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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/109964] auto-vectorization of shift ignores integral promotions
Date: Thu, 25 May 2023 11:15:42 +0000 [thread overview]
Message-ID: <bug-109964-4-v4JzmMNDTi@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-109964-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109964
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2023-05-25
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
CC| |rguenth at gcc dot gnu.org,
| |rsandifo at gcc dot gnu.org
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
using V [[gnu::vector_size(16)]] = short;
V f(V s)
{
return V{
short(1) >> s[0],
short(1) >> s[1],
short(1) >> s[2],
short(1) >> s[3],
short(1) >> s[4],
short(1) >> s[5],
short(1) >> s[6],
short(1) >> s[7]
};
}
the frontend gives us
return <retval> = {(short int) (1 >> (int) VIEW_CONVERT_EXPR<short
int[8]>(s)[0]), (short int) (1 >> (int) VIEW_CONVERT_EXPR<short int[8]>(s)[1]),
(short int) (1 >> (int) VIEW_CONVERT_EXPR<short int[8]>(s)[2]), (short int) (1
>> (int) VIEW_CONVERT_EXPR<short int[8]>(s)[3]), (short int) (1 >> (int)
VIEW_CONVERT_EXPR<short int[8]>(s)[4]), (short int) (1 >> (int)
VIEW_CONVERT_EXPR<short int[8]>(s)[5]), (short int) (1 >> (int)
VIEW_CONVERT_EXPR<short int[8]>(s)[6]), (short int) (1 >> (int)
VIEW_CONVERT_EXPR<short int[8]>(s)[7])};
and the promotion/demotion stays until eventually basic-block vectorization
vectorizes this without doing the promotion.
t.ii:14:5: note: vect_recog_over_widening_pattern: detected: _3 = 1 >> _2;
t.ii:14:5: note: demoting int to signed short
t.ii:14:5: note: created pattern stmt: patt_36 = 1 >> _1;
I don't think there's any way to query the target about whether vector
shifts "behave".
We end up with
V f (V s)
{
vector(8) signed short vect_patt_36.3;
<bb 2> [local count: 1073741824]:
vect_patt_36.3_62 = { 1, 1, 1, 1, 1, 1, 1, 1 } >> s_33(D);
return vect_patt_36.3_62;
next prev parent reply other threads:[~2023-05-25 11:15 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-25 10:49 [Bug target/109964] New: " mkretz at gcc dot gnu.org
2023-05-25 11:15 ` rguenth at gcc dot gnu.org [this message]
2023-05-25 11:17 ` [Bug target/109964] " rguenth at gcc dot gnu.org
2023-05-25 11:45 ` rguenth at gcc dot gnu.org
2023-05-25 13:01 ` rsandifo at gcc dot gnu.org
2023-07-28 12:05 ` rguenth at gcc dot gnu.org
2024-04-15 13:28 ` rguenth at gcc dot gnu.org
2024-04-15 13:40 ` mkretz at gcc dot gnu.org
2024-04-15 13:42 ` rguenth at gcc dot gnu.org
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