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. --- gcc/config/aarch64/aarch64.cc | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc index b91f77d7b1f..9fb94623693 100644 --- a/gcc/config/aarch64/aarch64.cc +++ b/gcc/config/aarch64/aarch64.cc @@ -10034,7 +10034,6 @@ aarch64_expand_prologue (void) poly_int64 initial_adjust = frame.initial_adjust; HOST_WIDE_INT callee_adjust = frame.callee_adjust; poly_int64 final_adjust = frame.final_adjust; - poly_int64 callee_offset = frame.callee_offset; poly_int64 sve_callee_adjust = frame.sve_callee_adjust; poly_int64 below_hard_fp_saved_regs_size = frame.below_hard_fp_saved_regs_size; @@ -10147,8 +10146,7 @@ aarch64_expand_prologue (void) implicit. */ if (!find_reg_note (insn, REG_CFA_ADJUST_CFA, NULL_RTX)) { - rtx src = plus_constant (Pmode, stack_pointer_rtx, - callee_offset); + rtx src = plus_constant (Pmode, stack_pointer_rtx, chain_offset); add_reg_note (insn, REG_CFA_ADJUST_CFA, gen_rtx_SET (hard_frame_pointer_rtx, src)); } -- 2.25.1