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[RS6000] PR81996, __builtin_return_address(0) fails

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rs6000_return_addr assumes that the stack link is at frame+0, which is
true for count>0.  For count==0, rs6000_return_addr is called with
frame==frame_pointer_rtx and the stack link is *not* at frame+0 if
-fstack-protector-all or -fsanitize=address because rs6000.h sets
FRAME_GROWS_DOWNWARD for those options.

	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.

From-SVN: r252901
This commit is contained in:
Alan Modra 2017-09-18 11:55:10 +09:30 • committed by Alan Modra
parent f26a27f300
commit a24f02ffdb
2 changed files with 19 additions and 13 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2017-09-18 Alan Modra <amodra@gmail.com>
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.
2017-09-17 Daniel Santos <daniel.santos@pobox.com>
config/i386/i386.c: (xlogue_layout::STUB_NAME_MAX_LEN): Increase to 20

25
gcc/config/rs6000/rs6000.c
View file

@ -25009,24 +25009,23 @@ 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;