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Clarify the wording on what it means for a SCEVAddRecExpr to be <NW>.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228587 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjoy Das 2015-02-09 18:44:42 +00:00
parent 2ceba77dfa
commit af30d1e97a
1 changed files with 6 additions and 6 deletions
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12
include/llvm/Analysis/ScalarEvolution.h
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@ -82,12 +82,12 @@ namespace llvm {
/// operator. NSW is a misnomer that we use to mean no signed overflow or
/// underflow.
///
/// AddRec expression may have a no-self-wraparound <NW> property if the
/// result can never reach the start value. This property is independent of
/// the actual start value and step direction. Self-wraparound is defined
/// purely in terms of the recurrence's loop, step size, and
/// bitwidth. Formally, a recurrence with no self-wraparound satisfies:
/// abs(step) * max-iteration(loop) <= unsigned-max(bitwidth).
/// AddRec expressions may have a no-self-wraparound <NW> property if, in
/// the integer domain, abs(step) * max-iteration(loop) <=
/// unsigned-max(bitwidth). This means that the recurrence will never reach
/// its start value if the step is non-zero. Computing the same value on
/// each iteration is not considered wrapping, and recurrences with step = 0
/// are trivially <NW>.
///
/// Note that NUW and NSW are also valid properties of a recurrence, and
/// either implies NW. For convenience, NW will be set for a recurrence