Mercurial > hg > CbC > CbC_gcc
view gcc/tree-eh.c @ 44:a14cd9f25ac4
merge.
| author | kent <kent@cr.ie.u-ryukyu.ac.jp> |
|---|---|
| date | Mon, 25 Jan 2010 17:27:45 +0900 |
| parents | a06113de4d67 |
| children | 77e2b8dfacca |
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/* Exception handling semantics and decomposition for trees. Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc. This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see <http://www.gnu.org/licenses/>. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "tree.h" #include "rtl.h" #include "tm_p.h" #include "flags.h" #include "function.h" #include "except.h" #include "tree-flow.h" #include "tree-dump.h" #include "tree-inline.h" #include "tree-iterator.h" #include "tree-pass.h" #include "timevar.h" #include "langhooks.h" #include "ggc.h" #include "toplev.h" #include "gimple.h" /* In some instances a tree and a gimple need to be stored in a same table, i.e. in hash tables. This is a structure to do this. */ typedef union {tree *tp; tree t; gimple g;} treemple; /* Nonzero if we are using EH to handle cleanups. */ static int using_eh_for_cleanups_p = 0; void using_eh_for_cleanups (void) { using_eh_for_cleanups_p = 1; } /* Misc functions used in this file. */ /* Compare and hash for any structure which begins with a canonical pointer. Assumes all pointers are interchangeable, which is sort of already assumed by gcc elsewhere IIRC. */ static int struct_ptr_eq (const void *a, const void *b) { const void * const * x = (const void * const *) a; const void * const * y = (const void * const *) b; return *x == *y; } static hashval_t struct_ptr_hash (const void *a) { const void * const * x = (const void * const *) a; return (size_t)*x >> 4; } /* Remember and lookup EH region data for arbitrary statements. Really this means any statement that could_throw_p. We could stuff this information into the stmt_ann data structure, but: (1) We absolutely rely on this information being kept until we get to rtl. Once we're done with lowering here, if we lose the information there's no way to recover it! (2) There are many more statements that *cannot* throw as compared to those that can. We should be saving some amount of space by only allocating memory for those that can throw. */ static void record_stmt_eh_region (struct eh_region *region, gimple t) { if (!region) return; add_stmt_to_eh_region (t, get_eh_region_number (region)); } /* Add statement T in function IFUN to EH region NUM. */ void add_stmt_to_eh_region_fn (struct function *ifun, gimple t, int num) { struct throw_stmt_node *n; void **slot; gcc_assert (num >= 0); gcc_assert (gimple_code (t) != GIMPLE_RESX); n = GGC_NEW (struct throw_stmt_node); n->stmt = t; n->region_nr = num; if (!get_eh_throw_stmt_table (ifun)) set_eh_throw_stmt_table (ifun, htab_create_ggc (31, struct_ptr_hash, struct_ptr_eq, ggc_free)); slot = htab_find_slot (get_eh_throw_stmt_table (ifun), n, INSERT); gcc_assert (!*slot); *slot = n; } /* Add statement T in the current function (cfun) to EH region number NUM. */ void add_stmt_to_eh_region (gimple t, int num) { add_stmt_to_eh_region_fn (cfun, t, num); } /* Remove statement T in function IFUN from the EH region holding it. */ bool remove_stmt_from_eh_region_fn (struct function *ifun, gimple t) { struct throw_stmt_node dummy; void **slot; if (!get_eh_throw_stmt_table (ifun)) return false; dummy.stmt = t; slot = htab_find_slot (get_eh_throw_stmt_table (ifun), &dummy, NO_INSERT); if (slot) { htab_clear_slot (get_eh_throw_stmt_table (ifun), slot); return true; } else return false; } /* Remove statement T in the current function (cfun) from the EH region holding it. */ bool remove_stmt_from_eh_region (gimple t) { return remove_stmt_from_eh_region_fn (cfun, t); } /* Determine if statement T is inside an EH region in function IFUN. Return the EH region number if found, return -2 if IFUN does not have an EH table and -1 if T could not be found in IFUN's EH region table. */ int lookup_stmt_eh_region_fn (struct function *ifun, gimple t) { struct throw_stmt_node *p, n; if (!get_eh_throw_stmt_table (ifun)) return -2; n.stmt = t; p = (struct throw_stmt_node *) htab_find (get_eh_throw_stmt_table (ifun), &n); return (p ? p->region_nr : -1); } /* Determine if statement T is inside an EH region in the current function (cfun). Return the EH region number if found, return -2 if cfun does not have an EH table and -1 if T could not be found in cfun's EH region table. */ int lookup_stmt_eh_region (gimple t) { /* We can get called from initialized data when -fnon-call-exceptions is on; prevent crash. */ if (!cfun) return -1; return lookup_stmt_eh_region_fn (cfun, t); } /* Determine if expression T is inside an EH region in the current function (cfun). Return the EH region number if found, return -2 if IFUN does not have an EH table and -1 if T could not be found in IFUN's EH region table. */ int lookup_expr_eh_region (tree t) { /* We can get called from initialized data when -fnon-call-exceptions is on; prevent crash. */ if (!cfun) return -1; if (!get_eh_throw_stmt_table (cfun)) return -2; if (t && EXPR_P (t)) { tree_ann_common_t ann = tree_common_ann (t); if (ann) return (int) ann->rn; } return -1; } /* First pass of EH node decomposition. Build up a tree of GIMPLE_TRY_FINALLY nodes and LABEL_DECL nodes. We will use this during the second phase to determine if a goto leaves the body of a TRY_FINALLY_EXPR node. */ struct finally_tree_node { /* When storing a GIMPLE_TRY, we have to record a gimple. However when deciding whether a GOTO to a certain LABEL_DECL (which is a tree) leaves the TRY block, its necessary to record a tree in this field. Thus a treemple is used. */ treemple child; gimple parent; }; /* Note that this table is *not* marked GTY. It is short-lived. */ static htab_t finally_tree; static void record_in_finally_tree (treemple child, gimple parent) { struct finally_tree_node *n; void **slot; n = XNEW (struct finally_tree_node); n->child = child; n->parent = parent; slot = htab_find_slot (finally_tree, n, INSERT); gcc_assert (!*slot); *slot = n; } static void collect_finally_tree (gimple stmt, gimple region); /* Go through the gimple sequence. Works with collect_finally_tree to record all GIMPLE_LABEL and GIMPLE_TRY statements. */ static void collect_finally_tree_1 (gimple_seq seq, gimple region) { gimple_stmt_iterator gsi; for (gsi = gsi_start (seq); !gsi_end_p (gsi); gsi_next (&gsi)) collect_finally_tree (gsi_stmt (gsi), region); } static void collect_finally_tree (gimple stmt, gimple region) { treemple temp; switch (gimple_code (stmt)) { case GIMPLE_LABEL: temp.t = gimple_label_label (stmt); record_in_finally_tree (temp, region); break; case GIMPLE_TRY: if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY) { temp.g = stmt; record_in_finally_tree (temp, region); collect_finally_tree_1 (gimple_try_eval (stmt), stmt); collect_finally_tree_1 (gimple_try_cleanup (stmt), region); } else if (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH) { collect_finally_tree_1 (gimple_try_eval (stmt), region); collect_finally_tree_1 (gimple_try_cleanup (stmt), region); } break; case GIMPLE_CATCH: collect_finally_tree_1 (gimple_catch_handler (stmt), region); break; case GIMPLE_EH_FILTER: collect_finally_tree_1 (gimple_eh_filter_failure (stmt), region); break; default: /* A type, a decl, or some kind of statement that we're not interested in. Don't walk them. */ break; } } /* Use the finally tree to determine if a jump from START to TARGET would leave the try_finally node that START lives in. */ static bool outside_finally_tree (treemple start, gimple target) { struct finally_tree_node n, *p; do { n.child = start; p = (struct finally_tree_node *) htab_find (finally_tree, &n); if (!p) return true; start.g = p->parent; } while (start.g != target); return false; } /* Second pass of EH node decomposition. Actually transform the GIMPLE_TRY nodes into a set of gotos, magic labels, and