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From: Richard Sandiford <rsandifo@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-9856] aarch64: Avoid a use of callee_offset Date: Tue, 12 Sep 2023 15:09:30 +0000 (GMT) [thread overview] Message-ID: <20230912150930.517533858C31@sourceware.org> (raw) https://gcc.gnu.org/g:12a8889de169f892d2e927584c00d20b8b7e456f commit r12-9856-g12a8889de169f892d2e927584c00d20b8b7e456f Author: Richard Sandiford <richard.sandiford@arm.com> Date: Tue Sep 12 16:08:49 2023 +0100 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. Diff: --- 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 ae42ffdedbeb..79253322fd7c 100644 --- a/gcc/config/aarch64/aarch64.cc +++ b/gcc/config/aarch64/aarch64.cc @@ -9670,7 +9670,6 @@ 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; @@ -9783,8 +9782,7 @@ 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)); }
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