2695 lines
82 KiB
C
2695 lines
82 KiB
C
/* Implements exception handling.
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Copyright (C) 1989, 92-97, 1998 Free Software Foundation, Inc.
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Contributed by Mike Stump <mrs@cygnus.com>.
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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/* An exception is an event that can be signaled from within a
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function. This event can then be "caught" or "trapped" by the
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callers of this function. This potentially allows program flow to
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be transferred to any arbitrary code associated with a function call
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several levels up the stack.
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The intended use for this mechanism is for signaling "exceptional
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events" in an out-of-band fashion, hence its name. The C++ language
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(and many other OO-styled or functional languages) practically
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requires such a mechanism, as otherwise it becomes very difficult
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or even impossible to signal failure conditions in complex
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situations. The traditional C++ example is when an error occurs in
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the process of constructing an object; without such a mechanism, it
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is impossible to signal that the error occurs without adding global
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state variables and error checks around every object construction.
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The act of causing this event to occur is referred to as "throwing
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an exception". (Alternate terms include "raising an exception" or
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"signaling an exception".) The term "throw" is used because control
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is returned to the callers of the function that is signaling the
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exception, and thus there is the concept of "throwing" the
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exception up the call stack.
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There are two major codegen options for exception handling. The
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flag -fsjlj-exceptions can be used to select the setjmp/longjmp
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approach, which is the default. -fno-sjlj-exceptions can be used to
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get the PC range table approach. While this is a compile time
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flag, an entire application must be compiled with the same codegen
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option. The first is a PC range table approach, the second is a
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setjmp/longjmp based scheme. We will first discuss the PC range
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table approach, after that, we will discuss the setjmp/longjmp
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based approach.
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It is appropriate to speak of the "context of a throw". This
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context refers to the address where the exception is thrown from,
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and is used to determine which exception region will handle the
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exception.
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Regions of code within a function can be marked such that if it
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contains the context of a throw, control will be passed to a
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designated "exception handler". These areas are known as "exception
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regions". Exception regions cannot overlap, but they can be nested
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to any arbitrary depth. Also, exception regions cannot cross
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function boundaries.
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Exception handlers can either be specified by the user (which we
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will call a "user-defined handler") or generated by the compiler
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(which we will designate as a "cleanup"). Cleanups are used to
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perform tasks such as destruction of objects allocated on the
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stack.
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In the current implementation, cleanups are handled by allocating an
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exception region for the area that the cleanup is designated for,
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and the handler for the region performs the cleanup and then
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rethrows the exception to the outer exception region. From the
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standpoint of the current implementation, there is little
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distinction made between a cleanup and a user-defined handler, and
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the phrase "exception handler" can be used to refer to either one
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equally well. (The section "Future Directions" below discusses how
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this will change).
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Each object file that is compiled with exception handling contains
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a static array of exception handlers named __EXCEPTION_TABLE__.
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Each entry contains the starting and ending addresses of the
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exception region, and the address of the handler designated for
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that region.
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If the target does not use the DWARF 2 frame unwind information, at
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program startup each object file invokes a function named
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__register_exceptions with the address of its local
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__EXCEPTION_TABLE__. __register_exceptions is defined in libgcc2.c, and
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is responsible for recording all of the exception regions into one list
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(which is kept in a static variable named exception_table_list).
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On targets that support crtstuff.c, the unwind information
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is stored in a section named .eh_frame and the information for the
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entire shared object or program is registered with a call to
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__register_frame_info. On other targets, the information for each
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translation unit is registered from the file generated by collect2.
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__register_frame_info is defined in frame.c, and is responsible for
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recording all of the unwind regions into one list (which is kept in a
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static variable named unwind_table_list).
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The function __throw is actually responsible for doing the
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throw. On machines that have unwind info support, __throw is generated
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by code in libgcc2.c, otherwise __throw is generated on a
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per-object-file basis for each source file compiled with
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-fexceptions by the C++ frontend. Before __throw is invoked,
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the current context of the throw needs to be placed in the global
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variable __eh_pc.
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__throw attempts to find the appropriate exception handler for the
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PC value stored in __eh_pc by calling __find_first_exception_table_match
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(which is defined in libgcc2.c). If __find_first_exception_table_match
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finds a relevant handler, __throw transfers control directly to it.
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If a handler for the context being thrown from can't be found, __throw
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walks (see Walking the stack below) the stack up the dynamic call chain to
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continue searching for an appropriate exception handler based upon the
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caller of the function it last sought a exception handler for. It stops
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then either an exception handler is found, or when the top of the
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call chain is reached.
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If no handler is found, an external library function named
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__terminate is called. If a handler is found, then we restart
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our search for a handler at the end of the call chain, and repeat
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the search process, but instead of just walking up the call chain,
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we unwind the call chain as we walk up it.
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Internal implementation details:
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To associate a user-defined handler with a block of statements, the
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function expand_start_try_stmts is used to mark the start of the
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block of statements with which the handler is to be associated
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(which is known as a "try block"). All statements that appear
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afterwards will be associated with the try block.
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A call to expand_start_all_catch marks the end of the try block,
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and also marks the start of the "catch block" (the user-defined
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handler) associated with the try block.
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This user-defined handler will be invoked for *every* exception
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thrown with the context of the try block. It is up to the handler
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to decide whether or not it wishes to handle any given exception,
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as there is currently no mechanism in this implementation for doing
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this. (There are plans for conditionally processing an exception
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based on its "type", which will provide a language-independent
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mechanism).
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If the handler chooses not to process the exception (perhaps by
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looking at an "exception type" or some other additional data
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supplied with the exception), it can fall through to the end of the
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handler. expand_end_all_catch and expand_leftover_cleanups
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add additional code to the end of each handler to take care of
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rethrowing to the outer exception handler.
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The handler also has the option to continue with "normal flow of
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code", or in other words to resume executing at the statement
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immediately after the end of the exception region. The variable
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caught_return_label_stack contains a stack of labels, and jumping
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to the topmost entry's label via expand_goto will resume normal
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flow to the statement immediately after the end of the exception
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region. If the handler falls through to the end, the exception will
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be rethrown to the outer exception region.
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The instructions for the catch block are kept as a separate
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sequence, and will be emitted at the end of the function along with
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the handlers specified via expand_eh_region_end. The end of the
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catch block is marked with expand_end_all_catch.
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Any data associated with the exception must currently be handled by
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some external mechanism maintained in the frontend. For example,
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the C++ exception mechanism passes an arbitrary value along with
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the exception, and this is handled in the C++ frontend by using a
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global variable to hold the value. (This will be changing in the
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future.)
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The mechanism in C++ for handling data associated with the
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exception is clearly not thread-safe. For a thread-based
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environment, another mechanism must be used (possibly using a
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per-thread allocation mechanism if the size of the area that needs
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to be allocated isn't known at compile time.)
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Internally-generated exception regions (cleanups) are marked by
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calling expand_eh_region_start to mark the start of the region,
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and expand_eh_region_end (handler) is used to both designate the
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end of the region and to associate a specified handler/cleanup with
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the region. The rtl code in HANDLER will be invoked whenever an
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exception occurs in the region between the calls to
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expand_eh_region_start and expand_eh_region_end. After HANDLER is
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executed, additional code is emitted to handle rethrowing the
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exception to the outer exception handler. The code for HANDLER will
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be emitted at the end of the function.
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TARGET_EXPRs can also be used to designate exception regions. A
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TARGET_EXPR gives an unwind-protect style interface commonly used
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in functional languages such as LISP. The associated expression is
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evaluated, and whether or not it (or any of the functions that it
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calls) throws an exception, the protect expression is always
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invoked. This implementation takes care of the details of
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associating an exception table entry with the expression and
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generating the necessary code (it actually emits the protect
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expression twice, once for normal flow and once for the exception
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case). As for the other handlers, the code for the exception case
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will be emitted at the end of the function.
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Cleanups can also be specified by using add_partial_entry (handler)
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and end_protect_partials. add_partial_entry creates the start of
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a new exception region; HANDLER will be invoked if an exception is
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thrown with the context of the region between the calls to
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add_partial_entry and end_protect_partials. end_protect_partials is
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used to mark the end of these regions. add_partial_entry can be
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called as many times as needed before calling end_protect_partials.
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However, end_protect_partials should only be invoked once for each
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group of calls to add_partial_entry as the entries are queued
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and all of the outstanding entries are processed simultaneously
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when end_protect_partials is invoked. Similarly to the other
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handlers, the code for HANDLER will be emitted at the end of the
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function.
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The generated RTL for an exception region includes
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NOTE_INSN_EH_REGION_BEG and NOTE_INSN_EH_REGION_END notes that mark
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the start and end of the exception region. A unique label is also
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generated at the start of the exception region, which is available
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by looking at the ehstack variable. The topmost entry corresponds
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to the current region.
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In the current implementation, an exception can only be thrown from
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a function call (since the mechanism used to actually throw an
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exception involves calling __throw). If an exception region is
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created but no function calls occur within that region, the region
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can be safely optimized away (along with its exception handlers)
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since no exceptions can ever be caught in that region. This
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optimization is performed unless -fasynchronous-exceptions is
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given. If the user wishes to throw from a signal handler, or other
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asynchronous place, -fasynchronous-exceptions should be used when
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compiling for maximally correct code, at the cost of additional
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exception regions. Using -fasynchronous-exceptions only produces
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code that is reasonably safe in such situations, but a correct
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program cannot rely upon this working. It can be used in failsafe
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code, where trying to continue on, and proceeding with potentially
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incorrect results is better than halting the program.
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Walking the stack:
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The stack is walked by starting with a pointer to the current
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frame, and finding the pointer to the callers frame. The unwind info
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tells __throw how to find it.
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Unwinding the stack:
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When we use the term unwinding the stack, we mean undoing the
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effects of the function prologue in a controlled fashion so that we
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still have the flow of control. Otherwise, we could just return
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(jump to the normal end of function epilogue).
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This is done in __throw in libgcc2.c when we know that a handler exists
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in a frame higher up the call stack than its immediate caller.
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To unwind, we find the unwind data associated with the frame, if any.
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If we don't find any, we call the library routine __terminate. If we do
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find it, we use the information to copy the saved register values from
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that frame into the register save area in the frame for __throw, return
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into a stub which updates the stack pointer, and jump to the handler.
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The normal function epilogue for __throw handles restoring the saved
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values into registers.
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When unwinding, we use this method if we know it will
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work (if DWARF2_UNWIND_INFO is defined). Otherwise, we know that
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an inline unwinder will have been emitted for any function that
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__unwind_function cannot unwind. The inline unwinder appears as a
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normal exception handler for the entire function, for any function
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that we know cannot be unwound by __unwind_function. We inform the
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compiler of whether a function can be unwound with
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__unwind_function by having DOESNT_NEED_UNWINDER evaluate to true
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when the unwinder isn't needed. __unwind_function is used as an
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action of last resort. If no other method can be used for
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unwinding, __unwind_function is used. If it cannot unwind, it
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should call __terminate.
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By default, if the target-specific backend doesn't supply a definition
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for __unwind_function and doesn't support DWARF2_UNWIND_INFO, inlined
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unwinders will be used instead. The main tradeoff here is in text space
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utilization. Obviously, if inline unwinders have to be generated
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repeatedly, this uses much more space than if a single routine is used.
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However, it is simply not possible on some platforms to write a
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generalized routine for doing stack unwinding without having some
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form of additional data associated with each function. The current
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implementation can encode this data in the form of additional
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machine instructions or as static data in tabular form. The later
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is called the unwind data.
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The backend macro DOESNT_NEED_UNWINDER is used to conditionalize whether
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or not per-function unwinders are needed. If DOESNT_NEED_UNWINDER is
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defined and has a non-zero value, a per-function unwinder is not emitted
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for the current function. If the static unwind data is supported, then
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a per-function unwinder is not emitted.
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On some platforms it is possible that neither __unwind_function
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nor inlined unwinders are available. For these platforms it is not
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possible to throw through a function call, and abort will be
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invoked instead of performing the throw.
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The reason the unwind data may be needed is that on some platforms
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the order and types of data stored on the stack can vary depending
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on the type of function, its arguments and returned values, and the
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compilation options used (optimization versus non-optimization,
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-fomit-frame-pointer, processor variations, etc).
