InstSimplify: Move a transform from InstCombine to InstSimplify

[oota-llvm.git] / lib / Transforms / Utils / LoopUnrollRuntime.cpp

diff --git a/lib/Transforms/Utils/LoopUnrollRuntime.cpp b/lib/Transforms/Utils/LoopUnrollRuntime.cpp
index d1ea2d6be64e7f522bb94881fdee693934e4c475..a96c46ad63e0d62d658dc51e49b30b2b221881d8 100644 (file)
--- a/lib/Transforms/Utils/LoopUnrollRuntime.cpp
+++ b/lib/Transforms/Utils/LoopUnrollRuntime.cpp
@@ -59,7 +59,7 @@ static void ConnectProlog(Loop *L, Value *TripCount, unsigned Count,
                           BasicBlock *OrigPH, BasicBlock *NewPH,
                           ValueToValueMapTy &LVMap, Pass *P) {
   BasicBlock *Latch = L->getLoopLatch();
-  assert(Latch != 0 && "Loop must have a latch");
+  assert(Latch && "Loop must have a latch");
 
   // Create a PHI node for each outgoing value from the original loop
   // (which means it is an outgoing value from the prolog code too).
@@ -111,7 +111,7 @@ static void ConnectProlog(Loop *L, Value *TripCount, unsigned Count,
     new ICmpInst(InsertPt, ICmpInst::ICMP_ULT, TripCount,
                  ConstantInt::get(TripCount->getType(), Count));
   BasicBlock *Exit = L->getUniqueExitBlock();
-  assert(Exit != 0 && "Loop must have a single exit block only");
+  assert(Exit && "Loop must have a single exit block only");
   // Split the exit to maintain loop canonicalization guarantees
   SmallVector<BasicBlock*, 4> Preds(pred_begin(Exit), pred_end(Exit));
   if (!Exit->isLandingPad()) {
@@ -280,17 +280,17 @@ bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count, LoopInfo *LI,
   SCEVExpander Expander(*SE, "loop-unroll");
   Value *TripCount = Expander.expandCodeFor(TripCountSC, TripCountSC->getType(),
                                             PreHeaderBR);
-  Type *CountTy = TripCount->getType();
-  BinaryOperator *ModVal =
-    BinaryOperator::CreateURem(TripCount,
-                               ConstantInt::get(CountTy, Count),
-                               "xtraiter");
-  ModVal->insertBefore(PreHeaderBR);
-
-  // Check if for no extra iterations, then jump to unrolled loop
-  Value *BranchVal = new ICmpInst(PreHeaderBR,
-                                  ICmpInst::ICMP_NE, ModVal,
-                                  ConstantInt::get(CountTy, 0), "lcmp");
+
+  IRBuilder<> B(PreHeaderBR);
+  Value *ModVal = B.CreateAnd(TripCount, Count - 1, "xtraiter");
+
+  // Check if for no extra iterations, then jump to unrolled loop.  We have to
+  // check that the trip count computation didn't overflow when adding one to
+  // the backedge taken count.
+  Value *LCmp = B.CreateIsNotNull(ModVal, "lcmp.mod");
+  Value *OverflowCheck = B.CreateIsNull(TripCount, "lcmp.overflow");
+  Value *BranchVal = B.CreateOr(OverflowCheck, LCmp, "lcmp.or");
+
   // Branch to either the extra iterations or the unrolled loop
   // We will fix up the true branch label when adding loop body copies
   BranchInst::Create(PEnd, PEnd, BranchVal, PreHeaderBR);
@@ -344,6 +344,7 @@ bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count, LoopInfo *LI,
       }
 
       // The comparison w/ the extra iteration value and branch
+      Type *CountTy = TripCount->getType();
       Value *BranchVal = new ICmpInst(*NewBB, ICmpInst::ICMP_EQ, ModVal,
                                       ConstantInt::get(CountTy, leftOverIters),
                                       "un.tmp");