Update clang, llvm, lld, lldb, compiler-rt and libc++ to 4.0.0 release:

MFC r309142 (by emaste):

Add WITH_LLD_AS_LD build knob

If set it installs LLD as /usr/bin/ld.  LLD (as of version 3.9) is not
capable of linking the world and kernel, but can self-host and link many
substantial applications. GNU ld continues to be used for the world and
kernel build, regardless of how this knob is set.

It is on by default for arm64, and off for all other CPU architectures.

Sponsored by:	The FreeBSD Foundation

MFC r310840:

Reapply 310775, now it also builds correctly if lldb is disabled:

Move llvm-objdump from CLANG_EXTRAS to installed by default

We currently install three tools from binutils 2.17.50: as, ld, and
objdump. Work is underway to migrate to a permissively-licensed
tool-chain, with one goal being the retirement of binutils 2.17.50.

LLVM's llvm-objdump is intended to be compatible with GNU objdump
although it is currently missing some options and may have formatting
differences. Enable it by default for testing and further investigation.
It may later be changed to install as /usr/bin/objdump, it becomes a
fully viable replacement.

Reviewed by:	emaste
Differential Revision:	https://reviews.freebsd.org/D8879

MFC r312855 (by emaste):

Rename LLD_AS_LD to LLD_IS_LD, for consistency with CLANG_IS_CC

Reported by:	Dan McGregor <dan.mcgregor usask.ca>

MFC r313559 | glebius | 2017-02-10 18:34:48 +0100 (Fri, 10 Feb 2017) | 5 lines

Don't check struct rtentry on FreeBSD, it is an internal kernel structure.
On other systems it may be API structure for SIOCADDRT/SIOCDELRT.

Reviewed by:	emaste, dim

MFC r314152 (by jkim):

Remove an assembler flag, which is redundant since r309124.  The upstream
took care of it by introducing a macro NO_EXEC_STACK_DIRECTIVE.

http://llvm.org/viewvc/llvm-project?rev=273500&view=rev

Reviewed by:	dim

MFC r314564:

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
4.0.0 (branches/release_40 296509).  The release will follow soon.

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

Also note that as of 4.0.0, lld should be able to link the base system
on amd64 and aarch64.  See the WITH_LLD_IS_LLD setting in src.conf(5).
Though please be aware that this is work in progress.

Release notes for llvm, clang and lld will be available here:
<http://releases.llvm.org/4.0.0/docs/ReleaseNotes.html>
<http://releases.llvm.org/4.0.0/tools/clang/docs/ReleaseNotes.html>
<http://releases.llvm.org/4.0.0/tools/lld/docs/ReleaseNotes.html>

Thanks to Ed Maste, Jan Beich, Antoine Brodin and Eric Fiselier for
their help.

Relnotes:	yes
Exp-run:	antoine
PR:		215969, 216008

MFC r314708:

For now, revert r287232 from upstream llvm trunk (by Daniil Fukalov):

  [SCEV] limit recursion depth of CompareSCEVComplexity

  Summary:
  CompareSCEVComplexity goes too deep (50+ on a quite a big unrolled
  loop) and runs almost infinite time.

  Added cache of "equal" SCEV pairs to earlier cutoff of further
  estimation. Recursion depth limit was also introduced as a parameter.

  Reviewers: sanjoy

  Subscribers: mzolotukhin, tstellarAMD, llvm-commits

  Differential Revision: https://reviews.llvm.org/D26389

This commit is the cause of excessive compile times on skein_block.c
(and possibly other files) during kernel builds on amd64.

We never saw the problematic behavior described in this upstream commit,
so for now it is better to revert it.  An upstream bug has been filed
here: https://bugs.llvm.org/show_bug.cgi?id=32142

Reported by:	mjg

MFC r314795:

Reapply r287232 from upstream llvm trunk (by Daniil Fukalov):

  [SCEV] limit recursion depth of CompareSCEVComplexity

  Summary:
  CompareSCEVComplexity goes too deep (50+ on a quite a big unrolled
  loop) and runs almost infinite time.

