MFC r309124:

Upgrade our copies of clang, llvm, lldb, compiler-rt and libc++ to 3.9.0
release, and add lld 3.9.0.  Also completely revamp the build system for
clang, llvm, lldb and their related tools.

Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.

Release notes for llvm, clang and lld are available here:
<http://llvm.org/releases/3.9.0/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.9.0/tools/clang/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.9.0/tools/lld/docs/ReleaseNotes.html>

Thanks to Ed Maste, Bryan Drewery, Andrew Turner, Antoine Brodin and Jan
Beich for their help.

Relnotes:	yes

MFC r309147:

Pull in r282174 from upstream llvm trunk (by Krzysztof Parzyszek):

  [PPC] Set SP after loading data from stack frame, if no red zone is
  present

  Follow-up to r280705: Make sure that the SP is only restored after
  all data is loaded from the stack frame, if there is no red zone.

  This completes the fix for
  https://llvm.org/bugs/show_bug.cgi?id=26519.

  Differential Revision: https://reviews.llvm.org/D24466

Reported by:    Mark Millard
PR:             214433

MFC r309149:

Pull in r283060 from upstream llvm trunk (by Hal Finkel):

  [PowerPC] Refactor soft-float support, and enable PPC64 soft float

  This change enables soft-float for PowerPC64, and also makes
  soft-float disable all vector instruction sets for both 32-bit and
  64-bit modes. This latter part is necessary because the PPC backend
  canonicalizes many Altivec vector types to floating-point types, and
  so soft-float breaks scalarization support for many operations. Both
  for embedded targets and for operating-system kernels desiring
  soft-float support, it seems reasonable that disabling hardware
  floating-point also disables vector instructions (embedded targets
  without hardware floating point support are unlikely to have Altivec,
  etc. and operating system kernels desiring not to use floating-point
  registers to lower syscall cost are unlikely to want to use vector
  registers either). If someone needs this to work, we'll need to
  change the fact that we promote many Altivec operations to act on
  v4f32. To make it possible to disable Altivec when soft-float is
  enabled, hardware floating-point support needs to be expressed as a
  positive feature, like the others, and not a negative feature,
  because target features cannot have dependencies on the disabling of
  some other feature. So +soft-float has now become -hard-float.

  Fixes PR26970.

Pull in r283061 from upstream clang trunk (by Hal Finkel):

  [PowerPC] Enable soft-float for PPC64, and +soft-float -> -hard-float

  Enable soft-float support on PPC64, as the backend now supports it.
  Also, the backend now uses -hard-float instead of +soft-float, so set
  the target features accordingly.

  Fixes PR26970.

Reported by:	Mark Millard
PR:		214433

MFC r309212:

Add a few missed clang 3.9.0 files to OptionalObsoleteFiles.

MFC r309262:

Fix packaging for clang, lldb and lld 3.9.0

During the upgrade of clang/llvm etc to 3.9.0 in r309124, the PACKAGE
directive in the usr.bin/clang/*.mk files got dropped accidentally.

Restore it, with a few minor changes and additions:
* Correct license in clang.ucl to NCSA
* Add PACKAGE=clang for clang and most of the "ll" tools
* Put lldb in its own package
* Put lld in its own package

Reviewed by:	gjb, jmallett
Differential Revision: https://reviews.freebsd.org/D8666

MFC r309656:

During the bootstrap phase, when building the minimal llvm library on
PowerPC, add lib/Support/Atomic.cpp.  This is needed because upstream
llvm revision r271821 disabled the use of std::call_once, which causes
some fallback functions from Atomic.cpp to be used instead.

Reported by:	Mark Millard
PR:		214902

MFC r309835:

Tentatively apply https://reviews.llvm.org/D18730 to work around gcc PR
70528 (bogus error: constructor required before non-static data member).
This should fix buildworld with the external gcc package.

Reported by:	https://jenkins.freebsd.org/job/FreeBSD_HEAD_amd64_gcc/

MFC r310194:

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
3.9.1 release.

Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.

Release notes for llvm, clang and lld will be available here:
<http://releases.llvm.org/3.9.1/docs/ReleaseNotes.html>
<http://releases.llvm.org/3.9.1/tools/clang/docs/ReleaseNotes.html>
<http://releases.llvm.org/3.9.1/tools/lld/docs/ReleaseNotes.html>

Relnotes:	yes

1 files changed, 284 insertions, 100 deletions

diff --git a/contrib/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/contrib/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
index 921403d..2e45bb8 100644
--- a/contrib/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/contrib/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -1,4 +1,4 @@
-//===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis --*- C++ -*-===//
+//===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis ------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -95,14 +95,12 @@ static BasicBlock::iterator findInsertPointAfter(Instruction *I,
   while (isa<PHINode>(IP))
     ++IP;
 
-  while (IP->isEHPad()) {
-    if (isa<FuncletPadInst>(IP) || isa<LandingPadInst>(IP)) {
-      ++IP;
-    } else if (isa<CatchSwitchInst>(IP)) {
-      IP = MustDominate->getFirstInsertionPt();
-    } else {
-      llvm_unreachable("unexpected eh pad!");
-    }
+  if (isa<FuncletPadInst>(IP) || isa<LandingPadInst>(IP)) {
+    ++IP;
+  } else if (isa<CatchSwitchInst>(IP)) {
+    IP = MustDominate->getFirstInsertionPt();
+  } else {
+    assert(!IP->isEHPad() && "unexpected eh pad!");
   }
 
   return IP;
@@ -198,7 +196,7 @@ Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
 
   // Save the original insertion point so we can restore it when we're done.
   DebugLoc Loc = Builder.GetInsertPoint()->getDebugLoc();
-  BuilderType::InsertPointGuard Guard(Builder);
+  SCEVInsertPointGuard Guard(Builder, this);
 
   // Move the insertion point out of as many loops as we can.
   while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
@@ -525,7 +523,7 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
     }
 
     // Save the original insertion point so we can restore it when we're done.
-    BuilderType::InsertPointGuard Guard(Builder);
+    SCEVInsertPointGuard Guard(Builder, this);
 
     // Move the insertion point out of as many loops as we can.
     while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
@@ -544,39 +542,37 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
     return GEP;
   }
 
-  // Save the original insertion point so we can restore it when we're done.
-  BuilderType::InsertPoint SaveInsertPt = Builder.saveIP();
+  {
+    SCEVInsertPointGuard Guard(Builder, this);
 
-  // Move the insertion point out of as many loops as we can.
-  while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
-    if (!L->isLoopInvariant(V)) break;
-
-    bool AnyIndexNotLoopInvariant =
-        std::any_of(GepIndices.begin(), GepIndices.end(),
-                    [L](Value *Op) { return !L->isLoopInvariant(Op); });
+    // Move the insertion point out of as many loops as we can.
+    while (const Loop *L = SE.LI.getLoopFor(Builder.GetInsertBlock())) {
+      if (!L->isLoopInvariant(V)) break;
 
-    if (AnyIndexNotLoopInvariant)
-      break;
+      bool AnyIndexNotLoopInvariant =
+          std::any_of(GepIndices.begin(), GepIndices.end(),
+                      [L](Value *Op) { return !L->isLoopInvariant(Op); });
 
-    BasicBlock *Preheader = L->getLoopPreheader();
-    if (!Preheader) break;
+      if (AnyIndexNotLoopInvariant)
+        break;
 
-    // Ok, move up a level.
-    Builder.SetInsertPoint(Preheader->getTerminator());
-  }
+      BasicBlock *Preheader = L->getLoopPreheader();
+      if (!Preheader) break;
 
