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, 57 insertions, 18 deletions

diff --git a/contrib/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp b/contrib/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp
index 1064d08..f29228c 100644
--- a/contrib/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp
+++ b/contrib/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp
@@ -28,6 +28,7 @@
 #include "llvm/IR/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/LoopVersioning.h"
 #include <forward_list>
 
@@ -61,7 +62,8 @@ struct StoreToLoadForwardingCandidate {
 
   /// \brief Return true if the dependence from the store to the load has a
   /// distance of one.  E.g. A[i+1] = A[i]
-  bool isDependenceDistanceOfOne(PredicatedScalarEvolution &PSE) const {
+  bool isDependenceDistanceOfOne(PredicatedScalarEvolution &PSE,
+                                 Loop *L) const {
     Value *LoadPtr = Load->getPointerOperand();
     Value *StorePtr = Store->getPointerOperand();
     Type *LoadPtrType = LoadPtr->getType();
@@ -72,6 +74,13 @@ struct StoreToLoadForwardingCandidate {
            LoadType == StorePtr->getType()->getPointerElementType() &&
            "Should be a known dependence");
 
+    // Currently we only support accesses with unit stride.  FIXME: we should be
+    // able to handle non unit stirde as well as long as the stride is equal to
+    // the dependence distance.
+    if (getPtrStride(PSE, LoadPtr, L) != 1 ||
+        getPtrStride(PSE, StorePtr, L) != 1)
+      return false;
+
     auto &DL = Load->getParent()->getModule()->getDataLayout();
     unsigned TypeByteSize = DL.getTypeAllocSize(const_cast<Type *>(LoadType));
 
@@ -83,7 +92,7 @@ struct StoreToLoadForwardingCandidate {
     auto *Dist = cast<SCEVConstant>(
         PSE.getSE()->getMinusSCEV(StorePtrSCEV, LoadPtrSCEV));
     const APInt &Val = Dist->getAPInt();
-    return Val.abs() == TypeByteSize;
+    return Val == TypeByteSize;
   }
 
   Value *getLoadPtr() const { return Load->getPointerOperand(); }
@@ -110,12 +119,17 @@ bool doesStoreDominatesAllLatches(BasicBlock *StoreBlock, Loop *L,
                      });
 }
 
+/// \brief Return true if the load is not executed on all paths in the loop.
+static bool isLoadConditional(LoadInst *Load, Loop *L) {
+  return Load->getParent() != L->getHeader();
+}
+
 /// \brief The per-loop class that does most of the work.
 class LoadEliminationForLoop {
 public:
   LoadEliminationForLoop(Loop *L, LoopInfo *LI, const LoopAccessInfo &LAI,
                          DominatorTree *DT)
-      : L(L), LI(LI), LAI(LAI), DT(DT), PSE(LAI.PSE) {}
+      : L(L), LI(LI), LAI(LAI), DT(DT), PSE(LAI.getPSE()) {}
 
   /// \brief Look through the loop-carried and loop-independent dependences in
   /// this loop and find store->load dependences.
@@ -162,6 +176,12 @@ public:
       auto *Load = dyn_cast<LoadInst>(Destination);
       if (!Load)
         continue;
+
+      // Only progagate the value if they are of the same type.
+      if (Store->getPointerOperand()->getType() !=
+          Load->getPointerOperand()->getType())
+        continue;
+
       Candidates.emplace_front(Load, Store);
     }
 
@@ -219,12 +239,12 @@ public:
         if (OtherCand == nullptr)
           continue;
 
-        // Handle the very basic of case when the two stores are in the same
-        // block so deciding which one forwards is easy.  The later one forwards
-        // as long as they both have a dependence distance of one to the load.
+        // Handle the very basic case when the two stores are in the same block
+        // so deciding which one forwards is easy.  The later one forwards as
+        // long as they both have a dependence distance of one to the load.
         if (Cand.Store->getParent() == OtherCand->Store->getParent() &&
-            Cand.isDependenceDistanceOfOne(PSE) &&
-            OtherCand->isDependenceDistanceOfOne(PSE)) {
+            Cand.isDependenceDistanceOfOne(PSE, L) &&
+            OtherCand->isDependenceDistanceOfOne(PSE, L)) {
           // They are in the same block, the later one will forward to the load.
           if (getInstrIndex(OtherCand->Store) < getInstrIndex(Cand.Store))
             OtherCand = &Cand;
@@ -429,14 +449,21 @@ public:
     unsigned NumForwarding = 0;
     for (const StoreToLoadForwardingCandidate Cand : StoreToLoadDependences) {
       DEBUG(dbgs() << "Candidate " << Cand);
+
       // Make sure that the stored values is available everywhere in the loop in
       // the next iteration.
       if (!doesStoreDominatesAllLatches(Cand.Store->getParent(), L, DT))
         continue;
 
