From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4451 invoked by alias); 6 Jul 2010 18:36:12 -0000 Received: (qmail 4407 invoked by uid 48); 6 Jul 2010 18:35:59 -0000 Date: Tue, 06 Jul 2010 18:36:00 -0000 Message-ID: <20100706183559.4406.qmail@sourceware.org> X-Bugzilla-Reason: CC References: Subject: [Bug tree-optimization/44794] pre- and post-loops should not be unrolled. In-Reply-To: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "changpeng dot fang at amd dot com" Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2010-07/txt/msg00628.txt.bz2 ------- Comment #3 from changpeng dot fang at amd dot com 2010-07-06 18:35 ------- Here is the impact of loop unrolling on the compilation time and code size on polyhedron test_fpu.f90: -O3 -ftree-vectorize -fno-prefetch-loop-arrays -fno-unroll-loops: timing: 12.62s, size: 67069 bytes -O3 -ftree-vectorize -fprefetch-loop-arrays -funroll-loops: timing: 51.77s, size: 234045 bytes I also did an experiment on prefetching that we don't unroll the pre- and post-loop generated by the vectorizer: -O3 -ftree-vectorize -fprefetch-loop-arrays: timing: 29.32s size: 92541 bytes -O3 -ftree-vectorize -fprefetch-loop-arrays (don't unroll pre- postloops) timing: 18.34s size: 78909 bytes -O3 -ftree-vectorize -fno-prefetch-loop-arrays timing: 12.62s, size: 67069 bytes -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44794