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| author | dim <dim@FreeBSD.org> | 2014-12-13 12:14:26 +0000 |
|---|---|---|
| committer | dim <dim@FreeBSD.org> | 2014-12-13 12:14:26 +0000 |
| commit | 3156db9097eabc078be1c06088d994af5df0b52d (patch) | |
| tree | a1ef4f975b82430cb58942c10fc0c804c65e18c2 | |
| parent | 8b3b3c8447148612e541ae4184534ac77184e978 (diff) | |
| download | FreeBSD-src-3156db9097eabc078be1c06088d994af5df0b52d.zip FreeBSD-src-3156db9097eabc078be1c06088d994af5df0b52d.tar.gz | |
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
| -rw-r--r-- | contrib/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | 8 | ||||
| -rw-r--r-- | sys/sys/param.h | 2 |
2 files changed, 9 insertions, 1 deletions
diff --git a/contrib/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/contrib/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp index f9f6b18..6a9b9dc 100644 --- a/contrib/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp +++ b/contrib/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp @@ -2864,6 +2864,14 @@ bool LoopVectorizationLegality::canVectorize() { 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'); diff --git a/sys/sys/param.h b/sys/sys/param.h index cc20497..033c4acc 100644 --- a/sys/sys/param.h +++ b/sys/sys/param.h @@ -58,7 +58,7 @@ * in the range 5 to 9. */ #undef __FreeBSD_version -#define __FreeBSD_version 1001503 /* Master, propagated to newvers */ +#define __FreeBSD_version 1001504 /* Master, propagated to newvers */ /* * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD, |