eh regions. The eh region creation is straight-forward, but frobbing all the gotos and such into shape isn't. */ /* State of the world while lowering. */ struct leh_state { /* What's "current" while constructing the eh region tree. These correspond to variables of the same name in cfun->eh, which we don't have easy access to. */ struct eh_region *cur_region; struct eh_region *prev_try; /* Processing of TRY_FINALLY requires a bit more state. This is split out into a separate structure so that we don't have to copy so much when processing other nodes. */ struct leh_tf_state *tf; }; struct leh_tf_state { /* Pointer to the GIMPLE_TRY_FINALLY node under discussion. The try_finally_expr is the original GIMPLE_TRY_FINALLY. We need to retain this so that outside_finally_tree can reliably reference the tree used in the collect_finally_tree data structures. */ gimple try_finally_expr; gimple top_p; /* While lowering a top_p usually it is expanded into multiple statements, thus we need the following field to store them. */ gimple_seq top_p_seq; /* The state outside this try_finally node. */ struct leh_state *outer; /* The exception region created for it. */ struct eh_region *region; /* The GOTO_QUEUE is is an array of GIMPLE_GOTO and GIMPLE_RETURN statements that are seen to escape this GIMPLE_TRY_FINALLY node. The idea is to record a gimple statement for everything except for the conditionals, which get their labels recorded. Since labels are of type 'tree', we need this node to store both gimple and tree objects. REPL_STMT is the sequence used to replace the goto/return statement. CONT_STMT is used to store the statement that allows the return/goto to jump to the original destination. */ struct goto_queue_node { treemple stmt; gimple_seq repl_stmt; gimple cont_stmt; int index; /* this is used when index >= 0 to indicate that stmt is a label(as opposed to a goto stmt) */ int is_label; } *goto_queue; size_t goto_queue_size; size_t goto_queue_active; /* Pointer map to help in searching goto_queue when it is large. */ struct pointer_map_t *goto_queue_map; /* The set of unique labels seen as entries in the goto queue. */ VEC(tree,heap) *dest_array; /* A label to be added at the end of the completed transformed sequence. It will be set if may_fallthru was true *at one time*, though subsequent transformations may have cleared that flag. */ tree fallthru_label; /* A label that has been registered with except.c to be the landing pad for this try block. */ tree eh_label; /* True if it is possible to fall out the bottom of the try block. Cleared if the fallthru is converted to a goto. */ bool may_fallthru; /* True if any entry in goto_queue is a GIMPLE_RETURN. */ bool may_return; /* True if the finally block can receive an exception edge. Cleared if the exception case is handled by code duplication. */ bool may_throw; }; static gimple_seq lower_eh_filter (struct leh_state *, gimple); /* Search for STMT in the goto queue. Return the replacement, or null if the statement isn't in the queue. */ #define LARGE_GOTO_QUEUE 20 static void lower_eh_constructs_1 (struct leh_state *state, gimple_seq seq); static gimple_seq find_goto_replacement (struct leh_tf_state *tf, treemple stmt) { unsigned int i; void **slot; if (tf->goto_queue_active < LARGE_GOTO_QUEUE) { for (i = 0; i < tf->goto_queue_active; i++) if ( tf->goto_queue[i].stmt.g == stmt.g) return tf->goto_queue[i].repl_stmt; return NULL; } /* If we have a large number of entries in the goto_queue, create a pointer map and use that for searching. */ if (!tf->goto_queue_map) { tf->goto_queue_map = pointer_map_create (); for (i = 0; i < tf->goto_queue_active; i++) { slot = pointer_map_insert (tf->goto_queue_map, tf->goto_queue[i].stmt.g); gcc_assert (*slot == NULL); *slot = &tf->goto_queue[i]; } } slot = pointer_map_contains (tf->goto_queue_map, stmt.g); if (slot != NULL) return (((struct goto_queue_node *) *slot)->repl_stmt); return NULL; } /* A subroutine of replace_goto_queue_1. Handles the sub-clauses of a lowered GIMPLE_COND. If, by chance, the replacement is a simple goto, then we can just splat it in, otherwise we add the new stmts immediately after the GIMPLE_COND and redirect. */ static void replace_goto_queue_cond_clause (tree *tp, struct leh_tf_state *tf, gimple_stmt_iterator *gsi) { tree label; gimple_seq new_seq; treemple temp; temp.tp = tp; new_seq = find_goto_replacement (tf, temp); if (!new_seq) return; if (gimple_seq_singleton_p (new_seq) && gimple_code (gimple_seq_first_stmt (new_seq)) == GIMPLE_GOTO) { *tp = gimple_goto_dest (gimple_seq_first_stmt (new_seq)); return; } label = create_artificial_label (); /* Set the new label for the GIMPLE_COND */ *tp = label; gsi_insert_after (gsi, gimple_build_label (label), GSI_CONTINUE_LINKING); gsi_insert_seq_after (gsi, gimple_seq_copy (new_seq), GSI_CONTINUE_LINKING); } /* The real work of replace_goto_queue. Returns with TSI updated to point to the next statement. */ static void replace_goto_queue_stmt_list (gimple_seq, struct leh_tf_state *); static void replace_goto_queue_1 (gimple stmt, struct leh_tf_state *tf, gimple_stmt_iterator *gsi) { gimple_seq seq; treemple temp; temp.g = NULL; switch (gimple_code (stmt)) { case GIMPLE_GOTO: case GIMPLE_RETURN: temp.g = stmt; seq = find_goto_replacement (tf, temp); if (seq) { gsi_insert_seq_before (gsi, gimple_seq_copy (seq), GSI_SAME_STMT); gsi_remove (gsi, false); return; } break; case GIMPLE_COND: replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 2), tf, gsi); replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 3), tf, gsi); break; case GIMPLE_TRY: replace_goto_queue_stmt_list (gimple_try_eval (stmt), tf); replace_goto_queue_stmt_list (gimple_try_cleanup (stmt), tf); break; case GIMPLE_CATCH: replace_goto_queue_stmt_list (gimple_catch_handler (stmt), tf); break; case GIMPLE_EH_FILTER: replace_goto_queue_stmt_list (gimple_eh_filter_failure (stmt), tf); break; default: /* These won't have gotos in them. */ break; } gsi_next (gsi); } /* A subroutine of replace_goto_queue. Handles GIMPLE_SEQ. */ static void replace_goto_queue_stmt_list (gimple_seq seq, struct leh_tf_state *tf) { gimple_stmt_iterator gsi = gsi_start (seq); while (!gsi_end_p (gsi)) replace_goto_queue_1 (gsi_stmt (gsi), tf, &gsi); } /* Replace all goto queue members. */ static void replace_goto_queue (struct leh_tf_state *tf) { if (tf->goto_queue_active == 0) return; replace_goto_queue_stmt_list (tf->top_p_seq, tf); } /* Add a new record to the goto queue contained in TF. NEW_STMT is the data to be added, IS_LABEL indicates whether NEW_STMT is a label or a gimple return. */ static void record_in_goto_queue (struct leh_tf_state *tf, treemple new_stmt, int index, bool is_label) { size_t active, size; struct goto_queue_node *q; gcc_assert (!tf->goto_queue_map); active = tf->goto_queue_active; size = tf->goto_queue_size; if (active >= size) { size = (size ? size * 2 : 32); tf->goto_queue_size = size; tf->goto_queue = XRESIZEVEC (struct goto_queue_node, tf->goto_queue, size); } q = &tf->goto_queue[active]; tf->goto_queue_active = active + 1; memset (q, 0, sizeof (*q)); q->stmt = new_stmt; q->index = index; q->is_label = is_label; } /* Record the LABEL label in the goto queue contained in TF. TF is not null. */ static void record_in_goto_queue_label (struct leh_tf_state *tf, treemple stmt, tree label) { int index; treemple temp, new_stmt; if (!label) return; /* Computed and non-local gotos do not get processed. Given their nature we can neither tell whether we've escaped the finally block nor redirect them if we knew. */ if (TREE_CODE (label) != LABEL_DECL) return; /* No need to record gotos that don't leave the try block. */ temp.t = label; if (!outside_finally_tree (temp, tf->try_finally_expr)) return; if (! tf->dest_array) { tf->dest_array = VEC_alloc (tree, heap, 10); VEC_quick_push (tree, tf->dest_array, label); index = 0; } else { int n = VEC_length (tree, tf->dest_array); for (index = 