  Added cache of "equal" SCEV pairs to earlier cutoff of further
  estimation. Recursion depth limit was also introduced as a parameter.

  Reviewers: sanjoy

  Subscribers: mzolotukhin, tstellarAMD, llvm-commits

  Differential Revision: https://reviews.llvm.org/D26389

Pull in r296992 from upstream llvm trunk (by Sanjoy Das):

  [SCEV] Decrease the recursion threshold for CompareValueComplexity

  Fixes PR32142.

  r287232 accidentally increased the recursion threshold for
  CompareValueComplexity from 2 to 32.  This change reverses that
  change by introducing a separate flag for CompareValueComplexity's
  threshold.

The latter revision fixes the excessive compile times for skein_block.c.

MFC r314907 | mmel | 2017-03-08 12:40:27 +0100 (Wed, 08 Mar 2017) | 7 lines

Unbreak ARMv6 world.

The new compiler_rt library imported with clang 4.0.0 have several fatal
issues (non-functional __udivsi3 for example) with ARM specific instrict
functions. As temporary workaround, until upstream solve these problems,
disable all thumb[1][2] related feature.

MFC r315016:

Update clang, llvm, lld, lldb, compiler-rt and libc++ to 4.0.0 release.
We were already very close to the last release candidate, so this is a
pretty minor update.

Relnotes:	yes

MFC r316005:

Revert r314907, and pull in r298713 from upstream compiler-rt trunk (by
Weiming Zhao):

  builtins: Select correct code fragments when compiling for Thumb1/Thum2/ARM ISA.

  Summary:
  Value of __ARM_ARCH_ISA_THUMB isn't based on the actual compilation
  mode (-mthumb, -marm), it reflect's capability of given CPU.

  Due to this:
   - use  __tbumb__ and __thumb2__ insteand of __ARM_ARCH_ISA_THUMB
   - use '.thumb' directive consistently  in all affected files
   - decorate all thumb functions using
     DEFINE_COMPILERRT_THUMB_FUNCTION()

  ---------
  Note: This patch doesn't fix broken Thumb1 variant of __udivsi3 !

  Reviewers: weimingz, rengolin, compnerd

  Subscribers: aemerson, dim

  Differential Revision: https://reviews.llvm.org/D30938

Discussed with:	mmel

1 files changed, 173 insertions, 178 deletions

diff --git a/contrib/llvm/lib/Analysis/AliasSetTracker.cpp b/contrib/llvm/lib/Analysis/AliasSetTracker.cpp
index d349ac5..701b0e1 100644
--- a/contrib/llvm/lib/Analysis/AliasSetTracker.cpp
+++ b/contrib/llvm/lib/Analysis/AliasSetTracker.cpp
@@ -26,12 +26,19 @@
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
+static cl::opt<unsigned>
+    SaturationThreshold("alias-set-saturation-threshold", cl::Hidden,
+                        cl::init(250),
+                        cl::desc("The maximum number of pointers may-alias "
+                                 "sets may contain before degradation"));
+
 /// mergeSetIn - Merge the specified alias set into this alias set.
 ///
 void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
   assert(!AS.Forward && "Alias set is already forwarding!");
   assert(!Forward && "This set is a forwarding set!!");
 
+  bool WasMustAlias = (Alias == SetMustAlias);
   // Update the alias and access types of this set...
   Access |= AS.Access;
   Alias  |= AS.Alias;
@@ -52,6 +59,13 @@ void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
       Alias = SetMayAlias;
   }
 
+  if (Alias == SetMayAlias) {
+    if (WasMustAlias)
+      AST.TotalMayAliasSetSize += size();
+    if (AS.Alias == SetMustAlias)
+      AST.TotalMayAliasSetSize += AS.size();
+  }
+
   bool ASHadUnknownInsts = !AS.UnknownInsts.empty();
   if (UnknownInsts.empty()) {            // Merge call sites...
     if (ASHadUnknownInsts) {
@@ -63,11 +77,13 @@ void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
     AS.UnknownInsts.clear();
   }
 
-  AS.Forward = this;  // Forward across AS now...
-  addRef();           // AS is now pointing to us...
+  AS.Forward = this; // Forward across AS now...
+  addRef();          // AS is now pointing to us...
 