-  // Insert a pretty getelementptr. Note that this GEP is not marked inbounds,
-  // because ScalarEvolution may have changed the address arithmetic to
-  // compute a value which is beyond the end of the allocated object.
-  Value *Casted = V;
-  if (V->getType() != PTy)
-    Casted = InsertNoopCastOfTo(Casted, PTy);
-  Value *GEP = Builder.CreateGEP(OriginalElTy, Casted, GepIndices, "scevgep");
-  Ops.push_back(SE.getUnknown(GEP));
-  rememberInstruction(GEP);
+      // Ok, move up a level.
+      Builder.SetInsertPoint(Preheader->getTerminator());
+    }
 
-  // Restore the original insert point.
-  Builder.restoreIP(SaveInsertPt);
+    // Insert a pretty getelementptr. Note that this GEP is not marked inbounds,
+    // because ScalarEvolution may have changed the address arithmetic to
+    // compute a value which is beyond the end of the allocated object.
+    Value *Casted = V;
+    if (V->getType() != PTy)
+      Casted = InsertNoopCastOfTo(Casted, PTy);
+    Value *GEP = Builder.CreateGEP(OriginalElTy, Casted, GepIndices, "scevgep");
+    Ops.push_back(SE.getUnknown(GEP));
+    rememberInstruction(GEP);
+  }
 
   return expand(SE.getAddExpr(Ops));
 }
@@ -907,6 +903,23 @@ Instruction *SCEVExpander::getIVIncOperand(Instruction *IncV,
   }
 }
 
+/// If the insert point of the current builder or any of the builders on the
+/// stack of saved builders has 'I' as its insert point, update it to point to
+/// the instruction after 'I'.  This is intended to be used when the instruction
+/// 'I' is being moved.  If this fixup is not done and 'I' is moved to a
+/// different block, the inconsistent insert point (with a mismatched
+/// Instruction and Block) can lead to an instruction being inserted in a block
+/// other than its parent.
+void SCEVExpander::fixupInsertPoints(Instruction *I) {
+  BasicBlock::iterator It(*I);
+  BasicBlock::iterator NewInsertPt = std::next(It);
+  if (Builder.GetInsertPoint() == It)
+    Builder.SetInsertPoint(&*NewInsertPt);
+  for (auto *InsertPtGuard : InsertPointGuards)
+    if (InsertPtGuard->GetInsertPoint() == It)
+      InsertPtGuard->SetInsertPoint(NewInsertPt);
+}
+
 /// hoistStep - Attempt to hoist a simple IV increment above InsertPos to make
 /// it available to other uses in this loop. Recursively hoist any operands,
 /// until we reach a value that dominates InsertPos.
@@ -936,6 +949,7 @@ bool SCEVExpander::hoistIVInc(Instruction *IncV, Instruction *InsertPos) {
       break;
   }
   for (auto I = IVIncs.rbegin(), E = IVIncs.rend(); I != E; ++I) {
+    fixupInsertPoints(*I);
     (*I)->moveBefore(InsertPos);
   }
   return true;
@@ -989,13 +1003,14 @@ Value *SCEVExpander::expandIVInc(PHINode *PN, Value *StepV, const Loop *L,
 
 /// \brief Hoist the addrec instruction chain rooted in the loop phi above the
 /// position. This routine assumes that this is possible (has been checked).
-static void hoistBeforePos(DominatorTree *DT, Instruction *InstToHoist,
-                           Instruction *Pos, PHINode *LoopPhi) {
+void SCEVExpander::hoistBeforePos(DominatorTree *DT, Instruction *InstToHoist,
+                                  Instruction *Pos, PHINode *LoopPhi) {
   do {
     if (DT->dominates(InstToHoist, Pos))
       break;
     // Make sure the increment is where we want it. But don't move it
     // down past a potential existing post-inc user.
+    fixupInsertPoints(InstToHoist);
     InstToHoist->moveBefore(Pos);
     Pos = InstToHoist;
     InstToHoist = cast<Instruction>(InstToHoist->getOperand(0));
@@ -1156,7 +1171,7 @@ SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
   }
 
