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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/114556] weird loop unrolling when there's attribute aligned inside the loop
Date: Wed, 03 Apr 2024 00:40:54 +0000	[thread overview]
Message-ID: <bug-114556-4-PB73thMWNl@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-114556-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114556

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2024-04-03

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
without the align:

Inserting a partition copy on edge BB2->BB3 : PART.0 = PART.3
Inserting a value copy on edge BB2->BB3 : PART.1 = 2048


vs with:

Inserting a partition copy on edge BB3->BB3 : PART.7 = PART.0
Inserting a partition copy on edge BB2->BB3 : PART.7 = PART.3
Inserting a value copy on edge BB2->BB3 : PART.1 = 2048


Basically out of ssa is doing an extra move because it could not "merge" the
loop induction variable for the (vector) addition due to the different
alignment requirements ... 

And then things go down hill from there.

      parent reply	other threads:[~2024-04-03  0:40 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-02  8:27 [Bug rtl-optimization/114556] New: weird loop unrolling when there's attribute aligned in side " liuhongt at gcc dot gnu.org
2024-04-03  0:35 ` [Bug middle-end/114556] weird loop unrolling when there's attribute aligned inside " pinskia at gcc dot gnu.org
2024-04-03  0:40 ` pinskia at gcc dot gnu.org [this message]

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