gas: Skip SFrame FDE if FP without RA on stack

The SFrame format cannot represent the frame pointer (FP) being saved
on the stack without the return address (RA) also being saved on the
stack, if RA tracking is used.

A SFrame FDE is followed by 1-3 offsets with the following information:

Without RA tracking:
1. Offset from base pointer (SP or FP) to locate the CFA
2. Optional: Offset to CFA to restore the frame pointer (FP)

With RA tracking:
1. Offset from base pointer (SP or FP) to locate the CFA
2. Optional: Offset to CFA to restore the return address (RA)
3. Optional: Offset to CFA to restore the frame pointer (FP)

When RA tracking is used and a FDE is followed by two offsets the
SFrame format does not provide any information to distinguish whether
the second offset is the RA or FP offset. SFrame assumes the offset to
be the RA offset, which may be wrong.

Therefore skip generation of SFrame FDE information and print the
following warning, if RA tracking is used and the FP is saved on the
stack without the RA being saved as well:

  skipping SFrame FDE; FP without RA on stack

gas/
	* gen-sframe.c (sframe_do_fde): Skip SFrame FDE if FP without RA
	on stack, as the SFrame format cannot represent this case.

Signed-off-by: Jens Remus <jremus@linux.ibm.com>

0 files changed, 0 insertions, 0 deletions