   // Save the original insertion point so we can restore it when we're done.
-  BuilderType::InsertPointGuard Guard(Builder);
+  SCEVInsertPointGuard Guard(Builder, this);
 
   // Another AddRec may need to be recursively expanded below. For example, if
   // this AddRec is quadratic, the StepV may itself be an AddRec in this
@@ -1273,6 +1288,13 @@ Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
   if (!SE.dominates(Step, L->getHeader())) {
     PostLoopScale = Step;
     Step = SE.getConstant(Normalized->getType(), 1);
+    if (!Start->isZero()) {
+        // The normalization below assumes that Start is constant zero, so if
+        // it isn't re-associate Start to PostLoopOffset.
+        assert(!PostLoopOffset && "Start not-null but PostLoopOffset set?");
+        PostLoopOffset = Start;
+        Start = SE.getConstant(Normalized->getType(), 0);
+    }
     Normalized =
       cast<SCEVAddRecExpr>(SE.getAddRecExpr(
                              Start, Step, Normalized->getLoop(),
@@ -1321,7 +1343,7 @@ Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
       Value *StepV;
       {
         // Expand the step somewhere that dominates the loop header.
-        BuilderType::InsertPointGuard Guard(Builder);
+        SCEVInsertPointGuard Guard(Builder, this);
         StepV = expandCodeFor(Step, IntTy, &L->getHeader()->front());
       }
       Result = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
@@ -1428,8 +1450,12 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
     }
 
     // Just do a normal add. Pre-expand the operands to suppress folding.
-    return expand(SE.getAddExpr(SE.getUnknown(expand(S->getStart())),
-                                SE.getUnknown(expand(Rest))));
+    //
+    // The LHS and RHS values are factored out of the expand call to make the
+    // output independent of the argument evaluation order.
+    const SCEV *AddExprLHS = SE.getUnknown(expand(S->getStart()));
+    const SCEV *AddExprRHS = SE.getUnknown(expand(Rest));
+    return expand(SE.getAddExpr(AddExprLHS, AddExprRHS));
   }
 
   // If we don't yet have a canonical IV, create one.
@@ -1584,8 +1610,7 @@ Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
 
 Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty,
                                    Instruction *IP) {
-  assert(IP);
-  Builder.SetInsertPoint(IP);
+  setInsertPoint(IP);
   return expandCodeFor(SH, Ty);
 }
 
@@ -1600,6 +1625,40 @@ Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty) {
   return V;
 }
 
+Value *SCEVExpander::FindValueInExprValueMap(const SCEV *S,
+                                             const Instruction *InsertPt) {
+  SetVector<Value *> *Set = SE.getSCEVValues(S);
+  // If the expansion is not in CanonicalMode, and the SCEV contains any
+  // sub scAddRecExpr type SCEV, it is required to expand the SCEV literally.
+  if (CanonicalMode || !SE.containsAddRecurrence(S)) {
+    // If S is scConstant, it may be worse to reuse an existing Value.
+    if (S->getSCEVType() != scConstant && Set) {
+      // Choose a Value from the set which dominates the insertPt.
+      // insertPt should be inside the Value's parent loop so as not to break
+      // the LCSSA form.
+      for (auto const &Ent : *Set) {
+        Instruction *EntInst = nullptr;
+        if (Ent && isa<Instruction>(Ent) &&
+            (EntInst = cast<Instruction>(Ent)) &&
+            S->getType() == Ent->getType() &&
+            EntInst->getFunction() == InsertPt->getFunction() &&
+            SE.DT.dominates(EntInst, InsertPt) &&
+            (SE.LI.getLoopFor(EntInst->getParent()) == nullptr ||
+             SE.LI.getLoopFor(EntInst->getParent())->contains(InsertPt))) {
+          return Ent;
+        }
+      }
+    }
+  }
+  return nullptr;
+}
+
+// The expansion of SCEV will either reuse a previous Value in ExprValueMap,
+// or expand the SCEV literally. Specifically, if the expansion is in LSRMode,
+// and the SCEV contains any sub scAddRecExpr type SCEV, it will be expanded
+// literally, to prevent LSR's transformed SCEV from being reverted. Otherwise,
+// the expansion will try to reuse Value from ExprValueMap, and only when it
+// fails, expand the SCEV literally.
 Value *SCEVExpander::expand(const SCEV *S) {
   // Compute an insertion point for this SCEV object. Hoist the instructions
   // as far out in the loop nest as possible.
@@ -1622,9 +1681,9 @@ Value *SCEVExpander::expand(const SCEV *S) {
       // there) so that it is guaranteed to dominate any user inside the loop.
       if (L && SE.hasComputableLoopEvolution(S, L) && !PostIncLoops.count(L))
         InsertPt = &*L->getHeader()->getFirstInsertionPt();
-      while (InsertPt != Builder.GetInsertPoint()
-             && (isInsertedInstruction(InsertPt)
-                 || isa<DbgInfoIntrinsic>(InsertPt))) {
+      while (InsertPt->getIterator() != Builder.GetInsertPoint() &&
+             (isInsertedInstruction(InsertPt) ||
+              isa<DbgInfoIntrinsic>(InsertPt))) {
         InsertPt = &*std::next(InsertPt->getIterator());
       }
       break;
@@ -1635,11 +1694,14 @@ Value *SCEVExpander::expand(const SCEV *S) {
   if (I != InsertedExpressions.end())
     return I->second;
 
