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(gcc-295.info)Exception Region Output

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Assembler Commands for Exception Regions
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   This describes commands marking the start and the end of an exception
region.

`ASM_OUTPUT_EH_REGION_BEG ()'
     A C expression to output text to mark the start of an exception
     region.

     This macro need not be defined on most platforms.

`ASM_OUTPUT_EH_REGION_END ()'
     A C expression to output text to mark the end of an exception
     region.

     This macro need not be defined on most platforms.

`EXCEPTION_SECTION ()'
     A C expression to switch to the section in which the main
     exception table is to be placed (Note: Sections.).  The default
     is a section named `.gcc_except_table' on machines that support
     named sections via `ASM_OUTPUT_SECTION_NAME', otherwise if `-fpic'
     or `-fPIC' is in effect, the `data_section', otherwise the
     `readonly_data_section'.

`EH_FRAME_SECTION_ASM_OP'
     If defined, a C string constant for the assembler operation to
     switch to the section for exception handling frame unwind
     information.  If not defined, GNU CC will provide a default
     definition if the target supports named sections.  `crtstuff.c'
     uses this macro to switch to the appropriate section.

     You should define this symbol if your target supports DWARF 2 frame
     unwind information and the default definition does not work.

`OMIT_EH_TABLE ()'
     A C expression that is nonzero if the normal exception table output
     should be omitted.

     This macro need not be defined on most platforms.

`EH_TABLE_LOOKUP ()'
     Alternate runtime support for looking up an exception at runtime
     and finding the associated handler, if the default method won't
     work.

     This macro need not be defined on most platforms.

`DOESNT_NEED_UNWINDER'
     A C expression that decides whether or not the current function
     needs to have a function unwinder generated for it.  See the file
     `except.c' for details on when to define this, and how.

`MASK_RETURN_ADDR'
     An rtx used to mask the return address found via RETURN_ADDR_RTX,
     so that it does not contain any extraneous set bits in it.

`DWARF2_UNWIND_INFO'
     Define this macro to 0 if your target supports DWARF 2 frame unwind
     information, but it does not yet work with exception handling.
     Otherwise, if your target supports this information (if it defines
     `INCOMING_RETURN_ADDR_RTX' and either `UNALIGNED_INT_ASM_OP' or
     `OBJECT_FORMAT_ELF'), GCC will provide a default definition of 1.

     If this macro is defined to 1, the DWARF 2 unwinder will be the
     default exception handling mechanism; otherwise, setjmp/longjmp
     will be used by default.

     If this macro is defined to anything, the DWARF 2 unwinder will be
     used instead of inline unwinders and __unwind_function in the
     non-setjmp case.