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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/97984] [10/11 Regression] Worse code for -O3 than -O2 on aarch64 vector multiply-add
Date: Wed, 25 Nov 2020 12:59:39 +0000 [thread overview]
Message-ID: <bug-97984-4-DkSM1NkBT6@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-97984-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97984
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Version|unknown |11.0
Ever confirmed|0 |1
Last reconfirmed| |2020-11-25
Target Milestone|--- |10.3
Status|UNCONFIRMED |NEW
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
We vectorize the add but not the multiplication. FMA discovery comes after
vectorization so it can't inhibit the transform (and vectorizer costing cannot
factor that in). Is there vector madd available?
arm vectorizer costing could honor the fact that there's ldp/stp instructions
and thus not artifically make a vector load cheaper than two adjacent scalar
loads. That would only make the costings equal though.
0x3151930 *b_11(D) 1 times unaligned_load (misalign -1) costs 1 in body
0x3151930 _2 + _3 1 times vector_stmt costs 1 in body
0x3151930 <unknown> 1 times vec_construct costs 2 in prologue
0x3151930 _7 1 times unaligned_store (misalign -1) costs 1 in body
0x31569d0 _7 1 times scalar_store costs 1 in body
0x31569d0 _8 1 times scalar_store costs 1 in body
0x31569d0 _2 + _3 1 times scalar_stmt costs 1 in body
0x31569d0 _5 + _6 1 times scalar_stmt costs 1 in body
0x31569d0 *b_11(D) 1 times scalar_load costs 1 in body
0x31569d0 MEM[(long int *)b_11(D) + 8B] 1 times scalar_load costs 1 in body
t.c:5:8: note: Cost model analysis:
Vector inside of basic block cost: 3
Vector prologue cost: 2
Vector epilogue cost: 0
Scalar cost of basic block: 6
t.c:5:8: note: Basic block will be vectorized using SLP
next prev parent reply other threads:[~2020-11-25 12:59 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-25 11:49 [Bug tree-optimization/97984] New: " ktkachov at gcc dot gnu.org
2020-11-25 12:59 ` rguenth at gcc dot gnu.org [this message]
2021-01-14 9:47 ` [Bug target/97984] " rguenth at gcc dot gnu.org
2021-04-08 12:02 ` rguenth at gcc dot gnu.org
2021-11-22 0:49 ` pinskia at gcc dot gnu.org
2021-12-08 14:24 ` marxin at gcc dot gnu.org
2021-12-08 19:51 ` pinskia at gcc dot gnu.org
2021-12-09 10:05 ` marxin at gcc dot gnu.org
2022-06-28 10:42 ` jakub at gcc dot gnu.org
2023-07-07 10:38 ` [Bug target/97984] [11 " rguenth at gcc dot gnu.org
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