   // Merge the list of constituent pointers...
   if (AS.PtrList) {
+    SetSize += AS.size();
+    AS.SetSize = 0;
     *PtrListEnd = AS.PtrList;
     AS.PtrList->setPrevInList(PtrListEnd);
     PtrListEnd = AS.PtrListEnd;
@@ -85,7 +101,12 @@ void AliasSetTracker::removeAliasSet(AliasSet *AS) {
     Fwd->dropRef(*this);
     AS->Forward = nullptr;
   }
+
+  if (AS->Alias == AliasSet::SetMayAlias)
+    TotalMayAliasSetSize -= AS->size();
+
   AliasSets.erase(AS);
+
 }
 
 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
@@ -105,10 +126,13 @@ void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
       AliasResult Result =
           AA.alias(MemoryLocation(P->getValue(), P->getSize(), P->getAAInfo()),
                    MemoryLocation(Entry.getValue(), Size, AAInfo));
-      if (Result != MustAlias)
+      if (Result != MustAlias) {
         Alias = SetMayAlias;
-      else                  // First entry of must alias must have maximum size!
+        AST.TotalMayAliasSetSize += size();
+      } else {
+        // First entry of must alias must have maximum size!        
         P->updateSizeAndAAInfo(Size, AAInfo);
+      }
       assert(Result != NoAlias && "Cannot be part of must set!");
     }
 
@@ -116,11 +140,16 @@ void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
   Entry.updateSizeAndAAInfo(Size, AAInfo);
 
   // Add it to the end of the list...
+  ++SetSize;
   assert(*PtrListEnd == nullptr && "End of list is not null?");
   *PtrListEnd = &Entry;
   PtrListEnd = Entry.setPrevInList(PtrListEnd);
   assert(*PtrListEnd == nullptr && "End of list is not null?");
-  addRef();               // Entry points to alias set.
+  // Entry points to alias set.
+  addRef();
+
+  if (Alias == SetMayAlias)
+    AST.TotalMayAliasSetSize++;
 }
 
 void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
@@ -145,6 +174,9 @@ void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
 bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
                               const AAMDNodes &AAInfo,
                               AliasAnalysis &AA) const {
+  if (AliasAny)
+    return true;
+
   if (Alias == SetMustAlias) {
     assert(UnknownInsts.empty() && "Illegal must alias set!");
 
@@ -177,6 +209,10 @@ bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
 
 bool AliasSet::aliasesUnknownInst(const Instruction *Inst,
                                   AliasAnalysis &AA) const {
+
+  if (AliasAny)
+    return true;
+
   if (!Inst->mayReadOrWriteMemory())
     return false;
 
@@ -229,17 +265,6 @@ AliasSet *AliasSetTracker::mergeAliasSetsForPointer(const Value *Ptr,
   return FoundSet;
 }
 
-/// containsPointer - Return true if the specified location is represented by
-/// this alias set, false otherwise.  This does not modify the AST object or
-/// alias sets.
-bool AliasSetTracker::containsPointer(const Value *Ptr, uint64_t Size,
-                                      const AAMDNodes &AAInfo) const {
-  for (const AliasSet &AS : *this)
-    if (!AS.Forward && AS.aliasesPointer(Ptr, Size, AAInfo, AA))
-      return true;
-  return false;
-}
-
 bool AliasSetTracker::containsUnknown(const Instruction *Inst) const {
   for (const AliasSet &AS : *this)
     if (!AS.Forward && AS.aliasesUnknownInst(Inst, AA))
@@ -261,16 +286,28 @@ AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
   return FoundSet;
 }
 
-
-
-
 /// getAliasSetForPointer - Return the alias set that the specified pointer
 /// lives in.
 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, uint64_t Size,
-                                                 const AAMDNodes &AAInfo,
-                                                 bool *New) {
+                                                 const AAMDNodes &AAInfo) {
   AliasSet::PointerRec &Entry = getEntryFor(Pointer);
 