-  BuilderType::InsertPointGuard Guard(Builder);
+  SCEVInsertPointGuard Guard(Builder, this);
   Builder.SetInsertPoint(InsertPt);
 
   // Expand the expression into instructions.
-  Value *V = visit(S);
+  Value *V = FindValueInExprValueMap(S, InsertPt);
+
+  if (!V)
+    V = visit(S);
 
   // Remember the expanded value for this SCEV at this location.
   //
@@ -1673,7 +1735,7 @@ SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L,
                                    SE.getConstant(Ty, 1), L, SCEV::FlagAnyWrap);
 
   // Emit code for it.
-  BuilderType::InsertPointGuard Guard(Builder);
+  SCEVInsertPointGuard Guard(Builder, this);
   PHINode *V =
       cast<PHINode>(expandCodeFor(H, nullptr, &L->getHeader()->front()));
 
@@ -1742,8 +1804,8 @@ unsigned SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
     PHINode *&OrigPhiRef = ExprToIVMap[SE.getSCEV(Phi)];
     if (!OrigPhiRef) {
       OrigPhiRef = Phi;
-      if (Phi->getType()->isIntegerTy() && TTI
-          && TTI->isTruncateFree(Phi->getType(), Phis.back()->getType())) {
+      if (Phi->getType()->isIntegerTy() && TTI &&
+          TTI->isTruncateFree(Phi->getType(), Phis.back()->getType())) {
         // This phi can be freely truncated to the narrowest phi type. Map the
         // truncated expression to it so it will be reused for narrow types.
         const SCEV *TruncExpr =
@@ -1759,56 +1821,59 @@ unsigned SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
       continue;
 
