Chapter 8. Assembler Directives

45

The syntax for

.comm

differs slightly on the HPPA. The syntax is

symbol .comm, length

;

symbol

is optional.

8.9.

.cfi_startproc

.cfi_startproc

is used at the beginning of each function that should have an entry in

.eh_frame

.

It initializes some internal data structures and emits architecture dependent initial CFI instructions.

Don't forget to close the function by

.cfi_endproc

.

8.10.

.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

.

8.11.

.cfi_def_cfa register, offset

.cfi_def_cfa

defines a rule for computing CFA as: take address from register and add offset to it.

8.12.

.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.

8.13.

.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.

8.14.

.cfi_adjust_cfa_offset offset

Same as

.cfi_def_cfa_offset

but

offset

is a relative value that is added/substracted from the

previous offset.

8.15.

.cfi_offset register, offset

Previous value of

register

is saved at offset

offset

from CFA.

8.16.

.cfi_rel_offset register, offset

Previous value of

register

is saved at offset

offset

from the current CFA register. This is trans 

formed 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.