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Mehdi Amini
887da0d8e8
This is fixing pr31761: BasicAA is deducing NoAlias on the result of the GEP if the base pointer is itself NoAlias. This is possible only if the NoAlias on the base pointer is deduced with a non-sized query: this should guarantee that the pointers are belonging to different memory allocation and that the GEP can't legally jump from one to another. Differential Revision: https://reviews.llvm.org/D29216 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293293 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))
//===---------------------------------------------------------------------===//