This describes commands marking the start and the end of an exception region.
If defined, a C string constant for the name of the section containing 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.
If defined, DWARF 2 frame unwind information will be placed in the data section even though the target supports named sections. This might be necessary, for instance, if the system linker does garbage collection and sections cannot be marked as not to be collected.
Do not define this macro unless
TARGET_ASM_NAMED_SECTIONis also defined.
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.
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,
longjmpwill be used by default.
If this macro is defined to anything, the DWARF 2 unwinder will be used instead of inline unwinders and
__unwind_functionin the non-
This macro need only be defined if
DWARF2_UNWIND_INFOis runtime-variable. In that case, except.h cannot correctly determine the corresponding definition of
MUST_USE_SJLJ_EXCEPTIONS, so the target must provide it directly.
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_DOWNWARDis defined, and the positive minimum alignment otherwise. See SDB and DWARF. Only applicable if the target supports DWARF 2 frame unwind information.
If defined, a function that switches to the section in which the main exception table is to be placed (see Sections). The default is a function that switches to a section named
.gcc_except_tableon machines that support named sections via
TARGET_ASM_NAMED_SECTION, otherwise if -fpic or -fPIC is in effect, the
data_section, otherwise the
If defined, a function that switches to the section in which the DWARF 2 frame unwind information to be placed (see Sections). The default is a function that outputs a standard GAS section directive, if
EH_FRAME_SECTION_NAMEis defined, or else a data section directive followed by a synthetic label.
Contains the value true if the target should add a zero word onto the end of a Dwarf-2 frame info section when used for exception handling. Default value is false if
EH_FRAME_SECTION_NAMEis defined, and true otherwise.
Given a register, this hook should return a parallel of registers to represent where to find the register pieces. Define this hook if the register and its mode are represented in Dwarf in non-contiguous locations, or if the register should be represented in more than one register in Dwarf. Otherwise, this hook should return
NULL_RTX. If not defined, the default is to return