MFC 261991:

Upgrade our copy of llvm/clang to 3.4 release.  This version supports
all of the features in the current working draft of the upcoming C++
standard, provisionally named C++1y.

The code generator's performance is greatly increased, and the loop
auto-vectorizer is now enabled at -Os and -O2 in addition to -O3.  The
PowerPC backend has made several major improvements to code generation
quality and compile time, and the X86, SPARC, ARM32, Aarch64 and SystemZ
backends have all seen major feature work.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.4/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.4/tools/clang/docs/ReleaseNotes.html>

MFC 262121 (by emaste):

Update lldb for clang/llvm 3.4 import

This commit largely restores the lldb source to the upstream r196259
snapshot with the addition of threaded inferior support and a few bug
fixes.

Specific upstream lldb revisions restored include:
   SVN      git
  181387  779e6ac
  181703  7bef4e2
  182099  b31044e
  182650  f2dcf35
  182683  0d91b80
  183862  15c1774
  183929  99447a6
  184177  0b2934b
  184948  4dc3761
  184954  007e7bc
  186990  eebd175

Sponsored by:	DARPA, AFRL

MFC 262186 (by emaste):

Fix mismerge in r262121

A break statement was lost in the merge.  The error had no functional
impact, but restore it to reduce the diff against upstream.

MFC 262303:

Pull in r197521 from upstream clang trunk (by rdivacky):

  Use the integrated assembler by default on FreeBSD/ppc and ppc64.

Requested by:	jhibbits

MFC 262611:

Pull in r196874 from upstream llvm trunk:

  Fix a crash that occurs when PWD is invalid.

  MCJIT needs to be able to run in hostile environments, even when PWD
  is invalid. There's no need to crash MCJIT in this case.

  The obvious fix is to simply leave MCContext's CompilationDir empty
  when PWD can't be determined. This way, MCJIT clients,
  and other clients that link with LLVM don't need a valid working directory.

  If we do want to guarantee valid CompilationDir, that should be done
  only for clients of getCompilationDir(). This is as simple as checking
  for an empty string.

  The only current use of getCompilationDir is EmitGenDwarfInfo, which
  won't conceivably run with an invalid working dir. However, in the
  purely hypothetically and untestable case that this happens, the
  AT_comp_dir will be omitted from the compilation_unit DIE.

This should help fix assertions occurring with ports-mgmt/tinderbox,
when it is using jails, and sometimes invalidates clang's current
working directory.

Reported by:	decke

MFC 262809:

Pull in r203007 from upstream clang trunk:

  Don't produce an alias between destructors with different calling conventions.

  Fixes pr19007.

(Please note that is an LLVM PR identifier, not a FreeBSD one.)

This should fix Firefox and/or libxul crashes (due to problems with
regparm/stdcall calling conventions) on i386.

Reported by:	multiple users on freebsd-current
PR:		bin/187103

MFC 263048:

Repair recognition of "CC" as an alias for the C++ compiler, since it
was silently broken by upstream for a Windows-specific use-case.

Apparently some versions of CMake still rely on this archaic feature...

Reported by:	rakuco

MFC 263049:

Garbage collect the old way of adding the libstdc++ include directories
in clang's InitHeaderSearch.cpp.  This has been superseded by David
Chisnall's commit in r255321.

Moreover, if libc++ is used, the libstdc++ include directories should
not be in the search path at all.  These directories are now only used
if you pass -stdlib=libstdc++.

