Merge llvm-project 12.0.1 release and follow-up fixes

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR:		255570

(cherry picked from commit e8d8bef961a50d4dc22501cde4fb9fb0be1b2532)

Merge llvm-project 12.0.0 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12.0.0-0-gd28af7c654d8, a.k.a. 12.0.0 release.

PR:		255570

(cherry picked from commit d409305fa3838fb39b38c26fc085fb729b8766d5)

Disable strict-fp for powerpcspe, as it does not work properly yet

Merge commit 5c18d1136665 from llvm git (by Qiu Chaofan)

  [SPE] Disable strict-fp for SPE by default

  As discussed in PR50385, strict-fp on PowerPC SPE has not been
  handled well. This patch disables it by default for SPE.

  Reviewed By: nemanjai, vit9696, jhibbits

  Differential Revision: https://reviews.llvm.org/D103235

PR:		255570

(cherry picked from commit 715df83abc049b23d9acddc81f2480bd4c056d64)

Apply upstream libc++ fix to allow building with devel/xxx-xtoolchain-gcc

Merge commit 52e9d80d5db2 from llvm git (by Jason Liu):

  [libc++] add `inline` for __open's definition in ifstream and ofstream

  Summary:

  When building with gcc on AIX, it seems that gcc does not like the
  `always_inline` without the `inline` keyword.
  So adding the inline keywords in for __open in ifstream and ofstream.
  That will also make it consistent with __open in basic_filebuf
  (it seems we added `inline` there before for gcc build as well).

  Differential Revision: https://reviews.llvm.org/D99422

PR:		255570

(cherry picked from commit d099db25464b826c5724cf2fb5b22292bbe15f6e)

Undefine HAVE_(DE)REGISTER_FRAME in llvm's config.h on arm

Otherwise, the lli tool (enable by WITH_CLANG_EXTRAS) won't link on arm,
stating that __register_frame is undefined. This function is normally
provided by libunwind, but explicitly not for the ARM Exception ABI.

Reported by:	oh
PR:		255570

(cherry picked from commit f336b45e943c7f9a90ffcea1a6c4c7039e54c73c)

Merge llvm-project 12.0.1 rc2

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12.0.1-rc2-0-ge7dac564cd0e, a.k.a. 12.0.1 rc2.

PR:		255570

(cherry picked from commit 23408297fbf3089f0388a8873b02fa75ab3f5bb9)

Revert libunwind change to fix backtrace segfault on aarch64

Revert commit 22b615a96593 from llvm git (by Daniel Kiss):

  [libunwind] Support for leaf function unwinding.

  Unwinding leaf function is useful in cases when the backtrace finds a
  leaf function for example when it caused a signal.
  This patch also add the support for the DW_CFA_undefined because it marks
  the end of the frames.

  Ryan Prichard provided code for the tests.

  Reviewed By: #libunwind, mstorsjo

  Differential Revision: https://reviews.llvm.org/D83573

  Reland with limit the test to the x86_64-linux target.

Bisection has shown that this particular upstream commit causes programs
using backtrace(3) on aarch64 to segfault. This affects the lang/rust
port, for instance. Until we can upstream to fix this problem, revert
the commit for now.

Reported by:	mikael
PR:		256864

(cherry picked from commit 5866c369e4fd917c0d456f0f10b92ee354b82279)

Merge llvm-project 12.0.1 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12.0.1-0-gfed41342a82f, a.k.a. 12.0.1 release.

PR:		255570

(cherry picked from commit 4652422eb477731f284b1345afeefef7f269da50)

compilert-rt: build out-of-line LSE atomics helpers for aarch64

Both clang >= 12 and gcc >= 10.1 now default to -moutline-atomics for
aarch64. This requires a bunch of helper functions in libcompiler_rt.a,
to avoid link errors like "undefined symbol: __aarch64_ldadd8_acq_rel".

