.cfi_startproc [simple].cfi_startproc is used at the beginning of each function that
should have an entry in .eh_frame. It initializes some internal
data structures. Don't forget to close the function by
.cfi_endproc.
Unless .cfi_startproc is used along with parameter simple
it also emits some architecture dependent initial CFI instructions.
.cfi_endproc.cfi_endproc is used at the end of a function where it closes its
unwind entry previously opened by
.cfi_startproc, and emits it to .eh_frame.
.cfi_personality encoding [, exp].cfi_personality defines personality routine and its encoding.
encoding must be a constant determining how the personality
should be encoded. If it is 255 (DW_EH_PE_omit), second
argument is not present, otherwise second argument should be
a constant or a symbol name. When using indirect encodings,
the symbol provided should be the location where personality
can be loaded from, not the personality routine itself.
The default after .cfi_startproc is .cfi_personality 0xff,
no personality routine.
.cfi_lsda encoding [, exp].cfi_lsda defines LSDA and its encoding.
encoding must be a constant determining how the LSDA
should be encoded. If it is 255 (DW_EH_PE_omit), second
argument is not present, otherwise second argument should be a constant
or a symbol name. The default after .cfi_startproc is .cfi_lsda 0xff,
no LSDA.
.cfi_def_cfa register, offset.cfi_def_cfa defines a rule for computing CFA as: take
address from register and add offset to it.
.cfi_def_cfa_register register.cfi_def_cfa_register modifies a rule for computing CFA. From
now on register will be used instead of the old one. Offset
remains the same.
.cfi_def_cfa_offset offset.cfi_def_cfa_offset modifies a rule for computing CFA. Register
remains the same, but offset is new. Note that it is the
absolute offset that will be added to a defined register to compute
CFA address.
.cfi_adjust_cfa_offset offsetSame as .cfi_def_cfa_offset but offset is a relative
value that is added/substracted from the previous offset.
.cfi_offset register, offsetPrevious value of register is saved at offset offset from CFA.
.cfi_rel_offset register, offsetPrevious value of register is saved at offset offset from
the current CFA register. This is transformed to .cfi_offset
using the known displacement of the CFA register from the CFA.
This is often easier to use, because the number will match the
code it's annotating.
.cfi_register register1, register2Previous value of register1 is saved in register register2.
.cfi_restore register.cfi_restore says that the rule for register is now the
same as it was at the beginning of the function, after all initial
instruction added by .cfi_startproc were executed.
.cfi_undefined registerFrom now on the previous value of register can't be restored anymore.
.cfi_same_value registerCurrent value of register is the same like in the previous frame, i.e. no restoration needed.
.cfi_remember_state,First save all current rules for all registers by .cfi_remember_state,
then totally screw them up by subsequent .cfi_* directives and when
everything is hopelessly bad, use .cfi_restore_state to restore
the previous saved state.
.cfi_return_column registerChange return column register, i.e. the return address is either directly in register or can be accessed by rules for register.
.cfi_signal_frameMark current function as signal trampoline.
.cfi_window_saveSPARC register window has been saved.
.cfi_escape expression[, ...]Allows the user to add arbitrary bytes to the unwind info. One might use this to add OS-specific CFI opcodes, or generic CFI opcodes that GAS does not yet support.
.cfi_val_encoded_addr register, encoding, labelThe current value of register is label. The value of label
will be encoded in the output file according to encoding; see the
description of .cfi_personality for details on this encoding.
The usefulness of equating a register to a fixed label is probably limited to the return address register. Here, it can be useful to mark a code segment that has only one return address which is reached by a direct branch and no copy of the return address exists in memory or another register.