1 files changed, 486 insertions, 0 deletions

diff --git a/contrib/llvm/lib/Transforms/Utils/FlattenCFG.cpp b/contrib/llvm/lib/Transforms/Utils/FlattenCFG.cpp
new file mode 100644
index 0000000..1da226b
--- /dev/null
+++ b/contrib/llvm/lib/Transforms/Utils/FlattenCFG.cpp
@@ -0,0 +1,486 @@
+//===- FlatternCFG.cpp - Code to perform CFG flattening ---------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Reduce conditional branches in CFG.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "flattencfg"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+using namespace llvm;
+
+namespace {
+class FlattenCFGOpt {
+  AliasAnalysis *AA;
+  /// \brief Use parallel-and or parallel-or to generate conditions for
+  /// conditional branches.
+  bool FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder, Pass *P = 0);
+  /// \brief If \param BB is the merge block of an if-region, attempt to merge
+  /// the if-region with an adjacent if-region upstream if two if-regions
+  /// contain identical instructions.
+  bool MergeIfRegion(BasicBlock *BB, IRBuilder<> &Builder, Pass *P = 0);
+  /// \brief Compare a pair of blocks: \p Block1 and \p Block2, which
+  /// are from two if-regions whose entry blocks are \p Head1 and \p
+  /// Head2.  \returns true if \p Block1 and \p Block2 contain identical
+  /// instructions, and have no memory reference alias with \p Head2.
+  /// This is used as a legality check for merging if-regions.
+  bool CompareIfRegionBlock(BasicBlock *Head1, BasicBlock *Head2,
+                            BasicBlock *Block1, BasicBlock *Block2);
+
+public:
+  FlattenCFGOpt(AliasAnalysis *AA) : AA(AA) {}
+  bool run(BasicBlock *BB);
+};
+}
+
+/// If \param [in] BB has more than one predecessor that is a conditional
+/// branch, attempt to use parallel and/or for the branch condition. \returns
+/// true on success.
+///
+/// Before:
+///   ......
+///   %cmp10 = fcmp une float %tmp1, %tmp2
+///   br i1 %cmp1, label %if.then, label %lor.rhs
+///
+/// lor.rhs:
+///   ......
+///   %cmp11 = fcmp une float %tmp3, %tmp4
+///   br i1 %cmp11, label %if.then, label %ifend
+///
+/// if.end:  // the merge block
+///   ......
+///
+/// if.then: // has two predecessors, both of them contains conditional branch.
+///   ......
+///   br label %if.end;
+///
+/// After:
+///  ......
+///  %cmp10 = fcmp une float %tmp1, %tmp2
+///  ......
+///  %cmp11 = fcmp une float %tmp3, %tmp4
+///  %cmp12 = or i1 %cmp10, %cmp11    // parallel-or mode.
+///  br i1 %cmp12, label %if.then, label %ifend
+///
+///  if.end:
+///    ......
+///
+///  if.then:
+///    ......
+///    br label %if.end;
+///
+///  Current implementation handles two cases.
+///  Case 1: \param BB is on the else-path.
+///
+///          BB1
+///        /     |
+///       BB2    |
+///      /   \   |
+///     BB3   \  |     where, BB1, BB2 contain conditional branches.
+///      \    |  /     BB3 contains unconditional branch.
+///       \   | /      BB4 corresponds to \param BB which is also the merge.
+///  BB => BB4
+///
+///
+///  Corresponding source code:
+///
+///  if (a == b && c == d)
+///    statement; // BB3
+///
+///  Case 2: \param BB BB is on the then-path.
+///
+///             BB1
+///          /      |
+///         |      BB2
+///         \    /    |  where BB1, BB2 contain conditional branches.
+///  BB =>   BB3      |  BB3 contains unconditiona branch and corresponds
+///           \     /    to \param BB.  BB4 is the merge.
+///             BB4
+///
+///  Corresponding source code:
+///
+///  if (a == b || c == d)
+///    statement;  // BB3
+///
+///  In both cases,  \param BB is the common successor of conditional branches.
+///  In Case 1, \param BB (BB4) has an unconditional branch (BB3) as
+///  its predecessor.  In Case 2, \param BB (BB3) only has conditional branches
+///  as its predecessors.
+///
+bool FlattenCFGOpt::FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
+                                         Pass *P) {
+  PHINode *PHI = dyn_cast<PHINode>(BB->begin());
