X-Git-Url: http://git.sourceforge.jp/view?a=blobdiff_plain;f=gcc%2Fada%2Fa-exexpr.adb;h=165b5cef3d812121f40e69eae3b129d6fea561d2;hb=c9d3640b2e9c6c5c8bb6925bad72408c4a3039fb;hp=0d0eb09475942ba7dbc0115300089d538fe6693f;hpb=a2877a77c08f7fb1c23523d10f44c1ff6093160f;p=pf3gnuchains%2Fgcc-fork.git diff --git a/gcc/ada/a-exexpr.adb b/gcc/ada/a-exexpr.adb index 0d0eb094759..165b5cef3d8 100644 --- a/gcc/ada/a-exexpr.adb +++ b/gcc/ada/a-exexpr.adb @@ -6,7 +6,7 @@ -- -- -- B o d y -- -- -- --- Copyright (C) 1992-2004 Free Software Foundation, Inc. -- +-- Copyright (C) 1992-2005 Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- @@ -16,8 +16,8 @@ -- 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 distributed with GNAT; see file COPYING. If not, write -- --- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- --- MA 02111-1307, USA. -- +-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- +-- Boston, MA 02110-1301, USA. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- @@ -31,10 +31,8 @@ -- -- ------------------------------------------------------------------------------ -with Interfaces; - -with Ada.Unchecked_Conversion; -with Ada.Unchecked_Deallocation; +-- This is the default version, using the __builtin_setjmp/longjmp EH +-- mechanism. with System.Storage_Elements; use System.Storage_Elements; @@ -45,608 +43,80 @@ pragma Warnings (Off); separate (Ada.Exceptions) package body Exception_Propagation is - ------------------------------------------------ - -- Entities to interface with the GCC runtime -- - ------------------------------------------------ - - -- These come from "C++ ABI for Itanium: Exception handling", which is - -- the reference for GCC. They are used only when we are relying on - -- back-end tables for exception propagation, which in turn is currenly - -- only the case for Zero_Cost_Exceptions in GNAT5. - - -- Return codes from the GCC runtime functions used to propagate - -- an exception. - - type Unwind_Reason_Code is - (URC_NO_REASON, - URC_FOREIGN_EXCEPTION_CAUGHT, - URC_PHASE2_ERROR, - URC_PHASE1_ERROR, - URC_NORMAL_STOP, - URC_END_OF_STACK, - URC_HANDLER_FOUND, - URC_INSTALL_CONTEXT, - URC_CONTINUE_UNWIND); - - pragma Unreferenced - (URC_FOREIGN_EXCEPTION_CAUGHT, - URC_PHASE2_ERROR, - URC_PHASE1_ERROR, - URC_NORMAL_STOP, - URC_END_OF_STACK, - URC_HANDLER_FOUND, - URC_INSTALL_CONTEXT, - URC_CONTINUE_UNWIND); - - pragma Convention (C, Unwind_Reason_Code); - - -- Phase identifiers - - type Unwind_Action is - (UA_SEARCH_PHASE, - UA_CLEANUP_PHASE, - UA_HANDLER_FRAME, - UA_FORCE_UNWIND); - - for Unwind_Action use - (UA_SEARCH_PHASE => 1, - UA_CLEANUP_PHASE => 2, - UA_HANDLER_FRAME => 4, - UA_FORCE_UNWIND => 8); - - pragma Convention (C, Unwind_Action); - - -- Mandatory common header for any exception object handled by the - -- GCC unwinding runtime. - - subtype Exception_Class is Interfaces.Unsigned_64; - - GNAT_Exception_Class : constant Exception_Class := 16#474e552d41646100#; - -- "GNU-Ada\0" - - type Unwind_Word is mod 2 ** System.Word_Size; - for Unwind_Word'Size use System.Word_Size; - -- Map the corresponding C type used in Unwind_Exception below. - - type Unwind_Exception is record - Class : Exception_Class := GNAT_Exception_Class; - Cleanup : System.Address := System.Null_Address; - Private1 : Unwind_Word; - Private2 : Unwind_Word; - end record; - -- Map the GCC struct used for exception handling. - - for Unwind_Exception'Alignment use Standard'Maximum_Alignment; - -- The C++ ABI mandates the common exception header to be at least - -- doubleword aligned, and the libGCC implementation actually makes it - -- maximally aligned (see unwind.h). We need to match this because: - - -- 1/ We pass pointers to such headers down to the underlying - -- libGCC unwinder, - - -- and - - -- 2/ The GNAT_GCC_Exception record below starts with this common - -- common header and has a C counterpart which needs to be laid - -- out identically in