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, 97 insertions, 73 deletions

diff --git a/contrib/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp b/contrib/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
index 2002e68..9fb8ddc 100644
--- a/contrib/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
+++ b/contrib/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
@@ -53,6 +53,7 @@
 #define DEBUG_TYPE "tailcallelim"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/CaptureTracking.h"
 #include "llvm/Analysis/InlineCost.h"
@@ -69,6 +70,7 @@
 #include "llvm/Support/CFG.h"
 #include "llvm/Support/CallSite.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ValueHandle.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Local.h"
@@ -97,16 +99,16 @@ namespace {
     bool EliminateRecursiveTailCall(CallInst *CI, ReturnInst *Ret,
                                     BasicBlock *&OldEntry,
                                     bool &TailCallsAreMarkedTail,
-                                    SmallVector<PHINode*, 8> &ArgumentPHIs,
+                                    SmallVectorImpl<PHINode *> &ArgumentPHIs,
                                     bool CannotTailCallElimCallsMarkedTail);
     bool FoldReturnAndProcessPred(BasicBlock *BB,
                                   ReturnInst *Ret, BasicBlock *&OldEntry,
                                   bool &TailCallsAreMarkedTail,
-                                  SmallVector<PHINode*, 8> &ArgumentPHIs,
+                                  SmallVectorImpl<PHINode *> &ArgumentPHIs,
                                   bool CannotTailCallElimCallsMarkedTail);
     bool ProcessReturningBlock(ReturnInst *RI, BasicBlock *&OldEntry,
                                bool &TailCallsAreMarkedTail,
-                               SmallVector<PHINode*, 8> &ArgumentPHIs,
+                               SmallVectorImpl<PHINode *> &ArgumentPHIs,
                                bool CannotTailCallElimCallsMarkedTail);
     bool CanMoveAboveCall(Instruction *I, CallInst *CI);
     Value *CanTransformAccumulatorRecursion(Instruction *I, CallInst *CI);
@@ -129,34 +131,44 @@ void TailCallElim::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequired<TargetTransformInfo>();
 }
 
-/// AllocaMightEscapeToCalls - Return true if this alloca may be accessed by
-/// callees of this function.  We only do very simple analysis right now, this
-/// could be expanded in the future to use mod/ref information for particular
-/// call sites if desired.
-static bool AllocaMightEscapeToCalls(AllocaInst *AI) {
-  // FIXME: do simple 'address taken' analysis.
-  return true;
+/// CanTRE - Scan the specified basic block for alloca instructions.
+/// If it contains any that are variable-sized or not in the entry block,
+/// returns false.
+static bool CanTRE(AllocaInst *AI) {
+  // Because of PR962, we don't TRE allocas outside the entry block.
+
+  // If this alloca is in the body of the function, or if it is a variable
+  // sized allocation, we cannot tail call eliminate calls marked 'tail'
+  // with this mechanism.
+  BasicBlock *BB = AI->getParent();
+  return BB == &BB->getParent()->getEntryBlock() &&
+         isa<ConstantInt>(AI->getArraySize());
 }
 
-/// CheckForEscapingAllocas - Scan the specified basic block for alloca
-/// instructions.  If it contains any that might be accessed by calls, return
-/// true.
-static bool CheckForEscapingAllocas(BasicBlock *BB,
-                                    bool &CannotTCETailMarkedCall) {
-  bool RetVal = false;
-  for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
-    if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
-      RetVal |= AllocaMightEscapeToCalls(AI);
-
-      // If this alloca is in the body of the function, or if it is a variable
-      // sized allocation, we cannot tail call eliminate calls marked 'tail'
-      // with this mechanism.
-      if (BB != &BB->getParent()->getEntryBlock() ||
-          !isa<ConstantInt>(AI->getArraySize()))
-        CannotTCETailMarkedCall = true;
-    }
-  return RetVal;
-}
+namespace {
+struct AllocaCaptureTracker : public CaptureTracker {
+  AllocaCaptureTracker() : Captured(false) {}
+
+  void tooManyUses() LLVM_OVERRIDE { Captured = true; }
+
+  bool shouldExplore(Use *U) LLVM_OVERRIDE {
+    Value *V = U->getUser();
+    if (isa<CallInst>(V) || isa<InvokeInst>(V))
+      UsesAlloca.insert(V);
+    return true;
+  }
+
+  bool captured(Use *U) LLVM_OVERRIDE {
+    if (isa<ReturnInst>(U->getUser()))
+      return false;
+    Captured = true;
+    return true;
+  }
+
+  bool Captured;
+  SmallPtrSet<const Value *, 16> UsesAlloca;
+};
+} // end anonymous namespace
 