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Unfortunately, this also means that throwing through functions that
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aren't compiled with exception handling support will still not be
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possible on some platforms. This problem is currently being
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investigated, but no solutions have been found that do not imply
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some unacceptable performance penalties.
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Future directions:
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Currently __throw makes no differentiation between cleanups and
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user-defined exception regions. While this makes the implementation
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simple, it also implies that it is impossible to determine if a
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user-defined exception handler exists for a given exception without
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completely unwinding the stack in the process. This is undesirable
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from the standpoint of debugging, as ideally it would be possible
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to trap unhandled exceptions in the debugger before the process of
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unwinding has even started.
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This problem can be solved by marking user-defined handlers in a
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special way (probably by adding additional bits to exception_table_list).
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A two-pass scheme could then be used by __throw to iterate
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through the table. The first pass would search for a relevant
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user-defined handler for the current context of the throw, and if
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one is found, the second pass would then invoke all needed cleanups
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before jumping to the user-defined handler.
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Many languages (including C++ and Ada) make execution of a
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user-defined handler conditional on the "type" of the exception
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thrown. (The type of the exception is actually the type of the data
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that is thrown with the exception.) It will thus be necessary for
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__throw to be able to determine if a given user-defined
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exception handler will actually be executed, given the type of
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exception.
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One scheme is to add additional information to exception_table_list
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as to the types of exceptions accepted by each handler. __throw
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can do the type comparisons and then determine if the handler is
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actually going to be executed.
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There is currently no significant level of debugging support
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available, other than to place a breakpoint on __throw. While
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this is sufficient in most cases, it would be helpful to be able to
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know where a given exception was going to be thrown to before it is
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actually thrown, and to be able to choose between stopping before
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every exception region (including cleanups), or just user-defined
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exception regions. This should be possible to do in the two-pass
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scheme by adding additional labels to __throw for appropriate
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breakpoints, and additional debugger commands could be added to
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||
query various state variables to determine what actions are to be
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performed next.
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||
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||
Another major problem that is being worked on is the issue with stack
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unwinding on various platforms. Currently the only platforms that have
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||
support for the generation of a generic unwinder are the SPARC and MIPS.
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||
All other ports require per-function unwinders, which produce large
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amounts of code bloat.
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|
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For setjmp/longjmp based exception handling, some of the details
|
||
are as above, but there are some additional details. This section
|
||
discusses the details.
|
||
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||
We don't use NOTE_INSN_EH_REGION_{BEG,END} pairs. We don't
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||
optimize EH regions yet. We don't have to worry about machine
|
||
specific issues with unwinding the stack, as we rely upon longjmp
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||
for all the machine specific details. There is no variable context
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||
of a throw, just the one implied by the dynamic handler stack
|
||
pointed to by the dynamic handler chain. There is no exception
|
||
table, and no calls to __register_exceptions. __sjthrow is used
|
||
instead of __throw, and it works by using the dynamic handler
|
||
chain, and longjmp. -fasynchronous-exceptions has no effect, as
|
||
the elimination of trivial exception regions is not yet performed.
|
||
|
||
A frontend can set protect_cleanup_actions_with_terminate when all
|
||
the cleanup actions should be protected with an EH region that
|
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calls terminate when an unhandled exception is throw. C++ does
|
||
this, Ada does not. */
|
||
|
||
|
||
#include "config.h"
|
||
#include "defaults.h"
|
||
#include "eh-common.h"
|
||
#include "system.h"
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||
#include "rtl.h"
|
||
#include "tree.h"
|
||
#include "flags.h"
|
||
#include "except.h"
|
||
#include "function.h"
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||
#include "insn-flags.h"
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||
#include "expr.h"
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||
#include "insn-codes.h"
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||
#include "regs.h"
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||
#include "hard-reg-set.h"
|
||
#include "insn-config.h"
|
||
#include "recog.h"
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||
#include "output.h"
|
||
#include "toplev.h"
|
||
|
||
/* One to use setjmp/longjmp method of generating code for exception
|
||
handling. */
|
||
|
||
int exceptions_via_longjmp = 2;
|
||
|
||
/* One to enable asynchronous exception support. */
|
||
|
||
int asynchronous_exceptions = 0;
|
||
|
||
/* One to protect cleanup actions with a handler that calls
|
||
__terminate, zero otherwise. */
|
||
|
||
int protect_cleanup_actions_with_terminate;
|
||
|
||
/* A list of labels used for exception handlers. Created by
|
||
find_exception_handler_labels for the optimization passes. */
|
||
|
||
rtx exception_handler_labels;
|
||
|
||
/* The EH context. Nonzero if the function has already
|
||
fetched a pointer to the EH context for exception handling. */
|
||
|
||
rtx current_function_ehc;
|
||
|
||
/* A stack used for keeping track of the currently active exception
|
||
handling region. As each exception region is started, an entry
|
||
describing the region is pushed onto this stack. The current
|
||
region can be found by looking at the top of the stack, and as we
|
||
exit regions, the corresponding entries are popped.
|
||
|
||
Entries cannot overlap; they can be nested. So there is only one
|
||
entry at most that corresponds to the current instruction, and that
|
||
is the entry on the top of the stack. */
|
||
|
||
static struct eh_stack ehstack;
|
||
|
||
|
||
/* This stack is used to represent what the current eh region is
|
||
for the catch blocks beings processed */
|
||
|
||
static struct eh_stack catchstack;
|
||
|
||
/* A queue used for tracking which exception regions have closed but
|
||
whose handlers have not yet been expanded. Regions are emitted in
|
||
groups in an attempt to improve paging performance.
|
||
|
||
As we exit a region, we enqueue a new entry. The entries are then
|
||
dequeued during expand_leftover_cleanups and expand_start_all_catch,
|
||
|
||
We should redo things so that we either take RTL for the handler,
|
||
or we expand the handler expressed as a tree immediately at region
|
||
end time. */
|
||
|
||
static struct eh_queue ehqueue;
|
||
|
||
/* Insns for all of the exception handlers for the current function.
|
||
They are currently emitted by the frontend code. */
|
||
|
||
rtx catch_clauses;
|
||
|
||
/* A TREE_CHAINed list of handlers for regions that are not yet
|
||
closed. The TREE_VALUE of each entry contains the handler for the
|
||
corresponding entry on the ehstack. */
|
||
|
||
static tree protect_list;
|
||
|
||
/* Stacks to keep track of various labels. */
|
||
|
||
/* Keeps track of the label to resume to should one want to resume
|
||
normal control flow out of a handler (instead of, say, returning to
|
||
the caller of the current function or exiting the program). */
|
||
|
||
struct label_node *caught_return_label_stack = NULL;
|
||
|
||
/* Keeps track of the label used as the context of a throw to rethrow an
|
||
exception to the outer exception region. */
|
||
|
||
struct label_node *outer_context_label_stack = NULL;
|
||
|
||
/* A random data area for the front end's own use. */
|
||
|
||
struct label_node *false_label_stack = NULL;
|
||
|
||
static void push_eh_entry PROTO((struct eh_stack *));
|
||
static struct eh_entry * pop_eh_entry PROTO((struct eh_stack *));
|
||
static void enqueue_eh_entry PROTO((struct eh_queue *, struct eh_entry *));
|
||
static struct eh_entry * dequeue_eh_entry PROTO((struct eh_queue *));
|
||
static rtx call_get_eh_context PROTO((void));
|
||
static void start_dynamic_cleanup PROTO((tree, tree));
|
||
static void start_dynamic_handler PROTO((void));
|
||
static void expand_rethrow PROTO((rtx));
|
||
static void output_exception_table_entry PROTO((FILE *, int));
|
||
static int can_throw PROTO((rtx));
|
||
static rtx scan_region PROTO((rtx, int, int *));
|
||
static void eh_regs PROTO((rtx *, rtx *, int));
|
||
static void set_insn_eh_region PROTO((rtx *, int));
|
||
#ifdef DONT_USE_BUILTIN_SETJMP
|
||
static void jumpif_rtx PROTO((rtx, rtx));
|
||
#endif
|
||
|
||
|
||
rtx expand_builtin_return_addr PROTO((enum built_in_function, int, rtx));
|
||
|
||
/* Various support routines to manipulate the various data structures
|
||
used by the exception handling code. */
|
||
|
||
/* Push a label entry onto the given STACK. */
|
||
|
||
void
|
||
push_label_entry (stack, rlabel, tlabel)
|
||
struct label_node **stack;
|
||
rtx rlabel;
|
||
tree tlabel;
|
||
{
|
||
struct label_node *newnode
|
||
= (struct label_node *) xmalloc (sizeof (struct label_node));
|
||
|
||
if (rlabel)
|
||
newnode->u.rlabel = rlabel;
|
||
else
|
||
newnode->u.tlabel = tlabel;
|
||
newnode->chain = *stack;
|
||
*stack = newnode;
|
||
}
|
||
|
||
/* Pop a label entry from the given STACK. */
|
||
|
||
rtx
|
||
pop_label_entry (stack)
|
||
struct label_node **stack;
|
||
{
|
||
rtx label;
|
||
struct label_node *tempnode;
|
||
|
||
if (! *stack)
|
||
return NULL_RTX;
|
||
|
||
tempnode = *stack;
|
||
label = tempnode->u.rlabel;
|
||
*stack = (*stack)->chain;
|
||
free (tempnode);
|
||
|
||
return label;
|
||
}
|
||
|
||
/* Return the top element of the given STACK. */
|
||
|
||
tree
|
||
top_label_entry (stack)
|
||
struct label_node **stack;
|
||
{
|
||
if (! *stack)
|
||
return NULL_TREE;
|
||
|
||
return (*stack)->u.tlabel;
|
||
