Owen Anderson 71802344fc Move the pass initialization helper functions into the llvm namespace, and add
a header declaring them all.  This is also where we will declare per-library pass-set
initializer functions down the road.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115900 91177308-0d34-0410-b5e6-96231b3b80d8
2010-10-07 04:13:08 +00:00
..
2010-07-28 10:57:28 +00:00
2010-09-04 18:12:00 +00:00
2010-09-04 18:12:00 +00:00
2010-09-04 18:12:00 +00:00

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.

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

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))

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