 bool TailCallElim::runOnFunction(Function &F) {
   // If this function is a varargs function, we won't be able to PHI the args
@@ -168,41 +180,44 @@ bool TailCallElim::runOnFunction(Function &F) {
   bool TailCallsAreMarkedTail = false;
   SmallVector<PHINode*, 8> ArgumentPHIs;
   bool MadeChange = false;
-  bool FunctionContainsEscapingAllocas = false;
 
-  // CannotTCETailMarkedCall - If true, we cannot perform TCE on tail calls
+  // CanTRETailMarkedCall - If false, we cannot perform TRE on tail calls
   // marked with the 'tail' attribute, because doing so would cause the stack
-  // size to increase (real TCE would deallocate variable sized allocas, TCE
+  // size to increase (real TRE would deallocate variable sized allocas, TRE
   // doesn't).
-  bool CannotTCETailMarkedCall = false;
-
-  // Loop over the function, looking for any returning blocks, and keeping track
-  // of whether this function has any non-trivially used allocas.
-  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
-    if (FunctionContainsEscapingAllocas && CannotTCETailMarkedCall)
-      break;
-
-    FunctionContainsEscapingAllocas |=
-      CheckForEscapingAllocas(BB, CannotTCETailMarkedCall);
+  bool CanTRETailMarkedCall = true;
+
+  // Find calls that can be marked tail.
+  AllocaCaptureTracker ACT;
+  for (Function::iterator BB = F.begin(), EE = F.end(); BB != EE; ++BB) {
+    for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
+      if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
+        CanTRETailMarkedCall &= CanTRE(AI);
+        PointerMayBeCaptured(AI, &ACT);
+        // If any allocas are captured, exit.
+        if (ACT.Captured)
+          return false;
+      }
+    }
   }
 
-  /// FIXME: The code generator produces really bad code when an 'escaping
-  /// alloca' is changed from being a static alloca to being a dynamic alloca.
-  /// Until this is resolved, disable this transformation if that would ever
-  /// happen.  This bug is PR962.
-  if (FunctionContainsEscapingAllocas)
-    return false;
-
-  // Second pass, change any tail calls to loops.
-  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
-    if (ReturnInst *Ret = dyn_cast<ReturnInst>(BB->getTerminator())) {
-      bool Change = ProcessReturningBlock(Ret, OldEntry, TailCallsAreMarkedTail,
-                                          ArgumentPHIs,CannotTCETailMarkedCall);
-      if (!Change && BB->getFirstNonPHIOrDbg() == Ret)
-        Change = FoldReturnAndProcessPred(BB, Ret, OldEntry,
-                                          TailCallsAreMarkedTail, ArgumentPHIs,
-                                          CannotTCETailMarkedCall);
-      MadeChange |= Change;
+  // Second pass, change any tail recursive calls to loops.
+  //
+  // FIXME: The code generator produces really bad code when an 'escaping
+  // alloca' is changed from being a static alloca to being a dynamic alloca.
+  // Until this is resolved, disable this transformation if that would ever
+  // happen.  This bug is PR962.
+  if (ACT.UsesAlloca.empty()) {
+    for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+      if (ReturnInst *Ret = dyn_cast<ReturnInst>(BB->getTerminator())) {
+        bool Change = ProcessReturningBlock(Ret, OldEntry, TailCallsAreMarkedTail,
+                                            ArgumentPHIs, !CanTRETailMarkedCall);
+        if (!Change && BB->getFirstNonPHIOrDbg() == Ret)
+          Change = FoldReturnAndProcessPred(BB, Ret, OldEntry,
+                                            TailCallsAreMarkedTail, ArgumentPHIs,
+                                            !CanTRETailMarkedCall);
+        MadeChange |= Change;
+      }
     }
   }
 
