (stmt));
510 lower_sequence (gimple_bind_body (stmt), data);
514 gcc_assert (data->block == new_block);
516 BLOCK_SUBBLOCKS (new_block)
517 = blocks_nreverse (BLOCK_SUBBLOCKS (new_block));
518 data->block = old_block;
521 /* The GIMPLE_BIND no longer carries any useful information -- kill it. */
522 gsi_insert_seq_before (gsi, gimple_bind_body (stmt), GSI_SAME_STMT);
523 gsi_remove (gsi, false);
526 /* Try to determine whether a TRY_CATCH expression can fall through.
527 This is a subroutine of block_may_fallthru. */
530 try_catch_may_fallthru (const_tree stmt)
532 tree_stmt_iterator i;
534 /* If the TRY block can fall through, the whole TRY_CATCH can
536 if (block_may_fallthru (TREE_OPERAND (stmt, 0)))
539 i = tsi_start (TREE_OPERAND (stmt, 1));
540 switch (TREE_CODE (tsi_stmt (i)))
543 /* We expect to see a sequence of CATCH_EXPR trees, each with a
544 catch expression and a body. The whole TRY_CATCH may fall
545 through iff any of the catch bodies falls through. */
546 for (; !tsi_end_p (i); tsi_next (&i))
548 if (block_may_fallthru (CATCH_BODY (tsi_stmt (i))))
554 /* The exception filter expression only matters if there is an
555 exception. If the exception does not match EH_FILTER_TYPES,
556 we will execute EH_FILTER_FAILURE, and we will fall through
557 if that falls through. If the exception does match
558 EH_FILTER_TYPES, the stack unwinder will continue up the
559 stack, so we will not fall through. We don't know whether we
560 will throw an exception which matches EH_FILTER_TYPES or not,
561 so we just ignore EH_FILTER_TYPES and assume that we might
562 throw an exception which doesn't match. */
563 return block_may_fallthru (EH_FILTER_FAILURE (tsi_stmt (i)));
566 /* This case represents statements to be executed when an
567 exception occurs. Those statements are implicitly followed
568 by a RESX statement to resume execution after the exception.
569 So in this case the TRY_CATCH never falls through. */
575 /* Same as above, but for a GIMPLE_TRY_CATCH. */
578 gimple_try_catch_may_fallthru (gimple stmt)
580 gimple_stmt_iterator i;
582 /* We don't handle GIMPLE_TRY_FINALLY. */
583 gcc_assert (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH);
585 /* If the TRY block can fall through, the whole TRY_CATCH can
587 if (gimple_seq_may_fallthru (gimple_try_eval (stmt)))
590 i = gsi_start (gimple_try_cleanup (stmt));
591 switch (gimple_code (gsi_stmt (i)))
594 /* We expect to see a sequence of GIMPLE_CATCH stmts, each with a
595 catch expression and a body. The whole try/catch may fall
596 through iff any of the catch bodies falls through. */
597 for (; !gsi_end_p (i); gsi_next (&i))
599 if (gimple_seq_may_fallthru (gimple_catch_handler (gsi_stmt (i))))
604 case GIMPLE_EH_FILTER:
605 /* The exception filter expression only matters if there is an
606 exception. If the exception does not match EH_FILTER_TYPES,
607 we will execute EH_FILTER_FAILURE, and we will fall through
608 if that falls through. If the exception does match
609 EH_FILTER_TYPES, the stack unwinder will continue up the
610 stack, so we will not fall through. We don't know whether we
611 will throw an exception which matches EH_FILTER_TYPES or not,
612 so we just ignore EH_FILTER_TYPES and assume that we might
613 throw an exception which doesn't match. */
614 return gimple_seq_may_fallthru (gimple_eh_filter_failure (gsi_stmt (i)));
617 /* This case represents statements to be executed when an
618 exception occurs. Those statements are implicitly followed
619 by a GIMPLE_RESX to resume execution after the exception. So
620 in this case the try/catch never falls through. */
626 /* Try to determine if we can fall out of the bottom of BLOCK. This guess
627 need not be 100% accurate; simply be conservative and return true if we
628 don't know. This is used only to avoid stupidly generating extra code.
629 If we're wrong, we'll just delete the extra code later. */
632 block_may_fallthru (const_tree block)
634 /* This CONST_CAST is okay because expr_last returns its argument
635 unmodified and we assign it to a const_tree. */
636 const_tree stmt = expr_last (CONST_CAST_TREE(block));
638 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
642 /* Easy cases. If the last statement of the block implies
643 control transfer, then we can't fall through. */
647 /* If SWITCH_LABELS is set, this is lowered, and represents a
648 branch to a selected label and hence can not fall through.
