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, 151 insertions, 79 deletions

diff --git a/contrib/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp b/contrib/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
index ddd8775..6b1d3dc 100644
--- a/contrib/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
+++ b/contrib/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -25,7 +25,6 @@
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
-#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 
@@ -71,14 +70,12 @@ namespace {
 
     bool eliminateIdentitySCEV(Instruction *UseInst, Instruction *IVOperand);
 
+    bool eliminateOverflowIntrinsic(CallInst *CI);
     bool eliminateIVUser(Instruction *UseInst, Instruction *IVOperand);
     void eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand);
     void eliminateIVRemainder(BinaryOperator *Rem, Value *IVOperand,
                               bool IsSigned);
     bool strengthenOverflowingOperation(BinaryOperator *OBO, Value *IVOperand);
-
-    Instruction *splitOverflowIntrinsic(Instruction *IVUser,
-                                        const DominatorTree *DT);
   };
 }
 
@@ -183,9 +180,8 @@ void SimplifyIndvar::eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand) {
     DeadInsts.emplace_back(ICmp);
     DEBUG(dbgs() << "INDVARS: Eliminated comparison: " << *ICmp << '\n');
   } else if (isa<PHINode>(IVOperand) &&
-             SE->isLoopInvariantPredicate(Pred, S, X, ICmpLoop,
-                                          InvariantPredicate, InvariantLHS,
-                                          InvariantRHS)) {
+             SE->isLoopInvariantPredicate(Pred, S, X, L, InvariantPredicate,
+                                          InvariantLHS, InvariantRHS)) {
 
     // Rewrite the comparison to a loop invariant comparison if it can be done
     // cheaply, where cheaply means "we don't need to emit any new
@@ -201,9 +197,48 @@ void SimplifyIndvar::eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand) {
       NewRHS =
           ICmp->getOperand(S == InvariantRHS ? IVOperIdx : (1 - IVOperIdx));
 
-    for (Value *Incoming : cast<PHINode>(IVOperand)->incoming_values()) {
-      if (NewLHS && NewRHS)
-        break;
+    auto *PN = cast<PHINode>(IVOperand);
+    for (unsigned i = 0, e = PN->getNumIncomingValues();
+         i != e && (!NewLHS || !NewRHS);
+         ++i) {
+
+      // If this is a value incoming from the backedge, then it cannot be a loop
+      // invariant value (since we know that IVOperand is an induction variable).
+      if (L->contains(PN->getIncomingBlock(i)))
+        continue;
+
+      // NB! This following assert does not fundamentally have to be true, but
+      // it is true today given how SCEV analyzes induction variables.
+      // Specifically, today SCEV will *not* recognize %iv as an induction
+      // variable in the following case:
+      //
+      // define void @f(i32 %k) {
+      // entry:
+      //   br i1 undef, label %r, label %l
+      //
+      // l:
+      //   %k.inc.l = add i32 %k, 1
+      //   br label %loop
+      //
+      // r:
+      //   %k.inc.r = add i32 %k, 1
+      //   br label %loop
+      //
+      // loop:
+      //   %iv = phi i32 [ %k.inc.l, %l ], [ %k.inc.r, %r ], [ %iv.inc, %loop ]
+      //   %iv.inc = add i32 %iv, 1
+      //   br label %loop
+      // }
+      //
+      // but if it starts to, at some point, then the assertion below will have
+      // to be changed to a runtime check.
+
+      Value *Incoming = PN->getIncomingValue(i);
+
+#ifndef NDEBUG
+      if (auto *I = dyn_cast<Instruction>(Incoming))
+        assert(DT->dominates(I, ICmp) && "Should be a unique loop dominating value!");
+#endif
 
       const SCEV *IncomingS = SE->getSCEV(Incoming);
 
@@ -280,6 +315,108 @@ void SimplifyIndvar::eliminateIVRemainder(BinaryOperator *Rem,
   DeadInsts.emplace_back(Rem);
 }
 