}
|
||
|
||
/* get an exception label. These must be on the permanent obstack */
|
||
|
||
rtx
|
||
gen_exception_label ()
|
||
{
|
||
rtx lab;
|
||
|
||
push_obstacks_nochange ();
|
||
end_temporary_allocation ();
|
||
lab = gen_label_rtx ();
|
||
pop_obstacks ();
|
||
return lab;
|
||
}
|
||
|
||
/* Push a new eh_node entry onto STACK. */
|
||
|
||
static void
|
||
push_eh_entry (stack)
|
||
struct eh_stack *stack;
|
||
{
|
||
struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
|
||
struct eh_entry *entry = (struct eh_entry *) xmalloc (sizeof (struct eh_entry));
|
||
|
||
entry->outer_context = gen_label_rtx ();
|
||
entry->finalization = NULL_TREE;
|
||
entry->label_used = 0;
|
||
entry->exception_handler_label = gen_exception_label ();
|
||
|
||
node->entry = entry;
|
||
node->chain = stack->top;
|
||
stack->top = node;
|
||
}
|
||
|
||
/* push an existing entry onto a stack. */
|
||
static void
|
||
push_entry (stack, entry)
|
||
struct eh_stack *stack;
|
||
struct eh_entry *entry;
|
||
{
|
||
struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
|
||
node->entry = entry;
|
||
node->chain = stack->top;
|
||
stack->top = node;
|
||
}
|
||
|
||
/* Pop an entry from the given STACK. */
|
||
|
||
static struct eh_entry *
|
||
pop_eh_entry (stack)
|
||
struct eh_stack *stack;
|
||
{
|
||
struct eh_node *tempnode;
|
||
struct eh_entry *tempentry;
|
||
|
||
tempnode = stack->top;
|
||
tempentry = tempnode->entry;
|
||
stack->top = stack->top->chain;
|
||
free (tempnode);
|
||
|
||
return tempentry;
|
||
}
|
||
|
||
/* Enqueue an ENTRY onto the given QUEUE. */
|
||
|
||
static void
|
||
enqueue_eh_entry (queue, entry)
|
||
struct eh_queue *queue;
|
||
struct eh_entry *entry;
|
||
{
|
||
struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
|
||
|
||
node->entry = entry;
|
||
node->chain = NULL;
|
||
|
||
if (queue->head == NULL)
|
||
{
|
||
queue->head = node;
|
||
}
|
||
else
|
||
{
|
||
queue->tail->chain = node;
|
||
}
|
||
queue->tail = node;
|
||
}
|
||
|
||
/* Dequeue an entry from the given QUEUE. */
|
||
|
||
static struct eh_entry *
|
||
dequeue_eh_entry (queue)
|
||
struct eh_queue *queue;
|
||
{
|
||
struct eh_node *tempnode;
|
||
struct eh_entry *tempentry;
|
||
|
||
if (queue->head == NULL)
|
||
return NULL;
|
||
|
||
tempnode = queue->head;
|
||
queue->head = queue->head->chain;
|
||
|
||
tempentry = tempnode->entry;
|
||
free (tempnode);
|
||
|
||
return tempentry;
|
||
}
|
||
|
||
static void
|
||
receive_exception_label (handler_label)
|
||
rtx handler_label;
|
||
{
|
||
emit_label (handler_label);
|
||
|
||
#ifdef HAVE_exception_receiver
|
||
if (! exceptions_via_longjmp)
|
||
if (HAVE_exception_receiver)
|
||
emit_insn (gen_exception_receiver ());
|
||
#endif
|
||
|
||
#ifdef HAVE_nonlocal_goto_receiver
|
||
if (! exceptions_via_longjmp)
|
||
if (HAVE_nonlocal_goto_receiver)
|
||
emit_insn (gen_nonlocal_goto_receiver ());
|
||
#endif
|
||
}
|
||
|
||
|
||
struct func_eh_entry
|
||
{
|
||
int range_number; /* EH region number from EH NOTE insn's */
|
||
struct handler_info *handlers;
|
||
};
|
||
|
||
|
||
/* table of function eh regions */
|
||
static struct func_eh_entry *function_eh_regions = NULL;
|
||
static int num_func_eh_entries = 0;
|
||
static int current_func_eh_entry = 0;
|
||
|
||
#define SIZE_FUNC_EH(X) (sizeof (struct func_eh_entry) * X)
|
||
|
||
/* Add a new eh_entry for this function, and base it off of the information
|
||
in the EH_ENTRY parameter. A NULL parameter is invalid. The number
|
||
returned is an number which uniquely identifies this exception range. */
|
||
|
||
int
|
||
new_eh_region_entry (note_eh_region)
|
||
int note_eh_region;
|
||
{
|
||
if (current_func_eh_entry == num_func_eh_entries)
|
||
{
|
||
if (num_func_eh_entries == 0)
|
||
{
|
||
function_eh_regions =
|
||
(struct func_eh_entry *) malloc (SIZE_FUNC_EH (50));
|
||
num_func_eh_entries = 50;
|
||
}
|
||
else
|
||
{
|
||
num_func_eh_entries = num_func_eh_entries * 3 / 2;
|
||
function_eh_regions = (struct func_eh_entry *)
|
||
realloc (function_eh_regions, SIZE_FUNC_EH (num_func_eh_entries));
|
||
}
|
||
}
|
||
function_eh_regions[current_func_eh_entry].range_number = note_eh_region;
|
||
function_eh_regions[current_func_eh_entry].handlers = NULL;
|
||
|
||
return current_func_eh_entry++;
|
||
}
|
||
|
||
/* Add new handler information to an exception range. The first parameter
|
||
specifies the range number (returned from new_eh_entry()). The second
|
||
parameter specifies the handler. By default the handler is inserted at
|
||
the end of the list. A handler list may contain only ONE NULL_TREE
|
||
typeinfo entry. Regardless where it is positioned, a NULL_TREE entry
|
||
is always output as the LAST handler in the exception table for a region. */
|
||
|
||
void
|
||
add_new_handler (region, newhandler)
|
||
int region;
|
||
struct handler_info *newhandler;
|
||
{
|
||
struct handler_info *last;
|
||
|
||
newhandler->next = NULL;
|
||
last = function_eh_regions[region].handlers;
|
||
if (last == NULL)
|
||
function_eh_regions[region].handlers = newhandler;
|
||
else
|
||
{
|
||
for ( ; last->next != NULL; last = last->next)
|
||
;
|
||
last->next = newhandler;
|
||
}
|
||
}
|
||
|
||
/* Remove a handler label. The handler label is being deleted, so all
|
||
regions which reference this handler should have it removed from their
|
||
list of possible handlers. Any region which has the final handler
|
||
removed can be deleted. */
|
||
|
||
void remove_handler (removing_label)
|
||
rtx removing_label;
|
||
{
|
||
struct handler_info *handler, *last;
|
||
int x;
|
||
for (x = 0 ; x < current_func_eh_entry; ++x)
|
||
{
|
||
last = NULL;
|
||
handler = function_eh_regions[x].handlers;
|
||
for ( ; handler; last = handler, handler = handler->next)
|
||
if (handler->handler_label == removing_label)
|
||
{
|
||
if (last)
|
||
{
|
||
last->next = handler->next;
|
||
handler = last;
|
||
}
|
||
else
|
||
function_eh_regions[x].handlers = handler->next;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* This function will return a malloc'd pointer to an array of
|
||
void pointer representing the runtime match values that
|
||
currently exist in all regions. */
|
||
|
||
int
|
||
find_all_handler_type_matches (array)
|
||
void ***array;
|
||
{
|
||
struct handler_info *handler, *last;
|
||
int x,y;
|
||
void *val;
|
||
void **ptr;
|
||
int max_ptr;
|
||
int n_ptr = 0;
|
||
|
||
*array = NULL;
|
||
|
||
if (!doing_eh (0) || ! flag_new_exceptions)
|
||
return 0;
|
||
|
||
max_ptr = 100;
|
||
ptr = (void **)malloc (max_ptr * sizeof (void *));
|
||
|
||
if (ptr == NULL)
|
||
return 0;
|
||
|
||
for (x = 0 ; x < current_func_eh_entry; x++)
|
||
{
|
||
last = NULL;
|
||
handler = function_eh_regions[x].handlers;
|
||
for ( ; handler; last = handler, handler = handler->next)
|
||
{
|
||
val = handler->type_info;
|
||
if (val != NULL && val != CATCH_ALL_TYPE)
|
||
{
|
||
/* See if this match value has already been found. */
|
||
for (y = 0; y < n_ptr; y++)
|
||
if (ptr[y] == val)
|
||
break;
|
||
|
||
/* If we break early, we already found this value. */
|
||
if (y < n_ptr)
|
||
continue;
|
||
|
||
/* Do we need to allocate more space? */
|
||
if (n_ptr >= max_ptr)
|
||
{
|
||
max_ptr += max_ptr / 2;
|
||
ptr = (void **)realloc (ptr, max_ptr * sizeof (void *));
|
||
if (ptr == NULL)
|
||
return 0;
|
||
}
|
||
ptr[n_ptr] = val;
|
||
n_ptr++;
|
||
}
|
||
}
|
||
}
|
||
*array = ptr;
|
||
return n_ptr;
|
||
}
|
||
|
||
/* Create a new handler structure initialized with the handler label and
|
||
typeinfo fields passed in. */
|
||
|
||
struct handler_info *
|
||
get_new_handler (handler, typeinfo)
|
||
rtx handler;
|
||
void *typeinfo;
|
||
{
|
||
struct handler_info* ptr;
|
||
ptr = (struct handler_info *) malloc (sizeof (struct handler_info));
|
||
ptr->handler_label = handler;
|
||
ptr->type_info = typeinfo;
|
||
ptr->next = NULL;
|
||
|
||
return ptr;
|
||
}
|
||
|
||
|
||
|
||
/* Find the index in function_eh_regions associated with a NOTE region. If
|
||
the region cannot be found, a -1 is returned. This should never happen! */
|
||
|
||
int
|
||
find_func_region (insn_region)
|
||
int insn_region;
|
||
{
|
||
int x;
|
||
for (x = 0; x < current_func_eh_entry; x++)
|
||
if (function_eh_regions[x].range_number == insn_region)
|
||
return x;
|
||
|
||
return -1;
|
||
}
|
||
|
||
/* Get a pointer to the first handler in an exception region's list. */
|
||
|
||
struct handler_info *
|
||
get_first_handler (region)
|
||
int region;
|
||
{
|
||
return function_eh_regions[find_func_region (region)].handlers;
|
||
}
|
||
|
||
/* Clean out the function_eh_region table and free all memory */
|
||
|
||
static void
|
||
clear_function_eh_region ()
|
||
{
|
||
int x;
|
||
struct handler_info *ptr, *next;
|
||
for (x = 0; x < current_func_eh_entry; x++)
|
||
for (ptr = function_eh_regions[x].handlers; ptr != NULL; ptr = next)
|
||
{
|
||
next = ptr->next;
|
||
free (ptr);
|
||
}
|
||
free (function_eh_regions);
|
||
num_func_eh_entries = 0;
|
||
current_func_eh_entry = 0;
|
||
}
|
||
|
||
/* Make a duplicate of an exception region by copying all the handlers
|
||
for an exception region. Return the new handler index. */
|
||
|
||
int
|
||
duplicate_handlers (old_note_eh_region, new_note_eh_region)
|
||
int old_note_eh_region, new_note_eh_region;
|
||
{
|
||
struct handler_info *ptr, *new_ptr;
|
||
int new_region, region;
|
||
|
||
region = find_func_region (old_note_eh_region);
|
||
if (region == -1)
|
||
error ("Cannot duplicate non-existant exception region.");
|
||
|
||
if (find_func_region (new_note_eh_region) != -1)
|
||
error ("Cannot duplicate EH region because new note region already exists");
|
||
|
||
new_region = new_eh_region_entry (new_note_eh_region);
|
||
ptr = function_eh_regions[region].handlers;
|
||
|
||
for ( ; ptr; ptr = ptr->next)
|
||
{
|
||
new_ptr = get_new_handler (ptr->handler_label, ptr->type_info);
|
||
add_new_handler (new_region, new_ptr);
|
||
}
|
||
|
||
return new_region;
|
||
}
|
||
|
||
|
||
/* Routine to see if exception handling is turned on.
|
||
DO_WARN is non-zero if we want to inform the user that exception
|
||
handling is turned off.
|
||
|
||
This is used to ensure that -fexceptions has been specified if the
|
||
compiler tries to use any exception-specific functions. */
|
||
|
||
int
|
||
doing_eh (do_warn)
|
||
int do_warn;
|
||
{
|
||
if (! flag_exceptions)
|
||
{
|
||
static int warned = 0;
|
||
if (! warned && do_warn)
|
||
{
|
||
error ("exception handling disabled, use -fexceptions to enable");
|
||
warned = 1;
|
||
}
|
||
return 0;
|
||
}
|
||
return 1;
|
||
}
|
||
|
||
/* Given a return address in ADDR, determine the address we should use
|
||
to find the corresponding EH region. */
|
||
|
||
rtx
|
||
eh_outer_context (addr)
|
||
rtx addr;
|
||
{
|
||
/* First mask out any unwanted bits. */
|
||
#ifdef MASK_RETURN_ADDR
|
||
expand_and (addr, MASK_RETURN_ADDR, addr);
|
||
#endif
|
||
|
||
/* Then adjust to find the real return address. */
|
||
#if defined (RETURN_ADDR_OFFSET)
|
||
addr = plus_constant (addr, RETURN_ADDR_OFFSET);
|
||
#endif
|
||
|
||
return addr;
|
||
}
|
||
|
||
/* Start a new exception region for a region of code that has a
|
||
cleanup action and push the HANDLER for the region onto
|
||
protect_list. All of the regions created with add_partial_entry
|
||
will be ended when end_protect_partials is invoked. */
|
||
|
||
void
|
||
add_partial_entry (handler)
|
||
tree handler;
|
||
{
|
||
expand_eh_region_start ();
|
||
|
||
/* Make sure the entry is on the correct obstack. */
|
||
push_obstacks_nochange ();
|
||
resume_temporary_allocation ();
|
||
|
||
/* Because this is a cleanup action, we may have to protect the handler
|
||
with __terminate. */
|
||
handler = protect_with_terminate (handler);
|
||
|
||
protect_list = tree_cons (NULL_TREE, handler, protect_list);
|
||
pop_obstacks ();
|
||
}
|
||
|
||
/* Emit code to get EH context to current function. */
|
||
|
||
static rtx
|
||
call_get_eh_context ()
|
||
{
|
||
static tree fn;
|
||
tree expr;
|
||
|
||
if (fn == NULL_TREE)
|
||
{
|
||
tree fntype;
|
||
fn = get_identifier ("__get_eh_context");
|
||
push_obstacks_nochange ();
|
||
end_temporary_allocation ();
|
||
fntype = build_pointer_type (build_pointer_type
|
||
(build_pointer_type (void_type_node)));
|
||
fntype = build_function_type (fntype, NULL_TREE);
|
||
fn = build_decl (FUNCTION_DECL, fn, fntype);
|
||
DECL_EXTERNAL (fn) = 1;
|
||
TREE_PUBLIC (fn) = 1;
|
||
DECL_ARTIFICIAL (fn) = 1;
|
||
TREE_READONLY (fn) = 1;
|
||
make_decl_rtl (fn, NULL_PTR, 1);
|
||
assemble_external (fn);
|
||
pop_obstacks ();
|
||
}
|
||
|
||
expr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (fn)), fn);
|
||
expr = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fn)),
|
||
expr, NULL_TREE, NULL_TREE);
|
||
TREE_SIDE_EFFECTS (expr) = 1;
|
||
|
||
return copy_to_reg (expand_expr (expr, NULL_RTX, VOIDmode, 0));
|
||
}
|
||
|
||
/* Get a reference to the EH context.
