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From: "Li, Pan2" <pan2.li@intel.com>
To: "Li, Pan2" <pan2.li@intel.com>, Jeff Law <jeffreyalaw@gmail.com>,
	"Robin Dapp" <rdapp.gcc@gmail.com>,
	"gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Cc: "juzhe.zhong@rivai.ai" <juzhe.zhong@rivai.ai>,
	"kito.cheng@gmail.com" <kito.cheng@gmail.com>,
	"richard.guenther@gmail.com" <richard.guenther@gmail.com>,
	"Liu, Hongtao" <hongtao.liu@intel.com>
Subject: RE: [PATCH v2] DSE: Bugfix ICE after allow vector type in get_stored_val
Date: Sun, 28 Apr 2024 12:10:49 +0000	[thread overview]
Message-ID: <MW5PR11MB59089BF11726D6F33C172B57A9142@MW5PR11MB5908.namprd11.prod.outlook.com> (raw)
In-Reply-To: <MW5PR11MB5908DCD1C2B3F1C7971FF54CA90E2@MW5PR11MB5908.namprd11.prod.outlook.com>

Kindly ping^^ for this ice fix.

Pan

-----Original Message-----
From: Li, Pan2 <pan2.li@intel.com> 
Sent: Thursday, April 18, 2024 9:46 AM
To: Jeff Law <jeffreyalaw@gmail.com>; Robin Dapp <rdapp.gcc@gmail.com>; gcc-patches@gcc.gnu.org
Cc: juzhe.zhong@rivai.ai; kito.cheng@gmail.com; richard.guenther@gmail.com; Liu, Hongtao <hongtao.liu@intel.com>
Subject: RE: [PATCH v2] DSE: Bugfix ICE after allow vector type in get_stored_val

Kindly ping^ for this ice fix.

Pan

-----Original Message-----
From: Li, Pan2 
Sent: Saturday, April 6, 2024 8:02 PM
To: Li, Pan2 <pan2.li@intel.com>; Jeff Law <jeffreyalaw@gmail.com>; Robin Dapp <rdapp.gcc@gmail.com>; gcc-patches@gcc.gnu.org
Cc: juzhe.zhong@rivai.ai; kito.cheng@gmail.com; richard.guenther@gmail.com; Wang, Yanzhang <yanzhang.wang@intel.com>; Liu, Hongtao <Hongtao.Liu@intel.com>
Subject: RE: [PATCH v2] DSE: Bugfix ICE after allow vector type in get_stored_val

Kindly ping for this ice.

Pan

-----Original Message-----
From: Li, Pan2 <pan2.li@intel.com> 
Sent: Saturday, March 23, 2024 1:45 PM
To: Jeff Law <jeffreyalaw@gmail.com>; Robin Dapp <rdapp.gcc@gmail.com>; gcc-patches@gcc.gnu.org
Cc: juzhe.zhong@rivai.ai; kito.cheng@gmail.com; richard.guenther@gmail.com; Wang, Yanzhang <yanzhang.wang@intel.com>; Liu, Hongtao <hongtao.liu@intel.com>
Subject: RE: [PATCH v2] DSE: Bugfix ICE after allow vector type in get_stored_val

Thanks Jeff for comments.

> As Richi noted using validate_subreg here isn't great.  Does it work to 
> factor out this code from extract_low_bits
>
>>   if (!int_mode_for_mode (src_mode).exists (&src_int_mode)
>>       || !int_mode_for_mode (mode).exists (&int_mode))
>>     return NULL_RTX;
>> 
>>   if (!targetm.modes_tieable_p (src_int_mode, src_mode))
>>     return NULL_RTX;
>>   if (!targetm.modes_tieable_p (int_mode, mode))
>>     return NULL_RTX;

> And use that in the condition (and in extract_low_bits rather than 
> duplicating the code)?

It can solve the ICE but will forbid all vector modes goes gen_lowpart.
Actually only the vector mode size is less than reg nature size will trigger the ICE.
Thus, how about just add one more condition before goes to gen_lowpart as below?

Feel free to correct me if any misunderstandings. 😉!

diff --git a/gcc/dse.cc b/gcc/dse.cc
index edc7a1dfecf..258d2ccc299 100644
--- a/gcc/dse.cc
+++ b/gcc/dse.cc
@@ -1946,7 +1946,9 @@ get_stored_val (store_info *store_info, machine_mode read_mode,
                                 copy_rtx (store_info->const_rhs));
   else if (VECTOR_MODE_P (read_mode) && VECTOR_MODE_P (store_mode)
     && known_le (GET_MODE_BITSIZE (read_mode), GET_MODE_BITSIZE (store_mode))
-    && targetm.modes_tieable_p (read_mode, store_mode))
+    && targetm.modes_tieable_p (read_mode, store_mode)
+    /* It's invalid in validate_subreg if read_mode size is < reg natural.  */
+    && known_ge (GET_MODE_SIZE (read_mode), REGMODE_NATURAL_SIZE (read_mode)))
     read_reg = gen_lowpart (read_mode, copy_rtx (store_info->rhs));
   else
     read_reg = extract_low_bits (read_mode, store_mode,