+bool SimplifyIndvar::eliminateOverflowIntrinsic(CallInst *CI) {
+  auto *F = CI->getCalledFunction();
+  if (!F)
+    return false;
+
+  typedef const SCEV *(ScalarEvolution::*OperationFunctionTy)(
+      const SCEV *, const SCEV *, SCEV::NoWrapFlags);
+  typedef const SCEV *(ScalarEvolution::*ExtensionFunctionTy)(
+      const SCEV *, Type *);
+
+  OperationFunctionTy Operation;
+  ExtensionFunctionTy Extension;
+
+  Instruction::BinaryOps RawOp;
+
+  // We always have exactly one of nsw or nuw.  If NoSignedOverflow is false, we
+  // have nuw.
+  bool NoSignedOverflow;
+
+  switch (F->getIntrinsicID()) {
+  default:
+    return false;
+
+  case Intrinsic::sadd_with_overflow:
+    Operation = &ScalarEvolution::getAddExpr;
+    Extension = &ScalarEvolution::getSignExtendExpr;
+    RawOp = Instruction::Add;
+    NoSignedOverflow = true;
+    break;
+
+  case Intrinsic::uadd_with_overflow:
+    Operation = &ScalarEvolution::getAddExpr;
+    Extension = &ScalarEvolution::getZeroExtendExpr;
+    RawOp = Instruction::Add;
+    NoSignedOverflow = false;
+    break;
+
+  case Intrinsic::ssub_with_overflow:
+    Operation = &ScalarEvolution::getMinusSCEV;
+    Extension = &ScalarEvolution::getSignExtendExpr;
+    RawOp = Instruction::Sub;
+    NoSignedOverflow = true;
+    break;
+
+  case Intrinsic::usub_with_overflow:
+    Operation = &ScalarEvolution::getMinusSCEV;
+    Extension = &ScalarEvolution::getZeroExtendExpr;
+    RawOp = Instruction::Sub;
+    NoSignedOverflow = false;
+    break;
+  }
+
+  const SCEV *LHS = SE->getSCEV(CI->getArgOperand(0));
+  const SCEV *RHS = SE->getSCEV(CI->getArgOperand(1));
+
+  auto *NarrowTy = cast<IntegerType>(LHS->getType());
+  auto *WideTy =
+    IntegerType::get(NarrowTy->getContext(), NarrowTy->getBitWidth() * 2);
+
+  const SCEV *A =
+      (SE->*Extension)((SE->*Operation)(LHS, RHS, SCEV::FlagAnyWrap), WideTy);
+  const SCEV *B =
+      (SE->*Operation)((SE->*Extension)(LHS, WideTy),
+                       (SE->*Extension)(RHS, WideTy), SCEV::FlagAnyWrap);
+
+  if (A != B)
+    return false;
+
+  // Proved no overflow, nuke the overflow check and, if possible, the overflow
+  // intrinsic as well.
+
+  BinaryOperator *NewResult = BinaryOperator::Create(
+      RawOp, CI->getArgOperand(0), CI->getArgOperand(1), "", CI);
+
+  if (NoSignedOverflow)
+    NewResult->setHasNoSignedWrap(true);
+  else
+    NewResult->setHasNoUnsignedWrap(true);
+
+  SmallVector<ExtractValueInst *, 4> ToDelete;
+
+  for (auto *U : CI->users()) {
+    if (auto *EVI = dyn_cast<ExtractValueInst>(U)) {
+      if (EVI->getIndices()[0] == 1)
+        EVI->replaceAllUsesWith(ConstantInt::getFalse(CI->getContext()));
+      else {
+        assert(EVI->getIndices()[0] == 0 && "Only two possibilities!");
+        EVI->replaceAllUsesWith(NewResult);
+      }
+      ToDelete.push_back(EVI);
+    }
+  }
+
+  for (auto *EVI : ToDelete)
+    EVI->eraseFromParent();
+
+  if (CI->use_empty())
+    CI->eraseFromParent();
+
+  return true;
+}
+
 /// Eliminate an operation that consumes a simple IV and has no observable
 /// side-effect given the range of IV values.  IVOperand is guaranteed SCEVable,
 /// but UseInst may not be.
@@ -297,6 +434,10 @@ bool SimplifyIndvar::eliminateIVUser(Instruction *UseInst,
     }
   }
 
