mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-01-20 12:31:40 +00:00
837be07979
same object to be a non-capture; Duncan pointed out a way that such a comparison could be a capture. Make the rule that considers a comparison against null more specific, and only consider noalias return values compared against null. This still supports test/Transforms/GVN/nonescaping-malloc.ll, and is not susceptible to the problem Duncan pointed out with noalias arguments. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89468 91177308-0d34-0410-b5e6-96231b3b80d8
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.
//===---------------------------------------------------------------------===//