     if (BasicBlock *LatchBlock = L->getLoopLatch()) {
-      Instruction *OrigInc =
-        cast<Instruction>(OrigPhiRef->getIncomingValueForBlock(LatchBlock));
+      Instruction *OrigInc = dyn_cast<Instruction>(
+          OrigPhiRef->getIncomingValueForBlock(LatchBlock));
       Instruction *IsomorphicInc =
-        cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock));
-
-      // If this phi has the same width but is more canonical, replace the
-      // original with it. As part of the "more canonical" determination,
-      // respect a prior decision to use an IV chain.
-      if (OrigPhiRef->getType() == Phi->getType()
-          && !(ChainedPhis.count(Phi)
-               || isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L))
-          && (ChainedPhis.count(Phi)
-              || isExpandedAddRecExprPHI(Phi, IsomorphicInc, L))) {
-        std::swap(OrigPhiRef, Phi);
-        std::swap(OrigInc, IsomorphicInc);
-      }
-      // Replacing the congruent phi is sufficient because acyclic redundancy
-      // elimination, CSE/GVN, should handle the rest. However, once SCEV proves
-      // that a phi is congruent, it's often the head of an IV user cycle that
-      // is isomorphic with the original phi. It's worth eagerly cleaning up the
-      // common case of a single IV increment so that DeleteDeadPHIs can remove
-      // cycles that had postinc uses.
-      const SCEV *TruncExpr = SE.getTruncateOrNoop(SE.getSCEV(OrigInc),
-                                                   IsomorphicInc->getType());
-      if (OrigInc != IsomorphicInc
-          && TruncExpr == SE.getSCEV(IsomorphicInc)
-          && ((isa<PHINode>(OrigInc) && isa<PHINode>(IsomorphicInc))
-              || hoistIVInc(OrigInc, IsomorphicInc))) {
-        DEBUG_WITH_TYPE(DebugType, dbgs()
-                        << "INDVARS: Eliminated congruent iv.inc: "
-                        << *IsomorphicInc << '\n');
-        Value *NewInc = OrigInc;
-        if (OrigInc->getType() != IsomorphicInc->getType()) {
-          Instruction *IP = nullptr;
-          if (PHINode *PN = dyn_cast<PHINode>(OrigInc))
-            IP = &*PN->getParent()->getFirstInsertionPt();
-          else
-            IP = OrigInc->getNextNode();
-
-          IRBuilder<> Builder(IP);
-          Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
-          NewInc = Builder.
-            CreateTruncOrBitCast(OrigInc, IsomorphicInc->getType(), IVName);
+          dyn_cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock));
+
+      if (OrigInc && IsomorphicInc) {
+        // If this phi has the same width but is more canonical, replace the
+        // original with it. As part of the "more canonical" determination,
+        // respect a prior decision to use an IV chain.
+        if (OrigPhiRef->getType() == Phi->getType() &&
+            !(ChainedPhis.count(Phi) ||
+              isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L)) &&
+            (ChainedPhis.count(Phi) ||
+             isExpandedAddRecExprPHI(Phi, IsomorphicInc, L))) {
+          std::swap(OrigPhiRef, Phi);
+          std::swap(OrigInc, IsomorphicInc);
+        }
+        // Replacing the congruent phi is sufficient because acyclic
+        // redundancy elimination, CSE/GVN, should handle the
+        // rest. However, once SCEV proves that a phi is congruent,
+        // it's often the head of an IV user cycle that is isomorphic
+        // with the original phi. It's worth eagerly cleaning up the
+        // common case of a single IV increment so that DeleteDeadPHIs
+        // can remove cycles that had postinc uses.
+        const SCEV *TruncExpr =
+            SE.getTruncateOrNoop(SE.getSCEV(OrigInc), IsomorphicInc->getType());
+        if (OrigInc != IsomorphicInc &&
+            TruncExpr == SE.getSCEV(IsomorphicInc) &&
+            SE.LI.replacementPreservesLCSSAForm(IsomorphicInc, OrigInc) &&
+            hoistIVInc(OrigInc, IsomorphicInc)) {
+          DEBUG_WITH_TYPE(DebugType,
+                          dbgs() << "INDVARS: Eliminated congruent iv.inc: "
+                                 << *IsomorphicInc << '\n');
+          Value *NewInc = OrigInc;
+          if (OrigInc->getType() != IsomorphicInc->getType()) {
+            Instruction *IP = nullptr;
+            if (PHINode *PN = dyn_cast<PHINode>(OrigInc))
+              IP = &*PN->getParent()->getFirstInsertionPt();
+            else
+              IP = OrigInc->getNextNode();
+
+            IRBuilder<> Builder(IP);
+            Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
+            NewInc = Builder.CreateTruncOrBitCast(
+                OrigInc, IsomorphicInc->getType(), IVName);
+          }
+          IsomorphicInc->replaceAllUsesWith(NewInc);
+          DeadInsts.emplace_back(IsomorphicInc);
         }
-        IsomorphicInc->replaceAllUsesWith(NewInc);
-        DeadInsts.emplace_back(IsomorphicInc);
       }
     }
-    DEBUG_WITH_TYPE(DebugType, dbgs()
-                    << "INDVARS: Eliminated congruent iv: " << *Phi << '\n');
+    DEBUG_WITH_TYPE(DebugType, dbgs() << "INDVARS: Eliminated congruent iv: "
+                                      << *Phi << '\n');
     ++NumElim;
     Value *NewIV = OrigPhiRef;
     if (OrigPhiRef->getType() != Phi->getType()) {
@@ -1847,6 +1912,11 @@ Value *SCEVExpander::findExistingExpansion(const SCEV *S,
       return RHS;
   }
 