649 Otherwise SWITCH_BODY is set, and the switch can fall
651 return SWITCH_LABELS (stmt) == NULL_TREE;
654 if (block_may_fallthru (COND_EXPR_THEN (stmt)))
656 return block_may_fallthru (COND_EXPR_ELSE (stmt));
659 return block_may_fallthru (BIND_EXPR_BODY (stmt));
662 return try_catch_may_fallthru (stmt);
664 case TRY_FINALLY_EXPR:
665 /* The finally clause is always executed after the try clause,
666 so if it does not fall through, then the try-finally will not
667 fall through. Otherwise, if the try clause does not fall
668 through, then when the finally clause falls through it will
669 resume execution wherever the try clause was going. So the
670 whole try-finally will only fall through if both the try
671 clause and the finally clause fall through. */
672 return (block_may_fallthru (TREE_OPERAND (stmt, 0))
673 && block_may_fallthru (TREE_OPERAND (stmt, 1)));
676 if (TREE_CODE (TREE_OPERAND (stmt, 1)) == CALL_EXPR)
677 stmt = TREE_OPERAND (stmt, 1);
683 /* Functions that do not return do not fall through. */
684 return (call_expr_flags (stmt) & ECF_NORETURN) == 0;
686 case CLEANUP_POINT_EXPR:
687 return block_may_fallthru (TREE_OPERAND (stmt, 0));
690 return block_may_fallthru (TREE_OPERAND (stmt, 1));
696 return lang_hooks.block_may_fallthru (stmt);
701 /* Try to determine if we can continue executing the statement
702 immediately following STMT. This guess need not be 100% accurate;
703 simply be conservative and return true if we don't know. This is
704 used only to avoid stupidly generating extra code. If we're wrong,
705 we'll just delete the extra code later. */
708 gimple_stmt_may_fallthru (gimple stmt)
713 switch (gimple_code (stmt))
718 /* Easy cases. If the last statement of the seq implies
719 control transfer, then we can't fall through. */
723 /* Switch has already been lowered and represents a branch
724 to a selected label and hence can't fall through. */
728 /* GIMPLE_COND's are already lowered into a two-way branch. They
729 can't fall through. */
733 return gimple_seq_may_fallthru (gimple_bind_body (stmt));
736 if (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH)
737 return gimple_try_catch_may_fallthru (stmt);
739 /* It must be a GIMPLE_TRY_FINALLY. */
741 /* The finally clause is always executed after the try clause,
742 so if it does not fall through, then the try-finally will not
743 fall through. Otherwise, if the try clause does not fall
744 through, then when the finally clause falls through it will
745 resume execution wherever the try clause was going. So the
746 whole try-finally will only fall through if both the try
747 clause and the finally clause fall through. */
748 return (gimple_seq_may_fallthru (gimple_try_eval (stmt))
749 && gimple_seq_may_fallthru (gimple_try_cleanup (stmt)));
752 return (gimple_seq_may_fallthru (gimple_eh_else_n_body (stmt))
753 || gimple_seq_may_fallthru (gimple_eh_else_e_body (stmt)));
756 /* Functions that do not return do not fall through. */
757 return (gimple_call_flags (stmt) & ECF_NORETURN) == 0;
765 /* Same as gimple_stmt_may_fallthru, but for the gimple sequence SEQ. */
768 gimple_seq_may_fallthru (gimple_seq seq)
770 return gimple_stmt_may_fallthru (gimple_seq_last_stmt (seq));
774 /* Lower a GIMPLE_RETURN GSI. DATA is passed through the recursion. */
777 lower_gimple_return (gimple_stmt_iterator *gsi, struct lower_data *data)
779 gimple stmt = gsi_stmt (*gsi);
782 return_statements_t tmp_rs;
784 /* Match this up with an existing return statement that's been created. */
785 for (i = VEC_length (return_statements_t, data->return_statements) - 1;
788 tmp_rs = *VEC_index (return_statements_t, data->return_statements, i);
790 if (gimple_return_retval (stmt) == gimple_return_retval (tmp_rs.stmt))
792 /* Remove the line number from the representative return statement.
793 It now fills in for many such returns. Failure to remove this
794 will result in incorrect results for coverage analysis. */
795 gimple_set_location (tmp_rs.stmt, UNKNOWN_LOCATION);
801 /* Not found. Create a new label and record the return statement. */
802 tmp_rs.label = create_artificial_label (cfun->function_end_locus);
804 VEC_safe_push (return_statements_t, heap, data->return_statements, &tmp_rs);
806 /* Generate a goto statement and remove the return statement. */
808 /* When not optimizing, make sure user returns are preserved. */
809 if (!optimize && gimple_has_location (stmt))
810 DECL_ARTIFICIAL (tmp_rs.label) = 0;
811 t = gimple_build_goto (tmp_rs.label);
812 gimple_set_location (t, gimple_location (stmt));
813 gimple_set_block (t, gimple_block (stmt));
814 gsi_insert_before (gsi, t, GSI_SAME_STMT);
815 gsi_remove (gsi, false);
818 /* Lower a __builtin_setjmp GSI.
