Re: Re: [PATCH 3/4] [RISC-V] resolve confilct between zcmp multi push/pop and shrink-wrap-separate
On 2023-06-13 03:26 Jeff Law wrote:
>
>
>
>On 6/6/23 23:52, Fei Gao wrote:
>> Disable zcmp multi push/pop if shrink-wrap-separate is active.
>>
>> So in -Os that prefers smaller code size, by default shrink-wrap-separate
>> is disabled while zcmp multi push/pop is enabled.
>>
>> And in -O2 and others that prefers speed, by default shrink-wrap-separate
>> is enabled while zcmp multi push/pop is disabled. To force enabling zcmp
>> multi
>> push/pop in this case, -fno-shrink-wrap-separate has to be explictly given.
>>
>> The following TC shows the issues in -O2 before this patch with both
>> shrink-wrap-separate and zcmp multi push/pop active.
>> 1. duplicated store of s regs.
>> 2. cm.push pushes ra, s0-s11 in reverse order than what normal
>> prologue does, causing stack corruption and failure to resotre s regs.
>>
>> TC: zcmp_shrink_wrap_separate.c included in this patch.
>>
>> output asm before this patch:
>> calc_func:
>> cm.push {ra, s0-s3}, -32
>> ...
>> beq a5,zero,.L2
>> ...
>> .L2:
>> ...
>> sw s1,20(sp) //issue here
>> sw s3,12(sp) //issue here
>> ...
>> sw s2,16(sp) //issue here
>>
>> output asm after this patch:
>> calc_func:
>> addi sp,sp,-32
>> sw s0,24(sp)
>> ...
>> beq a5,zero,.L2
>> ...
>> .L2:
>> ...
>> sw s1,20(sp)
>> sw s3,12(sp)
>> ...
>> sw s2,16(sp)
>> gcc/ChangeLog:
>>
>> * config/riscv/riscv.cc
>> (riscv_avoid_shrink_wrapping_separate): wrap the condition check in
>> riscv_avoid_shrink_wrapping_separate.
>> (riscv_avoid_multi_push): avoid multi push if
>>shrink_wrapping_separate
>> is active.
>> (riscv_get_separate_components): call
>>riscv_avoid_shrink_wrapping_separate
>> * shrink-wrap.cc (try_shrink_wrapping_separate): call
>> use_shrink_wrapping_separate.
>> (use_shrink_wrapping_separate):wrap the condition
>> check in use_shrink_wrapping_separate
>> * shrink-wrap.h (use_shrink_wrapping_separate): add to extern
>>
>> gcc/testsuite/ChangeLog:
>>
>> * gcc.target/riscv/zcmp_shrink_wrap_separate.c: New test.
>> * gcc.target/riscv/zcmp_shrink_wrap_separate2.c: New test.
>I know Kito asked for this to be broken up into target dependent vs
>target independent changes, that's a good ask.
>
>Can't we utilize the get_separate_components hook to accomplish what
>you're trying to do? ie, put the logic to avoid shrink wrapping for
>this case within the existing risc-v hook?
Thank Jeff and Kito for your comments.
My first try was to avoid shrink wrapping if zcmp is enabled.
But after discussion with Kito and Andrew Pinski, I realized it's better to
disable
zcmp push and pops if shrink wrapping is active.
For detailed discussion, please check link below.
thread: [PATCH 1/2] [RISC-V] disable shrink-wrap-separate if zcmp enabled.
link: https://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg307203.html
I will go ahead with Kito's advice if you're fine with the current solution.
Thanks.
BR,
Fei
>
>jeff
Re: [PATCH 3/4] [RISC-V] resolve confilct between zcmp multi push/pop and shrink-wrap-separate
On 6/6/23 23:52, Fei Gao wrote:
Disable zcmp multi push/pop if shrink-wrap-separate is active.
So in -Os that prefers smaller code size, by default shrink-wrap-separate
is disabled while zcmp multi push/pop is enabled.
