21.17.9 Assembler Commands for Exception Regions

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 (see section 21.15 Dividing the Output into Sections (Texts, Data, ...)). 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, including spacing, for the assembler operation to switch to the section for exception handling frame unwind information. If not defined, GCC 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.

DWARF_CIE_DATA_ALIGNMENT

This macro need only be defined if the target might save registers in the function prologue at an offset to the stack pointer that is not aligned to UNITS_PER_WORD. The definition should be the negative minimum alignment if STACK_GROWS_DOWNWARD is defined, and the positive minimum alignment otherwise. See section 21.18.5 Macros for SDB and DWARF Output. Only applicable if the target supports DWARF 2 frame unwind information.