|
||
We will only generate a register for the current function EH context here,
|
||
and emit a USE insn to mark that this is a EH context register.
|
||
|
||
Later, emit_eh_context will emit needed call to __get_eh_context
|
||
in libgcc2, and copy the value to the register we have generated. */
|
||
|
||
rtx
|
||
get_eh_context ()
|
||
{
|
||
if (current_function_ehc == 0)
|
||
{
|
||
rtx insn;
|
||
|
||
current_function_ehc = gen_reg_rtx (Pmode);
|
||
|
||
insn = gen_rtx_USE (GET_MODE (current_function_ehc),
|
||
current_function_ehc);
|
||
insn = emit_insn_before (insn, get_first_nonparm_insn ());
|
||
|
||
REG_NOTES (insn)
|
||
= gen_rtx_EXPR_LIST (REG_EH_CONTEXT, current_function_ehc,
|
||
REG_NOTES (insn));
|
||
}
|
||
return current_function_ehc;
|
||
}
|
||
|
||
/* Get a reference to the dynamic handler chain. It points to the
|
||
pointer to the next element in the dynamic handler chain. It ends
|
||
when there are no more elements in the dynamic handler chain, when
|
||
the value is &top_elt from libgcc2.c. Immediately after the
|
||
pointer, is an area suitable for setjmp/longjmp when
|
||
DONT_USE_BUILTIN_SETJMP is defined, and an area suitable for
|
||
__builtin_setjmp/__builtin_longjmp when DONT_USE_BUILTIN_SETJMP
|
||
isn't defined. */
|
||
|
||
rtx
|
||
get_dynamic_handler_chain ()
|
||
{
|
||
rtx ehc, dhc, result;
|
||
|
||
ehc = get_eh_context ();
|
||
|
||
/* This is the offset of dynamic_handler_chain in the eh_context struct
|
||
declared in eh-common.h. If its location is change, change this offset */
|
||
dhc = plus_constant (ehc, POINTER_SIZE / BITS_PER_UNIT);
|
||
|
||
result = copy_to_reg (dhc);
|
||
|
||
/* We don't want a copy of the dcc, but rather, the single dcc. */
|
||
return gen_rtx_MEM (Pmode, result);
|
||
}
|
||
|
||
/* Get a reference to the dynamic cleanup chain. It points to the
|
||
pointer to the next element in the dynamic cleanup chain.
|
||
Immediately after the pointer, are two Pmode variables, one for a
|
||
pointer to a function that performs the cleanup action, and the
|
||
second, the argument to pass to that function. */
|
||
|
||
rtx
|
||
get_dynamic_cleanup_chain ()
|
||
{
|
||
rtx dhc, dcc, result;
|
||
|
||
dhc = get_dynamic_handler_chain ();
|
||
dcc = plus_constant (dhc, POINTER_SIZE / BITS_PER_UNIT);
|
||
|
||
result = copy_to_reg (dcc);
|
||
|
||
/* We don't want a copy of the dcc, but rather, the single dcc. */
|
||
return gen_rtx_MEM (Pmode, result);
|
||
}
|
||
|
||
#ifdef DONT_USE_BUILTIN_SETJMP
|
||
/* Generate code to evaluate X and jump to LABEL if the value is nonzero.
|
||
LABEL is an rtx of code CODE_LABEL, in this function. */
|
||
|
||
static void
|
||
jumpif_rtx (x, label)
|
||
rtx x;
|
||
rtx label;
|
||
{
|
||
jumpif (make_tree (type_for_mode (GET_MODE (x), 0), x), label);
|
||
}
|
||
#endif
|
||
|
||
/* Start a dynamic cleanup on the EH runtime dynamic cleanup stack.
|
||
We just need to create an element for the cleanup list, and push it
|
||
into the chain.
|
||
|
||
A dynamic cleanup is a cleanup action implied by the presence of an
|
||
element on the EH runtime dynamic cleanup stack that is to be
|
||
performed when an exception is thrown. The cleanup action is
|
||
performed by __sjthrow when an exception is thrown. Only certain
|
||
actions can be optimized into dynamic cleanup actions. For the
|
||
restrictions on what actions can be performed using this routine,
|
||
see expand_eh_region_start_tree. */
|
||
|
||
static void
|
||
start_dynamic_cleanup (func, arg)
|
||
tree func;
|
||
tree arg;
|
||
{
|
||
rtx dcc;
|
||
rtx new_func, new_arg;
|
||
rtx x, buf;
|
||
int size;
|
||
|
||
/* We allocate enough room for a pointer to the function, and
|
||
one argument. */
|
||
size = 2;
|
||
|
||
/* XXX, FIXME: The stack space allocated this way is too long lived,
|
||
but there is no allocation routine that allocates at the level of
|
||
the last binding contour. */
|
||
buf = assign_stack_local (BLKmode,
|
||
GET_MODE_SIZE (Pmode)*(size+1),
|
||
0);
|
||
|
||
buf = change_address (buf, Pmode, NULL_RTX);
|
||
|
||
/* Store dcc into the first word of the newly allocated buffer. */
|
||
|
||
dcc = get_dynamic_cleanup_chain ();
|
||
emit_move_insn (buf, dcc);
|
||
|
||
/* Store func and arg into the cleanup list element. */
|
||
|
||
new_func = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0),
|
||
GET_MODE_SIZE (Pmode)));
|
||
new_arg = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0),
|
||
GET_MODE_SIZE (Pmode)*2));
|
||
x = expand_expr (func, new_func, Pmode, 0);
|
||
if (x != new_func)
|
||
emit_move_insn (new_func, x);
|
||
|
||
x = expand_expr (arg, new_arg, Pmode, 0);
|
||
if (x != new_arg)
|
||
emit_move_insn (new_arg, x);
|
||
|
||
/* Update the cleanup chain. */
|
||
|
||
emit_move_insn (dcc, XEXP (buf, 0));
|
||
}
|
||
|
||
/* Emit RTL to start a dynamic handler on the EH runtime dynamic
|
||
handler stack. This should only be used by expand_eh_region_start
|
||
or expand_eh_region_start_tree. */
|
||
|
||
static void
|
||
start_dynamic_handler ()
|
||
{
|
||
rtx dhc, dcc;
|
||
rtx x, arg, buf;
|
||
int size;
|
||
|
||
#ifndef DONT_USE_BUILTIN_SETJMP
|
||
/* The number of Pmode words for the setjmp buffer, when using the
|
||
builtin setjmp/longjmp, see expand_builtin, case
|
||
BUILT_IN_LONGJMP. */
|
||
size = 5;
|
||
#else
|
||
#ifdef JMP_BUF_SIZE
|
||
size = JMP_BUF_SIZE;
|
||
#else
|
||
/* Should be large enough for most systems, if it is not,
|
||
JMP_BUF_SIZE should be defined with the proper value. It will
|
||
also tend to be larger than necessary for most systems, a more
|
||
optimal port will define JMP_BUF_SIZE. */
|
||
size = FIRST_PSEUDO_REGISTER+2;
|
||
#endif
|
||
#endif
|
||
/* XXX, FIXME: The stack space allocated this way is too long lived,
|
||
but there is no allocation routine that allocates at the level of
|
||
the last binding contour. */
|
||
arg = assign_stack_local (BLKmode,
|
||
GET_MODE_SIZE (Pmode)*(size+1),
|
||
0);
|
||
|
||
arg = change_address (arg, Pmode, NULL_RTX);
|
||
|
||
/* Store dhc into the first word of the newly allocated buffer. */
|
||
|
||
dhc = get_dynamic_handler_chain ();
|
||
dcc = gen_rtx_MEM (Pmode, plus_constant (XEXP (arg, 0),
|
||
GET_MODE_SIZE (Pmode)));
|
||
emit_move_insn (arg, dhc);
|
||
|
||
/* Zero out the start of the cleanup chain. */
|
||
emit_move_insn (dcc, const0_rtx);
|
||
|
||
/* The jmpbuf starts two words into the area allocated. */
|
||
buf = plus_constant (XEXP (arg, 0), GET_MODE_SIZE (Pmode)*2);
|
||
|
||
#ifdef DONT_USE_BUILTIN_SETJMP
|
||
x = emit_library_call_value (setjmp_libfunc, NULL_RTX, 1, SImode, 1,
|
||
buf, Pmode);
|
||
/* If we come back here for a catch, transfer control to the handler. */
|
||
jumpif_rtx (x, ehstack.top->entry->exception_handler_label);
|
||
#else
|
||
{
|
||
/* A label to continue execution for the no exception case. */
|
||
rtx noex = gen_label_rtx();
|
||
x = expand_builtin_setjmp (buf, NULL_RTX, noex,
|
||
ehstack.top->entry->exception_handler_label);
|
||
emit_label (noex);
|
||
}
|
||
#endif
|
||
|
||
/* We are committed to this, so update the handler chain. */
|
||
|
||
emit_move_insn (dhc, XEXP (arg, 0));
|
||
}
|
||
|
||
/* Start an exception handling region for the given cleanup action.
|
||
All instructions emitted after this point are considered to be part
|
||
of the region until expand_eh_region_end is invoked. CLEANUP is
|
||
the cleanup action to perform. The return value is true if the
|
||
exception region was optimized away. If that case,
|
||
expand_eh_region_end does not need to be called for this cleanup,
|
||
nor should it be.