0; index < n; ++index) if (VEC_index (tree, tf->dest_array, index) == label) break; if (index == n) VEC_safe_push (tree, heap, tf->dest_array, label); } /* In the case of a GOTO we want to record the destination label, since with a GIMPLE_COND we have an easy access to the then/else labels. */ new_stmt = stmt; record_in_goto_queue (tf, new_stmt, index, true); } /* For any GIMPLE_GOTO or GIMPLE_RETURN, decide whether it leaves a try_finally node, and if so record that fact in the goto queue associated with that try_finally node. */ static void maybe_record_in_goto_queue (struct leh_state *state, gimple stmt) { struct leh_tf_state *tf = state->tf; treemple new_stmt; if (!tf) return; switch (gimple_code (stmt)) { case GIMPLE_COND: new_stmt.tp = gimple_op_ptr (stmt, 2); record_in_goto_queue_label (tf, new_stmt, gimple_cond_true_label (stmt)); new_stmt.tp = gimple_op_ptr (stmt, 3); record_in_goto_queue_label (tf, new_stmt, gimple_cond_false_label (stmt)); break; case GIMPLE_GOTO: new_stmt.g = stmt; record_in_goto_queue_label (tf, new_stmt, gimple_goto_dest (stmt)); break; case GIMPLE_RETURN: tf->may_return = true; new_stmt.g = stmt; record_in_goto_queue (tf, new_stmt, -1, false); break; default: gcc_unreachable (); } } #ifdef ENABLE_CHECKING /* We do not process GIMPLE_SWITCHes for now. As long as the original source was in fact structured, and we've not yet done jump threading, then none of the labels will leave outer GIMPLE_TRY_FINALLY nodes. Verify this. */ static void verify_norecord_switch_expr (struct leh_state *state, gimple switch_expr) { struct leh_tf_state *tf = state->tf; size_t i, n; if (!tf) return; n = gimple_switch_num_labels (switch_expr); for (i = 0; i < n; ++i) { treemple temp; tree lab = CASE_LABEL (gimple_switch_label (switch_expr, i)); temp.t = lab; gcc_assert (!outside_finally_tree (temp, tf->try_finally_expr)); } } #else #define verify_norecord_switch_expr(state, switch_expr) #endif /* Redirect a RETURN_EXPR pointed to by STMT_P to FINLAB. Place in CONT_P whatever is needed to finish the return. If MOD is non-null, insert it before the new branch. RETURN_VALUE_P is a cache containing a temporary variable to be used in manipulating the value returned from the function. */ static void do_return_redirection (struct goto_queue_node *q, tree finlab, gimple_seq mod, tree *return_value_p) { tree ret_expr; gimple x; /* In the case of a return, the queue node must be a gimple statement. */ gcc_assert (!q->is_label); ret_expr = gimple_return_retval (q->stmt.g); if (ret_expr) { if (!*return_value_p) *return_value_p = ret_expr; else gcc_assert (*return_value_p == ret_expr); q->cont_stmt = q->stmt.g; /* The nasty part about redirecting the return value is that the return value itself is to be computed before the FINALLY block is executed. e.g. int x; int foo (void) { x = 0; try { return x; } finally { x++; } } should return 0, not 1. Arrange for this to happen by copying computed the return value into a local temporary. This also allows us to redirect multiple return statements through the same destination block; whether this is a net win or not really depends, I guess, but it does make generation of the switch in lower_try_finally_switch easier. */ if (TREE_CODE (ret_expr) == RESULT_DECL) { if (!*return_value_p) *return_value_p = ret_expr; else gcc_assert (*return_value_p == ret_expr); q->cont_stmt = q->stmt.g; } else gcc_unreachable (); } else /* If we don't return a value, all return statements are the same. */ q->cont_stmt = q->stmt.g; if (!q->repl_stmt) q->repl_stmt = gimple_seq_alloc (); if (mod) gimple_seq_add_seq (&q->repl_stmt, mod); x = gimple_build_goto (finlab); gimple_seq_add_stmt (&q->repl_stmt, x); } /* Similar, but easier, for GIMPLE_GOTO. */ static void do_goto_redirection (struct goto_queue_node *q, tree finlab, gimple_seq mod, struct leh_tf_state *tf) { gimple x; gcc_assert (q->is_label); if (!q->repl_stmt) q->repl_stmt = gimple_seq_alloc (); q->cont_stmt = gimple_build_goto (VEC_index (tree, tf->dest_array,q->index)); if (mod) gimple_seq_add_seq (&q->repl_stmt, mod); x = gimple_build_goto (finlab); gimple_seq_add_stmt (&q->repl_stmt, x); } /* We want to transform try { body; } catch { stuff; } to body; goto over; lab: stuff; over: TP is a GIMPLE_TRY node. LAB is the label that should be placed before the second operand, or NULL. OVER is an existing label that should be put at the exit, or NULL. */ static gimple_seq frob_into_branch_around (gimple tp, tree lab, tree over) { gimple x; gimple_seq cleanup, result; cleanup = gimple_try_cleanup (tp); result = gimple_try_eval (tp); if (gimple_seq_may_fallthru (result)) { if (!over) over = create_artificial_label (); x = gimple_build_goto (over); gimple_seq_add_stmt (&result, x); } if (lab) { x = gimple_build_label (lab); gimple_seq_add_stmt (&result, x); } gimple_seq_add_seq (&result, cleanup); if (over) { x = gimple_build_label (over); gimple_seq_add_stmt (&result, x); } return result; } /* A subroutine of lower_try_finally. Duplicate the tree rooted at T. Make sure to record all new labels found. */ static gimple_seq lower_try_finally_dup_block (gimple_seq seq, struct leh_state *outer_state) { gimple region = NULL; gimple_seq new_seq; new_seq = copy_gimple_seq_and_replace_locals (seq); if (outer_state->tf) region = outer_state->tf->try_finally_expr; collect_finally_tree_1 (new_seq, region); return new_seq; } /* A subroutine of lower_try_finally. Create a fallthru label for the given try_finally state. The only tricky bit here is that we have to make sure to record the label in our outer context. */ static tree lower_try_finally_fallthru_label (struct leh_tf_state *tf) { tree label = tf->fallthru_label; treemple temp; if (!label) { label = create_artificial_label (); tf->fallthru_label = label; if (tf->outer->tf) { temp.t = label; record_in_finally_tree (temp, tf->outer->tf->try_finally_expr); } } return label; } /* A subroutine of lower_try_finally. If lang_protect_cleanup_actions returns non-null, then the language requires that the exception path out of a try_finally be treated specially. To wit: the code within the finally block may not itself throw an exception. We have two choices here. First we can duplicate the finally block and wrap it in a must_not_throw region. Second, we can generate code like try { finally_block; } catch { if (fintmp == eh_edge) protect_cleanup_actions; } where "fintmp" is the temporary used in the switch statement generation alternative considered below. For the nonce, we always choose the first option. THIS_STATE may be null if this is a try-cleanup, not a try-finally. */ static void honor_protect_cleanup_actions (struct leh_state *outer_state, struct leh_state *this_state, struct leh_tf_state *tf) { gimple protect_cleanup_actions; gimple_stmt_iterator gsi; bool finally_may_fallthru; gimple_seq finally; gimple x; /* First check for nothing to do. */ if (lang_protect_cleanup_actions) protect_cleanup_actions = lang_protect_cleanup_actions (); else protect_cleanup_actions = NULL; finally = gimple_try_cleanup (tf->top_p); /* If the EH case of the finally block can fall through, this may be a structure of the form try { try { throw ...; } cleanup { try { throw ...; } catch (...) { } } } catch (...) { yyy; } E.g. with an inline destructor with an embedded try block. In this case we must save the runtime EH data around the nested exception. This complication means that any time the previous runtime data might be used (via fallthru from the finally) we handle the eh case here, whether or not protect_cleanup_actions is active. */ finally_may_fallthru = gimple_seq_may_fallthru (finally); if (!finally_may_fallthru && !protect_cleanup_actions) return; /* Duplicate the FINALLY block. Only need to do this for try-finally, and not for cleanups. */ if (this_state) finally = lower_try_finally_dup_block (finally, outer_state); /* If this cleanup consists of a TRY_CATCH_EXPR with TRY_CATCH_IS_CLEANUP set, the