+  if (AliasAnyAS) {
+    // At this point, the AST is saturated, so we only have one active alias
+    // set. That means we already know which alias set we want to return, and
+    // just need to add the pointer to that set to keep the data structure
+    // consistent.
+    // This, of course, means that we will never need a merge here.
+    if (Entry.hasAliasSet()) {
+      Entry.updateSizeAndAAInfo(Size, AAInfo);
+      assert(Entry.getAliasSet(*this) == AliasAnyAS &&
+             "Entry in saturated AST must belong to only alias set");
+    } else {
+      AliasAnyAS->addPointer(*this, Entry, Size, AAInfo);
+    }
+    return *AliasAnyAS;
+  }
+
   // Check to see if the pointer is already known.
   if (Entry.hasAliasSet()) {
     // If the size changed, we may need to merge several alias sets.
@@ -290,68 +327,55 @@ AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, uint64_t Size,
     return *AS;
   }
   
-  if (New) *New = true;
   // Otherwise create a new alias set to hold the loaded pointer.
   AliasSets.push_back(new AliasSet());
   AliasSets.back().addPointer(*this, Entry, Size, AAInfo);
   return AliasSets.back();
 }
 
-bool AliasSetTracker::add(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
-  bool NewPtr;
-  addPointer(Ptr, Size, AAInfo, AliasSet::NoAccess, NewPtr);
-  return NewPtr;
+void AliasSetTracker::add(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
+  addPointer(Ptr, Size, AAInfo, AliasSet::NoAccess);
 }
 
-
-bool AliasSetTracker::add(LoadInst *LI) {
+void AliasSetTracker::add(LoadInst *LI) {
   if (isStrongerThanMonotonic(LI->getOrdering())) return addUnknown(LI);
 
   AAMDNodes AAInfo;
   LI->getAAMetadata(AAInfo);
 
   AliasSet::AccessLattice Access = AliasSet::RefAccess;
-  bool NewPtr;
   const DataLayout &DL = LI->getModule()->getDataLayout();
   AliasSet &AS = addPointer(LI->getOperand(0),
-                            DL.getTypeStoreSize(LI->getType()),
-                            AAInfo, Access, NewPtr);
+                            DL.getTypeStoreSize(LI->getType()), AAInfo, Access);
   if (LI->isVolatile()) AS.setVolatile();
-  return NewPtr;
 }
 
-bool AliasSetTracker::add(StoreInst *SI) {
+void AliasSetTracker::add(StoreInst *SI) {
   if (isStrongerThanMonotonic(SI->getOrdering())) return addUnknown(SI);
 
   AAMDNodes AAInfo;
   SI->getAAMetadata(AAInfo);
 
   AliasSet::AccessLattice Access = AliasSet::ModAccess;
-  bool NewPtr;
   const DataLayout &DL = SI->getModule()->getDataLayout();
   Value *Val = SI->getOperand(0);
-  AliasSet &AS = addPointer(SI->getOperand(1),
-                            DL.getTypeStoreSize(Val->getType()),
-                            AAInfo, Access, NewPtr);
+  AliasSet &AS = addPointer(
+      SI->getOperand(1), DL.getTypeStoreSize(Val->getType()), AAInfo, Access);
   if (SI->isVolatile()) AS.setVolatile();
-  return NewPtr;
 }
 
-bool AliasSetTracker::add(VAArgInst *VAAI) {
+void AliasSetTracker::add(VAArgInst *VAAI) {
   AAMDNodes AAInfo;
   VAAI->getAAMetadata(AAInfo);
 
-  bool NewPtr;
   addPointer(VAAI->getOperand(0), MemoryLocation::UnknownSize, AAInfo,
-             AliasSet::ModRefAccess, NewPtr);
-  return NewPtr;
+             AliasSet::ModRefAccess);
 }
 
-bool AliasSetTracker::add(MemSetInst *MSI) {
+void AliasSetTracker::add(MemSetInst *MSI) {
   AAMDNodes AAInfo;
   MSI->getAAMetadata(AAInfo);
 