And in -O2 and others that prefers speed, by default shrink-wrap-separate
is enabled while zcmp multi push/pop is disabled. To force enabling zcmp multi
push/pop in this case, -fno-shrink-wrap-separate has to be explictly given.
The following TC shows the issues in -O2 before this patch with both
shrink-wrap-separate and zcmp multi push/pop active.
1. duplicated store of s regs.
2. cm.push pushes ra, s0-s11 in reverse order than what normal
prologue does, causing stack corruption and failure to resotre s regs.
TC: zcmp_shrink_wrap_separate.c included in this patch.
output asm before this patch:
calc_func:
cm.push {ra, s0-s3}, -32
...
beq a5,zero,.L2
...
.L2:
...
sw s1,20(sp) //issue here
sw s3,12(sp) //issue here
...
sw s2,16(sp) //issue here
output asm after this patch:
calc_func:
addisp,sp,-32
sw s0,24(sp)
...
beq a5,zero,.L2
...
.L2:
...
sw s1,20(sp)
sw s3,12(sp)
...
sw s2,16(sp)
gcc/ChangeLog:
* config/riscv/riscv.cc
(riscv_avoid_shrink_wrapping_separate): wrap the condition check in
riscv_avoid_shrink_wrapping_separate.
(riscv_avoid_multi_push): avoid multi push if shrink_wrapping_separate
is active.
(riscv_get_separate_components): call
riscv_avoid_shrink_wrapping_separate
* shrink-wrap.cc (try_shrink_wrapping_separate): call
use_shrink_wrapping_separate.
(use_shrink_wrapping_separate):wrap the condition
check in use_shrink_wrapping_separate
* shrink-wrap.h (use_shrink_wrapping_separate): add to extern
gcc/testsuite/ChangeLog:
* gcc.target/riscv/zcmp_shrink_wrap_separate.c: New test.
* gcc.target/riscv/zcmp_shrink_wrap_separate2.c: New test.
I know Kito asked for this to be broken up into target dependent vs
target independent changes, that's a good ask.
Can't we utilize the get_separate_components hook to accomplish what
you're trying to do? ie, put the logic to avoid shrink wrapping for
this case within the existing risc-v hook?
jeff
Re: [PATCH 3/4] [RISC-V] resolve confilct between zcmp multi push/pop and shrink-wrap-separate
I would suggest breaking this patch into two parts: RISC-V part and
the rest part (shrink-wrap.h / shrink-wrap.cc).
On Wed, Jun 7, 2023 at 1:55 PM Fei Gao wrote:
>
> Disable zcmp multi push/pop if shrink-wrap-separate is active.
>
> So in -Os that prefers smaller code size, by default shrink-wrap-separate
> is disabled while zcmp multi push/pop is enabled.
>
> And in -O2 and others that prefers speed, by default shrink-wrap-separate
> is enabled while zcmp multi push/pop is disabled. To force enabling zcmp multi
> push/pop in this case, -fno-shrink-wrap-separate has to be explictly given.
>
> The following TC shows the issues in -O2 before this patch with both
> shrink-wrap-separate and zcmp multi push/pop active.
> 1. duplicated store of s regs.
> 2. cm.push pushes ra, s0-s11 in reverse order than what normal
>prologue does, causing stack corruption and failure to resotre s regs.
>
> TC: zcmp_shrink_wrap_separate.c included in this patch.
>
> output asm before this patch:
> calc_func:
> cm.push {ra, s0-s3}, -32
> ...
> beq a5,zero,.L2
> ...
> .L2:
> ...
> sw s1,20(sp) //issue here
> sw s3,12(sp) //issue here
> ...
> sw s2,16(sp) //issue here
>
> output asm after this patch:
> calc_func:
> addisp,sp,-32
> sw s0,24(sp)
> ...
> beq a5,zero,.L2
> ...
> .L2:
> ...
> sw s1,20(sp)
> sw s3,12(sp)
> ...
