Add some comments noting how IndVarSimplify facilitates

LoopInfo functionality.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72091 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-05-19 01:52:46 +00:00
parent 84e5cac70a
commit 6c3534c5aa

View File

@ -351,6 +351,9 @@ public:
/// by one each time through the loop. If so, return the phi node that
/// corresponds to it.
///
/// The IndVarSimplify pass transforms loops to have a canonical induction
/// variable.
///
inline PHINode *getCanonicalInductionVariable() const {
BlockT *H = getHeader();
@ -406,6 +409,9 @@ public:
/// of the loop executes N-1 times. If the trip-count cannot be determined,
/// this returns null.
///
/// The IndVarSimplify pass transforms loops to have a form that this
/// function easily understands.
///
inline Value *getTripCount() const {
// Canonical loops will end with a 'cmp ne I, V', where I is the incremented
// canonical induction variable and V is the trip count of the loop.