-  bool NewPtr;
   uint64_t Len;
 
   if (ConstantInt *C = dyn_cast<ConstantInt>(MSI->getLength()))
@@ -360,30 +384,61 @@ bool AliasSetTracker::add(MemSetInst *MSI) {
     Len = MemoryLocation::UnknownSize;
 
   AliasSet &AS =
-      addPointer(MSI->getRawDest(), Len, AAInfo, AliasSet::ModAccess, NewPtr);
+      addPointer(MSI->getRawDest(), Len, AAInfo, AliasSet::ModAccess);
   if (MSI->isVolatile())
     AS.setVolatile();
-  return NewPtr;
 }
 
-bool AliasSetTracker::addUnknown(Instruction *Inst) {
-  if (isa<DbgInfoIntrinsic>(Inst)) 
-    return true; // Ignore DbgInfo Intrinsics.
+void AliasSetTracker::add(MemTransferInst *MTI) {
+  AAMDNodes AAInfo;
+  MTI->getAAMetadata(AAInfo);
+
+  uint64_t Len;
+  if (ConstantInt *C = dyn_cast<ConstantInt>(MTI->getLength()))
+    Len = C->getZExtValue();
+  else
+    Len = MemoryLocation::UnknownSize;
+
+  AliasSet &ASSrc =
+      addPointer(MTI->getRawSource(), Len, AAInfo, AliasSet::RefAccess);
+  if (MTI->isVolatile())
+    ASSrc.setVolatile();
+
+  AliasSet &ASDst =
+      addPointer(MTI->getRawDest(), Len, AAInfo, AliasSet::ModAccess);
+  if (MTI->isVolatile())
+    ASDst.setVolatile();
+}
+
+void AliasSetTracker::addUnknown(Instruction *Inst) {
+  if (isa<DbgInfoIntrinsic>(Inst))
+    return; // Ignore DbgInfo Intrinsics.
+
+  if (auto *II = dyn_cast<IntrinsicInst>(Inst)) {
+    // These intrinsics will show up as affecting memory, but they are just
+    // markers.
+    switch (II->getIntrinsicID()) {
+    default:
+      break;
+      // FIXME: Add lifetime/invariant intrinsics (See: PR30807).
+    case Intrinsic::assume:
+      return;
+    }
+  }
   if (!Inst->mayReadOrWriteMemory())
-    return true; // doesn't alias anything
+    return; // doesn't alias anything
 
   AliasSet *AS = findAliasSetForUnknownInst(Inst);
   if (AS) {
     AS->addUnknownInst(Inst, AA);
-    return false;
+    return;
   }
   AliasSets.push_back(new AliasSet());
   AS = &AliasSets.back();
   AS->addUnknownInst(Inst, AA);
-  return true;
 }
 
-bool AliasSetTracker::add(Instruction *I) {
+void AliasSetTracker::add(Instruction *I) {
   // Dispatch to one of the other add methods.
   if (LoadInst *LI = dyn_cast<LoadInst>(I))
     return add(LI);
@@ -393,8 +448,9 @@ bool AliasSetTracker::add(Instruction *I) {
     return add(VAAI);
   if (MemSetInst *MSI = dyn_cast<MemSetInst>(I))
     return add(MSI);
+  if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(I))
+    return add(MTI);
   return addUnknown(I);
-  // FIXME: add support of memcpy and memmove. 
 }
 
 void AliasSetTracker::add(BasicBlock &BB) {
@@ -418,134 +474,15 @@ void AliasSetTracker::add(const AliasSetTracker &AST) {
       add(AS.UnknownInsts[i]);
 
     // Loop over all of the pointers in this alias set.
-    bool X;
     for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
-      AliasSet &NewAS = addPointer(ASI.getPointer(), ASI.getSize(),
-                                   ASI.getAAInfo(),
-                                   (AliasSet::AccessLattice)AS.Access, X);
+      AliasSet &NewAS =
+          addPointer(ASI.getPointer(), ASI.getSize(), ASI.getAAInfo(),
+                     (AliasSet::AccessLattice)AS.Access);
       if (AS.isVolatile()) NewAS.setVolatile();
     }
   }
 }
 