+  // Use expand's logic which is used for reusing a previous Value in
+  // ExprValueMap.
+  if (Value *Val = FindValueInExprValueMap(S, At))
+    return Val;
+
   // There is potential to make this significantly smarter, but this simple
   // heuristic already gets some interesting cases.
 
@@ -1940,6 +2010,10 @@ Value *SCEVExpander::expandCodeForPredicate(const SCEVPredicate *Pred,
     return expandUnionPredicate(cast<SCEVUnionPredicate>(Pred), IP);
   case SCEVPredicate::P_Equal:
     return expandEqualPredicate(cast<SCEVEqualPredicate>(Pred), IP);
+  case SCEVPredicate::P_Wrap: {
+    auto *AddRecPred = cast<SCEVWrapPredicate>(Pred);
+    return expandWrapPredicate(AddRecPred, IP);
+  }
   }
   llvm_unreachable("Unknown SCEV predicate type");
 }
@@ -1954,6 +2028,116 @@ Value *SCEVExpander::expandEqualPredicate(const SCEVEqualPredicate *Pred,
   return I;
 }
 
+Value *SCEVExpander::generateOverflowCheck(const SCEVAddRecExpr *AR,
+                                           Instruction *Loc, bool Signed) {
+  assert(AR->isAffine() && "Cannot generate RT check for "
+                           "non-affine expression");
+
+  SCEVUnionPredicate Pred;
+  const SCEV *ExitCount =
+      SE.getPredicatedBackedgeTakenCount(AR->getLoop(), Pred);
+
+  assert(ExitCount != SE.getCouldNotCompute() && "Invalid loop count");
+
+  const SCEV *Step = AR->getStepRecurrence(SE);
+  const SCEV *Start = AR->getStart();
+
+  unsigned SrcBits = SE.getTypeSizeInBits(ExitCount->getType());
+  unsigned DstBits = SE.getTypeSizeInBits(AR->getType());
+
+  // The expression {Start,+,Step} has nusw/nssw if
+  //   Step < 0, Start - |Step| * Backedge <= Start
+  //   Step >= 0, Start + |Step| * Backedge > Start
+  // and |Step| * Backedge doesn't unsigned overflow.
+
+  IntegerType *CountTy = IntegerType::get(Loc->getContext(), SrcBits);
+  Builder.SetInsertPoint(Loc);
+  Value *TripCountVal = expandCodeFor(ExitCount, CountTy, Loc);
+
+  IntegerType *Ty =
+      IntegerType::get(Loc->getContext(), SE.getTypeSizeInBits(AR->getType()));
+
+  Value *StepValue = expandCodeFor(Step, Ty, Loc);
+  Value *NegStepValue = expandCodeFor(SE.getNegativeSCEV(Step), Ty, Loc);
+  Value *StartValue = expandCodeFor(Start, Ty, Loc);
+
+  ConstantInt *Zero =
+      ConstantInt::get(Loc->getContext(), APInt::getNullValue(DstBits));
+
+  Builder.SetInsertPoint(Loc);
+  // Compute |Step|
+  Value *StepCompare = Builder.CreateICmp(ICmpInst::ICMP_SLT, StepValue, Zero);
+  Value *AbsStep = Builder.CreateSelect(StepCompare, NegStepValue, StepValue);
+
+  // Get the backedge taken count and truncate or extended to the AR type.
+  Value *TruncTripCount = Builder.CreateZExtOrTrunc(TripCountVal, Ty);
