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6 Commits

Author SHA1 Message Date
Andrew Trick
cd8e3c4dcf Prevent loop-unroll from making assumptions about undefined behavior.
Fixes rdar:14036816, PR16130.

There is an opportunity to compute precise trip counts for 'or'
expressions and multi-exit loops.
rdar:14038809: Optimize trip count computation for multi-exit loops.

To do this we need to record the fact that ExitLimit assumes NSW. When
it does not we can safely assume that the loop trip count is the
minimum ExitLimt across all subexpressions and loop exits.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183060 91177308-0d34-0410-b5e6-96231b3b80d8
2013-05-31 23:34:46 +00:00
Andrew Trick
b0598b14aa Reapply r139759. Disable IV rewriting by default. See PR10916.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139842 91177308-0d34-0410-b5e6-96231b3b80d8
2011-09-15 20:58:37 +00:00
Andrew Trick
effb647154 [indvars] Revert r139579 until 401.bzip -arch i386 miscompilation is fixed. PR10920.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139583 91177308-0d34-0410-b5e6-96231b3b80d8
2011-09-13 05:23:49 +00:00
Andrew Trick
dd9d758a31 Disable IV rewriting by default. See PR10916.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139579 91177308-0d34-0410-b5e6-96231b3b80d8
2011-09-13 03:23:21 +00:00
Andrew Trick
dc07321164 -unroll-scev flag removal
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139010 91177308-0d34-0410-b5e6-96231b3b80d8
2011-09-02 17:36:14 +00:00
Andrew Trick
b1831c6640 Allow loop unrolling to get known trip counts from ScalarEvolution.
SCEV unrolling can unroll loops with arbitrary induction variables. It
is a prerequisite for -disable-iv-rewrite performance. It is also
easily handles loops of arbitrary structure including multiple exits
and is generally more robust.

This is under a temporary option to avoid affecting default
behavior for the next couple of weeks. It is needed so that I can
checkin unit tests for updateUnloop.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137384 91177308-0d34-0410-b5e6-96231b3b80d8
2011-08-11 23:36:16 +00:00