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, 78 insertions, 81 deletions

diff --git a/contrib/llvm/lib/CodeGen/SpillPlacement.cpp b/contrib/llvm/lib/CodeGen/SpillPlacement.cpp
index c5bbba3..10a93b7 100644
--- a/contrib/llvm/lib/CodeGen/SpillPlacement.cpp
+++ b/contrib/llvm/lib/CodeGen/SpillPlacement.cpp
@@ -31,8 +31,8 @@
 #include "SpillPlacement.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/CodeGen/EdgeBundles.h"
-#include "llvm/CodeGen/LiveIntervalAnalysis.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/CodeGen/Passes.h"
@@ -53,11 +53,16 @@ char &llvm::SpillPlacementID = SpillPlacement::ID;
 
 void SpillPlacement::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.setPreservesAll();
+  AU.addRequired<MachineBlockFrequencyInfo>();
   AU.addRequiredTransitive<EdgeBundles>();
   AU.addRequiredTransitive<MachineLoopInfo>();
   MachineFunctionPass::getAnalysisUsage(AU);
 }
 
+/// Decision threshold. A node gets the output value 0 if the weighted sum of
+/// its inputs falls in the open interval (-Threshold;Threshold).
+static const BlockFrequency Threshold = 2;
+
 /// Node - Each edge bundle corresponds to a Hopfield node.
 ///
 /// The node contains precomputed frequency data that only depends on the CFG,
@@ -68,31 +73,25 @@ void SpillPlacement::getAnalysisUsage(AnalysisUsage &AU) const {
 /// because all weights are positive.
 ///
 struct SpillPlacement::Node {
-  /// Scale - Inverse block frequency feeding into[0] or out of[1] the bundle.
-  /// Ideally, these two numbers should be identical, but inaccuracies in the
-  /// block frequency estimates means that we need to normalize ingoing and
-  /// outgoing frequencies separately so they are commensurate.
-  float Scale[2];
-
-  /// Bias - Normalized contributions from non-transparent blocks.
-  /// A bundle connected to a MustSpill block has a huge negative bias,
-  /// otherwise it is a number in the range [-2;2].
-  float Bias;
+  /// BiasN - Sum of blocks that prefer a spill.
+  BlockFrequency BiasN;
+  /// BiasP - Sum of blocks that prefer a register.
+  BlockFrequency BiasP;
 
   /// Value - Output value of this node computed from the Bias and links.
-  /// This is always in the range [-1;1]. A positive number means the variable
-  /// should go in a register through this bundle.
-  float Value;
+  /// This is always on of the values {-1, 0, 1}. A positive number means the
+  /// variable should go in a register through this bundle.
+  int Value;
 
-  typedef SmallVector<std::pair<float, unsigned>, 4> LinkVector;
+  typedef SmallVector<std::pair<BlockFrequency, unsigned>, 4> LinkVector;
 
   /// Links - (Weight, BundleNo) for all transparent blocks connecting to other
-  /// bundles. The weights are all positive and add up to at most 2, weights
-  /// from ingoing and outgoing nodes separately add up to a most 1. The weight
-  /// sum can be less than 2 when the variable is not live into / out of some
-  /// connected basic blocks.
+  /// bundles. The weights are all positive block frequencies.
   LinkVector Links;
 
+  /// SumLinkWeights - Cached sum of the weights of all links + ThresHold.
+  BlockFrequency SumLinkWeights;
+
   /// preferReg - Return true when this node prefers to be in a register.
   bool preferReg() const {
     // Undecided nodes (Value==0) go on the stack.
@@ -101,28 +100,24 @@ struct SpillPlacement::Node {
 
   /// mustSpill - Return True if this node is so biased that it must spill.
   bool mustSpill() const {
-    // Actually, we must spill if Bias < sum(weights).
-    // It may be worth it to compute the weight sum here?
-    return Bias < -2.0f;
-  }
-
-  /// Node - Create a blank Node.
-  Node() {
-    Scale[0] = Scale[1] = 0;
+    // We must spill if Bias < -sum(weights) or the MustSpill flag was set.
+    // BiasN is saturated when MustSpill is set, make sure this still returns
+    // true when the RHS saturates. Note that SumLinkWeights includes Threshold.
+    return BiasN >= BiasP + SumLinkWeights;
   }
 