raise.c. If the alignment of the C and Ada - -- common headers mismatch, their size may also differ, and the - -- layouts may not match anymore. - - --------------------------------------------------------------- - -- GNAT specific entities to deal with the GCC eh circuitry -- - --------------------------------------------------------------- - - -- A GNAT exception object to be dealt with by the personality routine - -- called by the GCC unwinding runtime. This structure shall match the - -- one in raise.c and is currently experimental as it might be merged - -- with the GNAT runtime definition some day. - - type GNAT_GCC_Exception is record - Header : Unwind_Exception; - -- ABI Exception header first. - - Id : Exception_Id; - -- GNAT Exception identifier. This is used by the personality - -- routine to determine if the context it examines contains a - -- handler for the exception beeing propagated. - - N_Cleanups_To_Trigger : Integer; - -- Number of cleanup only frames encountered in SEARCH phase. - -- This is used to control the forced unwinding triggered when - -- no handler has been found. - - Next_Exception : EOA; - -- Used to create a linked list of exception occurrences. - end record; - - pragma Convention (C, GNAT_GCC_Exception); - - type GNAT_GCC_Exception_Access is access all GNAT_GCC_Exception; - - function To_GNAT_GCC_Exception is new - Unchecked_Conversion (System.Address, GNAT_GCC_Exception_Access); - - procedure Free is new Unchecked_Deallocation - (GNAT_GCC_Exception, GNAT_GCC_Exception_Access); - - procedure Free is new Unchecked_Deallocation - (Exception_Occurrence, EOA); - - function CleanupUnwind_Handler - (UW_Version : Integer; - UW_Phases : Unwind_Action; - UW_Eclass : Exception_Class; - UW_Exception : access GNAT_GCC_Exception; - UW_Context : System.Address; - UW_Argument : System.Address) return Unwind_Reason_Code; - -- Hook called at each step of the forced unwinding we perform to - -- trigger cleanups found during the propagation of an unhandled - -- exception. - - -- GCC runtime functions used. These are C non-void functions, actually, - -- but we ignore the return values. See raise.c as to why we are using - -- __gnat stubs for these. - - procedure Unwind_RaiseException - (UW_Exception : access GNAT_GCC_Exception); - pragma Import (C, Unwind_RaiseException, "__gnat_Unwind_RaiseException"); - - procedure Unwind_ForcedUnwind - (UW_Exception : access GNAT_GCC_Exception; - UW_Handler : System.Address; - UW_Argument : System.Address); - pragma Import (C, Unwind_ForcedUnwind, "__gnat_Unwind_ForcedUnwind"); - - -------------------------------------------- - -- Occurrence stack management facilities -- - -------------------------------------------- - - function Remove - (Top : EOA; - Excep : GNAT_GCC_Exception_Access) return Boolean; - -- Remove Excep from the stack starting at Top. - -- Return True if Excep was found and removed, false otherwise. - - -- Hooks called when entering/leaving an exception handler for a given - -- occurrence, aimed at handling the stack of active occurrences. The - -- calls are generated by gigi in tree_transform/N_Exception_Handler. - - procedure Begin_Handler (GCC_Exception : GNAT_GCC_Exception_Access); - pragma Export (C, Begin_Handler, "__gnat_begin_handler"); - - procedure End_Handler (GCC_Exception : GNAT_GCC_Exception_Access); - pragma Export (C, End_Handler, "__gnat_end_handler"); - - -- To handle the case of a task "transferring" an exception occurrence to - -- another task, for instance via Exceptional_Complete_Rendezvous, we need - -- to be able to identify occurrences which have been Setup and not yet - -- Propagated. We hijack one of the common header fields for that purpose, - -- setting it to a special key value during the setup process, clearing it - -- at the very beginning of the propagation phase, and expecting it never - -- to be reset to the special value later on. - - Setup_Key : constant := 16#DEAD_BEEF#; - - function Is_Setup_And_Not_Propagated (E : EOA) return Boolean; - - procedure Set_Setup_And_Not_Propagated (E : EOA); - procedure Clear_Setup_And_Not_Propagated (E : EOA); - - ------------------------------------------------------------ - -- Accessors to basic components of a GNAT exception data -- - ------------------------------------------------------------ - - -- As of today, these are only used by the C implementation of the - -- propagation personality routine to avoid having to rely on a C - -- counterpart of the whole exception_data structure, which is both - -- painful and error prone. These subprograms could be moved to a - -- more widely visible location if need be. - - function Is_Handled_By_Others (E : Exception_Data_Ptr) return Boolean; - pragma Export (C, Is_Handled_By_Others, "__gnat_is_handled_by_others"); - - function Language_For (E : Exception_Data_Ptr) return Character; - pragma Export (C, Language_For, "__gnat_language_for"); - - function Import_Code_For (E : Exception_Data_Ptr) return Exception_Code; - pragma Export (C, Import_Code_For, "__gnat_import_code_for"); - - ------------ - -- Remove -- - ------------ - - function Remove - (Top : EOA; - Excep : GNAT_GCC_Exception_Access) return Boolean - is - Prev : GNAT_GCC_Exception_Access := null; - Iter : EOA := Top; - GCC_Exception : GNAT_GCC_Exception_Access; - - begin - -- Pop stack - - loop - pragma Assert (Iter.Private_Data /= System.Null_Address); - - GCC_Exception := To_GNAT_GCC_Exception (Iter.Private_Data); - - if GCC_Exception = Excep then - if Prev = null then - - -- Special case for the top of the stack: shift the contents - -- of the next item to the top, since top is at a fixed - -- location and can't be changed. - - Iter := GCC_Exception.Next_Exception; - - if Iter = null then - - -- Stack is now empty - - Top.Private_Data := System.Null_Address; - - else - Save_Occurrence_And_Private (Top.all, Iter.all); - Free (Iter); - end if; - - else - Prev.Next_Exception := GCC_Exception.Next_Exception; - Free (Iter); - end if; - - Free (GCC_Exception); - - return True; - end if; - - exit when GCC_Exception.Next_Exception = null; - - Prev := GCC_Exception; - Iter := GCC_Exception.Next_Exception; - end loop; - - return False; - end Remove; - - --------------------------- - -- CleanupUnwind_Handler -- - --------------------------- - - function CleanupUnwind_Handler - (UW_Version : Integer; - UW_Phases : Unwind_Action; - UW_Eclass : Exception_Class; - UW_Exception : access GNAT_GCC_Exception; - UW_Context : System.Address; - UW_Argument : System.Address) return Unwind_Reason_Code - is - begin - -- Terminate as soon as we know there is nothing more to run. The - -- count is maintained by the personality routine. - - if UW_Exception.N_Cleanups_To_Trigger = 0 then - Unhandled_Exception_Terminate; - end if; - - -- We know there is at least one cleanup further up. Return so that it - -- is searched and entered, after which Unwind_Resume will be called - -- and this hook will gain control (with an updated count) again. - - return URC_NO_REASON; - end CleanupUnwind_Handler; - - --------------------------------- - -- Is_Setup_And_Not_Propagated -- - --------------------------------- - - function Is_Setup_And_Not_Propagated (E : EOA) return Boolean is - GCC_E : GNAT_GCC_Exception_Access := - To_GNAT_GCC_Exception (E.Private_Data); - begin - return GCC_E /= null and then GCC_E.Header.Private1 = Setup_Key; - end Is_Setup_And_Not_Propagated; - - ------------------------------------ - -- Clear_Setup_And_Not_Propagated -- - ------------------------------------ - - procedure Clear_Setup_And_Not_Propagated (E : EOA) is - GCC_E : GNAT_GCC_Exception_Access := - To_GNAT_GCC_Exception (E.Private_Data); - begin - pragma Assert (GCC_E /= null); - GCC_E.Header.Private1 := 0; - end Clear_Setup_And_Not_Propagated; - - ---------------------------------- - -- Set_Setup_And_Not_Propagated -- - ---------------------------------- - - procedure Set_Setup_And_Not_Propagated (E : EOA) is - GCC_E : GNAT_GCC_Exception_Access := - To_GNAT_GCC_Exception (E.Private_Data); - begin - pragma Assert (GCC_E /= null); - GCC_E.Header.Private1 := Setup_Key; - end Set_Setup_And_Not_Propagated; + procedure builtin_longjmp (buffer : Address; Flag : Integer); + pragma No_Return (builtin_longjmp); + pragma Import (C, builtin_longjmp, "_gnat_builtin_longjmp"); --------------------- -- Setup_Exception -- --------------------- - -- In this implementation of the exception propagation scheme, this - -- subprogram should be understood as: Setup the exception occurrence - -- stack headed at Current for a forthcoming raise of Excep. - procedure Setup_Exception (Excep : EOA; Current : EOA; Reraised : Boolean := False) is - Top : constant EOA := Current; - Next : EOA; - GCC_Exception : GNAT_GCC_Exception_Access; - + pragma Unreferenced (Excep, Current, Reraised); begin + -- In the GNAT-SJLJ case this "stack" only exists implicitely, by way of + -- local occurrence declarations together with save/restore operations + -- generated by the front-end, and this routine has nothing to do. - -- The exception Excep is soon to be propagated, and the storage used - -- for that will be the occurrence statically allocated for the current - -- thread. This storage might currently be used for a still active - -- occurrence, so we need to push it on the thread's occurrence stack - -- (headed at that static occurrence) before it gets clobbered. - - -- What we do here is to trigger this push when need be, and allocate a - -- Private_Data block for the forthcoming Propagation. - - -- Some tasking rendez-vous attempts lead to an occurrence transfer - -- from the server to the client (see Exceptional_Complete_Rendezvous). - -- In those cases Setup is called twice for the very same occurrence - -- before it gets propagated: once from the server, because this is - -- where the occurrence contents is elaborated and known, and then - -- once from the client when it detects the case and actually raises - -- the exception in its own context. - - -- The Is_Setup_And_Not_Propagated predicate tells us when we are in - -- the second call to Setup for a Transferred occurrence, and there is - -- nothing to be done here in this situation. This predicate cannot be - -- True if we are dealing with a Reraise, and we may even be called - -- with a raw uninitialized Excep occurrence in this case so we should - -- not check anyway. Observe the front-end expansion for a "raise;" to - -- see that happening. We get a local occurrence and a direct call to - -- Save_Occurrence without the intermediate init-proc call. - - if not Reraised and then Is_Setup_And_Not_Propagated (Excep) then - return; - end if; - - -- Allocate what will be the Private_Data block for the exception - -- to be propagated. - - GCC_Exception := new GNAT_GCC_Exception; - - -- If the Top of the occurrence stack is not currently used for an - -- active exception (the stack is empty) we just need to setup the - -- Private_Data pointer. - - -- Otherwise, we also need to shift the contents of the Top of the - -- stack in a freshly allocated entry and link everything together. - - if Top.Private_Data /= System.Null_Address then - Next := new Exception_Occurrence; - Save_Occurrence_And_Private (Next.all, Top.all); - - GCC_Exception.Next_Exception := Next; - Top.Private_Data := GCC_Exception.all'Address; - end if; - - Top.Private_Data := GCC_Exception.all'Address; - - Set_Setup_And_Not_Propagated (Top); - - end Setup_Exception; - - ------------------- - -- Begin_Handler -- - ------------------- - - procedure Begin_Handler (GCC_Exception : GNAT_GCC_Exception_Access) is - begin - -- Every necessary operation related to the occurrence stack has - -- already been performed by Propagate_Exception. This hook remains for - -- potential future necessity in optimizing