|
||
|
||
This routine notices one particular common case in C++ code
|
||
generation, and optimizes it so as to not need the exception
|
||
region. It works by creating a dynamic cleanup action, instead of
|
||
a using an exception region. */
|
||
|
||
int
|
||
expand_eh_region_start_tree (decl, cleanup)
|
||
tree decl;
|
||
tree cleanup;
|
||
{
|
||
/* This is the old code. */
|
||
if (! doing_eh (0))
|
||
return 0;
|
||
|
||
/* The optimization only applies to actions protected with
|
||
terminate, and only applies if we are using the setjmp/longjmp
|
||
codegen method. */
|
||
if (exceptions_via_longjmp
|
||
&& protect_cleanup_actions_with_terminate)
|
||
{
|
||
tree func, arg;
|
||
tree args;
|
||
|
||
/* Ignore any UNSAVE_EXPR. */
|
||
if (TREE_CODE (cleanup) == UNSAVE_EXPR)
|
||
cleanup = TREE_OPERAND (cleanup, 0);
|
||
|
||
/* Further, it only applies if the action is a call, if there
|
||
are 2 arguments, and if the second argument is 2. */
|
||
|
||
if (TREE_CODE (cleanup) == CALL_EXPR
|
||
&& (args = TREE_OPERAND (cleanup, 1))
|
||
&& (func = TREE_OPERAND (cleanup, 0))
|
||
&& (arg = TREE_VALUE (args))
|
||
&& (args = TREE_CHAIN (args))
|
||
|
||
/* is the second argument 2? */
|
||
&& TREE_CODE (TREE_VALUE (args)) == INTEGER_CST
|
||
&& TREE_INT_CST_LOW (TREE_VALUE (args)) == 2
|
||
&& TREE_INT_CST_HIGH (TREE_VALUE (args)) == 0
|
||
|
||
/* Make sure there are no other arguments. */
|
||
&& TREE_CHAIN (args) == NULL_TREE)
|
||
{
|
||
/* Arrange for returns and gotos to pop the entry we make on the
|
||
dynamic cleanup stack. */
|
||
expand_dcc_cleanup (decl);
|
||
start_dynamic_cleanup (func, arg);
|
||
return 1;
|
||
}
|
||
}
|
||
|
||
expand_eh_region_start_for_decl (decl);
|
||
ehstack.top->entry->finalization = cleanup;
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Just like expand_eh_region_start, except if a cleanup action is
|
||
entered on the cleanup chain, the TREE_PURPOSE of the element put
|
||
on the chain is DECL. DECL should be the associated VAR_DECL, if
|
||
any, otherwise it should be NULL_TREE. */
|
||
|
||
void
|
||
expand_eh_region_start_for_decl (decl)
|
||
tree decl;
|
||
{
|
||
rtx note;
|
||
|
||
/* This is the old code. */
|
||
if (! doing_eh (0))
|
||
return;
|
||
|
||
if (exceptions_via_longjmp)
|
||
{
|
||
/* We need a new block to record the start and end of the
|
||
dynamic handler chain. We could always do this, but we
|
||
really want to permit jumping into such a block, and we want
|
||
to avoid any errors or performance impact in the SJ EH code
|
||
for now. */
|
||
expand_start_bindings (0);
|
||
|
||
/* But we don't need or want a new temporary level. */
|
||
pop_temp_slots ();
|
||
|
||
/* Mark this block as created by expand_eh_region_start. This
|
||
is so that we can pop the block with expand_end_bindings
|
||
automatically. */
|
||
mark_block_as_eh_region ();
|
||
|
||
/* Arrange for returns and gotos to pop the entry we make on the
|
||
dynamic handler stack. */
|
||
expand_dhc_cleanup (decl);
|
||
}
|
||
|
||
push_eh_entry (&ehstack);
|
||
note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_BEG);
|
||
NOTE_BLOCK_NUMBER (note)
|
||
= CODE_LABEL_NUMBER (ehstack.top->entry->exception_handler_label);
|
||
if (exceptions_via_longjmp)
|
||
start_dynamic_handler ();
|
||
}
|
||
|
||
/* Start an exception handling region. All instructions emitted after
|
||
this point are considered to be part of the region until
|
||
expand_eh_region_end is invoked. */
|
||
|
||
void
|
||
expand_eh_region_start ()
|
||
{
|
||
expand_eh_region_start_for_decl (NULL_TREE);
|
||
}
|
||
|
||
/* End an exception handling region. The information about the region
|
||
is found on the top of ehstack.
|
||
|
||
HANDLER is either the cleanup for the exception region, or if we're
|
||
marking the end of a try block, HANDLER is integer_zero_node.
|
||
|
||
HANDLER will be transformed to rtl when expand_leftover_cleanups
|
||
is invoked. */
|
||
|
||
void
|
||
expand_eh_region_end (handler)
|
||
tree handler;
|
||
{
|
||
struct eh_entry *entry;
|
||
rtx note;
|
||
|
||
if (! doing_eh (0))
|
||
return;
|
||
|
||
entry = pop_eh_entry (&ehstack);
|
||
|
||
note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_END);
|
||
NOTE_BLOCK_NUMBER (note)
|
||
= CODE_LABEL_NUMBER (entry->exception_handler_label);
|
||
if (exceptions_via_longjmp == 0
|
||
/* We share outer_context between regions; only emit it once. */
|
||
&& INSN_UID (entry->outer_context) == 0)
|
||
{
|
||
rtx label;
|
||
|
||
label = gen_label_rtx ();
|
||
emit_jump (label);
|
||
|
||
/* Emit a label marking the end of this exception region that
|
||
is used for rethrowing into the outer context. */
|
||
emit_label (entry->outer_context);
|
||
expand_internal_throw ();
|
||
|
||
emit_label (label);
|
||
}
|
||
|
||
entry->finalization = handler;
|
||
|
||
/* create region entry in final exception table */
|
||
new_eh_region_entry (NOTE_BLOCK_NUMBER (note));
|
||
|
||
enqueue_eh_entry (&ehqueue, entry);
|
||
|
||
/* If we have already started ending the bindings, don't recurse.
|
||
This only happens when exceptions_via_longjmp is true. */
|
||
if (is_eh_region ())
|
||
{
|
||
/* Because we don't need or want a new temporary level and
|
||
because we didn't create one in expand_eh_region_start,
|
||
create a fake one now to avoid removing one in
|
||
expand_end_bindings. */
|
||
push_temp_slots ();
|
||
|
||
mark_block_as_not_eh_region ();
|
||
|
||
/* Maybe do this to prevent jumping in and so on... */
|
||
expand_end_bindings (NULL_TREE, 0, 0);
|
||
}
|
||
}
|
||
|
||
/* End the EH region for a goto fixup. We only need them in the region-based
|
||
EH scheme. */
|
||
|
||
void
|
||
expand_fixup_region_start ()
|
||
{
|
||
if (! doing_eh (0) || exceptions_via_longjmp)
|
||
return;
|
||
|
||
expand_eh_region_start ();
|
||
}
|
||
|
||
/* End the EH region for a goto fixup. CLEANUP is the cleanup we just
|
||
expanded; to avoid running it twice if it throws, we look through the
|
||
ehqueue for a matching region and rethrow from its outer_context. */
|
||
|
||
void
|
||
expand_fixup_region_end (cleanup)
|
||
tree cleanup;
|
||
{
|
||
struct eh_node *node;
|
||
int dont_issue;
|
||
|
||
if (! doing_eh (0) || exceptions_via_longjmp)
|
||
return;
|
||
|
||
for (node = ehstack.top; node && node->entry->finalization != cleanup; )
|
||
node = node->chain;
|
||
if (node == 0)
|
||
for (node = ehqueue.head; node && node->entry->finalization != cleanup; )
|
||
node = node->chain;
|
||
if (node == 0)
|
||
abort ();
|
||
|
||
/* If the outer context label has not been issued yet, we don't want
|
||
to issue it as a part of this region, unless this is the
|
||
correct region for the outer context. If we did, then the label for
|
||
the outer context will be WITHIN the begin/end labels,
|
||
and we could get an infinte loop when it tried to rethrow, or just
|
||
generally incorrect execution following a throw. */
|
||
|
||
dont_issue = ((INSN_UID (node->entry->outer_context) == 0)
|
||
&& (ehstack.top->entry != node->entry));
|
||
|
||
ehstack.top->entry->outer_context = node->entry->outer_context;
|
||
|
||
/* Since we are rethrowing to the OUTER region, we know we don't need
|
||
a jump around sequence for this region, so we'll pretend the outer
|
||
context label has been issued by setting INSN_UID to 1, then clearing
|
||
it again afterwards. */
|
||
|
||
if (dont_issue)
|
||
INSN_UID (node->entry->outer_context) = 1;
|
||
|
||
/* Just rethrow. size_zero_node is just a NOP. */
|
||
expand_eh_region_end (size_zero_node);
|
||
|
||
if (dont_issue)
|
||
INSN_UID (node->entry->outer_context) = 0;
|
||
}
|
||
|
||
/* If we are using the setjmp/longjmp EH codegen method, we emit a
|
||
call to __sjthrow.
|
||
|
||
Otherwise, we emit a call to __throw and note that we threw
|
||
something, so we know we need to generate the necessary code for
|
||
__throw.
|
||
|
||
Before invoking throw, the __eh_pc variable must have been set up
|
||
to contain the PC being thrown from. This address is used by
|
||
__throw to determine which exception region (if any) is
|
||
responsible for handling the exception. */
|
||
|
||
void
|
||
emit_throw ()
|
||
{
|
||
if (exceptions_via_longjmp)
|
||
{
|
||
emit_library_call (sjthrow_libfunc, 0, VOIDmode, 0);
|
||
}
|
||
else
|
||
{
|
||
#ifdef JUMP_TO_THROW
|
||
emit_indirect_jump (throw_libfunc);
|
||
#else
|
||
emit_library_call (throw_libfunc, 0, VOIDmode, 0);
|
||
#endif
|
||
}
|
||
emit_barrier ();
|
||
}
|
||
|
||
/* Throw the current exception. If appropriate, this is done by jumping
|
||
to the next handler. */
|
||
|
||
void
|
||
expand_internal_throw ()
|
||
{
|
||
emit_throw ();
|
||
}
|
||
|
||
/* Called from expand_exception_blocks and expand_end_catch_block to
|
||
emit any pending handlers/cleanups queued from expand_eh_region_end. */
|
||
|
||
void
|
||
expand_leftover_cleanups ()
|
||
{
|
||
struct eh_entry *entry;
|
||
|
||
while ((entry = dequeue_eh_entry (&ehqueue)) != 0)
|
||
{
|
||
rtx prev;
|
||
|
||
/* A leftover try block. Shouldn't be one here. */
|
||
if (entry->finalization == integer_zero_node)
|
||
abort ();
|
||
|
||
/* Output the label for the start of the exception handler. */
|
||
|
||
receive_exception_label (entry->exception_handler_label);
|
||
|
||
/* register a handler for this cleanup region */
|
||
add_new_handler (
|
||
find_func_region (CODE_LABEL_NUMBER (entry->exception_handler_label)),
|
||
get_new_handler (entry->exception_handler_label, NULL));
|
||
|
||
/* And now generate the insns for the handler. */
|
||
expand_expr (entry->finalization, const0_rtx, VOIDmode, 0);
|
||
|
||
prev = get_last_insn ();
|
||
if (prev == NULL || GET_CODE (prev) != BARRIER)
|
||
/* Emit code to throw to the outer context if we fall off
|
||
the end of the handler. */
|
||
expand_rethrow (entry->outer_context);
|
||
|
||
do_pending_stack_adjust ();
|
||
free (entry);
|
||
}
|
||
}
|
||
|
||
/* Called at the start of a block of try statements. */
|
||
void
|
||
expand_start_try_stmts ()
|
||
{
|
||
if (! doing_eh (1))
|
||
return;
|
||
|
||
expand_eh_region_start ();
|
||
}
|
||
|
||
/* Called to begin a catch clause. The parameter is the object which
|
||
will be passed to the runtime type check routine. */
|
||
void
|
||
start_catch_handler (rtime)
|
||
tree rtime;
|
||
{
|
||
rtx handler_label;
|
||
int insn_region_num;
|
||
int eh_region_entry;
|
||
|
||
if (! doing_eh (1))
|
||
return;
|
||
|
||
handler_label = catchstack.top->entry->exception_handler_label;
|
||
insn_region_num = CODE_LABEL_NUMBER (handler_label);
|
||
eh_region_entry = find_func_region (insn_region_num);
|
||
|
||
/* If we've already issued this label, pick a new one */
|
||
if (catchstack.top->entry->label_used)
|
||
handler_label = gen_exception_label ();
|
||
else
|
||
catchstack.top->entry->label_used = 1;
|
||
|
||
receive_exception_label (handler_label);
|
||
|
||
add_new_handler (eh_region_entry, get_new_handler (handler_label, rtime));
|
||
}
|
||
|
||
/* Generate RTL for the start of a group of catch clauses.
|
||
|
||
It is responsible for starting a new instruction sequence for the
|
||
instructions in the catch block, and expanding the handlers for the
|
||
internally-generated exception regions nested within the try block
|
||
corresponding to this catch block. */
|
||
|
||
void
|
||
expand_start_all_catch ()
|
||
{
|
||
struct eh_entry *entry;
|
||
tree label;
|
||
rtx outer_context;
|
||
|
||
if (! doing_eh (1))
|
||
return;
|
||
|
||
outer_context = ehstack.top->entry->outer_context;
|
||
|
||
/* End the try block. */
|
||
expand_eh_region_end (integer_zero_node);
|
||
|
||
emit_line_note (input_filename, lineno);
|
||
label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
|
||
|
||
/* The label for the exception handling block that we will save.
