Re: LRA for avr: Maintain live range info for pseudos assigned to FP?
Am 20.11.23 um 08:14 schrieb SenthilKumar.Selvaraj--- via Gcc: On Thu, 2023-10-05 at 15:33 -0400, Vladimir Makarov wrote: EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe On 9/7/23 07:21, senthilkumar.selva...@microchip.com wrote: Hi, One more execution failure for the avr target, this time from gcc.c-torture/execute/bitfld-3.c. Steps to reproduce Enable LRA in avr.cc by removing TARGET_LRA_P hook, build with $ make all-host && make install-host and then $ avr-gcc gcc/testsuite/gcc.c-torture/execute/bitfld-3.c -S -Os -mmcu=avr51 -fdump-rtl-all When lra_update_fp2sp_elimination runs and pseudos assigned to the FP have to be spilled to stack slots, they sometimes end up in a slot that already has a reg with an overlapping live range. This is because lra_reg_info[regno].live_ranges is NULL for such spilled pseudos, and therefore when assign_stack_slot_num_and_sort_pseduos checks if lra_intersected_live_ranges_p, it always returns false. In the below reload dump, all the pseudos assigned to FP get allocated to slot 0. The live ranges for some of them (r1241 for e.g.) conflicts with r603 that was originally assigned to slot 0, but they still end up in the same slot, causing the execution failure. Sorry for the delay with the answer, Senthil. Avr is unusual target and needs some changes in LRA but the changes improves LRA portability. So thank you for your work on porting LRA to AVR. The patch is ok for me. The only comment is that making calculation of the set only once would be nice. Live range calculation in LRA can take a lot of time, code of update_pseudo_point is hot and the worst the set will be really used rarely but it is calculated every time. You can commit the current patch and I'll do it by myself or, if you want, you can modify the patch by yourself and submit it for review and I'll review as soon as possible. Either way works for me. Apologies for the extreme delay in responding - had to sort out some medical issues. Is it ok if I commit the patch now? I have one more patch in ira.cc, after which I'm hoping the regression results would be good enough to switch the avr target to LRA. Regards Senthil I have two questions: 1) Is there a command line option to switch back to IRA? 2) Will the X register be used for memory accesses? I am asking because as far as I understand, there is no replacement for LEGITIMIZE_RELOAD_ADDRESS. Regards, Johann
Re: LRA for avr: Maintain live range info for pseudos assigned to FP?
On Thu, 2023-10-05 at 15:33 -0400, Vladimir Makarov wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the
> content is safe
>
> On 9/7/23 07:21, senthilkumar.selva...@microchip.com wrote:
> > Hi,
> >
> >One more execution failure for the avr target, this time from
> >gcc.c-torture/execute/bitfld-3.c.
> >
> >Steps to reproduce
> >
> >Enable LRA in avr.cc by removing TARGET_LRA_P hook, build with
> >
> > $ make all-host && make install-host
> >
> >and then
> >
> > $ avr-gcc gcc/testsuite/gcc.c-torture/execute/bitfld-3.c -S -Os -mmcu=avr51
> > -fdump-rtl-all
> >
> >When lra_update_fp2sp_elimination runs and pseudos assigned to the
> >FP have to be spilled to stack slots, they sometimes end up in a
> >slot that already has a reg with an overlapping live range. This is
> >because lra_reg_info[regno].live_ranges is NULL for such spilled
> >pseudos, and therefore when assign_stack_slot_num_and_sort_pseduos
> >checks if lra_intersected_live_ranges_p, it always returns false.
> >
> >In the below reload dump, all the pseudos assigned to FP get
> >allocated to slot 0. The live ranges for some of them (r1241 for
> >e.g.) conflicts with r603 that was originally assigned to slot 0,
> >but they still end up in the same slot, causing the execution failure.
> >
> Sorry for the delay with the answer, Senthil. Avr is unusual target and
> needs some changes in LRA but the changes improves LRA portability. So
> thank you for your work on porting LRA to AVR.
>
> The patch is ok for me. The only comment is that making calculation of
> the set only once would be nice. Live range calculation in LRA can take
> a lot of time, code of update_pseudo_point is hot and the worst the set
> will be really used rarely but it is calculated every time.
>
> You can commit the current patch and I'll do it by myself or, if you
> want, you can modify the patch by yourself and submit it for review and
> I'll review as soon as possible. Either way works for me.
Apologies for the extreme delay in responding - had to sort out some medical
issues.
Is it ok if I commit the patch now? I have one more patch in ira.cc, after
which I'm hoping the regression results would be good enough to switch the
avr target to LRA.