the overall scheme, as well - -- a useful debugging tool. null; - end Begin_Handler; - - ----------------- - -- End_Handler -- - ----------------- - - procedure End_Handler (GCC_Exception : GNAT_GCC_Exception_Access) is - Removed : Boolean; - - begin - Removed := Remove (Get_Current_Excep.all, GCC_Exception); - pragma Assert (Removed); - end End_Handler; + end Setup_Exception; ------------------------- -- Propagate_Exception -- ------------------------- - -- Build an object suitable for the libgcc processing and call - -- Unwind_RaiseException to actually throw, taking care of handling - -- the two phase scheme it implements. - procedure Propagate_Exception (From_Signal_Handler : Boolean) is - Excep : EOA := Get_Current_Excep.all; - GCC_Exception : GNAT_GCC_Exception_Access; - + Jumpbuf_Ptr : constant Address := Get_Jmpbuf_Address.all; + Excep : constant EOA := Get_Current_Excep.all; begin - pragma Assert (Excep.Private_Data /= System.Null_Address); - - -- Retrieve the Private_Data for this occurrence and set the useful - -- flags for the personality routine, which will be called for each - -- frame via Unwind_RaiseException below. - - GCC_Exception := To_GNAT_GCC_Exception (Excep.Private_Data); - - Clear_Setup_And_Not_Propagated (Excep); - - GCC_Exception.Id := Excep.Id; - GCC_Exception.N_Cleanups_To_Trigger := 0; + -- Compute the backtrace for this occurrence if corresponding binder + -- option has been set. Call_Chain takes care of the reraise case. - -- Compute the backtrace for this occurrence if the corresponding - -- binder option has been set. Call_Chain takes care of the reraise - -- case. + Call_Chain (Excep); - -- ??? Using Call_Chain here means we are going to walk up the stack - -- once only for backtracing purposes before doing it again for the - -- propagation per se. + -- Note on above call to Call_Chain: - -- The first inspection is much lighter, though, as it only requires - -- partial unwinding of each frame. Additionally, although we could use - -- the personality routine to record the addresses while propagating, - -- this method has two drawbacks: + -- We used to only do this if From_Signal_Handler was not set, + -- based on the assumption that backtracing from a signal handler + -- would not work due to stack layout oddities. However, since - -- 1) the trace is incomplete if the exception is handled since we - -- don't walk past the frame with the handler, + -- 1. The flag is never set in tasking programs (Notify_Exception + -- performs regular raise statements), and - -- and + -- 2. No problem has shown up in tasking programs around here so + -- far, this turned out to be too strong an assumption. - -- 2) we would miss the frames for which our personality routine is not - -- called, e.g. if C or C++ calls are on the way. + -- As, in addition, the test was - Call_Chain (Excep); + -- 1. preventing the production of backtraces in non-tasking + -- programs, and - -- Perform a standard raise first. If a regular handler is found, it - -- will be entered after all the intermediate cleanups have run. If - -- there is no regular handler, control will get back to after the - -- call, with N_Cleanups_To_Trigger set to the number of frames with - -- cleanups found on the way up, and none of these already run. + -- 2. introducing a behavior inconsistency between + -- the tasking and non-tasking cases, - Unwind_RaiseException (GCC_Exception); + -- we have simply removed it - -- If we get here we know the exception is not handled, as otherwise - -- Unwind_RaiseException arranges for the handler to be entered. Take - -- the necessary steps to enable the debugger to gain control while the - -- stack is still intact. + -- If the jump buffer pointer is non-null, transfer control using + -- it. Otherwise announce an unhandled exception (note that this + -- means that we have no finalizations to do other than at the outer + -- level). Perform the necessary