+  if (PHI)
+    return false; // For simplicity, avoid cases containing PHI nodes.
+
+  BasicBlock *LastCondBlock = NULL;
+  BasicBlock *FirstCondBlock = NULL;
+  BasicBlock *UnCondBlock = NULL;
+  int Idx = -1;
+
+  // Check predecessors of \param BB.
+  SmallPtrSet<BasicBlock *, 16> Preds(pred_begin(BB), pred_end(BB));
+  for (SmallPtrSetIterator<BasicBlock *> PI = Preds.begin(), PE = Preds.end();
+       PI != PE; ++PI) {
+    BasicBlock *Pred = *PI;
+    BranchInst *PBI = dyn_cast<BranchInst>(Pred->getTerminator());
+
+    // All predecessors should terminate with a branch.
+    if (!PBI)
+      return false;
+
+    BasicBlock *PP = Pred->getSinglePredecessor();
+
+    if (PBI->isUnconditional()) {
+      // Case 1: Pred (BB3) is an unconditional block, it should
+      // have a single predecessor (BB2) that is also a predecessor
+      // of \param BB (BB4) and should not have address-taken.
+      // There should exist only one such unconditional
+      // branch among the predecessors.
+      if (UnCondBlock || !PP || (Preds.count(PP) == 0) ||
+          Pred->hasAddressTaken())
+        return false;
+
+      UnCondBlock = Pred;
+      continue;
+    }
+
+    // Only conditional branches are allowed beyond this point.
+    assert(PBI->isConditional());
+
+    // Condition's unique use should be the branch instruction.
+    Value *PC = PBI->getCondition();
+    if (!PC || !PC->hasOneUse())
+      return false;
+
+    if (PP && Preds.count(PP)) {
+      // These are internal condition blocks to be merged from, e.g.,
+      // BB2 in both cases.
+      // Should not be address-taken.
+      if (Pred->hasAddressTaken())
+        return false;
+
+      // Instructions in the internal condition blocks should be safe
+      // to hoist up.
+      for (BasicBlock::iterator BI = Pred->begin(), BE = PBI; BI != BE;) {
+        Instruction *CI = BI++;
+        if (isa<PHINode>(CI) || !isSafeToSpeculativelyExecute(CI))
+          return false;
+      }
+    } else {
+      // This is the condition block to be merged into, e.g. BB1 in
+      // both cases.
+      if (FirstCondBlock)
+        return false;
+      FirstCondBlock = Pred;
+    }
+
+    // Find whether BB is uniformly on the true (or false) path
+    // for all of its predecessors.
+    BasicBlock *PS1 = PBI->getSuccessor(0);
+    BasicBlock *PS2 = PBI->getSuccessor(1);
+    BasicBlock *PS = (PS1 == BB) ? PS2 : PS1;
+    int CIdx = (PS1 == BB) ? 0 : 1;
+
+    if (Idx == -1)
+      Idx = CIdx;
+    else if (CIdx != Idx)
+      return false;
+
+    // PS is the successor which is not BB. Check successors to identify
+    // the last conditional branch.
+    if (Preds.count(PS) == 0) {
+      // Case 2.
+      LastCondBlock = Pred;
+    } else {
+      // Case 1
+      BranchInst *BPS = dyn_cast<BranchInst>(PS->getTerminator());
+      if (BPS && BPS->isUnconditional()) {
+        // Case 1: PS(BB3) should be an unconditional branch.
+        LastCondBlock = Pred;
+      }
+    }
+  }
+
+  if (!FirstCondBlock || !LastCondBlock || (FirstCondBlock == LastCondBlock))
+    return false;
+
+  TerminatorInst *TBB = LastCondBlock->getTerminator();
+  BasicBlock *PS1 = TBB->getSuccessor(0);
+  BasicBlock *PS2 = TBB->getSuccessor(1);
+  BranchInst *PBI1 = dyn_cast<BranchInst>(PS1->getTerminator());
+  BranchInst *PBI2 = dyn_cast<BranchInst>(PS2->getTerminator());
+
+  // If PS1 does not jump into PS2, but PS2 jumps into PS1,
+  // attempt branch inversion.
+  if (!PBI1 || !PBI1->isUnconditional() ||
+      (PS1->getTerminator()->getSuccessor(0) != PS2)) {
+    // Check whether PS2 jumps into PS1.
+    if (!PBI2 || !PBI2->isUnconditional() ||
+        (PS2->getTerminator()->getSuccessor(0) != PS1))
+      return false;
+
+    // Do branch inversion.
+    BasicBlock *CurrBlock = LastCondBlock;
+    bool EverChanged = false;
+    while (1) {
+      BranchInst *BI = dyn_cast<BranchInst>(CurrBlock->getTerminator());
+      CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition());