   /// clear - Reset per-query data, but preserve frequencies that only depend on
   // the CFG.
   void clear() {
-    Bias = Value = 0;
+    BiasN = BiasP = Value = 0;
+    SumLinkWeights = Threshold;
     Links.clear();
   }
 
   /// addLink - Add a link to bundle b with weight w.
-  /// out=0 for an ingoing link, and 1 for an outgoing link.
-  void addLink(unsigned b, float w, bool out) {
-    // Normalize w relative to all connected blocks from that direction.
-    w *= Scale[out];
+  void addLink(unsigned b, BlockFrequency w) {
+    // Update cached sum.
+    SumLinkWeights += w;
 
     // There can be multiple links to the same bundle, add them up.
     for (LinkVector::iterator I = Links.begin(), E = Links.end(); I != E; ++I)
@@ -134,33 +129,48 @@ struct SpillPlacement::Node {
     Links.push_back(std::make_pair(w, b));
   }
 
-  /// addBias - Bias this node from an ingoing[0] or outgoing[1] link.
-  /// Return the change to the total number of positive biases.
-  void addBias(float w, bool out) {
-    // Normalize w relative to all connected blocks from that direction.
-    w *= Scale[out];
-    Bias += w;
+  /// addBias - Bias this node.
+  void addBias(BlockFrequency freq, BorderConstraint direction) {
+    switch (direction) {
+    default:
+      break;
+    case PrefReg:
+      BiasP += freq;
+      break;
+    case PrefSpill:
+      BiasN += freq;
+      break;
+    case MustSpill:
+      BiasN = BlockFrequency::getMaxFrequency();
+      break;
+    }
   }
 
   /// update - Recompute Value from Bias and Links. Return true when node
   /// preference changes.
   bool update(const Node nodes[]) {
     // Compute the weighted sum of inputs.
-    float Sum = Bias;
-    for (LinkVector::iterator I = Links.begin(), E = Links.end(); I != E; ++I)
-      Sum += I->first * nodes[I->second].Value;
+    BlockFrequency SumN = BiasN;
+    BlockFrequency SumP = BiasP;
+    for (LinkVector::iterator I = Links.begin(), E = Links.end(); I != E; ++I) {
+      if (nodes[I->second].Value == -1)
+        SumN += I->first;
+      else if (nodes[I->second].Value == 1)
+        SumP += I->first;
+    }
 
-    // The weighted sum is going to be in the range [-2;2]. Ideally, we should
-    // simply set Value = sign(Sum), but we will add a dead zone around 0 for
-    // two reasons:
+    // Each weighted sum is going to be less than the total frequency of the
+    // bundle. Ideally, we should simply set Value = sign(SumP - SumN), but we
+    // will add a dead zone around 0 for two reasons:
+    //
     //  1. It avoids arbitrary bias when all links are 0 as is possible during
     //     initial iterations.
     //  2. It helps tame rounding errors when the links nominally sum to 0.
-    const float Thres = 1e-4f;
+    //
     bool Before = preferReg();
-    if (Sum < -Thres)
+    if (SumN >= SumP + Threshold)
       Value = -1;
-    else if (Sum > Thres)
+    else if (SumP >= SumN + Threshold)
       Value = 1;
     else
       Value = 0;
@@ -177,22 +187,13 @@ bool SpillPlacement::runOnMachineFunction(MachineFunction &mf) {
   nodes = new Node[bundles->getNumBundles()];
 
   // Compute total ingoing and outgoing block frequencies for all bundles.
-  BlockFrequency.resize(mf.getNumBlockIDs());
+  BlockFrequencies.resize(mf.getNumBlockIDs());
+  MachineBlockFrequencyInfo &MBFI = getAnalysis<MachineBlockFrequencyInfo>();
   for (MachineFunction::iterator I = mf.begin(), E = mf.end(); I != E; ++I) {
-    float Freq = LiveIntervals::getSpillWeight(true, false,
-                                               loops->getLoopDepth(I));
     unsigned Num = I->getNumber();
-    BlockFrequency[Num] = Freq;
-    nodes[bundles->getBundle(Num, 1)].Scale[0] += Freq;
-    nodes[bundles->getBundle(Num, 0)].Scale[1] += Freq;
+    BlockFrequencies[Num] = MBFI.getBlockFreq(I);
   }
 
