gas: scfi: make scfi_state_restore_reg function more precise

When the SCFI machinery detects that a register has been restored from
stack, it makes some state changes in the SCFI state object.

Prior to the patch, scfi_state_restore_reg () was setting a value of
(reg, CFI_IN_REG) for (base, state) respectively.  This was causing
issues in the cmp_scfi_state () function:
  - The default state of all (callee-saved) regs at the beginning of
    function is set to (0, CFI_UNDEFINED).
  - If a register is saved and restored on some control path, the state
    of reg is (reg, CFI_IN_REG) on that path.
  - On another control path where the register was perhaps not
    used (or saved/restored on stack) remains (0, CFI_UNDEFINED).
  - The two states should be treated equal, however, at the point in
    program after the register has been restored.

Fix this by resetting the state to (0, CFI_UNDEFINED) in
scfi_state_restore_reg ().

A testcase (scfi-cfg-4.s) for this is added in a subsequent commit.

gas/
        * scfi.c (scfi_state_restore_reg): Reset to 0, CFI_UNDEFINED
	for base, state.

0 files changed, 0 insertions, 0 deletions