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, 90 insertions, 35 deletions

diff --git a/contrib/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp b/contrib/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
index 95d7f8a..71980e8 100644
--- a/contrib/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/contrib/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -55,6 +55,7 @@
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Cloning.h"
 #include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/LoopUtils.h"
 #include <algorithm>
 #include <map>
 #include <set>
@@ -64,6 +65,7 @@ using namespace llvm;
 
 STATISTIC(NumBranches, "Number of branches unswitched");
 STATISTIC(NumSwitches, "Number of switches unswitched");
+STATISTIC(NumGuards,   "Number of guards unswitched");
 STATISTIC(NumSelects , "Number of selects unswitched");
 STATISTIC(NumTrivial , "Number of unswitches that are trivial");
 STATISTIC(NumSimplify, "Number of simplifications of unswitched code");
@@ -187,6 +189,9 @@ namespace {
     BasicBlock *loopHeader;
     BasicBlock *loopPreheader;
 
+    bool SanitizeMemory;
+    LoopSafetyInfo SafetyInfo;
+
     // LoopBlocks contains all of the basic blocks of the loop, including the
     // preheader of the loop, the body of the loop, and the exit blocks of the
     // loop, in that order.
@@ -211,17 +216,8 @@ namespace {
     ///
     void getAnalysisUsage(AnalysisUsage &AU) const override {
       AU.addRequired<AssumptionCacheTracker>();
-      AU.addRequiredID(LoopSimplifyID);
-      AU.addPreservedID(LoopSimplifyID);
-      AU.addRequired<LoopInfoWrapperPass>();
-      AU.addPreserved<LoopInfoWrapperPass>();
-      AU.addRequiredID(LCSSAID);
-      AU.addPreservedID(LCSSAID);
-      AU.addRequired<DominatorTreeWrapperPass>();
-      AU.addPreserved<DominatorTreeWrapperPass>();
-      AU.addPreserved<ScalarEvolutionWrapperPass>();
       AU.addRequired<TargetTransformInfoWrapperPass>();
-      AU.addPreserved<GlobalsAAWrapperPass>();
+      getLoopAnalysisUsage(AU);
     }
 
   private:
@@ -382,11 +378,9 @@ void LUAnalysisCache::cloneData(const Loop *NewLoop, const Loop *OldLoop,
 char LoopUnswitch::ID = 0;
 INITIALIZE_PASS_BEGIN(LoopUnswitch, "loop-unswitch", "Unswitch loops",
                       false, false)
-INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
-INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
-INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(LCSSA)
+INITIALIZE_PASS_DEPENDENCY(LoopPass)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
 INITIALIZE_PASS_END(LoopUnswitch, "loop-unswitch", "Unswitch loops",
                       false, false)
 
@@ -396,7 +390,11 @@ Pass *llvm::createLoopUnswitchPass(bool Os) {
 
 /// Cond is a condition that occurs in L. If it is invariant in the loop, or has
 /// an invariant piece, return the invariant. Otherwise, return null.
-static Value *FindLIVLoopCondition(Value *Cond, Loop *L, bool &Changed) {
+static Value *FindLIVLoopCondition(Value *Cond, Loop *L, bool &Changed,
+                                   DenseMap<Value *, Value *> &Cache) {
+  auto CacheIt = Cache.find(Cond);
+  if (CacheIt != Cache.end())
+    return CacheIt->second;
 
   // We started analyze new instruction, increment scanned instructions counter.
   ++TotalInsts;
@@ -411,8 +409,10 @@ static Value *FindLIVLoopCondition(Value *Cond, Loop *L, bool &Changed) {
   // TODO: Handle: br (VARIANT|INVARIANT).
 
   // Hoist simple values out.
-  if (L->makeLoopInvariant(Cond, Changed))
+  if (L->makeLoopInvariant(Cond, Changed)) {
+    Cache[Cond] = Cond;
     return Cond;
+  }
 
   if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Cond))
     if (BO->getOpcode() == Instruction::And ||
@@ -420,17 +420,29 @@ static Value *FindLIVLoopCondition(Value *Cond, Loop *L, bool &Changed) {
       // If either the left or right side is invariant, we can unswitch on this,
       // which will cause the branch to go away in one loop and the condition to
       // simplify in the other one.
-      if (Value *LHS = FindLIVLoopCondition(BO->getOperand(0), L, Changed))
+      if (Value *LHS =
+              FindLIVLoopCondition(BO->getOperand(0), L, Changed, Cache)) {
+        Cache[Cond] = LHS;
         return LHS;
-      if (Value *RHS = FindLIVLoopCondition(BO->getOperand(1), L, Changed))
+      }
+      if (Value *RHS =
+              FindLIVLoopCondition(BO->getOperand(1), L, Changed, Cache)) {
+        Cache[Cond] = RHS;
         return RHS;
+      }
     }
 
+  Cache[Cond] = nullptr;
   return nullptr;
 }
 
+static Value *FindLIVLoopCondition(Value *Cond, Loop *L, bool &Changed) {
+  DenseMap<Value *, Value *> Cache;
+  return FindLIVLoopCondition(Cond, L, Changed, Cache);
+}
+
 bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) {
-  if (skipOptnoneFunction(L))
+  if (skipLoop(L))
     return false;
 
   AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(
@@ -441,6 +453,10 @@ bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) {
   currentLoop = L;
   Function *F = currentLoop->getHeader()->getParent();
 