handler of the TRY_CATCH_EXPR is another cleanup which ought to be in an enclosing scope, but needs to be implemented at this level to avoid a nesting violation (see wrap_temporary_cleanups in cp/decl.c). Since it's logically at an outer level, we should call terminate before we get to it, so strip it away before adding the MUST_NOT_THROW filter. */ gsi = gsi_start (finally); x = gsi_stmt (gsi); if (protect_cleanup_actions && gimple_code (x) == GIMPLE_TRY && gimple_try_kind (x) == GIMPLE_TRY_CATCH && gimple_try_catch_is_cleanup (x)) { gsi_insert_seq_before (&gsi, gimple_try_eval (x), GSI_SAME_STMT); gsi_remove (&gsi, false); } /* Resume execution after the exception. Adding this now lets lower_eh_filter not add unnecessary gotos, as it is clear that we never fallthru from this copy of the finally block. */ if (finally_may_fallthru) { tree save_eptr, save_filt; tree tmp; save_eptr = create_tmp_var (ptr_type_node, "save_eptr"); save_filt = create_tmp_var (integer_type_node, "save_filt"); gsi = gsi_start (finally); tmp = build0 (EXC_PTR_EXPR, ptr_type_node); x = gimple_build_assign (save_eptr, tmp); gsi_insert_before (&gsi, x, GSI_CONTINUE_LINKING); tmp = build0 (FILTER_EXPR, integer_type_node); x = gimple_build_assign (save_filt, tmp); gsi_insert_before (&gsi, x, GSI_CONTINUE_LINKING); gsi = gsi_last (finally); tmp = build0 (EXC_PTR_EXPR, ptr_type_node); x = gimple_build_assign (tmp, save_eptr); gsi_insert_after (&gsi, x, GSI_CONTINUE_LINKING); tmp = build0 (FILTER_EXPR, integer_type_node); x = gimple_build_assign (tmp, save_filt); gsi_insert_after (&gsi, x, GSI_CONTINUE_LINKING); x = gimple_build_resx (get_eh_region_number (tf->region)); gsi_insert_after (&gsi, x, GSI_CONTINUE_LINKING); } /* Wrap the block with protect_cleanup_actions as the action. */ if (protect_cleanup_actions) { gimple_seq seq = NULL, failure = NULL; gimple_seq_add_stmt (&failure, protect_cleanup_actions); x = gimple_build_eh_filter (NULL, failure); gimple_eh_filter_set_must_not_throw (x, 1); gimple_seq_add_stmt (&seq, x); x = gimple_build_try (finally, seq, GIMPLE_TRY_CATCH); finally = lower_eh_filter (outer_state, x); } else lower_eh_constructs_1 (outer_state, finally); /* Hook this up to the end of the existing try block. If we previously fell through the end, we'll have to branch around. This means adding a new goto, and adding it to the queue. */ gsi = gsi_last (gimple_try_eval (tf->top_p)); if (tf->may_fallthru) { tree tmp; tmp = lower_try_finally_fallthru_label (tf); x = gimple_build_goto (tmp); gsi_insert_after (&gsi, x, GSI_CONTINUE_LINKING); if (this_state) maybe_record_in_goto_queue (this_state, x); tf->may_fallthru = false; } x = gimple_build_label (tf->eh_label); gsi_insert_after (&gsi, x, GSI_CONTINUE_LINKING); gsi_insert_seq_after (&gsi, finally, GSI_CONTINUE_LINKING); /* Having now been handled, EH isn't to be considered with the rest of the outgoing edges. */ tf->may_throw = false; } /* A subroutine of lower_try_finally. We have determined that there is no fallthru edge out of the finally block. This means that there is no outgoing edge corresponding to any incoming edge. Restructure the try_finally node for this special case. */ static void lower_try_finally_nofallthru (struct leh_state *state, struct leh_tf_state *tf) { tree lab, return_val; gimple x; gimple_seq finally; struct goto_queue_node *q, *qe; if (tf->may_throw) lab = tf->eh_label; else lab = create_artificial_label (); /* We expect that tf->top_p is a GIMPLE_TRY. */ finally = gimple_try_cleanup (tf->top_p); tf->top_p_seq = gimple_try_eval (tf->top_p); x = gimple_build_label (lab); gimple_seq_add_stmt (&tf->top_p_seq, x); return_val = NULL; q = tf->goto_queue; qe = q + tf->goto_queue_active; for (; q < qe; ++q) if (q->index < 0) do_return_redirection (q, lab, NULL, &return_val); else do_goto_redirection (q, lab, NULL, tf); replace_goto_queue (tf); lower_eh_constructs_1 (state, finally); gimple_seq_add_seq (&tf->top_p_seq, finally); } /* A subroutine of lower_try_finally. We have determined that there is exactly one destination of the finally block. Restructure the try_finally node for this special case. */ static void lower_try_finally_onedest (struct leh_state *state, struct leh_tf_state *tf) { struct goto_queue_node *q, *qe; gimple x; gimple_seq finally; tree finally_label; finally = gimple_try_cleanup (tf->top_p); tf->top_p_seq = gimple_try_eval (tf->top_p); lower_eh_constructs_1 (state, finally); if (tf->may_throw) { /* Only reachable via the exception edge. Add the given label to the head of the FINALLY block. Append a RESX at the end. */ x = gimple_build_label (tf->eh_label); gimple_seq_add_stmt (&tf->top_p_seq, x); gimple_seq_add_seq (&tf->top_p_seq, finally); x = gimple_build_resx (get_eh_region_number (tf->region)); gimple_seq_add_stmt (&tf->top_p_seq, x); return; } if (tf->may_fallthru) { /* Only reachable via the fallthru edge. Do nothing but let the two blocks run together; we'll fall out the bottom. */ gimple_seq_add_seq (&tf->top_p_seq, finally); return; } finally_label = create_artificial_label (); x = gimple_build_label (finally_label); gimple_seq_add_stmt (&tf->top_p_seq, x); gimple_seq_add_seq (&tf->top_p_seq, finally); q = tf->goto_queue; qe = q + tf->goto_queue_active; if (tf->may_return) { /* Reachable by return expressions only. Redirect them. */ tree return_val = NULL; for (; q < qe; ++q) do_return_redirection (q, finally_label, NULL, &return_val); replace_goto_queue (tf); } else { /* Reachable by goto expressions only. Redirect them. */ for (; q < qe; ++q) do_goto_redirection (q, finally_label, NULL, tf); replace_goto_queue (tf); if (VEC_index (tree, tf->dest_array, 0) == tf->fallthru_label) { /* Reachable by goto to fallthru label only. Redirect it to the new label (already created, sadly), and do not emit the final branch out, or the fallthru label. */ tf->fallthru_label = NULL; return; } } /* Place the original return/goto to the original destination immediately after the finally block. */ x = tf->goto_queue[0].cont_stmt; gimple_seq_add_stmt (&tf->top_p_seq, x); maybe_record_in_goto_queue (state, x); } /* A subroutine of lower_try_finally. There are multiple edges incoming and outgoing from the finally block. Implement this by duplicating the finally block for every destination. */ static void lower_try_finally_copy (struct leh_state *state, struct leh_tf_state *tf) { gimple_seq finally; gimple_seq new_stmt; gimple_seq seq; gimple x; tree tmp; finally = gimple_try_cleanup (tf->top_p); tf->top_p_seq = gimple_try_eval (tf->top_p); new_stmt = NULL; if (tf->may_fallthru) { seq = lower_try_finally_dup_block (finally, state); lower_eh_constructs_1 (state, seq); gimple_seq_add_seq (&new_stmt, seq); tmp = lower_try_finally_fallthru_label (tf); x = gimple_build_goto (tmp); gimple_seq_add_stmt (&new_stmt, x); } if (tf->may_throw) { x = gimple_build_label (tf->eh_label); gimple_seq_add_stmt (&new_stmt, x); seq = lower_try_finally_dup_block (finally, state); lower_eh_constructs_1 (state, seq); gimple_seq_add_seq (&new_stmt, seq); x = gimple_build_resx (get_eh_region_number (tf->region)); gimple_seq_add_stmt (&new_stmt, x); } if (tf->goto_queue) { struct goto_queue_node *q, *qe; tree return_val = NULL; int return_index, index; struct labels_s { struct goto_queue_node *q; tree label; } *labels; return_index = VEC_length (tree, tf->dest_array); labels = XCNEWVEC (struct labels_s, return_index + 1); q = tf->goto_queue; qe = q + tf->goto_queue_active; for (; q < qe; q++) { index = q->index < 0 ? return_index : q->index; if (!labels[index].q) labels[index].q = q; } for (index = 0; index < return_index + 1; index++) { tree lab; q = labels[index].q; if (! q) continue; lab = labels[index].label = create_artificial_label (); if (index == return_index) do_return_redirection (q, lab, NULL, &return_val); else do_goto_redirection (q, lab, NULL, tf); x = gimple_build_label (lab); gimple_seq_add_stmt (&new_stmt, x); seq = lower_try_finally_dup_block (finally, state); lower_eh_constructs_1 (state, seq); gimple_seq_add_seq (&new_stmt, seq); gimple_seq_add_stmt (&new_stmt, q->cont_stmt); maybe_record_in_goto_queue (state, q->cont_stmt); } for (q = tf->goto_queue; q < qe; q++) { tree lab; index = q->index < 0 ? return_index : q->index; if (labels[index].q == q) continue; lab = labels[index].label; if (index == return_index) do_return_redirection (q, lab, NULL, &return_val); else do_goto_redirection (q, lab, NULL, tf); } replace_goto_queue (tf); free (labels); } /* Need to link new stmts after running replace_goto_queue due to not wanting to process the same goto stmts twice. */ gimple_seq_add_seq (&tf->top_p_seq, new_stmt); } /* A subroutine of lower_try_finally. There are multiple edges incoming and outgoing from the finally block. Implement this by instrumenting each incoming edge and creating a switch statement at the end of the finally block that branches to the appropriate destination. */ static void lower_try_finally_switch (struct leh_state *state, struct leh_tf_state *tf) { struct goto_queue_node *q, *qe; tree return_val = NULL; tree finally_tmp, finally_label; int return_index, eh_index, fallthru_index; int nlabels, ndests, j, last_case_index; tree last_case; VEC (tree,heap) *case_label_vec; gimple_seq switch_body; gimple x; tree tmp; gimple switch_stmt; gimple_seq finally; struct pointer_map_t *cont_map = NULL; switch_body = gimple_seq_alloc (); /* Mash the TRY block to the head of the chain. */ finally = gimple_try_cleanup (tf->top_p); tf->top_p_seq = gimple_try_eval (tf->top_p); /* Lower the finally block itself. */ lower_eh_constructs_1 (state, finally); /* Prepare for switch statement generation. */ nlabels = VEC_length (tree, tf->dest_array); return_index = nlabels; eh_index = return_index + tf->may_return; fallthru_index = eh_index + tf->may_throw; ndests = fallthru_index + tf->may_fallthru; finally_tmp = create_tmp_var (integer_type_node, "finally_tmp"); finally_label = create_artificial_label (); /* We use VEC_quick_push on case_label_vec throughout this function, since we know the size in advance and allocate precisely as muce space as needed. */ case_label_vec = VEC_alloc (tree, heap, ndests); last_case = NULL; last_case_index = 0; /* Begin inserting code for getting to the finally block. Things are done in this order to correspond to the sequence the code is layed out. */ if (tf->may_fallthru) { x = gimple_build_assign (finally_tmp, build_int_cst (integer_type_node, fallthru_index)); gimple_seq_add_stmt (&tf->top_p_seq, x); if (tf->may_throw) { x = gimple_build_goto (finally_label); gimple_seq_add_stmt (&tf->top_p_seq, x); } last_case = build3 (CASE_LABEL_EXPR, void_type_node, build_int_cst (NULL_TREE, fallthru_index), NULL, create_artificial_label ()); VEC_quick_push (tree, case_label_vec, last_case); last_case_index++; x = gimple_build_label (CASE_LABEL (last_case)); gimple_seq_add_stmt (&switch_body, x); tmp = lower_try_finally_fallthru_label (tf); x = gimple_build_goto (tmp); gimple_seq_add_stmt (&switch_body, x); } if (tf->may_throw) { x = gimple_build_label (tf->eh_label); gimple_seq_add_stmt (&tf->top_p_seq, x); x = gimple_build_assign (finally_tmp, build_int_cst (integer_type_node, eh_index)); gimple_seq_add_stmt (&tf->top_p_seq, x); last_case = build3 (CASE_LABEL_EXPR, void_type_node, build_int_cst (NULL_TREE, eh_index), NULL, create_artificial_label ()); VEC_quick_push (tree, case_label_vec, last_case); last_case_index++; x = gimple_build_label (CASE_LABEL (last_case)); gimple_seq_add_stmt (&switch_body, x); x = gimple_build_resx (get_eh_region_number (tf->region)); gimple_seq_add_stmt (&switch_body, x); } x = gimple_build_label (finally_label); gimple_seq_add_stmt (&tf->top_p_seq, x); gimple_seq_add_seq (&tf->top_p_seq, finally); /* Redirect each incoming goto edge. */ q = tf->goto_queue; qe = q + tf->goto_queue_active; j = last_case_index + tf->may_return; /* Prepare the assignments to finally_tmp that are executed upon the entrance through a particular edge. */ for (; q < qe; ++q) { gimple_seq mod; int switch_id; unsigned int case_index; mod = gimple_seq_alloc (); if (q->index < 0) { x = gimple_build_assign (finally_tmp, build_int_cst (integer_type_node, return_index)); gimple_seq_add_stmt (&mod, x); do_return_redirection (q, finally_label, mod, &return_val); switch_id = return_index; } else { x = gimple_build_assign (finally_tmp, build_int_cst (integer_type_node, q->index)); gimple_seq_add_stmt (&mod, x); do_goto_redirection (q, finally_label, mod, tf); switch_id = q->index; } case_index = j + q->index; if (VEC_length (tree, case_label_vec) <= case_index || !VEC_index (tree, case_label_vec, case_index)) { tree case_lab; void **slot; case_lab = build3 (CASE_LABEL_EXPR, void_type_node, build_int_cst (NULL_TREE, switch_id), NULL, NULL); /* We store the cont_stmt in the pointer map, so that we can recover it in the loop below. We don't create the new label while walking the goto_queue because pointers don't offer a stable order. */ if (!cont_map) cont_map = pointer_map_create (); slot = pointer_map_insert (cont_map, case_lab); *slot = q->cont_stmt; VEC_quick_push (tree, case_label_vec, case_lab); } } for (j = last_case_index; j < last_case_index + nlabels; j++) { tree label; gimple cont_stmt; void **slot; last_case = VEC_index (tree, case_label_vec, j); gcc_assert (last_case); gcc_assert (cont_map); slot = pointer_map_contains (cont_map, last_case); /* As the comment above suggests, CASE_LABEL (last_case) was just a placeholder, it does not store an actual label, yet. */ gcc_assert (slot); cont_stmt = *(gimple *) slot; label = create_artificial_label (); CASE_LABEL (last_case) = label; x = gimple_build_label (label); gimple_seq_add_stmt (&switch_body, x); gimple_seq_add_stmt (&switch_body, cont_stmt); maybe_record_in_goto_queue (state, cont_stmt); } if (cont_map) pointer_map_destroy (cont_map); replace_goto_queue (tf); /* Make sure that the last case is the default label, as one is required. Then sort the labels, which is also required in GIMPLE. */ CASE_LOW (last_case) = NULL; sort_case_labels (case_label_vec); /* Build the switch statement, setting last_case to be the default label. */ switch_stmt = gimple_build_switch_vec (finally_tmp, last_case, case_label_vec); /* Need to link SWITCH_STMT after running replace_goto_queue due to not wanting to process the same goto stmts twice. */ gimple_seq_add_stmt (&tf->top_p_seq, switch_stmt); gimple_seq_add_seq (&tf->top_p_seq, switch_body); } /* Decide whether or not we are going to duplicate the finally block. There are several considerations. First, if this is Java, then the finally block contains code written by the user. It has line numbers associated with it, so duplicating the block means it's difficult to set a breakpoint. Since controlling code generation via -g is verboten, we simply never duplicate code without optimization. Second, we'd like to prevent egregious code growth. One way to do this is to estimate the size of the finally block, multiply that by the number of copies we'd need to make, and compare against the estimate of the size of the switch machinery we'd have to add. */ static bool decide_copy_try_finally (int ndests, gimple_seq finally) { int f_estimate, sw_estimate; if (!optimize) return false; /* Finally estimate N times, plus N gotos. */ f_estimate = count_insns_seq (finally, &eni_size_weights); f_estimate = (f_estimate + 1) * ndests; /* Switch statement (cost 10), N variable assignments, N gotos. */ sw_estimate = 10 + 2 * ndests; /* Optimize for size clearly wants our best guess. */ if (optimize_function_for_size_p (cfun)) return f_estimate < sw_estimate; /* ??? These numbers are completely made up so far. */ if (optimize > 1) return f_estimate < 100 || f_estimate < sw_estimate * 2; else return f_estimate < 40 || f_estimate * 2 < sw_estimate * 3; } /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_FINALLY nodes to a sequence of