Regards
Senthil
>
> > diff --git a/gcc/lra-lives.cc b/gcc/lra-lives.cc
> > index f60e564da82..e4289f13979 100644
> > --- a/gcc/lra-lives.cc
> > +++ b/gcc/lra-lives.cc
> > @@ -250,7 +250,17 @@ update_pseudo_point (int regno, int point, enum
> > point_type type)
> > if (HARD_REGISTER_NUM_P (regno))
> > return;
> >
> > - if (complete_info_p || lra_get_regno_hard_regno (regno) < 0)
> > + /* Pseudos assigned to the FP register could potentially get spilled
> > + to stack slots when lra_update_fp2sp_elimination runs, so keep
> > + their live range info up to date, even if they aren't in memory
> > + right now. */
> > + int hard_regno = lra_get_regno_hard_regno (regno);
> > + HARD_REG_SET set;
> > + CLEAR_HARD_REG_SET(set);
> > + add_to_hard_reg_set (, Pmode, HARD_FRAME_POINTER_REGNUM);
> > +
> > + if (complete_info_p || hard_regno < 0
> > + || overlaps_hard_reg_set_p (set, PSEUDO_REGNO_MODE (regno),
> > hard_regno))
> > {
> > if (type == DEF_POINT)
> > {
> >
> >
Re: LRA for avr: Maintain live range info for pseudos assigned to FP?
On 9/7/23 07:21, senthilkumar.selva...@microchip.com wrote:
Hi,
One more execution failure for the avr target, this time from
gcc.c-torture/execute/bitfld-3.c.
Steps to reproduce
Enable LRA in avr.cc by removing TARGET_LRA_P hook, build with
$ make all-host && make install-host
and then
$ avr-gcc gcc/testsuite/gcc.c-torture/execute/bitfld-3.c -S -Os -mmcu=avr51
-fdump-rtl-all
When lra_update_fp2sp_elimination runs and pseudos assigned to the
FP have to be spilled to stack slots, they sometimes end up in a
slot that already has a reg with an overlapping live range. This is
because lra_reg_info[regno].live_ranges is NULL for such spilled
pseudos, and therefore when assign_stack_slot_num_and_sort_pseduos
checks if lra_intersected_live_ranges_p, it always returns false.
In the below reload dump, all the pseudos assigned to FP get
allocated to slot 0. The live ranges for some of them (r1241 for
e.g.) conflicts with r603 that was originally assigned to slot 0,
but they still end up in the same slot, causing the execution failure.
Sorry for the delay with the answer, Senthil. Avr is unusual target and
needs some changes in LRA but the changes improves LRA portability. So
thank you for your work on porting LRA to AVR.
The patch is ok for me. The only comment is that making calculation of
the set only once would be nice. Live range calculation in LRA can take
a lot of time, code of update_pseudo_point is hot and the worst the set
will be really used rarely but it is calculated every time.
You can commit the current patch and I'll do it by myself or, if you
want, you can modify the patch by yourself and submit it for review and
I'll review as soon as possible. Either way works for me.
diff --git a/gcc/lra-lives.cc b/gcc/lra-lives.cc
index f60e564da82..e4289f13979 100644
--- a/gcc/lra-lives.cc
+++ b/gcc/lra-lives.cc
@@ -250,7 +250,17 @@ update_pseudo_point (int regno, int point, enum point_type
type)
if (HARD_REGISTER_NUM_P (regno))
return;
- if (complete_info_p || lra_get_regno_hard_regno (regno) < 0)
+ /* Pseudos assigned to the FP register could potentially get spilled
+ to stack slots when lra_update_fp2sp_elimination runs, so keep
+ their live range info up to date, even if they aren't in memory
+ right now. */
+ int hard_regno = lra_get_regno_hard_regno (regno);
+ HARD_REG_SET set;
+ CLEAR_HARD_REG_SET(set);
+ add_to_hard_reg_set (, Pmode, HARD_FRAME_POINTER_REGNUM);
+
+ if (complete_info_p || hard_regno < 0
+ || overlaps_hard_reg_set_p (set, PSEUDO_REGNO_MODE (regno), hard_regno))
{
if (type == DEF_POINT)
{
LRA for avr: Maintain live range info for pseudos assigned to FP?
Hi,
One more execution failure for the avr target, this time from
gcc.c-torture/execute/bitfld-3.c.