|
||
This is Lresume in the documentation. */
|
||
expand_label (label);
|
||
|
||
/* Push the label that points to where normal flow is resumed onto
|
||
the top of the label stack. */
|
||
push_label_entry (&caught_return_label_stack, NULL_RTX, label);
|
||
|
||
/* Start a new sequence for all the catch blocks. We will add this
|
||
to the global sequence catch_clauses when we have completed all
|
||
the handlers in this handler-seq. */
|
||
start_sequence ();
|
||
|
||
entry = dequeue_eh_entry (&ehqueue);
|
||
for ( ; entry->finalization != integer_zero_node;
|
||
entry = dequeue_eh_entry (&ehqueue))
|
||
{
|
||
rtx prev;
|
||
|
||
/* Emit the label for the cleanup handler for this region, and
|
||
expand the code for the handler.
|
||
|
||
Note that a catch region is handled as a side-effect here;
|
||
for a try block, entry->finalization will contain
|
||
integer_zero_node, so no code will be generated in the
|
||
expand_expr call below. But, the label for the handler will
|
||
still be emitted, so any code emitted after this point will
|
||
end up being the handler. */
|
||
|
||
receive_exception_label (entry->exception_handler_label);
|
||
|
||
/* register a handler for this cleanup region */
|
||
add_new_handler (
|
||
find_func_region (CODE_LABEL_NUMBER (entry->exception_handler_label)),
|
||
get_new_handler (entry->exception_handler_label, NULL));
|
||
|
||
/* And now generate the insns for the cleanup handler. */
|
||
expand_expr (entry->finalization, const0_rtx, VOIDmode, 0);
|
||
|
||
prev = get_last_insn ();
|
||
if (prev == NULL || GET_CODE (prev) != BARRIER)
|
||
/* Code to throw out to outer context when we fall off end
|
||
of the handler. We can't do this here for catch blocks,
|
||
so it's done in expand_end_all_catch instead. */
|
||
expand_rethrow (entry->outer_context);
|
||
|
||
do_pending_stack_adjust ();
|
||
free (entry);
|
||
}
|
||
|
||
/* At this point, all the cleanups are done, and the ehqueue now has
|
||
the current exception region at its head. We dequeue it, and put it
|
||
on the catch stack. */
|
||
|
||
push_entry (&catchstack, entry);
|
||
|
||
/* If we are not doing setjmp/longjmp EH, because we are reordered
|
||
out of line, we arrange to rethrow in the outer context. We need to
|
||
do this because we are not physically within the region, if any, that
|
||
logically contains this catch block. */
|
||
if (! exceptions_via_longjmp)
|
||
{
|
||
expand_eh_region_start ();
|
||
ehstack.top->entry->outer_context = outer_context;
|
||
}
|
||
|
||
/* We also have to start the handler if we aren't using the new model. */
|
||
if (! flag_new_exceptions)
|
||
start_catch_handler (NULL);
|
||
}
|
||
|
||
/* Finish up the catch block. At this point all the insns for the
|
||
catch clauses have already been generated, so we only have to add
|
||
them to the catch_clauses list. We also want to make sure that if
|
||
we fall off the end of the catch clauses that we rethrow to the
|
||
outer EH region. */
|
||
|
||
void
|
||
expand_end_all_catch ()
|
||
{
|
||
rtx new_catch_clause, outer_context = NULL_RTX;
|
||
struct eh_entry *entry;
|
||
|
||
if (! doing_eh (1))
|
||
return;
|
||
|
||
/* Dequeue the current catch clause region. */
|
||
entry = pop_eh_entry (&catchstack);
|
||
free (entry);
|
||
|
||
if (! exceptions_via_longjmp)
|
||
{
|
||
outer_context = ehstack.top->entry->outer_context;
|
||
|
||
/* Finish the rethrow region. size_zero_node is just a NOP. */
|
||
expand_eh_region_end (size_zero_node);
|
||
}
|
||
|
||
/* Code to throw out to outer context, if we fall off end of catch
|
||
handlers. This is rethrow (Lresume, same id, same obj) in the
|
||
documentation. We use Lresume because we know that it will throw
|
||
to the correct context.
|
||
|
||
In other words, if the catch handler doesn't exit or return, we
|
||
do a "throw" (using the address of Lresume as the point being
|
||
thrown from) so that the outer EH region can then try to process
|
||
the exception. */
|
||
expand_rethrow (outer_context);
|
||
|
||
/* Now we have the complete catch sequence. */
|
||
new_catch_clause = get_insns ();
|
||
end_sequence ();
|
||
|
||
/* This level of catch blocks is done, so set up the successful
|
||
catch jump label for the next layer of catch blocks. */
|
||
pop_label_entry (&caught_return_label_stack);
|
||
pop_label_entry (&outer_context_label_stack);
|
||
|
||
/* Add the new sequence of catches to the main one for this function. */
|
||
push_to_sequence (catch_clauses);
|
||
emit_insns (new_catch_clause);
|
||
catch_clauses = get_insns ();
|
||
end_sequence ();
|
||
|
||
/* Here we fall through into the continuation code. */
|
||
}
|
||
|
||
/* Rethrow from the outer context LABEL. */
|
||
|
||
static void
|
||
expand_rethrow (label)
|
||
rtx label;
|
||
{
|
||
if (exceptions_via_longjmp)
|
||
emit_throw ();
|
||
else
|
||
emit_jump (label);
|
||
}
|
||
|
||
/* End all the pending exception regions on protect_list. The handlers
|
||
will be emitted when expand_leftover_cleanups is invoked. */
|
||
|
||
void
|
||
end_protect_partials ()
|
||
{
|
||
while (protect_list)
|
||
{
|
||
expand_eh_region_end (TREE_VALUE (protect_list));
|
||
protect_list = TREE_CHAIN (protect_list);
|
||
}
|
||
}
|
||
|
||
/* Arrange for __terminate to be called if there is an unhandled throw
|
||
from within E. */
|
||
|
||
tree
|
||
protect_with_terminate (e)
|
||
tree e;
|
||
{
|
||
/* We only need to do this when using setjmp/longjmp EH and the
|
||
language requires it, as otherwise we protect all of the handlers
|
||
at once, if we need to. */
|
||
if (exceptions_via_longjmp && protect_cleanup_actions_with_terminate)
|
||
{
|
||
tree handler, result;
|
||
|
||
/* All cleanups must be on the function_obstack. */
|
||
push_obstacks_nochange ();
|
||
resume_temporary_allocation ();
|
||
|
||
handler = make_node (RTL_EXPR);
|
||
TREE_TYPE (handler) = void_type_node;
|
||
RTL_EXPR_RTL (handler) = const0_rtx;
|
||
TREE_SIDE_EFFECTS (handler) = 1;
|
||
start_sequence_for_rtl_expr (handler);
|
||
|
||
emit_library_call (terminate_libfunc, 0, VOIDmode, 0);
|
||
emit_barrier ();
|
||
|
||
RTL_EXPR_SEQUENCE (handler) = get_insns ();
|
||
end_sequence ();
|
||
|
||
result = build (TRY_CATCH_EXPR, TREE_TYPE (e), e, handler);
|
||
TREE_SIDE_EFFECTS (result) = TREE_SIDE_EFFECTS (e);
|
||
TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (e);
|
||
TREE_READONLY (result) = TREE_READONLY (e);
|
||
|
||
pop_obstacks ();
|
||
|
||
e = result;
|
||
}
|
||
|
||
return e;
|
||
}
|
||
|
||
/* The exception table that we build that is used for looking up and
|
||
dispatching exceptions, the current number of entries, and its
|
||
maximum size before we have to extend it.
|
||
|
||
The number in eh_table is the code label number of the exception
|
||
handler for the region. This is added by add_eh_table_entry and
|
||
used by output_exception_table_entry. */
|
||
|
||
static int *eh_table = NULL;
|
||
static int eh_table_size = 0;
|
||
static int eh_table_max_size = 0;
|
||
|
||
/* Note the need for an exception table entry for region N. If we
|
||
don't need to output an explicit exception table, avoid all of the
|
||
extra work.
|
||
|
||
Called from final_scan_insn when a NOTE_INSN_EH_REGION_BEG is seen.
|
||
(Or NOTE_INSN_EH_REGION_END sometimes)
|
||
N is the NOTE_BLOCK_NUMBER of the note, which comes from the code
|
||
label number of the exception handler for the region. */
|
||
|
||
void
|
||
add_eh_table_entry (n)
|
||
int n;
|
||
{
|
||
#ifndef OMIT_EH_TABLE
|
||
if (eh_table_size >= eh_table_max_size)
|
||
{
|
||
if (eh_table)
|
||
{
|
||
eh_table_max_size += eh_table_max_size>>1;
|
||
|
||
if (eh_table_max_size < 0)
|
||
abort ();
|
||
|
||
eh_table = (int *) xrealloc (eh_table,
|
||
eh_table_max_size * sizeof (int));
|
||
}
|
||
else
|
||
{
|
||
eh_table_max_size = 252;
|
||
eh_table = (int *) xmalloc (eh_table_max_size * sizeof (int));
|
||
}
|
||
}
|
||
eh_table[eh_table_size++] = n;
|
||
#endif
|
||
}
|
||
|
||
/* Return a non-zero value if we need to output an exception table.
|
||
|
||
On some platforms, we don't have to output a table explicitly.
|
||
This routine doesn't mean we don't have one. */
|
||
|
||
int
|
||
exception_table_p ()
|
||
{
|
||
if (eh_table)
|
||
return 1;
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Output the entry of the exception table corresponding to the
|
||
exception region numbered N to file FILE.
|
||
|
||
N is the code label number corresponding to the handler of the
|
||
region. */
|
||
|
||
static void
|
||
output_exception_table_entry (file, n)
|
||
FILE *file;
|
||
int n;
|
||
{
|
||
char buf[256];
|
||
rtx sym;
|
||
struct handler_info *handler;
|
||
|
||
handler = get_first_handler (n);
|
||
|
||
for ( ; handler != NULL; handler = handler->next)
|
||
{
|
||
ASM_GENERATE_INTERNAL_LABEL (buf, "LEHB", n);
|
||
sym = gen_rtx_SYMBOL_REF (Pmode, buf);
|
||
assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
|
||
|
||
ASM_GENERATE_INTERNAL_LABEL (buf, "LEHE", n);
|
||
sym = gen_rtx_SYMBOL_REF (Pmode, buf);
|
||
assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
|
||
|
||
assemble_integer (handler->handler_label,
|
||
POINTER_SIZE / BITS_PER_UNIT, 1);
|
||
|
||
if (flag_new_exceptions)
|
||
{
|
||
if (handler->type_info == NULL)
|
||
assemble_integer (const0_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
|
||
else
|
||
if (handler->type_info == CATCH_ALL_TYPE)
|
||
assemble_integer (GEN_INT (CATCH_ALL_TYPE),
|
||
POINTER_SIZE / BITS_PER_UNIT, 1);
|
||
else
|
||
output_constant ((tree)(handler->type_info),
|
||
POINTER_SIZE / BITS_PER_UNIT);
|
||
}
|
||
putc ('\n', file); /* blank line */
|
||
}
|
||
}
|
||
|
||
/* Output the exception table if we have and need one. */
|
||
|
||
static short language_code = 0;
|
||
static short version_code = 0;
|
||
|
||
/* This routine will set the language code for exceptions. */
|
||
void set_exception_lang_code (code)
|
||
short code;
|
||
{
|
||
language_code = code;
|
||
}
|
||
|
||
/* This routine will set the language version code for exceptions. */
|
||
void set_exception_version_code (code)
|
||
short code;
|
||
{
|
||
version_code = code;
|
||
}
|
||
|
||
|
||
void
|
||
output_exception_table ()
|
||
{
|
||
int i;
|
||
extern FILE *asm_out_file;
|
||
|
||
if (! doing_eh (0) || ! eh_table)
|
||
return;
|
||
|
||
exception_section ();
|
||
|
||
/* Beginning marker for table. */
|
||
assemble_align (GET_MODE_ALIGNMENT (ptr_mode));
|
||
assemble_label ("__EXCEPTION_TABLE__");
|
||
|
||
if (flag_new_exceptions)
|
||
{
|
||
assemble_integer (GEN_INT (NEW_EH_RUNTIME),
|
||
POINTER_SIZE / BITS_PER_UNIT, 1);
|
||
assemble_integer (GEN_INT (language_code), 2 , 1);
|
||
assemble_integer (GEN_INT (version_code), 2 , 1);
|
||
|
||
/* Add enough padding to make sure table aligns on a pointer boundry. */
|
||
i = GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT - 4;
|
||
for ( ; i < 0; i = i + GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT)
|
||
;
|
||
if (i != 0)
|
||
assemble_integer (const0_rtx, i , 1);
|
||
}
|
||
|
||
for (i = 0; i < eh_table_size; ++i)
|
||
output_exception_table_entry (asm_out_file, eh_table[i]);
|
||
|
||
free (eh_table);
|
||
clear_function_eh_region ();
|
||
|
||
/* Ending marker for table. */
|
||
assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
|
||
|
||
/* for binary compatability, the old __throw checked the second
|
||
position for a -1, so we should output at least 2 -1's */
|
||
if (! flag_new_exceptions)
|
||
assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
|
||
|
||
putc ('\n', asm_out_file); /* blank line */
|
||
}
|
||
|
||
/* Emit code to get EH context.