820 __builtin_setjmp is passed a pointer to an array of five words (not
821 all will be used on all machines). It operates similarly to the C
822 library function of the same name, but is more efficient.
824 It is lowered into 3 other builtins, namely __builtin_setjmp_setup,
825 __builtin_setjmp_dispatcher and __builtin_setjmp_receiver, but with
826 __builtin_setjmp_dispatcher shared among all the instances; that's
827 why it is only emitted at the end by lower_function_body.
829 After full lowering, the body of the function should look like:
838 __builtin_setjmp_setup (&buf, &<D1847>);
842 __builtin_setjmp_receiver (&<D1847>);
845 if (D.1844 == 0) goto <D1848>; else goto <D1849>;
849 __builtin_setjmp_setup (&buf, &<D2847>);
853 __builtin_setjmp_receiver (&<D2847>);
856 if (D.2844 == 0) goto <D2848>; else goto <D2849>;
862 <D3853>: [non-local];
863 setjmpvar.0 = __builtin_setjmp_dispatcher (&<D3853>);
867 The dispatcher block will be both the unique destination of all the
868 abnormal call edges and the unique source of all the abnormal edges
869 to the receivers, thus keeping the complexity explosion localized. */
872 lower_builtin_setjmp (gimple_stmt_iterator *gsi)
874 gimple stmt = gsi_stmt (*gsi);
875 location_t loc = gimple_location (stmt);
876 tree cont_label = create_artificial_label (loc);
877 tree next_label = create_artificial_label (loc);
881 /* NEXT_LABEL is the label __builtin_longjmp will jump to. Its address is
882 passed to both __builtin_setjmp_setup and __builtin_setjmp_receiver. */
883 FORCED_LABEL (next_label) = 1;
885 dest = gimple_call_lhs (stmt);
887 /* Build '__builtin_setjmp_setup (BUF, NEXT_LABEL)' and insert. */
888 arg = build_addr (next_label, current_function_decl);
889 t = builtin_decl_implicit (BUILT_IN_SETJMP_SETUP);
890 g = gimple_build_call (t, 2, gimple_call_arg (stmt, 0), arg);
891 gimple_set_location (g, loc);
892 gimple_set_block (g, gimple_block (stmt));
893 gsi_insert_before (gsi, g, GSI_SAME_STMT);
895 /* Build 'DEST = 0' and insert. */
898 g = gimple_build_assign (dest, build_zero_cst (TREE_TYPE (dest)));
899 gimple_set_location (g, loc);
900 gimple_set_block (g, gimple_block (stmt));
901 gsi_insert_before (gsi, g, GSI_SAME_STMT);
904 /* Build 'goto CONT_LABEL' and insert. */
905 g = gimple_build_goto (cont_label);
906 gsi_insert_before (gsi, g, GSI_SAME_STMT);
908 /* Build 'NEXT_LABEL:' and insert. */
909 g = gimple_build_label (next_label);
910 gsi_insert_before (gsi, g, GSI_SAME_STMT);
912 /* Build '__builtin_setjmp_receiver (NEXT_LABEL)' and insert. */
913 arg = build_addr (next_label, current_function_decl);
914 t = builtin_decl_implicit (BUILT_IN_SETJMP_RECEIVER);
915 g = gimple_build_call (t, 1, arg);
916 gimple_set_location (g, loc);
917 gimple_set_block (g, gimple_block (stmt));
918 gsi_insert_before (gsi, g, GSI_SAME_STMT);
920 /* Build 'DEST = 1' and insert. */
923 g = gimple_build_assign (dest, fold_convert_loc (loc, TREE_TYPE (dest),
925 gimple_set_location (g, loc);
926 gimple_set_block (g, gimple_block (stmt));
927 gsi_insert_before (gsi, g, GSI_SAME_STMT);
930 /* Build 'CONT_LABEL:' and insert. */
931 g = gimple_build_label (cont_label);
932 gsi_insert_before (gsi, g, GSI_SAME_STMT);
934 /* Remove the call to __builtin_setjmp. */
935 gsi_remove (gsi, false);
939 /* Record the variables in VARS into function FN. */
942 record_vars_into (tree vars, tree fn)
944 if (fn != current_function_decl)
945 push_cfun (DECL_STRUCT_FUNCTION (fn));
947 for (; vars; vars = DECL_CHAIN (vars))
951 /* BIND_EXPRs contains also function/type/constant declarations
952 we don't need to care about. */
953 if (TREE_CODE (var) != VAR_DECL)
956 /* Nothing to do in this case. */
957 if (DECL_EXTERNAL (var))
960 /* Record the variable. */
961 add_local_decl (cfun, var);
962 if (gimple_referenced_vars (cfun))
963 add_referenced_var (var);
966 if (fn != current_function_decl)
971 /* Record the variables in VARS into current_function_decl. */
974 record_vars (tree vars)
976 record_vars_into (vars, current_function_decl);