(Note: of course you can use -mno-outline-atomics as a workaround too,
but this would negate the potential performance benefit of the faster
LSE instructions.)

Bump __FreeBSD_version so ports maintainers can easily detect this.

PR:		257392

(cherry picked from commit cc55ee8009a550810d38777fd6ace9abf3a2f6b4)

1 files changed, 65 insertions, 37 deletions

diff --git a/contrib/llvm-project/llvm/lib/Analysis/MemorySSAUpdater.cpp b/contrib/llvm-project/llvm/lib/Analysis/MemorySSAUpdater.cpp
index 85af091772e7..99fa58b8872a 100644
--- a/contrib/llvm-project/llvm/lib/Analysis/MemorySSAUpdater.cpp
+++ b/contrib/llvm-project/llvm/lib/Analysis/MemorySSAUpdater.cpp
@@ -319,8 +319,7 @@ void MemorySSAUpdater::insertDef(MemoryDef *MD, bool RenameUses) {
   bool DefBeforeSameBlock = false;
   if (DefBefore->getBlock() == MD->getBlock() &&
       !(isa<MemoryPhi>(DefBefore) &&
-        std::find(InsertedPHIs.begin(), InsertedPHIs.end(), DefBefore) !=
-            InsertedPHIs.end()))
+        llvm::is_contained(InsertedPHIs, DefBefore)))
     DefBeforeSameBlock = true;
 
   // There is a def before us, which means we can replace any store/phi uses
@@ -343,6 +342,8 @@ void MemorySSAUpdater::insertDef(MemoryDef *MD, bool RenameUses) {
 
   SmallVector<WeakVH, 8> FixupList(InsertedPHIs.begin(), InsertedPHIs.end());
 
+  SmallSet<WeakVH, 8> ExistingPhis;
+
   // Remember the index where we may insert new phis.
   unsigned NewPhiIndex = InsertedPHIs.size();
   if (!DefBeforeSameBlock) {
@@ -383,6 +384,8 @@ void MemorySSAUpdater::insertDef(MemoryDef *MD, bool RenameUses) {
       if (!MPhi) {
         MPhi = MSSA->createMemoryPhi(BBIDF);
         NewInsertedPHIs.push_back(MPhi);
+      } else {
+        ExistingPhis.insert(MPhi);
       }
       // Add the phis created into the IDF blocks to NonOptPhis, so they are not
       // optimized out as trivial by the call to getPreviousDefFromEnd below.
@@ -428,10 +431,11 @@ void MemorySSAUpdater::insertDef(MemoryDef *MD, bool RenameUses) {
   if (NewPhiSize)
     tryRemoveTrivialPhis(ArrayRef<WeakVH>(&InsertedPHIs[NewPhiIndex], NewPhiSize));
 
-  // Now that all fixups are done, rename all uses if we are asked.
-  if (RenameUses) {
+  // Now that all fixups are done, rename all uses if we are asked. Skip
+  // renaming for defs in unreachable blocks.
+  BasicBlock *StartBlock = MD->getBlock();
+  if (RenameUses && MSSA->getDomTree().getNode(StartBlock)) {
     SmallPtrSet<BasicBlock *, 16> Visited;
-    BasicBlock *StartBlock = MD->getBlock();
     // We are guaranteed there is a def in the block, because we just got it
     // handed to us in this function.
     MemoryAccess *FirstDef = &*MSSA->getWritableBlockDefs(StartBlock)->begin();
@@ -448,6 +452,13 @@ void MemorySSAUpdater::insertDef(MemoryDef *MD, bool RenameUses) {
       if (Phi)
         MSSA->renamePass(Phi->getBlock(), nullptr, Visited);
     }
+    // Existing Phi blocks may need renaming too, if an access was previously
+    // optimized and the inserted Defs "covers" the Optimized value.
+    for (auto &MP : ExistingPhis) {
+      MemoryPhi *Phi = dyn_cast_or_null<MemoryPhi>(MP);
+      if (Phi)
+        MSSA->renamePass(Phi->getBlock(), nullptr, Visited);
+    }
   }
 }
 
