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From: "pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/18754] New: unrolling happens too late/SRA does not happen late enough Date: Wed, 01 Dec 2004 14:39:00 -0000 [thread overview] Message-ID: <20041201143906.18754.pinskia@gcc.gnu.org> (raw) Take the following code: struct X { float array[4]; }; X a,b; float foobar () { float s = 0; X c; for (unsigned int d=0; d<4; ++d) c.array[d] = a.array[d] * b.array[d]; for (unsigned int d=0; d<4; ++d) s+=c.array[d]; return s; } With -O3 -funroll-loops -fno-ivopts -ffast-math (the fno-ivopts is because there are some ADDR_EXPR which we don't mark as invariant/constant which I will file in another bug) we get in .vars: c.array[0] = a.array[0] * b.array[0]; c.array[1] = a.array[1] * b.array[1]; c.array[2] = a.array[2] * b.array[2]; D.1572 = a.array[3] * b.array[3]; c.array[3] = D.1572; return D.1572 + c.array[0] + c.array[1] + c.array[2]; Note how we could SRA c.array. -- Summary: unrolling happens too late/SRA does not happen late enough Product: gcc Version: 4.0.0 Status: UNCONFIRMED Keywords: missed-optimization, TREE Severity: enhancement Priority: P2 Component: tree-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: pinskia at gcc dot gnu dot org CC: gcc-bugs at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18754
next reply other threads:[~2004-12-01 14:39 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2004-12-01 14:39 pinskia at gcc dot gnu dot org [this message] 2004-12-06 5:01 ` [Bug tree-optimization/18754] " pinskia at gcc dot gnu dot org 2004-12-16 17:09 ` rguenth at tat dot physik dot uni-tuebingen dot de 2005-01-20 10:57 ` rguenth at tat dot physik dot uni-tuebingen dot de 2005-01-20 14:49 ` pinskia at gcc dot gnu dot org 2005-01-20 14:57 ` rguenth at tat dot physik dot uni-tuebingen dot de 2005-01-20 15:06 ` dberlin at dberlin dot org 2005-01-20 15:07 ` pinskia at gcc dot gnu dot org 2005-01-20 15:15 ` rguenth at tat dot physik dot uni-tuebingen dot de 2005-01-21 16:08 ` rguenth at tat dot physik dot uni-tuebingen dot de 2005-05-07 21:00 ` pinskia at gcc dot gnu dot org
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