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0eebc2900c
The sibling folds for 'and' with casts were added with https://reviews.llvm.org/rL273200. This is a preliminary step for adding the 'or' variants for the folds added with https://reviews.llvm.org/rL301260. The reason for the strange form with constant LHS in the 1st test is because there's another missing fold in that case for the inverted predicate. That should be fixed when we add the ConstantRange functionality for 'or-of-icmps' that already exists for 'and-of-icmps'. I'm hoping to share more code for the and/or cases, so we won't have these differences. This will allow us to remove code from InstCombine. It's also possible that we can remove some code here in InstSimplify. I think we have some duplicated folds because patterns are not matched in a general way. Differential Revision: https://reviews.llvm.org/D32876 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302189 91177308-0d34-0410-b5e6-96231b3b80d8
Analysis Opportunities:
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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))
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