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961e1acfb2
instsimplify+inline strategy. The crux of the problem is that instsimplify was reasonably relying on an invariant that is true within any single function, but is no longer true mid-inline the way we use it. This invariant is that an argument pointer != a local (alloca) pointer. The fix is really light weight though, and allows instsimplify to be resiliant to these situations: when checking the relation ships to function arguments, ensure that the argumets come from the same function. If they come from different functions, then none of these assumptions hold. All credit to Benjamin Kramer for coming up with this clever solution to the problem. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161410 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))
//===---------------------------------------------------------------------===//