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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/65832] Inefficient vector construction Date: Mon, 01 Jun 2015 10:30:00 -0000 [thread overview] Message-ID: <bug-65832-4-A5FrnZV8u3@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-65832-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65832 --- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> --- Testcase simulating all qi vector cases the vectorizer may create char a[1024]; char b[1024]; void foobar (int s) { for (int i = 0; i < 16; ++i) { b[i] = a[s*i]; } } void foo (int s) { for (int i = 0; i < 8; ++i) { b[2*i] = a[s*i]; b[2*i + 1] = a[s*i + 1]; } } void bar (int s) { for (int i = 0; i < 4; ++i) { b[4*i] = a[s*i]; b[4*i + 1] = a[s*i + 1]; b[4*i + 2] = a[s*i + 2]; b[4*i + 3] = a[s*i + 3]; } } void baz(int s) { for (int i = 0; i < 2; ++i) { b[8*i] = a[s*i]; b[8*i + 1] = a[s*i + 1]; b[8*i + 2] = a[s*i + 2]; b[8*i + 3] = a[s*i + 3]; b[8*i + 4] = a[s*i + 4]; b[8*i + 5] = a[s*i + 5]; b[8*i + 6] = a[s*i + 6]; b[8*i + 7] = a[s*i + 7]; } } Compile with -fdisable-tree-cunrolli. foobar creates absymal code and baz needlessly goes through the stack. For plain -msse2 all code-gen isn't great but for foo which ends up using pinsrw. baz fails to use pinsrq and foobar fails to use pinsrq with -msse4.
next prev parent reply other threads:[~2015-06-01 10:30 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-04-21 13:56 [Bug target/65832] New: " rguenth at gcc dot gnu.org 2015-04-21 14:03 ` [Bug target/65832] " rguenth at gcc dot gnu.org 2015-04-21 14:11 ` rguenth at gcc dot gnu.org 2015-04-28 8:51 ` rguenth at gcc dot gnu.org 2015-04-28 8:55 ` rguenth at gcc dot gnu.org 2015-05-22 12:15 ` rguenth at gcc dot gnu.org 2015-06-01 10:30 ` rguenth at gcc dot gnu.org [this message] 2020-06-24 20:45 ` [Bug middle-end/65832] " gabravier at gmail dot com
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