@@ -544,6 +555,20 @@ void MemorySSAUpdater::removeDuplicatePhiEdgesBetween(const BasicBlock *From,
   }
 }
 
+/// If all arguments of a MemoryPHI are defined by the same incoming
+/// argument, return that argument.
+static MemoryAccess *onlySingleValue(MemoryPhi *MP) {
+  MemoryAccess *MA = nullptr;
+
+  for (auto &Arg : MP->operands()) {
+    if (!MA)
+      MA = cast<MemoryAccess>(Arg);
+    else if (MA != Arg)
+      return nullptr;
+  }
+  return MA;
+}
+
 static MemoryAccess *getNewDefiningAccessForClone(MemoryAccess *MA,
                                                   const ValueToValueMapTy &VMap,
                                                   PhiToDefMap &MPhiMap,
@@ -700,6 +725,10 @@ void MemorySSAUpdater::updateForClonedLoop(const LoopBlocksRPO &LoopBlocks,
           NewPhi->addIncoming(IncPhi, IncBB);
       }
     }
+    if (auto *SingleAccess = onlySingleValue(NewPhi)) {
+      MPhiMap[Phi] = SingleAccess;
+      removeMemoryAccess(NewPhi);
+    }
   };
 
   auto ProcessBlock = [&](BasicBlock *BB) {
@@ -782,27 +811,42 @@ void MemorySSAUpdater::updateExitBlocksForClonedLoop(
 }
 
 void MemorySSAUpdater::applyUpdates(ArrayRef<CFGUpdate> Updates,
-                                    DominatorTree &DT) {
+                                    DominatorTree &DT, bool UpdateDT) {
   SmallVector<CFGUpdate, 4> DeleteUpdates;
+  SmallVector<CFGUpdate, 4> RevDeleteUpdates;
   SmallVector<CFGUpdate, 4> InsertUpdates;
   for (auto &Update : Updates) {
     if (Update.getKind() == DT.Insert)
       InsertUpdates.push_back({DT.Insert, Update.getFrom(), Update.getTo()});
-    else
+    else {
       DeleteUpdates.push_back({DT.Delete, Update.getFrom(), Update.getTo()});
+      RevDeleteUpdates.push_back({DT.Insert, Update.getFrom(), Update.getTo()});
+    }
   }
 
