aarch64: Avoid a use of callee_offset

When we emit the frame chain, i.e. when we reach Here in this statement
of aarch64_expand_prologue:

  if (emit_frame_chain)
    {
      // Here
      ...
    }

the stack is in one of two states:

- We've allocated up to the frame chain, but no more.

- We've allocated the whole frame, and the frame chain is within easy
  reach of the new SP.

The offset of the frame chain from the current SP is available
in aarch64_frame as callee_offset.  It is also available as the
chain_offset local variable, where the latter is calculated from other
data.  (However, chain_offset is not always equal to callee_offset when
!emit_frame_chain, so chain_offset isn't redundant.)

In c600df9a4060da3c6121ff4d0b93f179eafd69d1 I switched to using
chain_offset for the initialisation of the hard frame pointer:

       aarch64_add_offset (Pmode, hard_frame_pointer_rtx,
-                         stack_pointer_rtx, callee_offset,
+                         stack_pointer_rtx, chain_offset,
                          tmp1_rtx, tmp0_rtx, frame_pointer_needed);

But the later REG_CFA_ADJUST_CFA handling still used callee_offset.

I think the difference is harmless, but it's more logical for the
CFA note to be in sync, and it's more convenient for later patches
if it uses chain_offset.

gcc/
	* config/aarch64/aarch64.cc (aarch64_expand_prologue): Use
	chain_offset rather than callee_offset.

0 files changed, 0 insertions, 0 deletions