-/// remove - Remove the specified (potentially non-empty) alias set from the
-/// tracker.
-void AliasSetTracker::remove(AliasSet &AS) {
-  // Drop all call sites.
-  if (!AS.UnknownInsts.empty())
-    AS.dropRef(*this);
-  AS.UnknownInsts.clear();
-  
-  // Clear the alias set.
-  unsigned NumRefs = 0;
-  while (!AS.empty()) {
-    AliasSet::PointerRec *P = AS.PtrList;
-
-    Value *ValToRemove = P->getValue();
-    
-    // Unlink and delete entry from the list of values.
-    P->eraseFromList();
-    
-    // Remember how many references need to be dropped.
-    ++NumRefs;
-
-    // Finally, remove the entry.
-    PointerMap.erase(ValToRemove);
-  }
-  
-  // Stop using the alias set, removing it.
-  AS.RefCount -= NumRefs;
-  if (AS.RefCount == 0)
-    AS.removeFromTracker(*this);
-}
-
-bool
-AliasSetTracker::remove(Value *Ptr, uint64_t Size, const AAMDNodes &AAInfo) {
-  AliasSet *AS = mergeAliasSetsForPointer(Ptr, Size, AAInfo);
-  if (!AS) return false;
-  remove(*AS);
-  return true;
-}
-
-bool AliasSetTracker::remove(LoadInst *LI) {
-  const DataLayout &DL = LI->getModule()->getDataLayout();
-  uint64_t Size = DL.getTypeStoreSize(LI->getType());
-
-  AAMDNodes AAInfo;
-  LI->getAAMetadata(AAInfo);
-
-  AliasSet *AS = mergeAliasSetsForPointer(LI->getOperand(0), Size, AAInfo);
-  if (!AS) return false;
-  remove(*AS);
-  return true;
-}
-
-bool AliasSetTracker::remove(StoreInst *SI) {
-  const DataLayout &DL = SI->getModule()->getDataLayout();
-  uint64_t Size = DL.getTypeStoreSize(SI->getOperand(0)->getType());
-
-  AAMDNodes AAInfo;
-  SI->getAAMetadata(AAInfo);
-
-  AliasSet *AS = mergeAliasSetsForPointer(SI->getOperand(1), Size, AAInfo);
-  if (!AS) return false;
-  remove(*AS);
-  return true;
-}
-
-bool AliasSetTracker::remove(VAArgInst *VAAI) {
-  AAMDNodes AAInfo;
-  VAAI->getAAMetadata(AAInfo);
-
-  AliasSet *AS = mergeAliasSetsForPointer(VAAI->getOperand(0),
-                                          MemoryLocation::UnknownSize, AAInfo);
-  if (!AS) return false;
-  remove(*AS);
-  return true;
-}
-
-bool AliasSetTracker::remove(MemSetInst *MSI) {
-  AAMDNodes AAInfo;
-  MSI->getAAMetadata(AAInfo);
-  uint64_t Len;
-
-  if (ConstantInt *C = dyn_cast<ConstantInt>(MSI->getLength()))
-    Len = C->getZExtValue();
-  else
-    Len = MemoryLocation::UnknownSize;
-
-  AliasSet *AS = mergeAliasSetsForPointer(MSI->getRawDest(), Len, AAInfo);
-  if (!AS)
-    return false;
-  remove(*AS);
-  return true;
-}
-
-bool AliasSetTracker::removeUnknown(Instruction *I) {
-  if (!I->mayReadOrWriteMemory())
-    return false; // doesn't alias anything
-
-  AliasSet *AS = findAliasSetForUnknownInst(I);
-  if (!AS) return false;
-  remove(*AS);
-  return true;
-}
-
-bool AliasSetTracker::remove(Instruction *I) {
-  // Dispatch to one of the other remove methods...
-  if (LoadInst *LI = dyn_cast<LoadInst>(I))
-    return remove(LI);
-  if (StoreInst *SI = dyn_cast<StoreInst>(I))
-    return remove(SI);
-  if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
-    return remove(VAAI);
-  if (MemSetInst *MSI = dyn_cast<MemSetInst>(I))
-    return remove(MSI);
-  return removeUnknown(I);
-  // FIXME: add support of memcpy and memmove. 
-}
-
-
 // deleteValue method - This method is used to remove a pointer value from the
 // AliasSetTracker entirely.  It should be used when an instruction is deleted
 // from the program to update the AST.  If you don't use this, you would have
@@ -575,6 +512,11 @@ void AliasSetTracker::deleteValue(Value *PtrVal) {
 
