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Diffstat (limited to 'gcc-4.7/gcc/ada/a-exexpr-gcc.adb')
| -rw-r--r-- | gcc-4.7/gcc/ada/a-exexpr-gcc.adb | 527 |
1 files changed, 527 insertions, 0 deletions
diff --git a/gcc-4.7/gcc/ada/a-exexpr-gcc.adb b/gcc-4.7/gcc/ada/a-exexpr-gcc.adb new file mode 100644 index 000000000..6321099b8 --- /dev/null +++ b/gcc-4.7/gcc/ada/a-exexpr-gcc.adb @@ -0,0 +1,527 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- A D A . E X C E P T I O N S . E X C E P T I O N _ P R O P A G A T I O N -- +-- -- +-- B o d y -- +-- -- +-- Copyright (C) 1992-2011, 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- -- +-- ware Foundation; either version 3, or (at your option) any later ver- -- +-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- +-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- +-- or FITNESS FOR A PARTICULAR PURPOSE. -- +-- -- +-- As a special exception under Section 7 of GPL version 3, you are granted -- +-- additional permissions described in the GCC Runtime Library Exception, -- +-- version 3.1, as published by the Free Software Foundation. -- +-- -- +-- You should have received a copy of the GNU General Public License and -- +-- a copy of the GCC Runtime Library Exception along with this program; -- +-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- +-- <http://www.gnu.org/licenses/>. -- +-- -- +-- GNAT was originally developed by the GNAT team at New York University. -- +-- Extensive contributions were provided by Ada Core Technologies Inc. -- +-- -- +------------------------------------------------------------------------------ + +-- This is the version using the GCC EH mechanism + +with Ada.Unchecked_Conversion; +with Ada.Unchecked_Deallocation; + +with System.Storage_Elements; use System.Storage_Elements; + +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 currently + -- 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 new Integer; + pragma Convention (C, Unwind_Action); + + UA_SEARCH_PHASE : constant Unwind_Action := 1; + UA_CLEANUP_PHASE : constant Unwind_Action := 2; + UA_HANDLER_FRAME : constant Unwind_Action := 4; + UA_FORCE_UNWIND : constant Unwind_Action := 8; + UA_END_OF_STACK : constant Unwind_Action := 16; -- GCC extension ? + + pragma Unreferenced + (UA_SEARCH_PHASE, + UA_CLEANUP_PHASE, + UA_HANDLER_FRAME, + UA_FORCE_UNWIND); + + -- Mandatory common header for any exception object handled by the + -- GCC unwinding runtime. + + type Exception_Class is mod 2 ** 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; + Cleanup : System.Address; + Private1 : Unwind_Word; + Private2 : Unwind_Word; + end record; + pragma Convention (C, Unwind_Exception); + -- 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). See additional comments on the + -- alignment below. + + type GCC_Exception_Access is access all Unwind_Exception; + -- Pointer to a GCC exception. Do not use convention C as on VMS this + -- would imply the use of 32-bits pointers. + + procedure Unwind_DeleteException (Excp : not null GCC_Exception_Access); + pragma Import (C, Unwind_DeleteException, "_Unwind_DeleteException"); + -- Procedure to free any GCC exception + + Foreign_Exception : aliased System.Standard_Library.Exception_Data; + pragma Import (Ada, Foreign_Exception, + "system__exceptions__foreign_exception"); + -- Id for foreign exceptions + + -------------------------------------------------------------- + -- 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. + + type GNAT_GCC_Exception is record + Header : Unwind_Exception; + -- ABI Exception header first + + Occurrence : Exception_Occurrence; + -- The Ada occurrence + end record; + + pragma Convention (C, GNAT_GCC_Exception); + + -- There is a subtle issue with the common header alignment, since the C + -- version is aligned on BIGGEST_ALIGNMENT, the Ada version is aligned on + -- Standard'Maximum_Alignment, and those two values don't quite represent + -- the same concepts and so may be decoupled someday. One typical reason + -- is that BIGGEST_ALIGNMENT may be larger than what the underlying system + -- allocator guarantees, and there are extra costs involved in allocating + -- objects aligned to such factors. + + -- To deal with the potential alignment differences between the C and Ada + -- representations, the Ada part of the whole structure is only accessed + -- by the personality routine through the accessors declared below. Ada + -- specific fields are thus always accessed through consistent layout, and + -- we expect the actual alignment to always