Steps to reproduce
Enable LRA in avr.cc by removing TARGET_LRA_P hook, build with
$ make all-host && make install-host
and then
$ avr-gcc gcc/testsuite/gcc.c-torture/execute/bitfld-3.c -S -Os -mmcu=avr51
-fdump-rtl-all
When lra_update_fp2sp_elimination runs and pseudos assigned to the
FP have to be spilled to stack slots, they sometimes end up in a
slot that already has a reg with an overlapping live range. This is
because lra_reg_info[regno].live_ranges is NULL for such spilled
pseudos, and therefore when assign_stack_slot_num_and_sort_pseduos
checks if lra_intersected_live_ranges_p, it always returns false.
In the below reload dump, all the pseudos assigned to FP get
allocated to slot 0. The live ranges for some of them (r1241 for
e.g.) conflicts with r603 that was originally assigned to slot 0,
but they still end up in the same slot, causing the execution failure.
r472: [86..87]
r473: [0..85]
...
r603: [254..655]
...
r1241: [282..283]
r1242: [268..269]
r1243: [254..255]
r1244: [238..239]
r1245: [222..223]
r1314: [88..89]
Ranges after the compression:
r591: [0..1]
r603: [0..1]
r604: [0..1]
r605: [0..1]
r606: [0..1]
r607: [0..1]
r623: [0..1]
r624: [0..1]
r635: [0..1]
r636: [0..1]
r637: [0..1]
r638: [0..1]
r639: [0..1]
r668: [0..1]
r669: [0..1]
r670: [0..1]
r671: [0..1]
r672: [0..1]
Frame pointer can not be eliminated anymore
Spilling non-eliminable hard regs: 28 29
Spilling r472(28)
Spilling r473(28)
Spilling r589(29)
Spilling r590(28)
Spilling r704(29)
Spilling r1241(28)
Spilling r1242(28)
Spilling r1243(28)
Spilling r1244(28)
Spilling r1245(28)
Spilling r1314(28)
Slot 0 regnos (width = 0): 603 13141245124412431242
1241704 590 589 473 472
Live ranges for those pseudos is NULL because when
lra_create_live_ranges_1 ran with all_p = false, they were not in
memory (they were assigned to FP). Computing live range info for
pseudos assigned to FP fixes the problem for avr,
Is that the right fix for this problem? After applying the below
patch, the reload dump looks like this
Ranges after the compression:
r472: [2..3]
r473: [0..1]
r589: [16..17]
r590: [16..17]
r591: [16..17]
r603: [10..17]
r604: [10..17]
r605: [10..17]
r606: [10..17]
r607: [10..17]
r623: [6..17]
r624: [6..17]
r635: [8..17]
r636: [8..17]
r637: [8..17]
r638: [8..17]
r639: [8..17]
r668: [6..17]
r669: [6..17]
r670: [6..17]
r671: [6..17]
r672: [6..17]
r704: [0..1]
r1241: [14..15]
r1242: [12..13]
r1243: [10..11]
r1244: [8..9]
r1245: [6..7]
r1314: [4..5]
Frame pointer can not be eliminated anymore
Spilling non-eliminable hard regs: 28 29
Spilling r472(28)
Spilling r473(28)
Spilling r589(29)
Spilling r590(28)
Spilling r704(29)
Spilling r1241(28)
Spilling r1242(28)
Spilling r1243(28)
Spilling r1244(28)
Spilling r1245(28)
Spilling r1314(28)
Slot 0 regnos (width = 0): 603 131412451244473 472
Slot 1 regnos (width = 0): 604 704
...
Slot 17 regnos (width = 0):591 124312421241
Slot 18 regnos (width = 0):589
Slot 19 regnos (width = 0):590
Regards
Senthil
diff --git a/gcc/lra-lives.cc b/gcc/lra-lives.cc
index f60e564da82..e4289f13979 100644
--- a/gcc/lra-lives.cc
+++ b/gcc/lra-lives.cc
@@ -250,7 +250,17 @@ update_pseudo_point (int regno, int point, enum point_type
type)
if (HARD_REGISTER_NUM_P (regno))
return;
- if (complete_info_p || lra_get_regno_hard_regno (regno) < 0)
+ /* Pseudos assigned to the FP register could potentially get spilled
+ to stack slots when lra_update_fp2sp_elimination runs, so keep
+ their live range info up to date, even if they aren't in memory
+ right now. */
+ int hard_regno = lra_get_regno_hard_regno (regno);
+ HARD_REG_SET set;
+ CLEAR_HARD_REG_SET(set);
+ add_to_hard_reg_set (, Pmode, HARD_FRAME_POINTER_REGNUM);
+
+ if (complete_info_p || hard_regno < 0
+ || overlaps_hard_reg_set_p (set, PSEUDO_REGNO_MODE (regno), hard_regno))
{
if (type == DEF_POINT)
{
