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bef627e798
CGSCC can delete nodes in regions of the callgraph that have already been visited. If new CG nodes are allocated to the same pointer, we shouldn't abort, just handle it correctly by assigning a new number. This should restore stability by removing invalidated pointers that *will* be reused from the densemap in the iterator. llvm-svn: 101628
Analysis Opportunities:
//===---------------------------------------------------------------------===//
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.
//===---------------------------------------------------------------------===//