/* Handle exceptional things in C++. Copyright (C) 1989, 92-97, 1998, 1999 Free Software Foundation, Inc. Contributed by Michael Tiemann Rewritten by Mike Stump , based upon an initial re-implementation courtesy Tad Hunt. This file is part of GNU CC. GNU CC 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 2, or (at your option) any later version. GNU CC 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 GNU CC; see the file COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include "config.h" #include "system.h" #include "tree.h" #include "rtl.h" #include "cp-tree.h" #include "flags.h" #include "obstack.h" #include "expr.h" #include "output.h" #include "except.h" #include "function.h" #include "defaults.h" #include "toplev.h" #include "eh-common.h" rtx expand_builtin_return_addr PROTO((enum built_in_function, int, rtx)); /* Holds the fndecl for __builtin_return_address. */ tree builtin_return_address_fndecl; /* A couple of backend routines from m88k.c */ static void push_eh_cleanup PROTO((void)); static tree build_eh_type_type PROTO((tree)); static tree build_eh_type PROTO((tree)); static void expand_end_eh_spec PROTO((tree)); static tree call_eh_info PROTO((void)); static void push_eh_info PROTO((void)); static tree get_eh_info PROTO((void)); static tree get_eh_value PROTO((void)); #if 0 static tree get_eh_type PROTO((void)); static tree get_eh_caught PROTO((void)); static tree get_eh_handlers PROTO((void)); #endif static tree do_pop_exception PROTO((void)); static void process_start_catch_block PROTO((tree, tree)); static tree build_eh_type_type_ref PROTO((tree)); static tree build_terminate_handler PROTO((void)); static tree alloc_eh_object PROTO((tree)); #if 0 /* This is the startup, and finish stuff per exception table. */ /* XXX - Tad: exception handling section */ #ifndef EXCEPT_SECTION_ASM_OP #define EXCEPT_SECTION_ASM_OP "section\t.gcc_except_table,\"a\",@progbits" #endif #ifdef EXCEPT_SECTION_ASM_OP /* on machines which support it, the exception table lives in another section, but it needs a label so we can reference it... This sets up that label! */ asm (EXCEPT_SECTION_ASM_OP); exception_table __EXCEPTION_TABLE__[1] = { (void*)0, (void*)0, (void*)0 }; asm (TEXT_SECTION_ASM_OP); #endif /* EXCEPT_SECTION_ASM_OP */ #ifdef EXCEPT_SECTION_ASM_OP /* we need to know where the end of the exception table is... so this is how we do it! */ asm (EXCEPT_SECTION_ASM_OP); exception_table __EXCEPTION_END__[1] = { (void*)-1, (void*)-1, (void*)-1 }; asm (TEXT_SECTION_ASM_OP); #endif /* EXCEPT_SECTION_ASM_OP */ #endif #include "decl.h" #include "insn-flags.h" #include "obstack.h" /* ====================================================================== Briefly the algorithm works like this: When a constructor or start of a try block is encountered, push_eh_entry (&eh_stack) is called. Push_eh_entry () creates a new entry in the unwind protection stack and returns a label to output to start the protection for that block. When a destructor or end try block is encountered, pop_eh_entry (&eh_stack) is called. Pop_eh_entry () returns the eh_entry it created when push_eh_entry () was called. The eh_entry structure contains three things at this point. The start protect label, the end protect label, and the exception handler label. The end protect label should be output before the call to the destructor (if any). If it was a destructor, then its parse tree is stored in the finalization variable in the eh_entry structure. Otherwise the finalization variable is set to NULL to reflect the fact that it is the end of a try block. Next, this modified eh_entry node is enqueued in the finalizations queue by calling enqueue_eh_entry (&queue,entry). +---------------------------------------------------------------+ |XXX: Will need modification to deal with partially | | constructed arrays of objects | | | | Basically, this consists of keeping track of how many | | of the objects have been constructed already (this | | should be in a register though, so that shouldn't be a | | problem. | +---------------------------------------------------------------+ When a catch block is encountered, there is a lot of work to be done. Since we don't want to generate the catch block inline with the regular flow of the function, we need to have some way of doing so. Luckily, we can use sequences to defer the catch sections. When the start of a catch block is encountered, we start the sequence. After the catch block is generated, we end the sequence. Next we must insure that when the catch block is executed, all finalizations for the matching try block have been completed. If any of those finalizations throw an exception, we must call terminate according to the ARM (section r.15.6.1). What this means is that we need to dequeue and emit finalizations for each entry in the eh_queue until we get to an entry with a NULL finalization field. For any of the finalization entries, if it is not a call to terminate (), we must protect it by giving it another start label, end label, and exception handler label, setting its finalization tree to be a call to terminate (), and enqueue'ing this new eh_entry to be output at an outer level. Finally, after all that is done, we can get around to outputting the catch block which basically wraps all the "catch (...) {...