Date: Sat, 13 Dec 2014 12:14:27 +0000 (UTC) From: Dimitry Andric <dim@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org Subject: svn commit: r275742 - in stable: 10/contrib/llvm/lib/Transforms/Vectorize 10/sys/sys 9/contrib/llvm/lib/Transforms/Vectorize 9/sys/sys Message-ID: <201412131214.sBDCERJT033028@svn.freebsd.org>
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Author: dim Date: Sat Dec 13 12:14:26 2014 New Revision: 275742 URL: https://svnweb.freebsd.org/changeset/base/275742 Log: MFC r275633: Pull in r223171 from upstream llvm trunk (by Michael Zolotukhin): PR21302. Vectorize only bottom-tested loops. rdar://problem/18886083 This fixes a bug in the llvm vectorizer, which could sometimes cause vectorized loops to perform an additional iteration, leading to possible buffer overruns. Symptoms of this, which are usually segfaults, were first noticed when building gcc ports, here: https://lists.freebsd.org/pipermail/freebsd-ports/2014-September/095466.html https://lists.freebsd.org/pipermail/freebsd-toolchain/2014-September/001211.html Since this fix is very important for ports, bump __FreeBSD_version to make it easier for port maintainers to test whether the fix has been applied. Upstream PR: http://llvm.org/PR21302 Modified: stable/9/contrib/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp stable/9/sys/sys/param.h Directory Properties: stable/9/contrib/llvm/ (props changed) stable/9/sys/ (props changed) Changes in other areas also in this revision: Modified: stable/10/contrib/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp stable/10/sys/sys/param.h Directory Properties: stable/10/ (props changed) Modified: stable/9/contrib/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp ============================================================================== --- stable/9/contrib/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp Sat Dec 13 04:50:14 2014 (r275741) +++ stable/9/contrib/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp Sat Dec 13 12:14:26 2014 (r275742) @@ -2864,6 +2864,14 @@ bool LoopVectorizationLegality::canVecto if (!TheLoop->getExitingBlock()) return false; + // We only handle bottom-tested loops, i.e. loop in which the condition is + // checked at the end of each iteration. With that we can assume that all + // instructions in the loop are executed the same number of times. + if (TheLoop->getExitingBlock() != TheLoop->getLoopLatch()) { + DEBUG(dbgs() << "LV: loop control flow is not understood by vectorizer\n"); + return false; + } + // We need to have a loop header. DEBUG(dbgs() << "LV: Found a loop: " << TheLoop->getHeader()->getName() << '\n'); Modified: stable/9/sys/sys/param.h ============================================================================== --- stable/9/sys/sys/param.h Sat Dec 13 04:50:14 2014 (r275741) +++ stable/9/sys/sys/param.h Sat Dec 13 12:14:26 2014 (r275742) @@ -58,7 +58,7 @@ * in the range 5 to 9. */ #undef __FreeBSD_version -#define __FreeBSD_version 903506 /* Master, propagated to newvers */ +#define __FreeBSD_version 903507 /* Master, propagated to newvers */ /* * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,
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