   if (!DeleteUpdates.empty()) {
-    // Update for inserted edges: use newDT and snapshot CFG as if deletes had
-    // not occurred.
-    // FIXME: This creates a new DT, so it's more expensive to do mix
-    // delete/inserts vs just inserts. We can do an incremental update on the DT
-    // to revert deletes, than re-delete the edges. Teaching DT to do this, is
-    // part of a pending cleanup.
-    DominatorTree NewDT(DT, DeleteUpdates);
-    GraphDiff<BasicBlock *> GD(DeleteUpdates, /*ReverseApplyUpdates=*/true);
-    applyInsertUpdates(InsertUpdates, NewDT, &GD);
+    if (!UpdateDT) {
+      SmallVector<CFGUpdate, 0> Empty;
+      // Deletes are reversed applied, because this CFGView is pretending the
+      // deletes did not happen yet, hence the edges still exist.
+      DT.applyUpdates(Empty, RevDeleteUpdates);
+    } else {
+      // Apply all updates, with the RevDeleteUpdates as PostCFGView.
+      DT.applyUpdates(Updates, RevDeleteUpdates);
+    }
+
+    // Note: the MSSA update below doesn't distinguish between a GD with
+    // (RevDelete,false) and (Delete, true), but this matters for the DT
+    // updates above; for "children" purposes they are equivalent; but the
+    // updates themselves convey the desired update, used inside DT only.
+    GraphDiff<BasicBlock *> GD(RevDeleteUpdates);
+    applyInsertUpdates(InsertUpdates, DT, &GD);
+    // Update DT to redelete edges; this matches the real CFG so we can perform
+    // the standard update without a postview of the CFG.
+    DT.applyUpdates(DeleteUpdates);
   } else {
+    if (UpdateDT)
+      DT.applyUpdates(Updates);
     GraphDiff<BasicBlock *> GD;
     applyInsertUpdates(InsertUpdates, DT, &GD);
   }
@@ -832,8 +876,8 @@ void MemorySSAUpdater::applyInsertUpdates(ArrayRef<CFGUpdate> Updates,
       // Check number of predecessors, we only care if there's more than one.
       unsigned Count = 0;
       BasicBlock *Pred = nullptr;
-      for (auto &Pair : children<GraphDiffInvBBPair>({GD, BB})) {
-        Pred = Pair.second;
+      for (auto *Pi : GD->template getChildren</*InverseEdge=*/true>(BB)) {
+        Pred = Pi;
         Count++;
         if (Count == 2)
           break;
@@ -926,8 +970,7 @@ void MemorySSAUpdater::applyInsertUpdates(ArrayRef<CFGUpdate> Updates,
     auto *BB = BBPredPair.first;
     const auto &AddedBlockSet = BBPredPair.second.Added;
     auto &PrevBlockSet = BBPredPair.second.Prev;
-    for (auto &Pair : children<GraphDiffInvBBPair>({GD, BB})) {
-      BasicBlock *Pi = Pair.second;
+    for (auto *Pi : GD->template getChildren</*InverseEdge=*/true>(BB)) {
       if (!AddedBlockSet.count(Pi))
         PrevBlockSet.insert(Pi);
       EdgeCountMap[{Pi, BB}]++;
@@ -1078,10 +1121,8 @@ void MemorySSAUpdater::applyInsertUpdates(ArrayRef<CFGUpdate> Updates,
         for (unsigned I = 0, E = IDFPhi->getNumIncomingValues(); I < E; ++I)
           IDFPhi->setIncomingValue(I, GetLastDef(IDFPhi->getIncomingBlock(I)));
       } else {
-        for (auto &Pair : children<GraphDiffInvBBPair>({GD, BBIDF})) {
-          BasicBlock *Pi = Pair.second;
+        for (auto *Pi : GD->template getChildren</*InverseEdge=*/true>(BBIDF))
           IDFPhi->addIncoming(GetLastDef(Pi), Pi);
-        }
       }
     }
   }
@@ -1227,20 +1268,6 @@ void MemorySSAUpdater::moveAllAfterMergeBlocks(BasicBlock *From, BasicBlock *To,
       MPhi->setIncomingBlock(MPhi->getBasicBlockIndex(From), To);
 }
 
-/// If all arguments of a MemoryPHI are defined by the same incoming
-/// argument, return that argument.
-static MemoryAccess *onlySingleValue(MemoryPhi *MP) {
-  MemoryAccess *MA = nullptr;
-
-  for (auto &Arg : MP->operands()) {
-    if (!MA)
-      MA = cast<MemoryAccess>(Arg);
-    else if (MA != Arg)
-      return nullptr;
-  }
-  return MA;
-}
-
 void MemorySSAUpdater::wireOldPredecessorsToNewImmediatePredecessor(
     BasicBlock *Old, BasicBlock *New, ArrayRef<BasicBlock *> Preds,
     bool IdenticalEdgesWereMerged) {
@@ -1314,6 +1341,7 @@ void MemorySSAUpdater::removeMemoryAccess(MemoryAccess *MA, bool OptimizePhis) {
     // Note: We assume MemorySSA is not used in metadata since it's not really
     // part of the IR.
 
+    assert(NewDefTarget != MA && "Going into an infinite loop");
     while (!MA->use_empty()) {
       Use &U = *MA->use_begin();
       if (auto *MUD = dyn_cast<MemoryUseOrDef>(U.getUser()))