}" statements in a big if/then/else construct that matches the correct block to call. ===================================================================== */ /* local globals for function calls ====================================================================== */ /* Used to cache "terminate" and "__throw_type_match*". */ static tree Terminate, CatchMatch; /* Used to cache __find_first_exception_table_match for throw. */ static tree FirstExceptionMatch; /* Used to cache a call to __unwind_function. */ static tree Unwind; /* ====================================================================== */ /* ========================================================================= */ /* local globals - these local globals are for storing data necessary for generating the exception table and code in the correct order. ========================================================================= */ extern rtx catch_clauses; extern tree const_ptr_type_node; /* ========================================================================= */ /* sets up all the global eh stuff that needs to be initialized at the start of compilation. This includes: - Setting up all the function call trees. */ void init_exception_processing () { /* void vtype () */ tree vtype = build_function_type (void_type_node, void_list_node); if (flag_honor_std) push_namespace (get_identifier ("std")); Terminate = auto_function (get_identifier ("terminate"), vtype, NOT_BUILT_IN); TREE_THIS_VOLATILE (Terminate) = 1; if (flag_honor_std) pop_namespace (); push_lang_context (lang_name_c); set_exception_lang_code (EH_LANG_C_plus_plus); set_exception_version_code (1); CatchMatch = builtin_function (flag_rtti ? "__throw_type_match_rtti" : "__throw_type_match", build_function_type (ptr_type_node, tree_cons (NULL_TREE, const_ptr_type_node, tree_cons (NULL_TREE, const_ptr_type_node, tree_cons (NULL_TREE, ptr_type_node, void_list_node)))), NOT_BUILT_IN, NULL_PTR); FirstExceptionMatch = builtin_function ("__find_first_exception_table_match", build_function_type (ptr_type_node, tree_cons (NULL_TREE, ptr_type_node, void_list_node)), NOT_BUILT_IN, NULL_PTR); Unwind = builtin_function ("__unwind_function", build_function_type (void_type_node, tree_cons (NULL_TREE, ptr_type_node, void_list_node)), NOT_BUILT_IN, NULL_PTR); pop_lang_context (); /* If we use setjmp/longjmp EH, arrange for all cleanup actions to be protected with __terminate. */ protect_cleanup_actions_with_terminate = 1; } /* Retrieve a pointer to the cp_eh_info node for the current exception. */ static tree call_eh_info () { tree fn; fn = get_identifier ("__start_cp_handler"); if (IDENTIFIER_GLOBAL_VALUE (fn)) fn = IDENTIFIER_GLOBAL_VALUE (fn); else { tree t1, t, fields[7]; /* Declare cp_eh_info * __start_cp_handler (void), as defined in exception.cc. */ push_obstacks_nochange (); end_temporary_allocation (); /* struct cp_eh_info. This must match exception.cc. Note that this type is not pushed anywhere. */ t1= make_lang_type (RECORD_TYPE); fields[0] = build_lang_field_decl (FIELD_DECL, get_identifier ("handler_label"), ptr_type_node); fields[1] = build_lang_field_decl (FIELD_DECL, get_identifier ("dynamic_handler_chain"), ptr_type_node); fields[2] = build_lang_field_decl (FIELD_DECL, get_identifier ("info"), ptr_type_node); fields[3] = build_lang_field_decl (FIELD_DECL, get_identifier ("table_index"), ptr_type_node); /* N.B.: The fourth field LEN is expected to be the number of fields - 1, not the total number of fields. */ finish_builtin_type (t1, "eh_context", fields, 3, ptr_type_node); t1 = build_pointer_type (t1); t1= make_lang_type (RECORD_TYPE); fields[0] = build_lang_field_decl (FIELD_DECL, get_identifier ("match_function"), ptr_type_node); fields[1] = build_lang_field_decl (FIELD_DECL, get_identifier ("language"), short_integer_type_node); fields[2] = build_lang_field_decl (FIELD_DECL, get_identifier ("version"), short_integer_type_node); /* N.B.: The fourth field LEN is expected to be the number of fields - 1, not the total number of fields. */ finish_builtin_type (t1, "__eh_info", fields, 2, ptr_type_node); t = make_lang_type (RECORD_TYPE); fields[0] = build_lang_field_decl (FIELD_DECL, get_identifier ("eh_info"), t1); fields[1] = build_lang_field_decl (FIELD_DECL, get_identifier ("value"), ptr_type_node); fields[2] = build_lang_field_decl (FIELD_DECL, get_identifier ("type"), ptr_type_node); fields[3] = build_lang_field_decl (FIELD_DECL, get_identifier ("cleanup"), build_pointer_type (build_function_type (ptr_type_node, tree_cons (NULL_TREE, ptr_type_node, void_list_node)))); fields[4] = build_lang_field_decl (FIELD_DECL, get_identifier ("caught"), boolean_type_node); fields[5] = build_lang_field_decl (FIELD_DECL, get_identifier ("next"), build_pointer_type (t)); fields[6] = build_lang_field_decl (FIELD_DECL, get_identifier ("handlers"), long_integer_type_node); /* N.B.: The fourth field LEN is expected to be the number of fields - 1, not the total number of fields. */ finish_builtin_type (t, "cp_eh_info", fields, 6, ptr_type_node); t = build_pointer_type (t); /* And now the function. */ fn = build_lang_decl (FUNCTION_DECL, fn, build_function_type (t, void_list_node)); DECL_EXTERNAL (fn) = 1; TREE_PUBLIC (fn) = 1; DECL_ARTIFICIAL (fn) = 1; pushdecl_top_level (fn); make_function_rtl (fn); pop_obstacks (); } mark_used (fn); return build_function_call (fn, NULL_TREE); } /* Retrieve a pointer to the cp_eh_info node for the current exception and save it in the current binding level. */ static void push_eh_info () { tree decl, fn = call_eh_info (); /* Remember the pointer to the current exception info; it won't change during this catch block. */ decl = build_decl (VAR_DECL, get_identifier ("__exception_info"), TREE_TYPE (fn)); DECL_ARTIFICIAL (decl) = 1; DECL_INITIAL (decl) = fn; decl = pushdecl (decl); cp_finish_decl (decl, fn, NULL_TREE, 0, 0); } /* Returns a reference to the cp_eh_info node for the current exception. */ static tree get_eh_info () { /* Look for the pointer pushed in push_eh_info. */ tree t = lookup_name (get_identifier ("__exception_info"), 0); return build_indirect_ref (t, NULL_PTR); } /* Returns a reference to the current exception object. */ static tree get_eh_value () { return build_component_ref (get_eh_info (), get_identifier ("value"), NULL_TREE, 0); } /* Returns a reference to the current exception type. */ #if 0 static tree get_eh_type () { return build_component_ref (get_eh_info (), get_identifier ("type"), NULL_TREE, 0); } /* Returns a reference to whether or not the current exception has been caught. */ static tree get_eh_caught () { return build_component_ref (get_eh_info (), get_identifier ("caught"), NULL_TREE, 0); } /* Returns a reference to whether or not the current exception has been caught. */ static tree get_eh_handlers () { return build_component_ref (get_eh_info (), get_identifier ("handlers"), NULL_TREE, 0); } #endif /* Build a type value for use at runtime for a type that is matched against by the exception handling system. */ static tree build_eh_type_type (type) tree type; { const char *typestring; tree exp; if (type == error_mark_node) return error_mark_node; /* peel back references, so they match. */ if (TREE_CODE (type) == REFERENCE_TYPE) type = TREE_TYPE (type); /* Peel off cv qualifiers. */ type = TYPE_MAIN_VARIANT (type); if (flag_rtti) return build1 (ADDR_EXPR, ptr_type_node, get_typeid_1 (type)); typestring = build_overload_name (type, 1, 1); exp = combine_strings (build_string (strlen (typestring)+1, typestring)); return build1 (ADDR_EXPR, ptr_type_node, exp); } /* Build the address of a runtime type for use in the runtime matching field of the new exception model */ static tree build_eh_type_type_ref (type) tree type; { const char *typestring; tree exp; if (type == error_mark_node) return error_mark_node; /* peel back references, so they match. */ if (TREE_CODE (type) == REFERENCE_TYPE) type = TREE_TYPE (type); /* Peel off cv qualifiers. */ type = TYPE_MAIN_VARIANT (type); push_obstacks_nochange (); end_temporary_allocation (); if (flag_rtti) { exp = get_tinfo_fn (type); TREE_USED (exp) = 1; mark_inline_for_output (exp); exp = build1 (ADDR_EXPR, ptr_type_node, exp); } else { typestring = build_overload_name (type, 1, 1); exp = combine_strings (build_string (strlen (typestring)+1, typestring)); exp = build1 (ADDR_EXPR, ptr_type_node, exp); } pop_obstacks (); return (exp); } /* Build a type value for use at runtime for a exp that is thrown or matched against by the exception handling system. */ static tree build_eh_type (exp) tree exp; { if (flag_rtti) { exp = build_typeid (exp); return build1 (ADDR_EXPR, ptr_type_node, exp); } return build_eh_type_type (TREE_TYPE (exp)); } /* This routine is called to mark all the symbols representing runtime type functions in the exception table as haveing been referenced. This will make sure code is emitted for them. Called from finish_file. */ void mark_all_runtime_matches () { int x,num; void **ptr; tree exp; num = find_all_handler_type_matches (&ptr); if (num == 0 || ptr == NULL) return; for (x=0; x