@@ -223,16 +238,24 @@ bool TailCallElim::runOnFunction(Function &F) {
     }
   }
 
-  // Finally, if this function contains no non-escaping allocas, or calls
-  // setjmp, mark all calls in the function as eligible for tail calls
-  //(there is no stack memory for them to access).
-  if (!FunctionContainsEscapingAllocas && !F.callsFunctionThatReturnsTwice())
-    for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
-      for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
+  // At this point, we know that the function does not have any captured
+  // allocas. If additionally the function does not call setjmp, mark all calls
+  // in the function that do not access stack memory with the tail keyword. This
+  // implies ensuring that there does not exist any path from a call that takes
+  // in an alloca but does not capture it and the call which we wish to mark
+  // with "tail".
+  if (!F.callsFunctionThatReturnsTwice()) {
+    for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+      for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
         if (CallInst *CI = dyn_cast<CallInst>(I)) {
-          CI->setTailCall();
-          MadeChange = true;
+          if (!ACT.UsesAlloca.count(CI)) {
+            CI->setTailCall();
+            MadeChange = true;
+          }
         }
+      }
+    }
+  }
 
   return MadeChange;
 }
@@ -424,7 +447,7 @@ TailCallElim::FindTRECandidate(Instruction *TI,
 bool TailCallElim::EliminateRecursiveTailCall(CallInst *CI, ReturnInst *Ret,
                                        BasicBlock *&OldEntry,
                                        bool &TailCallsAreMarkedTail,
-                                       SmallVector<PHINode*, 8> &ArgumentPHIs,
+                                       SmallVectorImpl<PHINode *> &ArgumentPHIs,
                                        bool CannotTailCallElimCallsMarkedTail) {
   // If we are introducing accumulator recursion to eliminate operations after
   // the call instruction that are both associative and commutative, the initial
@@ -600,7 +623,7 @@ bool TailCallElim::EliminateRecursiveTailCall(CallInst *CI, ReturnInst *Ret,
 bool TailCallElim::FoldReturnAndProcessPred(BasicBlock *BB,
                                        ReturnInst *Ret, BasicBlock *&OldEntry,
                                        bool &TailCallsAreMarkedTail,
-                                       SmallVector<PHINode*, 8> &ArgumentPHIs,
+                                       SmallVectorImpl<PHINode *> &ArgumentPHIs,
                                        bool CannotTailCallElimCallsMarkedTail) {
   bool Change = false;
 
@@ -634,10 +657,11 @@ bool TailCallElim::FoldReturnAndProcessPred(BasicBlock *BB,
   return Change;
 }
 
-bool TailCallElim::ProcessReturningBlock(ReturnInst *Ret, BasicBlock *&OldEntry,
-                                         bool &TailCallsAreMarkedTail,
-                                         SmallVector<PHINode*, 8> &ArgumentPHIs,
-                                       bool CannotTailCallElimCallsMarkedTail) {
+bool
+TailCallElim::ProcessReturningBlock(ReturnInst *Ret, BasicBlock *&OldEntry,
+                                    bool &TailCallsAreMarkedTail,
+                                    SmallVectorImpl<PHINode *> &ArgumentPHIs,
+                                    bool CannotTailCallElimCallsMarkedTail) {
   CallInst *CI = FindTRECandidate(Ret, CannotTailCallElimCallsMarkedTail);
   if (!CI)
     return false;