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Teach SCEV to handle more cases of 'and X, CST', specifically where CST is any number of contiguous 1 bits in a row, with any number of leading and trailing 0 bits.

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Unfortunately, this in turn led to some lower quality SCEVs due to some different paths through expression simplification, so add getUDivExactExpr and use it. This fixes all instances of the problems that I found, but we can make that function smarter as necessary.

Merge test "xor-and.ll" into "and-xor.ll" since I needed to update it anyways. Test 'nsw-offset.ll' analyzes a little deeper, %n now gets a scev in terms of %no instead of a SCEVUnknown.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200203 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky
2014-01-27 10:04:03 +00:00
parent 9019340120
commit f2282cac95
6 changed files with 120 additions and 37 deletions
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include/llvm/Analysis/ScalarEvolution.h
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@@ -624,6 +624,7 @@ namespace llvm {
return getMulExpr(Ops, Flags);
}
const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS);
const SCEV *getUDivExactExpr(const SCEV *LHS, const SCEV *RHS);
const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step,
const Loop *L, SCEV::NoWrapFlags Flags);
const SCEV *getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,