Issue 230103.1: Clarify that DW_CFA_remember_state includes the current CFA
| Author: | Fangrui Song |
|---|---|
| Champion: | Fangrui Song |
| Date submitted: | 2023-01-03 |
| Date revised: | 2023-07-24 |
| Date closed: | 2023-07-04 |
| Type: | Clarification |
| Status: | Accepted |
| DWARF Version: | 6 |
Section 6.4.2.4, pg 181
p181 6.4.2.4 Row State Instructions describes the required actions for
DW_CFA_remember_state and DW_CFA_restore_state:
DW_CFA_remember_state
TheDW_CFA_remember_stateinstruction takes no operands. The required action is to push the set of rules for every register onto an implicit stack.
DW_CFA_restore_state
TheDW_CFA_restore_stateinstruction takes no operands. The required action is to pop the set of rules off the implicit stack and place them in the current row.
The description of DW_CFA_remember_state should take the current CFA into
account. Suggested change:
DW_CFA_remember_stateTheDW_CFA_remember_stateinstruction takes no operands. The required action is to push the set of rules for the current CFA and every register onto an implicit stack.
The description of DW_CFA_restore_state can remain as is as "the set of
rules" clearly includes the current CFA described by DW_CFA_remember_state.
The stack implementations of libunwind src/dwarf/Gparser.c, gcc
libgcc/unwind-dw2.c, and llvm-project libunwind/src/DwarfParser.hpp all
include the current CFA in the implicit stack.
2023-07-24: Accepted.