+  auto *MulF = Intrinsic::getDeclaration(Loc->getModule(),
+                                         Intrinsic::umul_with_overflow, Ty);
+
+  // Compute |Step| * Backedge
+  CallInst *Mul = Builder.CreateCall(MulF, {AbsStep, TruncTripCount}, "mul");
+  Value *MulV = Builder.CreateExtractValue(Mul, 0, "mul.result");
+  Value *OfMul = Builder.CreateExtractValue(Mul, 1, "mul.overflow");
+
+  // Compute:
+  //   Start + |Step| * Backedge < Start
+  //   Start - |Step| * Backedge > Start
+  Value *Add = Builder.CreateAdd(StartValue, MulV);
+  Value *Sub = Builder.CreateSub(StartValue, MulV);
+
+  Value *EndCompareGT = Builder.CreateICmp(
+      Signed ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT, Sub, StartValue);
+
+  Value *EndCompareLT = Builder.CreateICmp(
+      Signed ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT, Add, StartValue);
+
+  // Select the answer based on the sign of Step.
+  Value *EndCheck =
+      Builder.CreateSelect(StepCompare, EndCompareGT, EndCompareLT);
+
+  // If the backedge taken count type is larger than the AR type,
+  // check that we don't drop any bits by truncating it. If we are
+  // droping bits, then we have overflow (unless the step is zero).
+  if (SE.getTypeSizeInBits(CountTy) > SE.getTypeSizeInBits(Ty)) {
+    auto MaxVal = APInt::getMaxValue(DstBits).zext(SrcBits);
+    auto *BackedgeCheck =
+        Builder.CreateICmp(ICmpInst::ICMP_UGT, TripCountVal,
+                           ConstantInt::get(Loc->getContext(), MaxVal));
+    BackedgeCheck = Builder.CreateAnd(
+        BackedgeCheck, Builder.CreateICmp(ICmpInst::ICMP_NE, StepValue, Zero));
+
+    EndCheck = Builder.CreateOr(EndCheck, BackedgeCheck);
+  }
+
+  EndCheck = Builder.CreateOr(EndCheck, OfMul);
+  return EndCheck;
+}
+
+Value *SCEVExpander::expandWrapPredicate(const SCEVWrapPredicate *Pred,
+                                         Instruction *IP) {
+  const auto *A = cast<SCEVAddRecExpr>(Pred->getExpr());
+  Value *NSSWCheck = nullptr, *NUSWCheck = nullptr;
+
+  // Add a check for NUSW
+  if (Pred->getFlags() & SCEVWrapPredicate::IncrementNUSW)
+    NUSWCheck = generateOverflowCheck(A, IP, false);
+
+  // Add a check for NSSW
+  if (Pred->getFlags() & SCEVWrapPredicate::IncrementNSSW)
+    NSSWCheck = generateOverflowCheck(A, IP, true);
+
+  if (NUSWCheck && NSSWCheck)
+    return Builder.CreateOr(NUSWCheck, NSSWCheck);
+
+  if (NUSWCheck)
+    return NUSWCheck;
+
+  if (NSSWCheck)
+    return NSSWCheck;
+
+  return ConstantInt::getFalse(IP->getContext());
+}
+
 Value *SCEVExpander::expandUnionPredicate(const SCEVUnionPredicate *Union,
                                           Instruction *IP) {
   auto *BoolType = IntegerType::get(IP->getContext(), 1);