Reid Kleckner 7dedaabcae Stop calling DwarfEHPrepare from WinEHPrepare
Instead, run both EH preparation passes, and have them both ignore
functions with unrecognized EH personalities. Pass delegation involved
some hacky code for creating an AnalysisResolver that we don't need now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231995 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-12 00:36:20 +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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In formatValue in test/CodeGen/X86/lsr-delayed-fold.ll,

ScalarEvolution is forming this expression:

((trunc i64 (-1 * %arg5) to i32) + (trunc i64 %arg5 to i32) + (-1 * (trunc i64 undef to i32)))

This could be folded to

(-1 * (trunc i64 undef to i32))

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