mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-01-14 16:33:28 +00:00
7550f96b2f
instead of the instruction. I've left a forwarding wrapper for the instruction so users with the instruction don't need to create a GEPOperator themselves. This lets us remove the copy of this code in instsimplify. I've looked at most of the other copies of similar code, and this is the only one I've found that is actually exactly the same. The one in InlineCost is very close, but it requires re-mapping non-constant indices through the cost analysis value simplification map. I could add direct support for this to the generic routine, but it seems overly specific. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169853 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.
//===---------------------------------------------------------------------===//
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))
//===---------------------------------------------------------------------===//