> sw s2,16(sp)
> gcc/ChangeLog:
>
> * config/riscv/riscv.cc
> (riscv_avoid_shrink_wrapping_separate): wrap the condition check in
> riscv_avoid_shrink_wrapping_separate.
> (riscv_avoid_multi_push): avoid multi push if shrink_wrapping_separate
> is active.
> (riscv_get_separate_components): call
> riscv_avoid_shrink_wrapping_separate
> * shrink-wrap.cc (try_shrink_wrapping_separate): call
> use_shrink_wrapping_separate.
> (use_shrink_wrapping_separate):wrap the condition
> check in use_shrink_wrapping_separate
> * shrink-wrap.h (use_shrink_wrapping_separate): add to extern
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/riscv/zcmp_shrink_wrap_separate.c: New test.
> * gcc.target/riscv/zcmp_shrink_wrap_separate2.c: New test.
>
> Signed-off-by: Fei Gao
> Co-Authored-By: Zhangjin Liao
> ---
> gcc/config/riscv/riscv.cc | 19 +++-
> gcc/shrink-wrap.cc| 25 +++--
> gcc/shrink-wrap.h | 1 +
> .../riscv/zcmp_shrink_wrap_separate.c | 97 +++
> .../riscv/zcmp_shrink_wrap_separate2.c| 97 +++
> 5 files changed, 228 insertions(+), 11 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/riscv/zcmp_shrink_wrap_separate.c
> create mode 100644
> gcc/testsuite/gcc.target/riscv/zcmp_shrink_wrap_separate2.c
>
> diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
> index f60c241a526..b505cdeca34 100644
> --- a/gcc/config/riscv/riscv.cc
> +++ b/gcc/config/riscv/riscv.cc
> @@ -64,6 +64,7 @@ along with GCC; see the file COPYING3. If not see
> #include "cfghooks.h"
> #include "cfgloop.h"
> #include "cfgrtl.h"
> +#include "shrink-wrap.h"
> #include "sel-sched.h"
> #include "fold-const.h"
> #include "gimple-iterator.h"
> @@ -389,6 +390,7 @@ static const struct riscv_tune_param
> optimize_size_tune_info = {
>false, /* use_divmod_expansion */
> };
>
> +static bool riscv_avoid_shrink_wrapping_separate ();
> static tree riscv_handle_fndecl_attribute (tree *, tree, tree, int, bool *);
> static tree riscv_handle_type_attribute (tree *, tree, tree, int, bool *);
>
> @@ -4910,6 +4912,8 @@ riscv_avoid_multi_push(const struct riscv_frame_info
> *frame)
>|| cfun->machine->interrupt_handler_p
>|| cfun->machine->varargs_size != 0
>|| crtl->args.pretend_args_size != 0
> + || (use_shrink_wrapping_separate ()
> + && !riscv_avoid_shrink_wrapping_separate ())
>|| (frame->mask & ~ MULTI_PUSH_GPR_MASK))
> return true;
>
> @@ -6077,6 +6081,17 @@ riscv_epilogue_uses (unsigned int regno)
>return false;
> }
>
> +static bool
> +riscv_avoid_shrink_wrapping_separate ()
> +{
> + if (riscv_use_save_libcall (&cfun->machine->frame)
> + || cfun->machine->interrupt_handler_p
> + || !cfun->machine->frame.gp_sp_offset.is_constant ())
> +return true;
> +
> + return false;
> +}
> +
> /* Implement TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS. */
>
> static sbitmap
> @@ -6086,9 +6101,7 @@ riscv_get_separate_components (void)
>sbitmap components = sbitmap_alloc (FIRST_PSEUDO_REGISTER);
>bitmap_clear (components);
>
> - if (riscv_use_save_libcall (&cfun->machine->frame)
> - || cfun->machine->interrupt_handler_p
> - || !cfun->machine->frame.gp_sp_offset.is_constant ())
> + if (ris