|
||
|
||
We have to scan thru the code to find possible EH context registers.
|
||
Inlined functions may use it too, and thus we'll have to be able
|
||
to change them too.
|
||
|
||
This is done only if using exceptions_via_longjmp. */
|
||
|
||
void
|
||
emit_eh_context ()
|
||
{
|
||
rtx insn;
|
||
rtx ehc = 0;
|
||
|
||
if (! doing_eh (0))
|
||
return;
|
||
|
||
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
|
||
if (GET_CODE (insn) == INSN
|
||
&& GET_CODE (PATTERN (insn)) == USE)
|
||
{
|
||
rtx reg = find_reg_note (insn, REG_EH_CONTEXT, 0);
|
||
if (reg)
|
||
{
|
||
rtx insns;
|
||
|
||
start_sequence ();
|
||
|
||
/* If this is the first use insn, emit the call here. This
|
||
will always be at the top of our function, because if
|
||
expand_inline_function notices a REG_EH_CONTEXT note, it
|
||
adds a use insn to this function as well. */
|
||
if (ehc == 0)
|
||
ehc = call_get_eh_context ();
|
||
|
||
emit_move_insn (XEXP (reg, 0), ehc);
|
||
insns = get_insns ();
|
||
end_sequence ();
|
||
|
||
emit_insns_before (insns, insn);
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Scan the current insns and build a list of handler labels. The
|
||
resulting list is placed in the global variable exception_handler_labels.
|
||
|
||
It is called after the last exception handling region is added to
|
||
the current function (when the rtl is almost all built for the
|
||
current function) and before the jump optimization pass. */
|
||
|
||
void
|
||
find_exception_handler_labels ()
|
||
{
|
||
rtx insn;
|
||
|
||
exception_handler_labels = NULL_RTX;
|
||
|
||
/* If we aren't doing exception handling, there isn't much to check. */
|
||
if (! doing_eh (0))
|
||
return;
|
||
|
||
/* For each start of a region, add its label to the list. */
|
||
|
||
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
|
||
{
|
||
struct handler_info* ptr;
|
||
if (GET_CODE (insn) == NOTE
|
||
&& NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
|
||
{
|
||
ptr = get_first_handler (NOTE_BLOCK_NUMBER (insn));
|
||
for ( ; ptr; ptr = ptr->next)
|
||
{
|
||
/* make sure label isn't in the list already */
|
||
rtx x;
|
||
for (x = exception_handler_labels; x; x = XEXP (x, 1))
|
||
if (XEXP (x, 0) == ptr->handler_label)
|
||
break;
|
||
if (! x)
|
||
exception_handler_labels = gen_rtx_EXPR_LIST (VOIDmode,
|
||
ptr->handler_label, exception_handler_labels);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Return a value of 1 if the parameter label number is an exception handler
|
||
label. Return 0 otherwise. */
|
||
|
||
int
|
||
is_exception_handler_label (lab)
|
||
int lab;
|
||
{
|
||
rtx x;
|
||
for (x = exception_handler_labels ; x ; x = XEXP (x, 1))
|
||
if (lab == CODE_LABEL_NUMBER (XEXP (x, 0)))
|
||
return 1;
|
||
return 0;
|
||
}
|
||
|
||
/* Perform sanity checking on the exception_handler_labels list.
|
||
|
||
Can be called after find_exception_handler_labels is called to
|
||
build the list of exception handlers for the current function and
|
||
before we finish processing the current function. */
|
||
|
||
void
|
||
check_exception_handler_labels ()
|
||
{
|
||
rtx insn, insn2;
|
||
|
||
/* If we aren't doing exception handling, there isn't much to check. */
|
||
if (! doing_eh (0))
|
||
return;
|
||
|
||
/* Make sure there is no more than 1 copy of a label */
|
||
for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
|
||
{
|
||
int count = 0;
|
||
for (insn2 = exception_handler_labels; insn2; insn2 = XEXP (insn2, 1))
|
||
if (XEXP (insn, 0) == XEXP (insn2, 0))
|
||
count++;
|
||
if (count != 1)
|
||
warning ("Counted %d copies of EH region %d in list.\n", count,
|
||
CODE_LABEL_NUMBER (insn));
|
||
}
|
||
|
||
}
|
||
|
||
/* This group of functions initializes the exception handling data
|
||
structures at the start of the compilation, initializes the data
|
||
structures at the start of a function, and saves and restores the
|
||
exception handling data structures for the start/end of a nested
|
||
function. */
|
||
|
||
/* Toplevel initialization for EH things. */
|
||
|
||
void
|
||
init_eh ()
|
||
{
|
||
}
|
||
|
||
/* Initialize the per-function EH information. */
|
||
|
||
void
|
||
init_eh_for_function ()
|
||
{
|
||
ehstack.top = 0;
|
||
catchstack.top = 0;
|
||
ehqueue.head = ehqueue.tail = 0;
|
||
catch_clauses = NULL_RTX;
|
||
false_label_stack = 0;
|
||
caught_return_label_stack = 0;
|
||
protect_list = NULL_TREE;
|
||
current_function_ehc = NULL_RTX;
|
||
}
|
||
|
||
/* Save some of the per-function EH info into the save area denoted by
|
||
P.
|
||
|
||
This is currently called from save_stmt_status. */
|
||
|
||
void
|
||
save_eh_status (p)
|
||
struct function *p;
|
||
{
|
||
if (p == NULL)
|
||
abort ();
|
||
|
||
p->ehstack = ehstack;
|
||
p->catchstack = catchstack;
|
||
p->ehqueue = ehqueue;
|
||
p->catch_clauses = catch_clauses;
|
||
p->false_label_stack = false_label_stack;
|
||
p->caught_return_label_stack = caught_return_label_stack;
|
||
p->protect_list = protect_list;
|
||
p->ehc = current_function_ehc;
|
||
|
||
init_eh_for_function ();
|
||
}
|
||
|
||
/* Restore the per-function EH info saved into the area denoted by P.
|
||
|
||
This is currently called from restore_stmt_status. */
|
||
|
||
void
|
||
restore_eh_status (p)
|
||
struct function *p;
|
||
{
|
||
if (p == NULL)
|
||
abort ();
|
||
|
||
protect_list = p->protect_list;
|
||
caught_return_label_stack = p->caught_return_label_stack;
|
||
false_label_stack = p->false_label_stack;
|
||
catch_clauses = p->catch_clauses;
|
||
ehqueue = p->ehqueue;
|
||
ehstack = p->ehstack;
|
||
catchstack = p->catchstack;
|
||
current_function_ehc = p->ehc;
|
||
}
|
||
|
||
/* This section is for the exception handling specific optimization
|
||
pass. First are the internal routines, and then the main
|
||
optimization pass. */
|
||
|
||
/* Determine if the given INSN can throw an exception. */
|
||
|
||
static int
|
||
can_throw (insn)
|
||
rtx insn;
|
||
{
|
||
/* Calls can always potentially throw exceptions. */
|
||
if (GET_CODE (insn) == CALL_INSN)
|
||
return 1;
|
||
|
||
if (asynchronous_exceptions)
|
||
{
|
||
/* If we wanted asynchronous exceptions, then everything but NOTEs
|
||
and CODE_LABELs could throw. */
|
||
if (GET_CODE (insn) != NOTE && GET_CODE (insn) != CODE_LABEL)
|
||
return 1;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
/* Scan a exception region looking for the matching end and then
|
||
remove it if possible. INSN is the start of the region, N is the
|
||
region number, and DELETE_OUTER is to note if anything in this
|
||
region can throw.
|
||
|
||
Regions are removed if they cannot possibly catch an exception.
|
||
This is determined by invoking can_throw on each insn within the
|
||
region; if can_throw returns true for any of the instructions, the
|
||
region can catch an exception, since there is an insn within the
|
||
region that is capable of throwing an exception.
|
||
|
||
Returns the NOTE_INSN_EH_REGION_END corresponding to this region, or
|
||
calls abort if it can't find one.
|
||
|
||
Can abort if INSN is not a NOTE_INSN_EH_REGION_BEGIN, or if N doesn't
|
||
correspond to the region number, or if DELETE_OUTER is NULL. */
|
||
|
||
static rtx
|
||
scan_region (insn, n, delete_outer)
|
||
rtx insn;
|
||
int n;
|
||
int *delete_outer;
|
||
{
|
||
rtx start = insn;
|
||
|
||
/* Assume we can delete the region. */
|
||
int delete = 1;
|
||
|
||
if (insn == NULL_RTX
|
||
|| GET_CODE (insn) != NOTE
|
||
|| NOTE_LINE_NUMBER (insn) != NOTE_INSN_EH_REGION_BEG
|
||
|| NOTE_BLOCK_NUMBER (insn) != n
|
||
|| delete_outer == NULL)
|
||
abort ();
|
||
|
||
insn = NEXT_INSN (insn);
|
||
|
||
/* Look for the matching end. */
|
||
while (! (GET_CODE (insn) == NOTE
|
||
&& NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
|
||
{
|
||
/* If anything can throw, we can't remove the region. */
|
||
if (delete && can_throw (insn))
|
||
{
|
||
delete = 0;
|
||
}
|
||
|
||
/* Watch out for and handle nested regions. */
|
||
if (GET_CODE (insn) == NOTE
|
||
&& NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
|
||
{
|
||
insn = scan_region (insn, NOTE_BLOCK_NUMBER (insn), &delete);
|
||
}
|
||
|
||
insn = NEXT_INSN (insn);
|
||
}
|
||
|
||
/* The _BEG/_END NOTEs must match and nest. */
|
||
if (NOTE_BLOCK_NUMBER (insn) != n)
|
||
abort ();
|
||
|
||
/* If anything in this exception region can throw, we can throw. */
|
||
if (! delete)
|
||
*delete_outer = 0;
|
||
else
|
||
{
|
||
/* Delete the start and end of the region. */
|
||
delete_insn (start);
|
||
delete_insn (insn);
|
||
|
||
/* We no longer removed labels here, since flow will now remove any
|
||
handler which cannot be called any more. */
|
||
|
||
#if 0
|
||
/* Only do this part if we have built the exception handler
|
||
labels. */
|
||
if (exception_handler_labels)
|
||
{
|
||
rtx x, *prev = &exception_handler_labels;
|
||
|
||
/* Find it in the list of handlers. */
|
||
for (x = exception_handler_labels; x; x = XEXP (x, 1))
|
||
{
|
||
rtx label = XEXP (x, 0);
|
||
if (CODE_LABEL_NUMBER (label) == n)
|
||
{
|
||
/* If we are the last reference to the handler,
|
||
delete it. */
|
||
if (--LABEL_NUSES (label) == 0)
|
||
delete_insn (label);
|
||
|
||
if (optimize)
|
||
{
|
||
/* Remove it from the list of exception handler
|
||
labels, if we are optimizing. If we are not, then
|
||
leave it in the list, as we are not really going to
|
||
remove the region. */
|
||
*prev = XEXP (x, 1);
|
||
XEXP (x, 1) = 0;
|
||
XEXP (x, 0) = 0;
|
||
}
|
||
|
||
break;
|
||
}
|
||
prev = &XEXP (x, 1);
|
||
}
|
||
}
|
||
#endif
|
||
}
|
||
return insn;
|
||
}
|
||
|
||
/* Perform various interesting optimizations for exception handling
|
||
code.