be large enough to avoid traps + -- from the C accesses to the common header. Besides, accessors alleviate + -- the need for a C struct whole counterpart, both painful and error-prone + -- to maintain anyway. + + type GNAT_GCC_Exception_Access is access all GNAT_GCC_Exception; + + function To_GCC_Exception is new + Unchecked_Conversion (GNAT_GCC_Exception_Access, GCC_Exception_Access); + + function To_GNAT_GCC_Exception is new + Unchecked_Conversion (GCC_Exception_Access, GNAT_GCC_Exception_Access); + + procedure GNAT_GCC_Exception_Cleanup + (Reason : Unwind_Reason_Code; + Excep : not null GNAT_GCC_Exception_Access); + pragma Convention (C, GNAT_GCC_Exception_Cleanup); + -- Procedure called when a GNAT GCC exception is free. + + procedure Propagate_GCC_Exception + (GCC_Exception : not null GCC_Exception_Access); + pragma No_Return (Propagate_GCC_Exception); + -- Propagate a GCC exception + + procedure Reraise_GCC_Exception + (GCC_Exception : not null GCC_Exception_Access); + pragma No_Return (Reraise_GCC_Exception); + pragma Export (C, Reraise_GCC_Exception, "__gnat_reraise_zcx"); + -- Called to implement raise without exception, ie reraise. Called + -- directly from gigi. + + procedure Setup_Current_Excep + (GCC_Exception : not null GCC_Exception_Access); + pragma Export (C, Setup_Current_Excep, "__gnat_setup_current_excep"); + -- Write Get_Current_Excep.all from GCC_Exception + + function CleanupUnwind_Handler + (UW_Version : Integer; + UW_Phases : Unwind_Action; + UW_Eclass : Exception_Class; + UW_Exception : not null GCC_Exception_Access; + 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 : not null GCC_Exception_Access); + pragma Import (C, Unwind_RaiseException, "__gnat_Unwind_RaiseException"); + + procedure Unwind_ForcedUnwind + (UW_Exception : not null GCC_Exception_Access; + UW_Handler : System.Address; + UW_Argument : System.Address); + pragma Import (C, Unwind_ForcedUnwind, "__gnat_Unwind_ForcedUnwind"); + + -- 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 : not null GCC_Exception_Access); + pragma Export (C, Begin_Handler, "__gnat_begin_handler"); + + procedure End_Handler (GCC_Exception : GCC_Exception_Access); + pragma Export (C, End_Handler, "__gnat_end_handler"); + + -------------------------------------------------------------------- + -- Accessors to Basic Components of a GNAT Exception Data Pointer -- + -------------------------------------------------------------------- + + -- As of today, these are only used by the C implementation of the GCC + -- 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"); + pragma Warnings (Off, 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"); + + function EID_For (GNAT_Exception : not null GNAT_GCC_Exception_Access) + return Exception_Id; + pragma Export (C, EID_For, "__gnat_eid_for"); + + --------------------------------------------------------------------------- + -- Objects to materialize "others" and "all others" in the GCC EH tables -- + --------------------------------------------------------------------------- + + -- Currently, these only have their address taken and compared so there is + -- no real point having whole exception data blocks allocated. In any case + -- the types should match what gigi and the personality routine expect. + -- The initial value is an arbitrary value that will not exceed the range + -- of Integer on 16-bit targets (such as AAMP). + + Others_Value : constant Integer := 16#7FFF#; + pragma Export (C, Others_Value, "__gnat_others_value"); + + All_Others_Value : constant Integer := 16#7FFF#; + pragma Export (C, All_Others_Value, "__gnat_all_others_value"); + + -------------------------------- + -- GNAT_GCC_Exception_Cleanup -- + -------------------------------- + + procedure GNAT_GCC_Exception_Cleanup + (Reason : Unwind_Reason_Code; + Excep : not null GNAT_GCC_Exception_Access) + is + pragma Unreferenced (Reason); + + procedure Free is new Unchecked_Deallocation + (GNAT_GCC_Exception, GNAT_GCC_Exception_Access); + + Copy : GNAT_GCC_Exception_Access := Excep; + + begin + -- Simply free the memory + + Free (Copy); + end GNAT_GCC_Exception_Cleanup; + + --------------------------- + -- CleanupUnwind_Handler -- + --------------------------- + + function CleanupUnwind_Handler + (UW_Version : Integer; + UW_Phases : Unwind_Action; + UW_Eclass : Exception_Class; + UW_Exception : not null GCC_Exception_Access; + UW_Context : System.Address; + UW_Argument : System.Address) return Unwind_Reason_Code + is + pragma Unreferenced (UW_Version, UW_Eclass, UW_Context, UW_Argument); + + begin + -- Terminate when the end of the stack is reached + + if UW_Phases >= UA_END_OF_STACK then + Setup_Current_Excep (UW_Exception); + 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 again. + + return URC_NO_REASON; + end CleanupUnwind_Handler; + + ------------------------- + -- Setup_Current_Excep -- + ------------------------- + + procedure Setup_Current_Excep + (GCC_Exception : not null GCC_Exception_Access) + is + Excep : constant EOA := Get_Current_Excep.all; + + begin + -- Setup the exception occurrence + + if GCC_Exception.Class = GNAT_Exception_Class then + + -- From the GCC exception + + declare + GNAT_Occurrence : constant GNAT_GCC_Exception_Access := + To_GNAT_GCC_Exception (GCC_Exception); + begin + Excep.all := GNAT_Occurrence.Occurrence; + end; + else + + -- A default one + + Excep.Id := Foreign_Exception'Access; + Excep.Msg_Length := 0; + Excep.Exception_Raised := True; + Excep.Pid := Local_Partition_ID; + Excep.Num_Tracebacks := 0; + end if; + end Setup_Current_Excep; + + ------------------- + -- Begin_Handler -- + ------------------- + + procedure Begin_Handler (GCC_Exception : not null GCC_Exception_Access) is + pragma Unreferenced (GCC_Exception); + begin + null; + end Begin_Handler; + + ----------------- + -- End_Handler -- + ----------------- + + procedure End_Handler (GCC_Exception : GCC_Exception_Access) is + begin + if GCC_Exception /= null then + + -- The exception might have been reraised, in this case the cleanup + -- mustn't be called. + + Unwind_DeleteException (GCC_Exception); + end if; + end End_Handler; + + ----------------------------- + -- Reraise_GCC_Exception -- + ----------------------------- + + procedure Reraise_GCC_Exception + (GCC_Exception : not null GCC_Exception_Access) + is + begin + -- Simply propagate it + Propagate_GCC_Exception (GCC_Exception); + end Reraise_GCC_Exception; + + ----------------------------- + -- Propagate_GCC_Exception -- + ----------------------------- + + -- Call Unwind_RaiseException to actually throw, taking care of handling + -- the two phase scheme it implements. + + procedure Propagate_GCC_Exception + (GCC_Exception : not null GCC_Exception_Access) + is + begin + -- 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, it will return. + + Unwind_RaiseException (GCC_Exception); + + -- 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. + + Setup_Current_Excep (GCC_Exception); + Notify_Unhandled_Exception; + + -- Now, un a forced unwind to trigger cleanups. Control should not + -- resume there, if there are cleanups and in any cases as the + -- unwinding hook calls Unhandled_Exception_Terminate when end of + -- stack is reached. + + Unwind_ForcedUnwind (GCC_Exception, + CleanupUnwind_Handler'Address, + System.Null_Address); + + -- We get here in case of error. The debugger has been notified before + -- the second step above. + + Setup_Current_Excep (GCC_Exception); + Unhandled_Exception_Terminate; + end Propagate_GCC_Exception; + + ------------------------- + -- Propagate_Exception -- + ------------------------- + + -- Build an object suitable for the libgcc processing and call + -- Unwind_RaiseException to actually do the raise, taking care of + -- handling the two phase scheme it implements. + + procedure Propagate_Exception is + Excep : constant EOA := Get_Current_Excep.all; + GCC_Exception : GNAT_GCC_Exception_Access; + + begin + -- Compute the backtrace for this occurrence if the corresponding + -- binder option has been set. Call_Chain takes care of the reraise + -- case. + + -- ??? 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. + + -- 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: + + -- 1) the trace is incomplete if the exception is handled since we + -- don't walk past the frame with the handler, + + -- and + + -- 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. + + Call_Chain (Excep); + + -- Allocate the GCC exception + + GCC_Exception := + new GNAT_GCC_Exception' + (Header => (Class => GNAT_Exception_Class, + Cleanup => GNAT_GCC_Exception_Cleanup'Address, + Private1 => 0, + Private2 => 0), + Occurrence => Excep.all); + + -- Propagate it + + Propagate_GCC_Exception (To_GCC_Exception (GCC_Exception)); + end Propagate_Exception; + + ------------- + -- EID_For -- + ------------- + + function EID_For + (GNAT_Exception : not null GNAT_GCC_Exception_Access) return Exception_Id + is + begin + return GNAT_Exception.Occurrence.Id; + end EID_For; + + --------------------- + -- 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; + +end Exception_Propagation; |