[PATCH] LoongArch: Fix bug in loongarch_emit_stack_tie [PR110484].

[PATCH] LoongArch: Fix bug in loongarch_emit_stack_tie [PR110484].

[chenglulu]

From: Lulu Cheng <chenglulu@loongson.cn>

Which may result in implicit references to $fp when frame_pointer_needed is false,
causing regs_ever_live[$fp] to be true when $fp is not explicitly used,
resulting in $fp being used as the target replacement register in the rnreg pass.

The bug originates from SPEC2017 541.leela_r(-flto).

gcc/ChangeLog:

	PR target/110484
	* config/loongarch/loongarch.cc (loongarch_emit_stack_tie): Use the
	frame_pointer_needed to determine whether to use the $fp register.

Co-authored-by: Guo Jie <guojie@loongson.cn>
---
 gcc/config/loongarch/loongarch.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/gcc/config/loongarch/loongarch.cc b/gcc/config/loongarch/loongarch.cc
index 5b8b93eb24b..aa470aafd7b 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -1112,7 +1112,9 @@ loongarch_first_stack_step (struct loongarch_frame_info *frame)
 static void
 loongarch_emit_stack_tie (void)
 {
-  emit_insn (gen_stack_tie (Pmode, stack_pointer_rtx, hard_frame_pointer_rtx));
+  emit_insn (gen_stack_tie (Pmode, stack_pointer_rtx,
+			    frame_pointer_needed ? hard_frame_pointer_rtx
+			    : stack_pointer_rtx));
 }
 
 #define PROBE_INTERVAL (1 << STACK_CHECK_PROBE_INTERVAL_EXP)
-- 
2.31.1