+      // If the load is conditional we can't hoist its 0-iteration instance to
+      // the preheader because that would make it unconditional.  Thus we would
+      // access a memory location that the original loop did not access.
+      if (isLoadConditional(Cand.Load, L))
+        continue;
+
       // Check whether the SCEV difference is the same as the induction step,
       // thus we load the value in the next iteration.
-      if (!Cand.isDependenceDistanceOfOne(PSE))
+      if (!Cand.isDependenceDistanceOfOne(PSE, L))
         continue;
 
       ++NumForwarding;
@@ -459,18 +486,25 @@ public:
       return false;
     }
 
-    if (LAI.PSE.getUnionPredicate().getComplexity() >
+    if (LAI.getPSE().getUnionPredicate().getComplexity() >
         LoadElimSCEVCheckThreshold) {
       DEBUG(dbgs() << "Too many SCEV run-time checks needed.\n");
       return false;
     }
 
-    // Point of no-return, start the transformation.  First, version the loop if
-    // necessary.
-    if (!Checks.empty() || !LAI.PSE.getUnionPredicate().isAlwaysTrue()) {
+    if (!Checks.empty() || !LAI.getPSE().getUnionPredicate().isAlwaysTrue()) {
+      if (L->getHeader()->getParent()->optForSize()) {
+        DEBUG(dbgs() << "Versioning is needed but not allowed when optimizing "
+                        "for size.\n");
+        return false;
+      }
+
+      // Point of no-return, start the transformation.  First, version the loop
+      // if necessary.
+
       LoopVersioning LV(LAI, L, LI, DT, PSE.getSE(), false);
       LV.setAliasChecks(std::move(Checks));
-      LV.setSCEVChecks(LAI.PSE.getUnionPredicate());
+      LV.setSCEVChecks(LAI.getPSE().getUnionPredicate());
       LV.versionLoop();
     }
 
@@ -508,8 +542,11 @@ public:
   }
 
   bool runOnFunction(Function &F) override {
+    if (skipFunction(F))
+      return false;
+
     auto *LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
-    auto *LAA = &getAnalysis<LoopAccessAnalysis>();
+    auto *LAA = &getAnalysis<LoopAccessLegacyAnalysis>();
     auto *DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
 
     // Build up a worklist of inner-loops to vectorize. This is necessary as the
@@ -526,7 +563,7 @@ public:
     // Now walk the identified inner loops.
     bool Changed = false;
     for (Loop *L : Worklist) {
-      const LoopAccessInfo &LAI = LAA->getInfo(L, ValueToValueMap());
+      const LoopAccessInfo &LAI = LAA->getInfo(L);
       // The actual work is performed by LoadEliminationForLoop.
       LoadEliminationForLoop LEL(L, LI, LAI, DT);
       Changed |= LEL.processLoop();
@@ -537,9 +574,10 @@ public:
   }
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequiredID(LoopSimplifyID);
     AU.addRequired<LoopInfoWrapperPass>();
     AU.addPreserved<LoopInfoWrapperPass>();
-    AU.addRequired<LoopAccessAnalysis>();
+    AU.addRequired<LoopAccessLegacyAnalysis>();
     AU.addRequired<ScalarEvolutionWrapperPass>();
     AU.addRequired<DominatorTreeWrapperPass>();
     AU.addPreserved<DominatorTreeWrapperPass>();
@@ -554,9 +592,10 @@ static const char LLE_name[] = "Loop Load Elimination";
 
 INITIALIZE_PASS_BEGIN(LoopLoadElimination, LLE_OPTION, LLE_name, false, false)
 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(LoopAccessAnalysis)
+INITIALIZE_PASS_DEPENDENCY(LoopAccessLegacyAnalysis)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
 INITIALIZE_PASS_END(LoopLoadElimination, LLE_OPTION, LLE_name, false, false)
 
 namespace llvm {