-  // Scales are reciprocal frequencies.
-  for (unsigned i = 0, e = bundles->getNumBundles(); i != e; ++i)
-    for (unsigned d = 0; d != 2; ++d)
-      if (nodes[i].Scale[d] > 0)
-        nodes[i].Scale[d] = 1 / nodes[i].Scale[d];
-
   // We never change the function.
   return false;
 }
@@ -213,12 +214,15 @@ void SpillPlacement::activate(unsigned n) {
   // landing pads, or loops with many 'continue' statements. It is difficult to
   // allocate registers when so many different blocks are involved.
   //
-  // Give a small negative bias to large bundles such that 1/32 of the
-  // connected blocks need to be interested before we consider expanding the
-  // region through the bundle. This helps compile time by limiting the number
-  // of blocks visited and the number of links in the Hopfield network.
-  if (bundles->getBlocks(n).size() > 100)
-    nodes[n].Bias = -0.0625f;
+  // Give a small negative bias to large bundles such that a substantial
+  // fraction of the connected blocks need to be interested before we consider
+  // expanding the region through the bundle. This helps compile time by
+  // limiting the number of blocks visited and the number of links in the
+  // Hopfield network.
+  if (bundles->getBlocks(n).size() > 100) {
+    nodes[n].BiasP = 0;
+    nodes[n].BiasN = (BlockFrequency::getEntryFrequency() / 16);
+  }
 }
 
 
@@ -227,27 +231,20 @@ void SpillPlacement::activate(unsigned n) {
 void SpillPlacement::addConstraints(ArrayRef<BlockConstraint> LiveBlocks) {
   for (ArrayRef<BlockConstraint>::iterator I = LiveBlocks.begin(),
        E = LiveBlocks.end(); I != E; ++I) {
-    float Freq = getBlockFrequency(I->Number);
-    const float Bias[] = {
-      0,           // DontCare,
-      1,           // PrefReg,
-      -1,          // PrefSpill
-      0,           // PrefBoth
-      -HUGE_VALF   // MustSpill
-    };
+    BlockFrequency Freq = BlockFrequencies[I->Number];
 
     // Live-in to block?
     if (I->Entry != DontCare) {
       unsigned ib = bundles->getBundle(I->Number, 0);
       activate(ib);
-      nodes[ib].addBias(Freq * Bias[I->Entry], 1);
+      nodes[ib].addBias(Freq, I->Entry);
     }
 
     // Live-out from block?
     if (I->Exit != DontCare) {
       unsigned ob = bundles->getBundle(I->Number, 1);
       activate(ob);
-      nodes[ob].addBias(Freq * Bias[I->Exit], 0);
+      nodes[ob].addBias(Freq, I->Exit);
     }
   }
 }
@@ -256,15 +253,15 @@ void SpillPlacement::addConstraints(ArrayRef<BlockConstraint> LiveBlocks) {
 void SpillPlacement::addPrefSpill(ArrayRef<unsigned> Blocks, bool Strong) {
   for (ArrayRef<unsigned>::iterator I = Blocks.begin(), E = Blocks.end();
        I != E; ++I) {
-    float Freq = getBlockFrequency(*I);
+    BlockFrequency Freq = BlockFrequencies[*I];
     if (Strong)
       Freq += Freq;
     unsigned ib = bundles->getBundle(*I, 0);
     unsigned ob = bundles->getBundle(*I, 1);
     activate(ib);
     activate(ob);
-    nodes[ib].addBias(-Freq, 1);
-    nodes[ob].addBias(-Freq, 0);
+    nodes[ib].addBias(Freq, PrefSpill);
+    nodes[ob].addBias(Freq, PrefSpill);
   }
 }
 
@@ -284,9 +281,9 @@ void SpillPlacement::addLinks(ArrayRef<unsigned> Links) {
       Linked.push_back(ib);
     if (nodes[ob].Links.empty() && !nodes[ob].mustSpill())
       Linked.push_back(ob);
-    float Freq = getBlockFrequency(Number);
-    nodes[ib].addLink(ob, Freq, 1);
-    nodes[ob].addLink(ib, Freq, 0);
+    BlockFrequency Freq = BlockFrequencies[Number];
+    nodes[ib].addLink(ob, Freq);
+    nodes[ob].addLink(ib, Freq);
   }
 }