   // Unlink and delete from the list of values.
   PtrValEnt->eraseFromList();
+
+  if (AS->Alias == AliasSet::SetMayAlias) {
+    AS->SetSize--;
+    TotalMayAliasSetSize--;
+  }
   
   // Stop using the alias set.
   AS->dropRef(*this);
@@ -597,15 +539,68 @@ void AliasSetTracker::copyValue(Value *From, Value *To) {
   AliasSet::PointerRec &Entry = getEntryFor(To);
   if (Entry.hasAliasSet()) return;    // Already in the tracker!
 
-  // Add it to the alias set it aliases...
+  // getEntryFor above may invalidate iterator \c I, so reinitialize it.
   I = PointerMap.find_as(From);
+  // Add it to the alias set it aliases...
   AliasSet *AS = I->second->getAliasSet(*this);
   AS->addPointer(*this, Entry, I->second->getSize(),
                  I->second->getAAInfo(),
                  true);
 }
 
+AliasSet &AliasSetTracker::mergeAllAliasSets() {
+  assert(!AliasAnyAS && (TotalMayAliasSetSize > SaturationThreshold) &&
+         "Full merge should happen once, when the saturation threshold is "
+         "reached");
+
+  // Collect all alias sets, so that we can drop references with impunity
+  // without worrying about iterator invalidation.
+  std::vector<AliasSet *> ASVector;
+  ASVector.reserve(SaturationThreshold);
+  for (iterator I = begin(), E = end(); I != E; I++)
+    ASVector.push_back(&*I);
+
+  // Copy all instructions and pointers into a new set, and forward all other
+  // sets to it.
+  AliasSets.push_back(new AliasSet());
+  AliasAnyAS = &AliasSets.back();
+  AliasAnyAS->Alias = AliasSet::SetMayAlias;
+  AliasAnyAS->Access = AliasSet::ModRefAccess;
+  AliasAnyAS->AliasAny = true;
+
+  for (auto Cur : ASVector) {
+    
+    // If Cur was already forwarding, just forward to the new AS instead.
+    AliasSet *FwdTo = Cur->Forward;
+    if (FwdTo) {
+      Cur->Forward = AliasAnyAS;
+      AliasAnyAS->addRef();      
+      FwdTo->dropRef(*this);
+      continue;
+    }
+
+    // Otherwise, perform the actual merge.
+    AliasAnyAS->mergeSetIn(*Cur, *this);
+  }
+
+  return *AliasAnyAS;
+}
+
+AliasSet &AliasSetTracker::addPointer(Value *P, uint64_t Size,
+                                      const AAMDNodes &AAInfo,
+                                      AliasSet::AccessLattice E) {
+
+  AliasSet &AS = getAliasSetForPointer(P, Size, AAInfo);
+  AS.Access |= E;
+
+  if (!AliasAnyAS && (TotalMayAliasSetSize > SaturationThreshold)) {
+    // The AST is now saturated. From here on, we conservatively consider all
+    // pointers to alias each-other.
+    return mergeAllAliasSets();
+  }
 
+  return AS;
+}
 
 //===----------------------------------------------------------------------===//
 //               AliasSet/AliasSetTracker Printing Support
@@ -700,7 +695,7 @@ namespace {
     bool runOnFunction(Function &F) override {
       auto &AAWP = getAnalysis<AAResultsWrapperPass>();
       Tracker = new AliasSetTracker(AAWP.getAAResults());
-
+      errs() << "Alias sets for function '" << F.getName() << "':\n";
       for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
         Tracker->add(&*I);
       Tracker->print(errs());