+      CmpInst::Predicate Predicate = CI->getPredicate();
+      // Cannonicalize icmp_ne -> icmp_eq, fcmp_one -> fcmp_oeq
+      if ((Predicate == CmpInst::ICMP_NE) || (Predicate == CmpInst::FCMP_ONE)) {
+        CI->setPredicate(ICmpInst::getInversePredicate(Predicate));
+        BI->swapSuccessors();
+        EverChanged = true;
+      }
+      if (CurrBlock == FirstCondBlock)
+        break;
+      CurrBlock = CurrBlock->getSinglePredecessor();
+    }
+    return EverChanged;
+  }
+
+  // PS1 must have a conditional branch.
+  if (!PBI1 || !PBI1->isUnconditional())
+    return false;
+
+  // PS2 should not contain PHI node.
+  PHI = dyn_cast<PHINode>(PS2->begin());
+  if (PHI)
+    return false;
+
+  // Do the transformation.
+  BasicBlock *CB;
+  BranchInst *PBI = dyn_cast<BranchInst>(FirstCondBlock->getTerminator());
+  bool Iteration = true;
+  IRBuilder<>::InsertPointGuard Guard(Builder);
+  Value *PC = PBI->getCondition();
+
+  do {
+    CB = PBI->getSuccessor(1 - Idx);
+    // Delete the conditional branch.
+    FirstCondBlock->getInstList().pop_back();
+    FirstCondBlock->getInstList()
+        .splice(FirstCondBlock->end(), CB->getInstList());
+    PBI = cast<BranchInst>(FirstCondBlock->getTerminator());
+    Value *CC = PBI->getCondition();
+    // Merge conditions.
+    Builder.SetInsertPoint(PBI);
+    Value *NC;
+    if (Idx == 0)
+      // Case 2, use parallel or.
+      NC = Builder.CreateOr(PC, CC);
+    else
+      // Case 1, use parallel and.
+      NC = Builder.CreateAnd(PC, CC);
+
+    PBI->replaceUsesOfWith(CC, NC);
+    PC = NC;
+    if (CB == LastCondBlock)
+      Iteration = false;
+    // Remove internal conditional branches.
+    CB->dropAllReferences();
+    // make CB unreachable and let downstream to delete the block.
+    new UnreachableInst(CB->getContext(), CB);
+  } while (Iteration);
+
+  DEBUG(dbgs() << "Use parallel and/or in:\n" << *FirstCondBlock);
+  return true;
+}
+
+/// Compare blocks from two if-regions, where \param Head1 is the entry of the
+/// 1st if-region. \param Head2 is the entry of the 2nd if-region. \param
+/// Block1 is a block in the 1st if-region to compare. \param Block2 is a block
+//  in the 2nd if-region to compare.  \returns true if \param Block1 and \param
+/// Block2 have identical instructions and do not have memory reference alias
+/// with \param Head2.
+///
+bool FlattenCFGOpt::CompareIfRegionBlock(BasicBlock *Head1, BasicBlock *Head2,
+                                         BasicBlock *Block1,
+                                         BasicBlock *Block2) {
+  TerminatorInst *PTI2 = Head2->getTerminator();
+  Instruction *PBI2 = Head2->begin();
+
+  bool eq1 = (Block1 == Head1);
+  bool eq2 = (Block2 == Head2);
+  if (eq1 || eq2) {
+    // An empty then-path or else-path.
+    return (eq1 == eq2);
+  }
+
+  // Check whether instructions in Block1 and Block2 are identical
+  // and do not alias with instructions in Head2.
+  BasicBlock::iterator iter1 = Block1->begin();
+  BasicBlock::iterator end1 = Block1->getTerminator();
+  BasicBlock::iterator iter2 = Block2->begin();
+  BasicBlock::iterator end2 = Block2->getTerminator();
+
+  while (1) {
+    if (iter1 == end1) {
+      if (iter2 != end2)
+        return false;
+      break;
+    }
+
+    if (!iter1->isIdenticalTo(iter2))
+      return false;
+
+    // Illegal to remove instructions with side effects except
+    // non-volatile stores.
+    if (iter1->mayHaveSideEffects()) {
+      Instruction *CurI = &*iter1;
+      StoreInst *SI = dyn_cast<StoreInst>(CurI);
+      if (!SI || SI->isVolatile())
+        return false;
+    }
+
+    // For simplicity and speed, data dependency check can be
+    // avoided if read from memory doesn't exist.
+    if (iter1->mayReadFromMemory())
+      return false;
+
+    if (iter1->mayWriteToMemory()) {
+      for (BasicBlock::iterator BI = PBI2, BE = PTI2; BI != BE; ++BI) {
+        if (BI->mayReadFromMemory() || BI->mayWriteToMemory()) {
