Rafael Espindola c9ae8cc24c Change the implementation of dominates(inst, inst) to one based on what the
verifier does. This correctly handles invoke.
Thanks to Duncan, Andrew and Chris for the comments.
Thanks to Joerg for the early testing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151469 91177308-0d34-0410-b5e6-96231b3b80d8
2012-02-26 02:19:19 +00:00
..
2012-02-01 07:49:51 +00:00
2012-02-22 17:25:00 +00:00
2012-02-01 07:49:51 +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.

//===---------------------------------------------------------------------===//

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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