1 files changed, 41 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 0365862cc16..2f0347771ba 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -1454,6 +1454,11 @@ const SCEV *ScalarEvolution::getZeroExtendExpr(const SCEV *Op,
       unsigned BitWidth = getTypeSizeInBits(AR->getType());
       const Loop *L = AR->getLoop();
 
+      if (!AR->hasNoUnsignedWrap()) {
+        auto NewFlags = proveNoWrapViaConstantRanges(AR);
+        const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
+      }
+
       // If we have special knowledge that this addrec won't overflow,
       // we don't need to do any further analysis.
       if (AR->hasNoUnsignedWrap())
@@ -1663,6 +1668,11 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op,
       unsigned BitWidth = getTypeSizeInBits(AR->getType());
       const Loop *L = AR->getLoop();
 
+      if (!AR->hasNoSignedWrap()) {
+        auto NewFlags = proveNoWrapViaConstantRanges(AR);
+        const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
+      }
+
       // If we have special knowledge that this addrec won't overflow,
       // we don't need to do any further analysis.
       if (AR->hasNoSignedWrap())
@@ -3757,6 +3767,37 @@ private:
 };
 } // end anonymous namespace
 
+SCEV::NoWrapFlags
+ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) {
+  if (!AR->isAffine())
+    return SCEV::FlagAnyWrap;
+
+  typedef OverflowingBinaryOperator OBO;
+  SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap;
+
+  if (!AR->hasNoSignedWrap()) {
+    ConstantRange AddRecRange = getSignedRange(AR);
+    ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this));
+
+    auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
+        Instruction::Add, IncRange, OBO::NoSignedWrap);
+    if (NSWRegion.contains(AddRecRange))
+      Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW);
+  }
+
+  if (!AR->hasNoUnsignedWrap()) {
+    ConstantRange AddRecRange = getUnsignedRange(AR);
+    ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this));
+
+    auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
+        Instruction::Add, IncRange, OBO::NoUnsignedWrap);
+    if (NUWRegion.contains(AddRecRange))
+      Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW);
+  }
+
+  return Result;
+}
+
 const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) {
   const Loop *L = LI.getLoopFor(PN->getParent());
   if (!L || L->getHeader() != PN->getParent())