+          // Check alias with Head2.
+          if (!AA || AA->alias(iter1, BI))
+            return false;
+        }
+      }
+    }
+    ++iter1;
+    ++iter2;
+  }
+
+  return true;
+}
+
+/// Check whether \param BB is the merge block of a if-region.  If yes, check
+/// whether there exists an adjacent if-region upstream, the two if-regions
+/// contain identical instructions and can be legally merged.  \returns true if
+/// the two if-regions are merged.
+///
+/// From:
+/// if (a)
+///   statement;
+/// if (b)
+///   statement;
+///
+/// To:
+/// if (a || b)
+///   statement;
+///
+bool FlattenCFGOpt::MergeIfRegion(BasicBlock *BB, IRBuilder<> &Builder,
+                                  Pass *P) {
+  BasicBlock *IfTrue2, *IfFalse2;
+  Value *IfCond2 = GetIfCondition(BB, IfTrue2, IfFalse2);
+  Instruction *CInst2 = dyn_cast_or_null<Instruction>(IfCond2);
+  if (!CInst2)
+    return false;
+
+  BasicBlock *SecondEntryBlock = CInst2->getParent();
+  if (SecondEntryBlock->hasAddressTaken())
+    return false;
+
+  BasicBlock *IfTrue1, *IfFalse1;
+  Value *IfCond1 = GetIfCondition(SecondEntryBlock, IfTrue1, IfFalse1);
+  Instruction *CInst1 = dyn_cast_or_null<Instruction>(IfCond1);
+  if (!CInst1)
+    return false;
+
+  BasicBlock *FirstEntryBlock = CInst1->getParent();
+
+  // Either then-path or else-path should be empty.
+  if ((IfTrue1 != FirstEntryBlock) && (IfFalse1 != FirstEntryBlock))
+    return false;
+  if ((IfTrue2 != SecondEntryBlock) && (IfFalse2 != SecondEntryBlock))
+    return false;
+
+  TerminatorInst *PTI2 = SecondEntryBlock->getTerminator();
+  Instruction *PBI2 = SecondEntryBlock->begin();
+
+  if (!CompareIfRegionBlock(FirstEntryBlock, SecondEntryBlock, IfTrue1,
+                            IfTrue2))
+    return false;
+
+  if (!CompareIfRegionBlock(FirstEntryBlock, SecondEntryBlock, IfFalse1,
+                            IfFalse2))
+    return false;
+
+  // Check whether \param SecondEntryBlock has side-effect and is safe to
+  // speculate.
+  for (BasicBlock::iterator BI = PBI2, BE = PTI2; BI != BE; ++BI) {
+    Instruction *CI = BI;
+    if (isa<PHINode>(CI) || CI->mayHaveSideEffects() ||
+        !isSafeToSpeculativelyExecute(CI))
+      return false;
+  }
+
+  // Merge \param SecondEntryBlock into \param FirstEntryBlock.
+  FirstEntryBlock->getInstList().pop_back();
+  FirstEntryBlock->getInstList()
+      .splice(FirstEntryBlock->end(), SecondEntryBlock->getInstList());
+  BranchInst *PBI = dyn_cast<BranchInst>(FirstEntryBlock->getTerminator());
+  Value *CC = PBI->getCondition();
+  BasicBlock *SaveInsertBB = Builder.GetInsertBlock();
+  BasicBlock::iterator SaveInsertPt = Builder.GetInsertPoint();
+  Builder.SetInsertPoint(PBI);
+  Value *NC = Builder.CreateOr(CInst1, CC);
+  PBI->replaceUsesOfWith(CC, NC);
+  Builder.SetInsertPoint(SaveInsertBB, SaveInsertPt);
+
+  // Remove IfTrue1
+  if (IfTrue1 != FirstEntryBlock) {
+    IfTrue1->dropAllReferences();
+    IfTrue1->eraseFromParent();
+  }
+
+  // Remove IfFalse1
+  if (IfFalse1 != FirstEntryBlock) {
+    IfFalse1->dropAllReferences();
+    IfFalse1->eraseFromParent();
+  }
+
+  // Remove \param SecondEntryBlock
+  SecondEntryBlock->dropAllReferences();
+  SecondEntryBlock->eraseFromParent();
+  DEBUG(dbgs() << "If conditions merged into:\n" << *FirstEntryBlock);
+  return true;
+}
+
+bool FlattenCFGOpt::run(BasicBlock *BB) {
+  bool Changed = false;
+  assert(BB && BB->getParent() && "Block not embedded in function!");
+  assert(BB->getTerminator() && "Degenerate basic block encountered!");
+
+  IRBuilder<> Builder(BB);
+
+  if (FlattenParallelAndOr(BB, Builder))
+    return true;
+
+  if (MergeIfRegion(BB, Builder))
+    return true;
+
+  return Changed;
+}
+
+/// FlattenCFG - This function is used to flatten a CFG.  For
+/// example, it uses parallel-and and parallel-or mode to collapse
+//  if-conditions and merge if-regions with identical statements.
+///
+bool llvm::FlattenCFG(BasicBlock *BB, AliasAnalysis *AA) {
+  return FlattenCFGOpt(AA).run(BB);
+}