LoongArch: Fix bug in loongarch_emit_stack_tie [PR110484].

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>

diff --git a/gcc/config/loongarch/loongarch.cc b/gcc/config/loongarch/loongarch.cc
index 1905599b9e8bacd15d45ab3f2fc6fdfeabd3db87..c72229cad87cc9cc0b6c5a195e3b20847f59661c 100644 (file)
--- 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)