+  SanitizeMemory = F->hasFnAttribute(Attribute::SanitizeMemory);
+  if (SanitizeMemory)
+    computeLoopSafetyInfo(&SafetyInfo, L);
+
   EnabledPGO = F->getEntryCount().hasValue();
 
   if (LoopUnswitchWithBlockFrequency && EnabledPGO) {
@@ -499,17 +515,34 @@ bool LoopUnswitch::processCurrentLoop() {
     return true;
   }
 
-  // Do not unswitch loops containing convergent operations, as we might be
-  // making them control dependent on the unswitch value when they were not
-  // before.
-  // FIXME: This could be refined to only bail if the convergent operation is
-  // not already control-dependent on the unswitch value.
+  // Run through the instructions in the loop, keeping track of three things:
+  //
+  //  - That we do not unswitch loops containing convergent operations, as we
+  //    might be making them control dependent on the unswitch value when they
+  //    were not before.
+  //    FIXME: This could be refined to only bail if the convergent operation is
+  //    not already control-dependent on the unswitch value.
+  //
+  //  - That basic blocks in the loop contain invokes whose predecessor edges we
+  //    cannot split.
+  //
+  //  - The set of guard intrinsics encountered (these are non terminator
+  //    instructions that are also profitable to be unswitched).
+
+  SmallVector<IntrinsicInst *, 4> Guards;
+
   for (const auto BB : currentLoop->blocks()) {
     for (auto &I : *BB) {
       auto CS = CallSite(&I);
       if (!CS) continue;
       if (CS.hasFnAttr(Attribute::Convergent))
         return false;
+      if (auto *II = dyn_cast<InvokeInst>(&I))
+        if (!II->getUnwindDest()->canSplitPredecessors())
+          return false;
+      if (auto *II = dyn_cast<IntrinsicInst>(&I))
+        if (II->getIntrinsicID() == Intrinsic::experimental_guard)
+          Guards.push_back(II);
     }
   }
 
@@ -529,12 +562,36 @@ bool LoopUnswitch::processCurrentLoop() {
       return false;
   }
 
+  for (IntrinsicInst *Guard : Guards) {
+    Value *LoopCond =
+        FindLIVLoopCondition(Guard->getOperand(0), currentLoop, Changed);
+    if (LoopCond &&
+        UnswitchIfProfitable(LoopCond, ConstantInt::getTrue(Context))) {
+      // NB! Unswitching (if successful) could have erased some of the
+      // instructions in Guards leaving dangling pointers there.  This is fine
+      // because we're returning now, and won't look at Guards again.
+      ++NumGuards;
+      return true;
+    }
+  }
+
   // Loop over all of the basic blocks in the loop.  If we find an interior
   // block that is branching on a loop-invariant condition, we can unswitch this
   // loop.
   for (Loop::block_iterator I = currentLoop->block_begin(),
          E = currentLoop->block_end(); I != E; ++I) {
     TerminatorInst *TI = (*I)->getTerminator();
+
+    // Unswitching on a potentially uninitialized predicate is not
+    // MSan-friendly. Limit this to the cases when the original predicate is
+    // guaranteed to execute, to avoid creating a use-of-uninitialized-value
+    // in the code that did not have one.
+    // This is a workaround for the discrepancy between LLVM IR and MSan
+    // semantics. See PR28054 for more details.
+    if (SanitizeMemory &&
+        !isGuaranteedToExecute(*TI, DT, currentLoop, &SafetyInfo))
+      continue;
+
     if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
       // If this isn't branching on an invariant condition, we can't unswitch
       // it.
@@ -628,8 +685,8 @@ static bool isTrivialLoopExitBlockHelper(Loop *L, BasicBlock *BB,
 
   // Okay, everything after this looks good, check to make sure that this block
   // doesn't include any side effects.
-  for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
-    if (I->mayHaveSideEffects())
+  for (Instruction &I : *BB)
+    if (I.mayHaveSideEffects())
       return false;
 
   return true;
@@ -679,8 +736,8 @@ static Loop *CloneLoop(Loop *L, Loop *PL, ValueToValueMapTy &VM,
       New.addBasicBlockToLoop(cast<BasicBlock>(VM[*I]), *LI);
 
   // Add all of the subloops to the new loop.
-  for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
-    CloneLoop(*I, &New, VM, LI, LPM);
+  for (Loop *I : *L)
+    CloneLoop(I, &New, VM, LI, LPM);
 
   return &New;
 }
@@ -1075,10 +1132,9 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
 
   // Rewrite the code to refer to itself.
   for (unsigned i = 0, e = NewBlocks.size(); i != e; ++i)
-    for (BasicBlock::iterator I = NewBlocks[i]->begin(),
-           E = NewBlocks[i]->end(); I != E; ++I)
-      RemapInstruction(&*I, VMap,
-                       RF_NoModuleLevelChanges | RF_IgnoreMissingEntries);
+    for (Instruction &I : *NewBlocks[i])
+      RemapInstruction(&I, VMap,
+                       RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
 
   // Rewrite the original preheader to select between versions of the loop.
   BranchInst *OldBR = cast<BranchInst>(loopPreheader->getTerminator());
@@ -1180,9 +1236,8 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
       Worklist.push_back(UI);
     }
 
-    for (std::vector<Instruction*>::iterator UI = Worklist.begin(),
-         UE = Worklist.end(); UI != UE; ++UI)
-      (*UI)->replaceUsesOfWith(LIC, Replacement);
+    for (Instruction *UI : Worklist)
+      UI->replaceUsesOfWith(LIC, Replacement);
 
     SimplifyCode(Worklist, L);
     return;