labels and blocks, plus the exception region trees that record all the magic. This is complicated by the need to arrange for the FINALLY block to be executed on all exits. */ static gimple_seq lower_try_finally (struct leh_state *state, gimple tp) { struct leh_tf_state this_tf; struct leh_state this_state; int ndests; /* Process the try block. */ memset (&this_tf, 0, sizeof (this_tf)); this_tf.try_finally_expr = tp; this_tf.top_p = tp; this_tf.outer = state; if (using_eh_for_cleanups_p) this_tf.region = gen_eh_region_cleanup (state->cur_region, state->prev_try); else this_tf.region = NULL; this_state.cur_region = this_tf.region; this_state.prev_try = state->prev_try; this_state.tf = &this_tf; lower_eh_constructs_1 (&this_state, gimple_try_eval(tp)); /* Determine if the try block is escaped through the bottom. */ this_tf.may_fallthru = gimple_seq_may_fallthru (gimple_try_eval (tp)); /* Determine if any exceptions are possible within the try block. */ if (using_eh_for_cleanups_p) this_tf.may_throw = get_eh_region_may_contain_throw (this_tf.region); if (this_tf.may_throw) { this_tf.eh_label = create_artificial_label (); set_eh_region_tree_label (this_tf.region, this_tf.eh_label); honor_protect_cleanup_actions (state, &this_state, &this_tf); } /* Determine how many edges (still) reach the finally block. Or rather, how many destinations are reached by the finally block. Use this to determine how we process the finally block itself. */ ndests = VEC_length (tree, this_tf.dest_array); ndests += this_tf.may_fallthru; ndests += this_tf.may_return; ndests += this_tf.may_throw; /* If the FINALLY block is not reachable, dike it out. */ if (ndests == 0) { gimple_seq_add_seq (&this_tf.top_p_seq, gimple_try_eval (tp)); gimple_try_set_cleanup (tp, NULL); } /* If the finally block doesn't fall through, then any destination we might try to impose there isn't reached either. There may be some minor amount of cleanup and redirection still needed. */ else if (!gimple_seq_may_fallthru (gimple_try_cleanup (tp))) lower_try_finally_nofallthru (state, &this_tf); /* We can easily special-case redirection to a single destination. */ else if (ndests == 1) lower_try_finally_onedest (state, &this_tf); else if (decide_copy_try_finally (ndests, gimple_try_cleanup (tp))) lower_try_finally_copy (state, &this_tf); else lower_try_finally_switch (state, &this_tf); /* If someone requested we add a label at the end of the transformed block, do so. */ if (this_tf.fallthru_label) { /* This must be reached only if ndests == 0. */ gimple x = gimple_build_label (this_tf.fallthru_label); gimple_seq_add_stmt (&this_tf.top_p_seq, x); } VEC_free (tree, heap, this_tf.dest_array); if (this_tf.goto_queue) free (this_tf.goto_queue); if (this_tf.goto_queue_map) pointer_map_destroy (this_tf.goto_queue_map); return this_tf.top_p_seq; } /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_CATCH with a list of GIMPLE_CATCH to a sequence of labels and blocks, plus the exception region trees that records all the magic. */ static gimple_seq lower_catch (struct leh_state *state, gimple tp) { struct eh_region *try_region; struct leh_state this_state; gimple_stmt_iterator gsi; tree out_label; try_region = gen_eh_region_try (state->cur_region); this_state.cur_region = try_region; this_state.prev_try = try_region; this_state.tf = state->tf; lower_eh_constructs_1 (&this_state, gimple_try_eval (tp)); if (!get_eh_region_may_contain_throw (try_region)) { return gimple_try_eval (tp); } out_label = NULL; for (gsi = gsi_start (gimple_try_cleanup (tp)); !gsi_end_p (gsi); ) { struct eh_region *catch_region; tree eh_label; gimple x, gcatch; gcatch = gsi_stmt (gsi); catch_region = gen_eh_region_catch (try_region, gimple_catch_types (gcatch)); this_state.cur_region = catch_region; this_state.prev_try = state->prev_try; lower_eh_constructs_1 (&this_state, gimple_catch_handler (gcatch)); eh_label = create_artificial_label (); set_eh_region_tree_label (catch_region, eh_label); x = gimple_build_label (eh_label); gsi_insert_before (&gsi, x, GSI_SAME_STMT); if (gimple_seq_may_fallthru (gimple_catch_handler (gcatch))) { if (!out_label) out_label = create_artificial_label (); x = gimple_build_goto (out_label); gimple_seq_add_stmt (gimple_catch_handler_ptr (gcatch), x); } gsi_insert_seq_before (&gsi, gimple_catch_handler (gcatch), GSI_SAME_STMT); gsi_remove (&gsi, false); } return frob_into_branch_around (tp, NULL, out_label); } /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with a GIMPLE_EH_FILTER to a sequence of labels and blocks, plus the exception region trees that record all the magic. */ static gimple_seq lower_eh_filter (struct leh_state *state, gimple tp) { struct leh_state this_state; struct eh_region *this_region; gimple inner; tree eh_label; inner = gimple_seq_first_stmt (gimple_try_cleanup (tp)); if (gimple_eh_filter_must_not_throw (inner)) this_region = gen_eh_region_must_not_throw (state->cur_region); else this_region = gen_eh_region_allowed (state->cur_region, gimple_eh_filter_types (inner)); this_state = *state; this_state.cur_region = this_region; /* For must not throw regions any cleanup regions inside it can't reach outer catch regions. */ if (gimple_eh_filter_must_not_throw (inner)) this_state.prev_try = NULL; lower_eh_constructs_1 (&this_state, gimple_try_eval (tp)); if (!get_eh_region_may_contain_throw (this_region)) { return gimple_try_eval (tp); } lower_eh_constructs_1 (state, gimple_eh_filter_failure (inner)); gimple_try_set_cleanup (tp, gimple_eh_filter_failure (inner)); eh_label = create_artificial_label (); set_eh_region_tree_label (this_region, eh_label); return frob_into_branch_around (tp, eh_label, NULL); } /* Implement a cleanup expression. This is similar to try-finally, except that we only execute the cleanup block for exception edges. */ static gimple_seq lower_cleanup (struct leh_state *state, gimple tp) { struct leh_state this_state; struct eh_region *this_region; struct leh_tf_state fake_tf; gimple_seq result; /* If not using eh, then exception-only cleanups are no-ops. */ if (!flag_exceptions) { result = gimple_try_eval (tp); lower_eh_constructs_1 (state, result); return result; } this_region = gen_eh_region_cleanup (state->cur_region, state->prev_try); this_state = *state; this_state.cur_region = this_region; lower_eh_constructs_1 (&this_state, gimple_try_eval (tp)); if (!get_eh_region_may_contain_throw (this_region)) { return gimple_try_eval (tp); } /* Build enough of a try-finally state so that we can reuse honor_protect_cleanup_actions. */ memset (&fake_tf, 0, sizeof (fake_tf)); fake_tf.top_p = tp; fake_tf.outer = state; fake_tf.region = this_region; fake_tf.may_fallthru = gimple_seq_may_fallthru (gimple_try_eval (tp)); fake_tf.may_throw = true; fake_tf.eh_label = create_artificial_label (); set_eh_region_tree_label (this_region, fake_tf.eh_label); honor_protect_cleanup_actions (state, NULL, &fake_tf); if (fake_tf.may_throw) { /* In this case honor_protect_cleanup_actions had nothing to do, and we should process this normally. */ lower_eh_constructs_1 (state, gimple_try_cleanup (tp)); result = frob_into_branch_around (tp, fake_tf.eh_label, fake_tf.fallthru_label); } else { /* In this case honor_protect_cleanup_actions did nearly all of the work. All we have left is to append the fallthru_label. */ result = gimple_try_eval (tp); if (fake_tf.fallthru_label) { gimple x = gimple_build_label (fake_tf.fallthru_label); gimple_seq_add_stmt (&result, x); } } return result; } /* Main loop for lowering eh constructs. Also moves gsi to the next statement. */ static void lower_eh_constructs_2 (struct leh_state *state, gimple_stmt_iterator *gsi) { gimple_seq replace; gimple x; gimple stmt = gsi_stmt (*gsi); switch (gimple_code (stmt)) { case GIMPLE_CALL: case GIMPLE_ASSIGN: /* Look for things that can throw exceptions, and record them. */ if (state->cur_region && stmt_could_throw_p (stmt)) { record_stmt_eh_region (state->cur_region, stmt); note_eh_region_may_contain_throw (state->cur_region); } break; case GIMPLE_COND: case GIMPLE_GOTO: case GIMPLE_RETURN: maybe_record_in_goto_queue (state, stmt); break; case GIMPLE_SWITCH: verify_norecord_switch_expr (state, stmt); break; case GIMPLE_TRY: if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY) replace = lower_try_finally (state, stmt); else { x = gimple_seq_first_stmt (gimple_try_cleanup (stmt)); switch (gimple_code (x)) { case GIMPLE_CATCH: replace = lower_catch (state, stmt); break; case GIMPLE_EH_FILTER: replace = lower_eh_filter (state, stmt); break; default: replace = lower_cleanup (state, stmt); break; } } /* Remove the old stmt and insert the transformed sequence instead. */ gsi_insert_seq_before (gsi, replace, GSI_SAME_STMT); gsi_remove (gsi, true); /* Return since we don't want gsi_next () */ return; default: /* A type, a decl, or some kind of statement that we're not interested in. Don't walk them. */ break; } gsi_next (gsi); } /* A helper to unwrap a gimple_seq and feed stmts to lower_eh_constructs_2. */ static void lower_eh_constructs_1 (struct leh_state *state, gimple_seq seq) { gimple_stmt_iterator gsi; for (gsi = gsi_start (seq); !gsi_end_p (gsi);) lower_eh_constructs_2 (state, &gsi); } static unsigned int lower_eh_constructs (void) { struct leh_state null_state; gimple_seq bodyp = gimple_body (current_function_decl); finally_tree = htab_create (31, struct_ptr_hash, struct_ptr_eq, free); collect_finally_tree_1 (bodyp, NULL); memset (&null_state, 0, sizeof (null_state)); lower_eh_constructs_1 (&null_state, bodyp); htab_delete (finally_tree); collect_eh_region_array (); return 0; } struct gimple_opt_pass pass_lower_eh = { { GIMPLE_PASS, "eh", /* name */ NULL, /* gate */ lower_eh_constructs, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_TREE_EH, /* tv_id */ PROP_gimple_lcf, /* properties_required */ PROP_gimple_leh, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ TODO_dump_func /* todo_flags_finish */ } }; /* Construct EH edges for STMT. */ static void make_eh_edge (struct eh_region *region, void *data) { gimple stmt; tree lab; basic_block src, dst; stmt = (gimple) data; lab = get_eh_region_tree_label (region); src = gimple_bb (stmt); dst = label_to_block (lab); make_edge (src, dst, EDGE_ABNORMAL | EDGE_EH); } void make_eh_edges (gimple stmt) { int region_nr; bool is_resx; if (gimple_code (stmt) == GIMPLE_RESX) { region_nr = gimple_resx_region (stmt); is_resx = true; } else { region_nr = lookup_stmt_eh_region (stmt); if (region_nr < 0) return; is_resx = false; } foreach_reachable_handler (region_nr, is_resx, make_eh_edge, stmt); } static bool mark_eh_edge_found_error; /* Mark edge make_eh_edge would create for given region by setting it aux field, output error if something goes wrong. */ static void mark_eh_edge (struct eh_region *region, void *data) { gimple stmt; tree lab; basic_block src, dst; edge e; stmt = (gimple) data; lab = get_eh_region_tree_label (region); src = gimple_bb (stmt); dst = label_to_block (lab); e = find_edge (src, dst); if (!e) { error ("EH edge %i->%i is missing", src->index, dst->index); mark_eh_edge_found_error = true; } else if (!(e->flags & EDGE_EH)) { error ("EH edge %i->%i miss EH flag", src->index, dst->index); mark_eh_edge_found_error = true; } else if (e->aux) { /* ??? might not be mistake. */ error ("EH edge %i->%i has duplicated regions", src->index, dst->index); mark_eh_edge_found_error = true; } else e->aux = (void *)1; } /* Verify that BB containing STMT as the last statement, has precisely the edges that make_eh_edges would create. */ bool verify_eh_edges (gimple stmt) { int region_nr; bool is_resx; basic_block bb = gimple_bb (stmt); edge_iterator ei; edge e; FOR_EACH_EDGE (e, ei, bb->succs) gcc_assert (!e->aux); mark_eh_edge_found_error = false; if (gimple_code (stmt) == GIMPLE_RESX) { region_nr = gimple_resx_region (stmt); is_resx = true; } else { region_nr = lookup_stmt_eh_region (stmt); if (region_nr < 0) { FOR_EACH_EDGE (e, ei, bb->succs) if (e->flags & EDGE_EH) { error ("BB %i can not throw but has EH edges", bb->index); return true; } return false; } if (!stmt_could_throw_p (stmt)) { error ("BB %i last statement has incorrectly set region", bb->index); return true; } is_resx = false; } foreach_reachable_handler (region_nr, is_resx, mark_eh_edge, stmt); FOR_EACH_EDGE (e, ei, bb->succs) { if ((e->flags & EDGE_EH) && !e->aux) { error ("unnecessary EH edge %i->%i", bb->index, e->dest->index); mark_eh_edge_found_error = true; return true; } e->aux = NULL; } return mark_eh_edge_found_error; } /* Helper function for operation_could_trap_p and stmt_could_throw_p. */ bool operation_could_trap_helper_p (enum tree_code op, bool fp_operation, bool honor_trapv, bool honor_nans, bool honor_snans, tree divisor, bool *handled) { *handled = true; switch (op) { case TRUNC_DIV_EXPR: case CEIL_DIV_EXPR: case FLOOR_DIV_EXPR: case ROUND_DIV_EXPR: case EXACT_DIV_EXPR: case CEIL_MOD_EXPR: case FLOOR_MOD_EXPR: case ROUND_MOD_EXPR: case TRUNC_MOD_EXPR: case RDIV_EXPR: if (honor_snans || honor_trapv) return true; if (fp_operation) return flag_trapping_math; if (!TREE_CONSTANT (divisor) || integer_zerop (divisor)) return true; return false; case LT_EXPR: case LE_EXPR: case GT_EXPR: case GE_EXPR: case LTGT_EXPR: /* Some floating point comparisons may trap. */ return honor_nans; case EQ_EXPR: case NE_EXPR: case UNORDERED_EXPR: case ORDERED_EXPR: case UNLT_EXPR: case UNLE_EXPR: case UNGT_EXPR: case UNGE_EXPR: case UNEQ_EXPR: return honor_snans; case CONVERT_EXPR: case FIX_TRUNC_EXPR: /* Conversion of floating point might trap. */ return honor_nans; case NEGATE_EXPR: case ABS_EXPR: case CONJ_EXPR: /* These operations don't trap with floating point. */ if (honor_trapv) return true; return false; case PLUS_EXPR: case MINUS_EXPR: case MULT_EXPR: /* Any floating arithmetic may trap. */ if (fp_operation && flag_trapping_math) return true; if (honor_trapv) return true; return false; default: /* Any floating arithmetic may trap. */ if (fp_operation && flag_trapping_math) return true; *handled = false; return false; } } /* Return true if operation OP may trap. FP_OPERATION is true if OP is applied on floating-point values. HONOR_TRAPV is true if OP is applied on integer type operands that may trap. If OP is a division operator, DIVISOR contains the value of the divisor. */ bool operation_could_trap_p (enum tree_code op, bool fp_operation, bool honor_trapv, tree divisor) { bool honor_nans = (fp_operation && flag_trapping_math && !flag_finite_math_only); bool honor_snans = fp_operation && flag_signaling_nans != 0; bool handled; if (TREE_CODE_CLASS (op) != tcc_comparison && TREE_CODE_CLASS (op) != tcc_unary && TREE_CODE_CLASS (op) != tcc_binary) return false; return operation_could_trap_helper_p (op, fp_operation, honor_trapv, honor_nans, honor_snans, divisor, &handled); } /* Return true if EXPR can trap, as in dereferencing an invalid pointer location or floating point arithmetic. C.f. the rtl version, may_trap_p. This routine expects only GIMPLE lhs or rhs input. */ bool tree_could_trap_p (tree expr) { enum tree_code code; bool fp_operation = false; bool honor_trapv = false; tree t, base, div = NULL_TREE; if (!expr) return false; code = TREE_CODE (expr); t = TREE_TYPE (expr); if (t) { if (COMPARISON_CLASS_P (expr)) fp_operation = FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))); else fp_operation = FLOAT_TYPE_P (t); honor_trapv = INTEGRAL_TYPE_P (t) && TYPE_OVERFLOW_TRAPS (t); } if (TREE_CODE_CLASS (code) == tcc_binary) div = TREE_OPERAND (expr, 1); if (operation_could_trap_p (code, fp_operation, honor_trapv, div)) return true; restart: switch (code) { case TARGET_MEM_REF: /* For TARGET_MEM_REFs use the information based on the original reference. */ expr = TMR_ORIGINAL (expr); code = TREE_CODE (expr); goto restart; case COMPONENT_REF: case REALPART_EXPR: case IMAGPART_EXPR: case BIT_FIELD_REF: case VIEW_CONVERT_EXPR: case WITH_SIZE_EXPR: expr = TREE_OPERAND (expr, 0); code = TREE_CODE (expr); goto restart; case ARRAY_RANGE_REF: base = TREE_OPERAND (expr, 0); if (tree_could_trap_p (base)) return true; if (TREE_THIS_NOTRAP (expr)) return false; return !range_in_array_bounds_p (expr); case ARRAY_REF: base = TREE_OPERAND (expr, 0); if (tree_could_trap_p (base)) return true; if (TREE_THIS_NOTRAP (expr)) return false; return !in_array_bounds_p (expr); case INDIRECT_REF: case ALIGN_INDIRECT_REF: case MISALIGNED_INDIRECT_REF: return !TREE_THIS_NOTRAP (expr); case ASM_EXPR: return TREE_THIS_VOLATILE (expr); case CALL_EXPR: t = get_callee_fndecl (expr); /* Assume that calls to weak functions may trap. */ if (!t || !DECL_P (t) || DECL_WEAK (t)) return true; return false; default: return false; } } /* Helper for stmt_could_throw_p. Return true if STMT (assumed to be a an assignment or a conditional) may throw. */ static bool stmt_could_throw_1_p (gimple stmt) { enum tree_code code = gimple_expr_code (stmt); bool honor_nans = false; bool honor_snans = false; bool fp_operation = false; bool honor_trapv = false; tree t; size_t i; bool handled, ret; if (TREE_CODE_CLASS (code) == tcc_comparison || TREE_CODE_CLASS (code) == tcc_unary || TREE_CODE_CLASS (code) == tcc_binary) { t = gimple_expr_type (stmt); fp_operation = FLOAT_TYPE_P (t); if (fp_operation) { honor_nans = flag_trapping_math && !flag_finite_math_only; honor_snans = flag_signaling_nans != 0; } else if (INTEGRAL_TYPE_P (t) && TYPE_OVERFLOW_TRAPS (t)) honor_trapv = true; } /* Check if the main expression may trap. */ t = is_gimple_assign (stmt) ? gimple_assign_rhs2 (stmt) : NULL; ret = operation_could_trap_helper_p (code, fp_operation, honor_trapv, honor_nans, honor_snans, t, &handled); if (handled) return ret; /* If the expression does not trap, see if any of the individual operands may trap. */ for (i = 0; i < gimple_num_ops (stmt); i++) if (tree_could_trap_p (gimple_op (stmt, i))) return true; return false; } /* Return true if statement STMT could throw an exception. */ bool stmt_could_throw_p (gimple stmt) { enum gimple_code code; if (!flag_exceptions) return false; /* The only statements that can throw an exception are assignments, conditionals, calls and asms. */ code = gimple_code (stmt); if (code != GIMPLE_ASSIGN && code != GIMPLE_COND && code != GIMPLE_CALL && code != GIMPLE_ASM) return false; /* If exceptions can only be thrown by function calls and STMT is not a GIMPLE_CALL, the statement cannot throw. */ if (!flag_non_call_exceptions && code != GIMPLE_CALL) return false; if (code == GIMPLE_ASSIGN || code == GIMPLE_COND) return stmt_could_throw_1_p (stmt); else if (is_gimple_call (stmt)) { tree t = gimple_call_fndecl (stmt); /* Assume that calls to weak functions may trap. */ if (!t || !DECL_P (t) || DECL_WEAK (t)) return true; return (gimple_call_flags (stmt) & ECF_NOTHROW) == 0; } else if (gimple_code (stmt) == GIMPLE_ASM) return (gimple_asm_volatile_p (stmt)); else gcc_unreachable (); return false; } /* Return true if expression T could throw an exception. */ bool tree_could_throw_p (tree t) { if (!flag_exceptions) return false; if (TREE_CODE (t) == MODIFY_EXPR) { if (flag_non_call_exceptions && tree_could_trap_p (TREE_OPERAND (t, 0))) return true; t = TREE_OPERAND (t, 1); } if (TREE_CODE (t) == WITH_SIZE_EXPR) t = TREE_OPERAND (t, 0); if (TREE_CODE (t) == CALL_EXPR) return (call_expr_flags (t) & ECF_NOTHROW) == 0; if (flag_non_call_exceptions) return tree_could_trap_p (t); return false; } /* Return true if STMT can throw an exception that is caught within the current function (CFUN). */ bool stmt_can_throw_internal (gimple stmt) { int region_nr; bool is_resx = false; if (gimple_code (stmt) == GIMPLE_RESX) { region_nr = gimple_resx_region (stmt); is_resx = true; } else region_nr = lookup_stmt_eh_region (stmt); if (region_nr < 0) return false; return can_throw_internal_1 (region_nr, is_resx); } /* Given a statement OLD_STMT and a new statement NEW_STMT that has replaced OLD_STMT in the function, remove OLD_STMT from the EH table and put NEW_STMT in the table if it should be in there. Return TRUE if a replacement was done that my require an EH edge purge. */ bool maybe_clean_or_replace_eh_stmt (gimple old_stmt, gimple new_stmt) { int region_nr = lookup_stmt_eh_region (old_stmt); if (region_nr >= 0) { bool new_stmt_could_throw = stmt_could_throw_p (new_stmt); if (new_stmt == old_stmt && new_stmt_could_throw) return false; remove_stmt_from_eh_region (old_stmt); if (new_stmt_could_throw) { add_stmt_to_eh_region (new_stmt, region_nr); return false; } else return true; } return false; } /* Returns TRUE if oneh and twoh are exception handlers (gimple_try_cleanup of GIMPLE_TRY) that are similar enough to be considered the same. Currently this only handles handlers consisting of a single call, as that's the important case for C++: a destructor call for a particular object showing up in multiple handlers. */ static bool same_handler_p (gimple_seq oneh, gimple_seq twoh) { gimple_stmt_iterator gsi; gimple ones, twos; unsigned int ai; gsi = gsi_start (oneh); if (!gsi_one_before_end_p (gsi)) return false; ones = gsi_stmt (gsi); gsi = gsi_start (twoh); if (!gsi_one_before_end_p (gsi)) return false; twos = gsi_stmt (gsi); if (!is_gimple_call (ones) || !is_gimple_call (twos) || gimple_call_lhs (ones) || gimple_call_lhs (twos) || gimple_call_chain (ones) || gimple_call_chain (twos) || !operand_equal_p (gimple_call_fn (ones), gimple_call_fn (twos), 0) || gimple_call_num_args (ones) != gimple_call_num_args (twos)) return false; for (ai = 0; ai < gimple_call_num_args (ones); ++ai) if (!operand_equal_p (gimple_call_arg (ones, ai), gimple_call_arg (twos, ai), 0)) return false; return true; } /* Optimize try { A() } finally { try { ~B() } catch { ~A() } } try { ... } finally { ~A() } into try { A() } catch { ~B() } try { ~B() ... } finally { ~A() } This occurs frequently in C++, where A is a local variable and B is a temporary used in the initializer for A. */ static void optimize_double_finally (gimple one, gimple two) { gimple oneh; gimple_stmt_iterator gsi; gsi = gsi_start (gimple_try_cleanup (one)); if (!gsi_one_before_end_p (gsi)) return; oneh = gsi_stmt (gsi); if (gimple_code (oneh) != GIMPLE_TRY || gimple_try_kind (oneh) != GIMPLE_TRY_CATCH) return; if (same_handler_p (gimple_try_cleanup (oneh), gimple_try_cleanup (two))) { gimple_seq seq = gimple_try_eval (oneh); gimple_try_set_cleanup (one, seq); gimple_try_set_kind (one, GIMPLE_TRY_CATCH); seq = copy_gimple_seq_and_replace_locals (seq); gimple_seq_add_seq (&seq, gimple_try_eval (two)); gimple_try_set_eval (two, seq); } } /* Perform EH refactoring optimizations that are simpler to do when code flow has been lowered but EH structures haven't. */ static void refactor_eh_r (gimple_seq seq) { gimple_stmt_iterator gsi; gimple one, two; one = NULL; two = NULL; gsi = gsi_start (seq); while (1) { one = two; if (gsi_end_p (gsi)) two = NULL; else two = gsi_stmt (gsi); if (one && two && gimple_code (one) == GIMPLE_TRY && gimple_code (two) == GIMPLE_TRY && gimple_try_kind (one) == GIMPLE_TRY_FINALLY && gimple_try_kind (two) == GIMPLE_TRY_FINALLY) optimize_double_finally (one, two); if (one) switch (gimple_code (one)) { case GIMPLE_TRY: refactor_eh_r (gimple_try_eval (one)); refactor_eh_r (gimple_try_cleanup (one)); break; case GIMPLE_CATCH: refactor_eh_r (gimple_catch_handler (one)); break; case GIMPLE_EH_FILTER: refactor_eh_r (gimple_eh_filter_failure (one)); break; default: break; } if (two) gsi_next (&gsi); else break; } } static unsigned refactor_eh (void) { refactor_eh_r (gimple_body (current_function_decl)); return 0; } struct gimple_opt_pass pass_refactor_eh = { { GIMPLE_PASS, "ehopt", /* name */ NULL, /* gate */ refactor_eh, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_TREE_EH, /* tv_id */ PROP_gimple_lcf, /* properties_required */ 0, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ TODO_dump_func /* todo_flags_finish */ } };