Dan Gohman bc58eb97fe Fix another place that calls Loop::contains a lot to construct a sorted
container of the blocks and do efficient lookups. This makes
isLoopSimplifyForm much faster on large loops, fixing a significant
compile-time issue in builds with assertions enabled.

llvm-svn: 84673
2009-10-20 20:41:13 +00:00
..
2009-08-11 16:02:12 +00:00
2009-10-17 23:48:54 +00:00
2009-07-26 08:34:35 +00:00
2009-09-11 08:43:15 +00:00

Analysis Opportunities:

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In test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll, the
ScalarEvolution expression for %r is this:

  {1,+,3,+,2}<loop>

Outside the loop, this could be evaluated simply as (%n * %n), however
ScalarEvolution currently evaluates it as

  (-2 + (2 * (trunc i65 (((zext i64 (-2 + %n) to i65) * (zext i64 (-1 + %n) to i65)) /u 2) to i64)) + (3 * %n))

In addition to being much more complicated, it involves i65 arithmetic,
which is very inefficient when expanded into code.

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