+  if (auto *CI = dyn_cast<CallInst>(UseInst))
+    if (eliminateOverflowIntrinsic(CI))
+      return true;
+
   if (eliminateIdentitySCEV(UseInst, IVOperand))
     return true;
 
@@ -408,69 +549,6 @@ bool SimplifyIndvar::strengthenOverflowingOperation(BinaryOperator *BO,
   return Changed;
 }
 
-/// \brief Split sadd.with.overflow into add + sadd.with.overflow to allow
-/// analysis and optimization.
-///
-/// \return A new value representing the non-overflowing add if possible,
-/// otherwise return the original value.
-Instruction *SimplifyIndvar::splitOverflowIntrinsic(Instruction *IVUser,
-                                                    const DominatorTree *DT) {
-  IntrinsicInst *II = dyn_cast<IntrinsicInst>(IVUser);
-  if (!II || II->getIntrinsicID() != Intrinsic::sadd_with_overflow)
-    return IVUser;
-
-  // Find a branch guarded by the overflow check.
-  BranchInst *Branch = nullptr;
-  Instruction *AddVal = nullptr;
-  for (User *U : II->users()) {
-    if (ExtractValueInst *ExtractInst = dyn_cast<ExtractValueInst>(U)) {
-      if (ExtractInst->getNumIndices() != 1)
-        continue;
-      if (ExtractInst->getIndices()[0] == 0)
-        AddVal = ExtractInst;
-      else if (ExtractInst->getIndices()[0] == 1 && ExtractInst->hasOneUse())
-        Branch = dyn_cast<BranchInst>(ExtractInst->user_back());
-    }
-  }
-  if (!AddVal || !Branch)
-    return IVUser;
-
-  BasicBlock *ContinueBB = Branch->getSuccessor(1);
-  if (std::next(pred_begin(ContinueBB)) != pred_end(ContinueBB))
-    return IVUser;
-
-  // Check if all users of the add are provably NSW.
-  bool AllNSW = true;
-  for (Use &U : AddVal->uses()) {
-    if (Instruction *UseInst = dyn_cast<Instruction>(U.getUser())) {
-      BasicBlock *UseBB = UseInst->getParent();
-      if (PHINode *PHI = dyn_cast<PHINode>(UseInst))
-        UseBB = PHI->getIncomingBlock(U);
-      if (!DT->dominates(ContinueBB, UseBB)) {
-        AllNSW = false;
-        break;
-      }
-    }
-  }
-  if (!AllNSW)
-    return IVUser;
-
-  // Go for it...
-  IRBuilder<> Builder(IVUser);
-  Instruction *AddInst = dyn_cast<Instruction>(
-    Builder.CreateNSWAdd(II->getOperand(0), II->getOperand(1)));
-
-  // The caller expects the new add to have the same form as the intrinsic. The
-  // IV operand position must be the same.
-  assert((AddInst->getOpcode() == Instruction::Add &&
-          AddInst->getOperand(0) == II->getOperand(0)) &&
-         "Bad add instruction created from overflow intrinsic.");
-
-  AddVal->replaceAllUsesWith(AddInst);
-  DeadInsts.emplace_back(AddVal);
-  return AddInst;
-}
-
 /// Add all uses of Def to the current IV's worklist.
 static void pushIVUsers(
   Instruction *Def,
@@ -545,12 +623,6 @@ void SimplifyIndvar::simplifyUsers(PHINode *CurrIV, IVVisitor *V) {
     // Bypass back edges to avoid extra work.
     if (UseInst == CurrIV) continue;
 
-    if (V && V->shouldSplitOverflowInstrinsics()) {
-      UseInst = splitOverflowIntrinsic(UseInst, V->getDomTree());
-      if (!UseInst)
-        continue;
-    }
-
     Instruction *IVOperand = UseOper.second;
     for (unsigned N = 0; IVOperand; ++N) {
       assert(N <= Simplified.size() && "runaway iteration");