|
||
|
||
We look for empty exception regions and make them go (away). The
|
||
jump optimization code will remove the handler if nothing else uses
|
||
it. */
|
||
|
||
void
|
||
exception_optimize ()
|
||
{
|
||
rtx insn;
|
||
int n;
|
||
|
||
/* Remove empty regions. */
|
||
for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
|
||
{
|
||
if (GET_CODE (insn) == NOTE
|
||
&& NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
|
||
{
|
||
/* Since scan_region will return the NOTE_INSN_EH_REGION_END
|
||
insn, we will indirectly skip through all the insns
|
||
inbetween. We are also guaranteed that the value of insn
|
||
returned will be valid, as otherwise scan_region won't
|
||
return. */
|
||
insn = scan_region (insn, NOTE_BLOCK_NUMBER (insn), &n);
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Various hooks for the DWARF 2 __throw routine. */
|
||
|
||
/* Do any necessary initialization to access arbitrary stack frames.
|
||
On the SPARC, this means flushing the register windows. */
|
||
|
||
void
|
||
expand_builtin_unwind_init ()
|
||
{
|
||
/* Set this so all the registers get saved in our frame; we need to be
|
||
able to copy the saved values for any registers from frames we unwind. */
|
||
current_function_has_nonlocal_label = 1;
|
||
|
||
#ifdef SETUP_FRAME_ADDRESSES
|
||
SETUP_FRAME_ADDRESSES ();
|
||
#endif
|
||
}
|
||
|
||
/* Given a value extracted from the return address register or stack slot,
|
||
return the actual address encoded in that value. */
|
||
|
||
rtx
|
||
expand_builtin_extract_return_addr (addr_tree)
|
||
tree addr_tree;
|
||
{
|
||
rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0);
|
||
return eh_outer_context (addr);
|
||
}
|
||
|
||
/* Given an actual address in addr_tree, do any necessary encoding
|
||
and return the value to be stored in the return address register or
|
||
stack slot so the epilogue will return to that address. */
|
||
|
||
rtx
|
||
expand_builtin_frob_return_addr (addr_tree)
|
||
tree addr_tree;
|
||
{
|
||
rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0);
|
||
#ifdef RETURN_ADDR_OFFSET
|
||
addr = plus_constant (addr, -RETURN_ADDR_OFFSET);
|
||
#endif
|
||
return addr;
|
||
}
|
||
|
||
/* Given an actual address in addr_tree, set the return address register up
|
||
so the epilogue will return to that address. If the return address is
|
||
not in a register, do nothing. */
|
||
|
||
void
|
||
expand_builtin_set_return_addr_reg (addr_tree)
|
||
tree addr_tree;
|
||
{
|
||
rtx tmp;
|
||
rtx ra = expand_builtin_return_addr (BUILT_IN_RETURN_ADDRESS,
|
||
0, hard_frame_pointer_rtx);
|
||
|
||
if (GET_CODE (ra) != REG || REGNO (ra) >= FIRST_PSEUDO_REGISTER)
|
||
return;
|
||
|
||
tmp = force_operand (expand_builtin_frob_return_addr (addr_tree), ra);
|
||
if (tmp != ra)
|
||
emit_move_insn (ra, tmp);
|
||
}
|
||
|
||
/* Choose two registers for communication between the main body of
|
||
__throw and the stub for adjusting the stack pointer. The first register
|
||
is used to pass the address of the exception handler; the second register
|
||
is used to pass the stack pointer offset.
|
||
|
||
For register 1 we use the return value register for a void *.
|
||
For register 2 we use the static chain register if it exists and is
|
||
different from register 1, otherwise some arbitrary call-clobbered
|
||
register. */
|
||
|
||
static void
|
||
eh_regs (r1, r2, outgoing)
|
||
rtx *r1, *r2;
|
||
int outgoing;
|
||
{
|
||
rtx reg1, reg2;
|
||
|
||
#ifdef FUNCTION_OUTGOING_VALUE
|
||
if (outgoing)
|
||
reg1 = FUNCTION_OUTGOING_VALUE (build_pointer_type (void_type_node),
|
||
current_function_decl);
|
||
else
|
||
#endif
|
||
reg1 = FUNCTION_VALUE (build_pointer_type (void_type_node),
|
||
current_function_decl);
|
||
|
||
#ifdef STATIC_CHAIN_REGNUM
|
||
if (outgoing)
|
||
reg2 = static_chain_incoming_rtx;
|
||
else
|
||
reg2 = static_chain_rtx;
|
||
if (REGNO (reg2) == REGNO (reg1))
|
||
#endif /* STATIC_CHAIN_REGNUM */
|
||
reg2 = NULL_RTX;
|
||
|
||
if (reg2 == NULL_RTX)
|
||
{
|
||
int i;
|
||
for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
|
||
if (call_used_regs[i] && ! fixed_regs[i] && i != REGNO (reg1))
|
||
{
|
||
reg2 = gen_rtx_REG (Pmode, i);
|
||
break;
|
||
}
|
||
|
||
if (reg2 == NULL_RTX)
|
||
abort ();
|
||
}
|
||
|
||
*r1 = reg1;
|
||
*r2 = reg2;
|
||
}
|
||
|
||
|
||
/* Retrieve the register which contains the pointer to the eh_context
|
||
structure set the __throw. */
|
||
|
||
rtx
|
||
get_reg_for_handler ()
|
||
{
|
||
rtx reg1;
|
||
reg1 = FUNCTION_VALUE (build_pointer_type (void_type_node),
|
||
current_function_decl);
|
||
return reg1;
|
||
}
|
||
|
||
|
||
/* Emit inside of __throw a stub which adjusts the stack pointer and jumps
|
||
to the exception handler. __throw will set up the necessary values
|
||
and then return to the stub. */
|
||
|
||
rtx
|
||
expand_builtin_eh_stub_old ()
|
||
{
|
||
rtx stub_start = gen_label_rtx ();
|
||
rtx after_stub = gen_label_rtx ();
|
||
rtx handler, offset;
|
||
|
||
emit_jump (after_stub);
|
||
emit_label (stub_start);
|
||
|
||
eh_regs (&handler, &offset, 0);
|
||
|
||
adjust_stack (offset);
|
||
emit_indirect_jump (handler);
|
||
emit_label (after_stub);
|
||
return gen_rtx_LABEL_REF (Pmode, stub_start);
|
||
}
|
||
|
||
rtx
|
||
expand_builtin_eh_stub ()
|
||
{
|
||
rtx stub_start = gen_label_rtx ();
|
||
rtx after_stub = gen_label_rtx ();
|
||
rtx handler, offset;
|
||
rtx temp;
|
||
|
||
emit_jump (after_stub);
|
||
emit_label (stub_start);
|
||
|
||
eh_regs (&handler, &offset, 0);
|
||
|
||
adjust_stack (offset);
|
||
|
||
/* Handler is in fact a pointer to the _eh_context structure, we need
|
||
to pick out the handler field (first element), and jump to there,
|
||
leaving the pointer to _eh_conext in the same hardware register. */
|
||
|
||
temp = gen_rtx_MEM (Pmode, handler);
|
||
MEM_IN_STRUCT_P (temp) = 1;
|
||
RTX_UNCHANGING_P (temp) = 1;
|
||
emit_move_insn (offset, temp);
|
||
emit_insn (gen_rtx_USE (Pmode, handler));
|
||
|
||
emit_indirect_jump (offset);
|
||
|
||
emit_label (after_stub);
|
||
return gen_rtx_LABEL_REF (Pmode, stub_start);
|
||
}
|
||
|
||
/* Set up the registers for passing the handler address and stack offset
|
||
to the stub above. */
|
||
|
||
void
|
||
expand_builtin_set_eh_regs (handler, offset)
|
||
tree handler, offset;
|
||
{
|
||
rtx reg1, reg2;
|
||
|
||
eh_regs (®1, ®2, 1);
|
||
|
||
store_expr (offset, reg2, 0);
|
||
store_expr (handler, reg1, 0);
|
||
|
||
/* These will be used by the stub. */
|
||
emit_insn (gen_rtx_USE (VOIDmode, reg1));
|
||
emit_insn (gen_rtx_USE (VOIDmode, reg2));
|
||
}
|
||
|
||
|
||
|
||
/* This contains the code required to verify whether arbitrary instructions
|
||
are in the same exception region. */
|
||
|
||
static int *insn_eh_region = (int *)0;
|
||
static int maximum_uid;
|
||
|
||
static void
|
||
set_insn_eh_region (first, region_num)
|
||
rtx *first;
|
||
int region_num;
|
||
{
|
||
rtx insn;
|
||
int rnum;
|
||
|
||
for (insn = *first; insn; insn = NEXT_INSN (insn))
|
||
{
|
||
if ((GET_CODE (insn) == NOTE) &&
|
||
(NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG))
|
||
{
|
||
rnum = NOTE_BLOCK_NUMBER (insn);
|
||
insn_eh_region[INSN_UID (insn)] = rnum;
|
||
insn = NEXT_INSN (insn);
|
||
set_insn_eh_region (&insn, rnum);
|
||
/* Upon return, insn points to the EH_REGION_END of nested region */
|
||
continue;
|
||
}
|
||
insn_eh_region[INSN_UID (insn)] = region_num;
|
||
if ((GET_CODE (insn) == NOTE) &&
|
||
(NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
|
||
break;
|
||
}
|
||
*first = insn;
|
||
}
|
||
|
||
/* Free the insn table, an make sure it cannot be used again. */
|
||
|
||
void
|
||
free_insn_eh_region ()
|
||
{
|
||
if (!doing_eh (0))
|
||
return;
|
||
|
||
if (insn_eh_region)
|
||
{
|
||
free (insn_eh_region);
|
||
insn_eh_region = (int *)0;
|
||
}
|
||
}
|
||
|
||
/* Initialize the table. max_uid must be calculated and handed into
|
||
this routine. If it is unavailable, passing a value of 0 will
|
||
cause this routine to calculate it as well. */
|
||
|
||
void
|
||
init_insn_eh_region (first, max_uid)
|
||
rtx first;
|
||
int max_uid;
|
||
{
|
||
rtx insn;
|
||
|
||
if (!doing_eh (0))
|
||
return;
|
||
|
||
if (insn_eh_region)
|
||
free_insn_eh_region();
|
||
|
||
if (max_uid == 0)
|
||
for (insn = first; insn; insn = NEXT_INSN (insn))
|
||
if (INSN_UID (insn) > max_uid) /* find largest UID */
|
||
max_uid = INSN_UID (insn);
|
||
|
||
maximum_uid = max_uid;
|
||
insn_eh_region = (int *) malloc ((max_uid + 1) * sizeof (int));
|
||
insn = first;
|
||
set_insn_eh_region (&insn, 0);
|
||
}
|
||
|
||
|
||
/* Check whether 2 instructions are within the same region. */
|
||
|
||
int
|
||
in_same_eh_region (insn1, insn2)
|
||
rtx insn1, insn2;
|
||
{
|
||
int ret, uid1, uid2;
|
||
|
||
/* If no exceptions, instructions are always in same region. */
|
||
if (!doing_eh (0))
|
||
return 1;
|
||
|
||
/* If the table isn't allocated, assume the worst. */
|
||
if (!insn_eh_region)
|
||
return 0;
|
||
|
||
uid1 = INSN_UID (insn1);
|
||
uid2 = INSN_UID (insn2);
|
||
|
||
/* if instructions have been allocated beyond the end, either
|
||
the table is out of date, or this is a late addition, or
|
||
something... Assume the worst. */
|
||
if (uid1 > maximum_uid || uid2 > maximum_uid)
|
||
return 0;
|
||
|
||
ret = (insn_eh_region[uid1] == insn_eh_region[uid2]);
|
||
return ret;
|
||
}
|
||
|