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7d30f78dc2
This debugger was designed to catch places where the old update API was failing to be used correctly. As I've removed the update API, it no longer serves any purpose. We can introduce new debugging aid passes around any future work w.r.t. updating AAs. Note that I've updated the documentation here, but really I need to rewrite the documentation to carefully spell out the ideas around stateful AA and how things are changing in the AA world. However, I'm hoping to do that as a follow-up to the refactoring of the AA infrastructure to work in both old and new pass managers so that I can write the documentation specific to that world. Differential Revision: http://reviews.llvm.org/D11984 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244825 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))
//===---------------------------------------------------------------------===//