diff options
| -rw-r--r-- | llvm/lib/Transforms/Utils/LoopUnroll.cpp | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp index fb74505518e..553a2049ae5 100644 --- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp +++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp @@ -178,14 +178,14 @@ static bool needToInsertPhisForLCSSA(Loop *L, std::vector<BasicBlock *> Blocks, /// branch instruction. However, if the trip count (and multiple) are not known, /// loop unrolling will mostly produce more code that is no faster. /// -/// TripCount is generally defined as the number of times the loop header -/// executes. UnrollLoop relaxes the definition to permit early exits: here -/// TripCount is the iteration on which control exits LatchBlock if no early -/// exits were taken. Note that UnrollLoop assumes that the loop counter test -/// terminates LatchBlock in order to remove unnecesssary instances of the -/// test. In other words, control may exit the loop prior to TripCount -/// iterations via an early branch, but control may not exit the loop from the -/// LatchBlock's terminator prior to TripCount iterations. +/// TripCount is the upper bound of the iteration on which control exits +/// LatchBlock. Control may exit the loop prior to TripCount iterations either +/// via an early branch in other loop block or via LatchBlock terminator. This +/// is relaxed from the general definition of trip count which is the number of +/// times the loop header executes. Note that UnrollLoop assumes that the loop +/// counter test is in LatchBlock in order to remove unnecesssary instances of +/// the test. If control can exit the loop from the LatchBlock's terminator +/// prior to TripCount iterations, flag PreserveCondBr needs to be set. /// /// PreserveCondBr indicates whether the conditional branch of the LatchBlock /// needs to be preserved. It is needed when we use trip count upper bound to |
