Chris Lattner b065b06c12 Revamp the "ConstantStruct::get" methods. Previously, these were scattered
all over the place in different styles and variants.  Standardize on two
preferred entrypoints: one that takes a StructType and ArrayRef, and one that
takes StructType and varargs.

In cases where there isn't a struct type convenient, we now add a
ConstantStruct::getAnon method (whose name will make more sense after a few
more patches land).  

It would be "really really nice" if the ConstantStruct::get and 
ConstantVector::get methods didn't make temporary std::vectors.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133412 91177308-0d34-0410-b5e6-96231b3b80d8
2011-06-20 04:01:31 +00:00
..
2011-05-27 18:42:33 +00:00
2011-06-03 17:15:37 +00:00
2011-06-18 21:46:23 +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))

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