When -fstack-protector-all or -fsanitize=address, rs6000.h sets
FRAME_GROWS_DOWNWARD. This breaks the assumption in
rs6000_return_addr that the stack link is at frame_pointer+0.
Bootstrapped and regression tested powerpc64le-linux and
powerpc64-linux -m32/-m64. OK?
PR target/81996
* gcc/config/rs6000/rs6000.c (rs6000_return_addr): Use
stack_pointer_rtx for count 0. Update comments. Break up
large rtl expression.
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index e611c45..f14392d 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -24988,24 +24988,23 @@ debug_stack_info (rs6000_stack_t *info)
rtx
rs6000_return_addr (int count, rtx frame)
{
- /* Currently we don't optimize very well between prolog and body
- code and for PIC code the code can be actually quite bad, so
- don't try to be too clever here. */
+ /* We can't use get_hard_reg_initial_val for LR when count == 0 if LR
+ is trashed by the prologue, as it is for PIC on ABI_V4 and Darwin. */
if (count != 0
|| ((DEFAULT_ABI == ABI_V4 || DEFAULT_ABI == ABI_DARWIN) && flag_pic))
{
cfun->machine->ra_needs_full_frame = 1;
- return
- gen_rtx_MEM
- (Pmode,
- memory_address
- (Pmode,
- plus_constant (Pmode,
- copy_to_reg
- (gen_rtx_MEM (Pmode,
- memory_address (Pmode, frame))),
- RETURN_ADDRESS_OFFSET)));
+ if (count == 0)
+ /* FRAME is set to frame_pointer_rtx by the generic code, but that
+ is good for loading 0(r1) only when !FRAME_GROWS_DOWNWARD. */
+ frame = stack_pointer_rtx;
+ rtx prev_frame_addr = memory_address (Pmode, frame);
+ rtx prev_frame = copy_to_reg (gen_rtx_MEM (Pmode, prev_frame_addr));
+ rtx lr_save_off = plus_constant (Pmode,
+ prev_frame, RETURN_ADDRESS_OFFSET);
+ rtx lr_save_addr = memory_address (Pmode, lr_save_off);
+ return gen_rtx_MEM (Pmode, lr_save_addr);
}
cfun->machine->ra_need_lr = 1;
--
Alan Modra
Australia Development Lab, IBM
