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PR60580: Fix frame pointer option magic 

To fix PR60580 simplify the logic in aarch64_override_options_after_change_1 (). 
If the frame pointer is enabled, set it to a special value that behaves similar
to frame pointer omission.  If we don't do this all leaf functions will get a
frame pointer even if flag_omit_leaf_frame_pointer is set.

If flag_omit_frame_pointer has this special value, we must force the frame
pointer if not in a leaf function.  We also need to force it in a leaf function
if flag_omit_frame_pointer is not set or if LR is used.

Doing this allows both -fomit-frame-pointer and -fomit-leaf-frame-pointer to be
independently set and changed in each function with the expected behaviour.

    gcc/
	PR middle-end/60580
	* config/aarch64/aarch64.c (aarch64_frame_pointer_required)
	Check special value of flag_omit_frame_pointer.
	(aarch64_can_eliminate): Likewise.
	(aarch64_override_options_after_change_1): Simplify handling of
	-fomit-frame-pointer and -fomit-leaf-frame-pointer.

From-SVN: r254377
This commit is contained in:
Wilco Dijkstra 2017-11-03 15:01:10 +00:00 committed by Wilco Dijkstra
parent a3d5fd7670
commit cebaca3600
2 changed files with 26 additions and 23 deletions
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9
gcc/ChangeLog
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@ -1,3 +1,12 @@
2017-11-03 Wilco Dijkstra <wdijkstr@arm.com>
PR middle-end/60580
* config/aarch64/aarch64.c (aarch64_frame_pointer_required)
Check special value of flag_omit_frame_pointer.
(aarch64_can_eliminate): Likewise.
(aarch64_override_options_after_change_1): Simplify handling of
-fomit-frame-pointer and -fomit-leaf-frame-pointer.
2017-11-01 Martin Jambor <mjambor@suse.cz>
PR c++/81702

40
gcc/config/aarch64/aarch64.c
View File

@ -2764,12 +2764,13 @@ aarch64_output_probe_stack_range (rtx reg1, rtx reg2)
static bool
aarch64_frame_pointer_required (void)
{
/* In aarch64_override_options_after_change
flag_omit_leaf_frame_pointer turns off the frame pointer by
default. Turn it back on now if we've not got a leaf
function. */
if (flag_omit_leaf_frame_pointer
&& (!crtl->is_leaf || df_regs_ever_live_p (LR_REGNUM)))
/* Use the frame pointer if enabled and it is not a leaf function, unless
leaf frame pointer omission is disabled. If the frame pointer is enabled,
force the frame pointer in leaf functions which use LR. */
if (flag_omit_frame_pointer == 2
&& !(flag_omit_leaf_frame_pointer
&& crtl->is_leaf
&& !df_regs_ever_live_p (LR_REGNUM)))
return true;
/* Force a frame pointer for EH returns so the return address is at FP+8. */
@ -5623,6 +5624,7 @@ aarch64_can_eliminate (const int from, const int to)
LR in the function, then we'll want a frame pointer after all, so
prevent this elimination to ensure a frame pointer is used. */
if (to == STACK_POINTER_REGNUM
&& flag_omit_frame_pointer == 2
&& flag_omit_leaf_frame_pointer
&& df_regs_ever_live_p (LR_REGNUM))
return false;
@ -8573,24 +8575,16 @@ aarch64_parse_override_string (const char* input_string,
static void
aarch64_override_options_after_change_1 (struct gcc_options *opts)
{
/* The logic here is that if we are disabling all frame pointer generation
then we do not need to disable leaf frame pointer generation as a
separate operation. But if we are *only* disabling leaf frame pointer
generation then we set flag_omit_frame_pointer to true, but in
aarch64_frame_pointer_required we return false only for leaf functions.
/* PR 70044: We have to be careful about being called multiple times for the
same function. This means all changes should be repeatable. */
PR 70044: We have to be careful about being called multiple times for the
same function. Once we have decided to set flag_omit_frame_pointer just
so that we can omit leaf frame pointers, we must then not interpret a
second call as meaning that all frame pointer generation should be
omitted. We do this by setting flag_omit_frame_pointer to a special,
non-zero value. */
if (opts->x_flag_omit_frame_pointer == 2)
opts->x_flag_omit_frame_pointer = 0;
if (opts->x_flag_omit_frame_pointer)
opts->x_flag_omit_leaf_frame_pointer = false;
else if (opts->x_flag_omit_leaf_frame_pointer)
/* If the frame pointer is enabled, set it to a special value that behaves
similar to frame pointer omission. If we don't do this all leaf functions
will get a frame pointer even if flag_omit_leaf_frame_pointer is set.
If flag_omit_frame_pointer has this special value, we must force the
frame pointer if not in a leaf function. We also need to force it in a
leaf function if flag_omit_frame_pointer is not set or if LR is used. */
if (opts->x_flag_omit_frame_pointer == 0)
opts->x_flag_omit_frame_pointer = 2;
/* If not optimizing for size, set the default