notification tasks in both cases. - Notify_Unhandled_Exception; + if Jumpbuf_Ptr /= Null_Address then + if not Excep.Exception_Raised then + Excep.Exception_Raised := True; + Exception_Traces.Notify_Handled_Exception; + end if; - -- Now, if cleanups have been found, run a forced unwind to trigger - -- them. Control should not resume there, as the unwinding hook calls - -- Unhandled_Exception_Terminate as soon as the last cleanup has been - -- triggered. + builtin_longjmp (Jumpbuf_Ptr, 1); - if GCC_Exception.N_Cleanups_To_Trigger /= 0 then - Unwind_ForcedUnwind (GCC_Exception, - CleanupUnwind_Handler'Address, - System.Null_Address); + else + Exception_Traces.Notify_Unhandled_Exception; + Exception_Traces.Unhandled_Exception_Terminate; end if; - - -- We get here when there is no handler or cleanup to be run at - -- all. The debugger has been notified before the second step above. - - Unhandled_Exception_Terminate; end Propagate_Exception; - --------------------- - -- Import_Code_For -- - --------------------- - - function Import_Code_For - (E : SSL.Exception_Data_Ptr) return Exception_Code - is - begin - return E.all.Import_Code; - end Import_Code_For; - - -------------------------- - -- Is_Handled_By_Others -- - -------------------------- - - function Is_Handled_By_Others - (E : SSL.Exception_Data_Ptr) return Boolean - is - begin - return not E.all.Not_Handled_By_Others; - end Is_Handled_By_Others; - - ------------------ - -- Language_For -- - ------------------ - - function Language_For - (E : SSL.Exception_Data_Ptr) return Character - is - begin - return E.all.Lang; - end Language_For; - - ----------- - -- Notes -- - ----------- - - -- The current model implemented for the stack of occurrences is a - -- simplification of previous attempts, which all prooved to be flawed or - -- would have needed significant additional circuitry to be made to work - -- correctly. - - -- We now represent every propagation by a new entry on the stack, which - -- means that an exception occurrence may appear more than once (e.g. when - -- it is reraised during the course of its own handler). - - -- This may seem overcostly compared to the C++ model as implemented in - -- the g++ v3 libstd. This is actually understandable when one considers - -- the extra variations of possible run-time configurations induced by the - -- freedom offered by the Save_Occurrence/Reraise_Occurrence public - -- interface. - - -- The basic point is that arranging for an occurrence to always appear at - -- most once on the stack requires a way to determine if a given occurence - -- is already there, which is not as easy as it might seem. - - -- An attempt was made to use the Private_Data pointer for this purpose. - -- It did not work because: - - -- 1/ The Private_Data has to be saved by Save_Occurrence to be usable - -- as a key in case of a later reraise, - - -- 2/ There is no easy way to synchronize End_Handler for an occurrence - -- and the data attached to potential copies, so these copies may end - -- up pointing to stale data. Moreover ... - - -- 3/ The same address may be reused for different occurrences, which - -- defeats the idea of using it as a key. - - -- The example below illustrates: - - -- Saved_CE : Exception_Occurrence; - -- - -- begin - -- raise Constraint_Error; - -- exception - -- when CE: others => - -- Save_Occurrence (Saved_CE, CE); <= Saved_CE.PDA = CE.PDA - -- end; - -- - -- <= Saved_CE.PDA is stale (!) - -- - -- begin - -- raise Program_Error; <= Saved_CE.PDA = PE.PDA (!!) - -- exception - -- when others => - -- Reraise_Occurrence (Saved_CE); - -- end; - - -- Not releasing the Private_Data via End_Handler could be an option, - -- but making this to work while still avoiding memory leaks is far - -- from trivial. - - -- The current scheme has the advantage of beeing simple, and induces - -- extra costs only in reraise cases which is acceptable. - end Exception_Propagation;