Move trip count discovery outside of the generic LoopUnroll helper. This

removes its dependence on canonical induction variables.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135829 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 9 insertions, 14 deletions

diff --git a/lib/Transforms/Scalar/LoopUnrollPass.cpp b/lib/Transforms/Scalar/LoopUnrollPass.cpp
index 38259f0f24..6d7901f88c 100644
--- a/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -137,9 +137,14 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
 
   // Find trip count
   unsigned TripCount = L->getSmallConstantTripCount();
-  unsigned Count = CurrentCount;
+
+  // Find trip multiple if count is not available
+  unsigned TripMultiple = 1;
+  if (TripCount == 0)
+    TripMultiple = L->getSmallConstantTripMultiple();
 
   // Automatically select an unroll count.
+  unsigned Count = CurrentCount;
   if (Count == 0) {
     // Conservative heuristic: if we know the trip count, see if we can
     // completely unroll (subject to the threshold, checked below); otherwise
@@ -183,7 +188,7 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
 
   // Unroll the loop.
   Function *F = L->getHeader()->getParent();
-  if (!UnrollLoop(L, Count, LI, &LPM))
+  if (!UnrollLoop(L, Count, TripCount, TripMultiple, LI, &LPM))
     return false;
 
   // FIXME: Reconstruct dom info, because it is not preserved properly.
diff --git a/lib/Transforms/Utils/LoopUnroll.cpp b/lib/Transforms/Utils/LoopUnroll.cpp
index ce04da78e1..27382c2de9 100644
--- a/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/lib/Transforms/Utils/LoopUnroll.cpp
@@ -11,9 +11,6 @@
 // actual pass or policy, but provides a single function to perform loop
 // unrolling.
 //
-// It works best when loops have been canonicalized by the -indvars pass,
-// allowing it to determine the trip counts of loops easily.
-//
 // The process of unrolling can produce extraneous basic blocks linked with
 // unconditional branches.  This will be corrected in the future.
 //
@@ -113,8 +110,8 @@ static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI) {
 ///
 /// If a LoopPassManager is passed in, and the loop is fully removed, it will be
 /// removed from the LoopPassManager as well. LPM can also be NULL.
-bool llvm::UnrollLoop(Loop *L, unsigned Count,
-                      LoopInfo *LI, LPPassManager *LPM) {
+bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
+                      unsigned TripMultiple, LoopInfo *LI, LPPassManager *LPM) {
   BasicBlock *Preheader = L->getLoopPreheader();
   if (!Preheader) {
     DEBUG(dbgs() << "  Can't unroll; loop preheader-insertion failed.\n");
@@ -149,13 +146,6 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count,
   if (ScalarEvolution *SE = LPM->getAnalysisIfAvailable<ScalarEvolution>())
     SE->forgetLoop(L);
 
-  // Find trip count
-  unsigned TripCount = L->getSmallConstantTripCount();
-  // Find trip multiple if count is not available
-  unsigned TripMultiple = 1;
-  if (TripCount == 0)
-    TripMultiple = L->getSmallConstantTripMultiple();
-
   if (TripCount != 0)
     DEBUG(dbgs() << "  Trip Count = " << TripCount << "\n");
   if (TripMultiple != 1)