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1b85e47f06
Refactored so that a LSRUse owns its fixups, as oppsed to letting the LSRInstance own them. This makes it easier to rate formulas for LSRUses, since the fixups are available directly. The Offsets vector has been removed since it was no longer necessary. New target hook isFoldableMemAccessOffset(), which is used during formula rating. For SystemZ, this is useful to express that loads and stores with float or vector types with a big/negative offset should be avoided in loops. Without this, LSR will generate a lot of negative offsets that would require extra instructions for loading the address. Updated tests: test/CodeGen/SystemZ/loop-01.ll Reviewed by: Quentin Colombet and Ulrich Weigand. https://reviews.llvm.org/D19152 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278927 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))
//===---------------------------------------------------------------------===//