Pan

-----Original Message-----
From: Jeff Law <jeffreyalaw@gmail.com> 
Sent: Saturday, March 23, 2024 2:54 AM
To: Li, Pan2 <pan2.li@intel.com>; Robin Dapp <rdapp.gcc@gmail.com>; gcc-patches@gcc.gnu.org
Cc: juzhe.zhong@rivai.ai; kito.cheng@gmail.com; richard.guenther@gmail.com; Wang, Yanzhang <yanzhang.wang@intel.com>; Liu, Hongtao <hongtao.liu@intel.com>
Subject: Re: [PATCH v2] DSE: Bugfix ICE after allow vector type in get_stored_val



On 3/4/24 11:22 PM, Li, Pan2 wrote:
> Thanks Jeff for comments.
> 
>> But in the case of a vector modes, we can usually reinterpret the
>> underlying bits in whatever mode we want and do any of the usual
>> operations on those bits.
> 
> Yes, I think that is why we can allow vector mode in get_stored_val if my understanding is correct.
> And then the different modes will return by gen_low_part. Unfortunately, there are some modes
>   (less than a vector bit size like V2SF, V2QI for vlen=128) are considered as invalid by validate_subreg,
> and return NULL_RTX result in the final ICE.
That doesn't make a lot of sense to me.  Even for vlen=128 I would have 
expected that we can still use a subreg to access low bits.  After all 
we might have had a V16QI vector and done a reduction of some sort 
storing the result in the first element and we have to be able to 
extract that result and move it around.

I'm not real keen on a target workaround.  While extremely safe, I 
wouldn't be surprised if other ports could trigger the ICE and we'd end 
up patching up multiple targets for what is, IMHO, a more generic issue.

As Richi noted using validate_subreg here isn't great.  Does it work to 
factor out this code from extract_low_bits:


>   if (!int_mode_for_mode (src_mode).exists (&src_int_mode)
>       || !int_mode_for_mode (mode).exists (&int_mode))
>     return NULL_RTX;
> 
>   if (!targetm.modes_tieable_p (src_int_mode, src_mode))
>     return NULL_RTX;
>   if (!targetm.modes_tieable_p (int_mode, mode))
>     return NULL_RTX;

And use that in the condition (and in extract_low_bits rather than 
duplicating the code)?

jeff

ps.  No need to apologize for the pings.  This completely fell off my radar.

  reply	other threads:[~2024-04-28 12:11 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-26  3:25 [PATCH v1] RTL: Bugfix ICE after allow vector type in DSE pan2.li
2024-02-26  3:41 ` Hongtao Liu
2024-02-26  3:42   ` Li, Pan2
2024-02-26  5:13     ` Hongtao Liu
2024-02-26  7:38 ` Richard Biener
2024-02-26  7:41   ` Li, Pan2
2024-02-26 14:22 ` [PATCH v2] DSE: Bugfix ICE after allow vector type in get_stored_val pan2.li
2024-02-27  9:47   ` Richard Biener
2024-02-27 15:02   ` Jeff Law
2024-02-28  1:40     ` Li, Pan2
2024-02-28  4:51       ` Li, Pan2
2024-02-28 17:33         ` Jeff Law
2024-02-29  1:38           ` Li, Pan2
2024-02-29 13:28             ` Robin Dapp
2024-03-02  1:04               ` Li, Pan2
2024-03-03 22:46               ` Jeff Law
2024-03-05  6:22                 ` Li, Pan2
2024-03-12  2:08                   ` Li, Pan2
2024-03-22  1:15                     ` Li, Pan2
2024-03-22 18:53                   ` Jeff Law
2024-03-23  5:45                     ` Li, Pan2
2024-04-06 12:02                       ` Li, Pan2
2024-04-18  1:46                         ` Li, Pan2
2024-04-28 12:10                           ` Li, Pan2 [this message]
2024-04-29 15:20                       ` Jeff Law
2024-04-30  1:02                         ` Li, Pan2
2024-04-30  7:17 ` [PATCH v3] DSE: Fix " pan2.li
2024-04-30 11:35   ` Li, Pan2
2024-05-03  1:57     ` Li, Pan2
2024-05-03  1:51 ` [PATCH v4] " pan2.li
2024-05-16  4:06   ` Li, Pan2
2024-05-19 16:23   ` Jeff Law
2024-05-20  1:08     ` Li, Pan2

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