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From 89a9fa287706c5011f61926eaf65e7b996b963a3 Mon Sep 17 00:00:00 2001
From: Richard Sandiford <richard.sandiford@arm.com>
Date: Tue, 12 Sep 2023 16:07:12 +0100
Subject: [PATCH 15/32] 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.
---
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 5d473d161d97..4f233c95140e 100644
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -9985,7 +9985,6 @@ 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;
@@ -10098,8 +10097,7 @@ 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));
}
--
2.42.0
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