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, 100 insertions, 27 deletions

diff --git a/contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp b/contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp
index 9b0e76f..031f19c 100644
--- a/contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp
+++ b/contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp
@@ -23,6 +23,7 @@
 #define DEBUG_TYPE "execution-fix"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/CodeGen/LiveRegUnits.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/Support/Allocator.h"
@@ -91,7 +92,7 @@ struct DomainValue {
 
   // First domain available.
   unsigned getFirstDomain() const {
-    return CountTrailingZeros_32(AvailableDomains);
+    return countTrailingZeros(AvailableDomains);
   }
 
   DomainValue() : Refs(0) { clear(); }
@@ -136,6 +137,12 @@ class ExeDepsFix : public MachineFunctionPass {
   typedef DenseMap<MachineBasicBlock*, LiveReg*> LiveOutMap;
   LiveOutMap LiveOuts;
 
+  /// List of undefined register reads in this block in forward order.
+  std::vector<std::pair<MachineInstr*, unsigned> > UndefReads;
+
+  /// Storage for register unit liveness.
+  LiveRegUnits LiveUnits;
+
   /// Current instruction number.
   /// The first instruction in each basic block is 0.
   int CurInstr;
@@ -185,6 +192,8 @@ private:
   void processDefs(MachineInstr*, bool Kill);
   void visitSoftInstr(MachineInstr*, unsigned mask);
   void visitHardInstr(MachineInstr*, unsigned domain);
+  bool shouldBreakDependence(MachineInstr*, unsigned OpIdx, unsigned Pref);
+  void processUndefReads(MachineBasicBlock*);
 };
 }
 
@@ -341,6 +350,10 @@ void ExeDepsFix::enterBasicBlock(MachineBasicBlock *MBB) {
   // Reset instruction counter in each basic block.
   CurInstr = 0;
 
+  // Set up UndefReads to track undefined register reads.
+  UndefReads.clear();
+  LiveUnits.clear();
+
   // Set up LiveRegs to represent registers entering MBB.
   if (!LiveRegs)
     LiveRegs = new LiveReg[NumRegs];
@@ -448,10 +461,46 @@ void ExeDepsFix::visitInstr(MachineInstr *MI) {
   processDefs(MI, !DomP.first);
 }
 
+/// \brief Return true to if it makes sense to break dependence on a partial def
+/// or undef use.
+bool ExeDepsFix::shouldBreakDependence(MachineInstr *MI, unsigned OpIdx,
+                                       unsigned Pref) {
+  int rx = regIndex(MI->getOperand(OpIdx).getReg());
+  if (rx < 0)
+    return false;
+
+  unsigned Clearance = CurInstr - LiveRegs[rx].Def;
+  DEBUG(dbgs() << "Clearance: " << Clearance << ", want " << Pref);
+
+  if (Pref > Clearance) {
+    DEBUG(dbgs() << ": Break dependency.\n");
+    return true;
+  }
+  // The current clearance seems OK, but we may be ignoring a def from a
+  // back-edge.
+  if (!SeenUnknownBackEdge || Pref <= unsigned(CurInstr)) {
+    DEBUG(dbgs() << ": OK .\n");
+    return false;
+  }
+  // A def from an unprocessed back-edge may make us break this dependency.
+  DEBUG(dbgs() << ": Wait for back-edge to resolve.\n");
+  return false;
+}
+
 // Update def-ages for registers defined by MI.
 // If Kill is set, also kill off DomainValues clobbered by the defs.
+//
+// Also break dependencies on partial defs and undef uses.
 void ExeDepsFix::processDefs(MachineInstr *MI, bool Kill) {
   assert(!MI->isDebugValue() && "Won't process debug values");
+
+  // Break dependence on undef uses. Do this before updating LiveRegs below.
+  unsigned OpNum;
+  unsigned Pref = TII->getUndefRegClearance(MI, OpNum, TRI);
+  if (Pref) {
+    if (shouldBreakDependence(MI, OpNum, Pref))
+      UndefReads.push_back(std::make_pair(MI, OpNum));
+  }
   const MCInstrDesc &MCID = MI->getDesc();
   for (unsigned i = 0,
          e = MI->isVariadic() ? MI->getNumOperands() : MCID.getNumDefs();
@@ -471,37 +520,58 @@ void ExeDepsFix::processDefs(MachineInstr *MI, bool Kill) {
     DEBUG(dbgs() << TRI->getName(RC->getRegister(rx)) << ":\t" << CurInstr
                  << '\t' << *MI);
 
+    // Check clearance before partial register updates.
+    // Call breakDependence before setting LiveRegs[rx].Def.
+    unsigned Pref = TII->getPartialRegUpdateClearance(MI, i, TRI);
+    if (Pref && shouldBreakDependence(MI, i, Pref))
+      TII->breakPartialRegDependency(MI, i, TRI);
+
     // How many instructions since rx was last written?
-    unsigned Clearance = CurInstr - LiveRegs[rx].Def;
     LiveRegs[rx].Def = CurInstr;
 
     // Kill off domains redefined by generic instructions.
     if (Kill)
       kill(rx);
+  }
+  ++CurInstr;
+}
 
-    // Verify clearance before partial register updates.
-    unsigned Pref = TII->getPartialRegUpdateClearance(MI, i, TRI);
-    if (!Pref)
-      continue;
-    DEBUG(dbgs() << "Clearance: " << Clearance << ", want " << Pref);
-    if (Pref > Clearance) {
-      DEBUG(dbgs() << ": Break dependency.\n");
-      TII->breakPartialRegDependency(MI, i, TRI);
-      continue;
-    }
-
-    // The current clearance seems OK, but we may be ignoring a def from a
-    // back-edge.
-    if (!SeenUnknownBackEdge || Pref <= unsigned(CurInstr)) {
-      DEBUG(dbgs() << ": OK.\n");
-      continue;
-    }
+/// \break Break false dependencies on undefined register reads.
+///
+/// Walk the block backward computing precise liveness. This is expensive, so we
+/// only do it on demand. Note that the occurrence of undefined register reads
+/// that should be broken is very rare, but when they occur we may have many in
+/// a single block.
+void ExeDepsFix::processUndefReads(MachineBasicBlock *MBB) {
+  if (UndefReads.empty())
+    return;
 
-    // A def from an unprocessed back-edge may make us break this dependency.
-    DEBUG(dbgs() << ": Wait for back-edge to resolve.\n");
+  // Collect this block's live out register units.
+  LiveUnits.init(TRI);
+  for (MachineBasicBlock::const_succ_iterator SI = MBB->succ_begin(),
+         SE = MBB->succ_end(); SI != SE; ++SI) {
+    LiveUnits.addLiveIns(*SI, *TRI);
   }
+  MachineInstr *UndefMI = UndefReads.back().first;
+  unsigned OpIdx = UndefReads.back().second;
 
-  ++CurInstr;
+  for (MachineBasicBlock::reverse_iterator I = MBB->rbegin(), E = MBB->rend();
+       I != E; ++I) {
+    // Update liveness, including the current instrucion's defs.
+    LiveUnits.stepBackward(*I, *TRI);
+
+    if (UndefMI == &*I) {
+      if (!LiveUnits.contains(UndefMI->getOperand(OpIdx).getReg(), *TRI))
+        TII->breakPartialRegDependency(UndefMI, OpIdx, TRI);
+
+      UndefReads.pop_back();
+      if (UndefReads.empty())
+        return;
+
+      UndefMI = UndefReads.back().first;
+      OpIdx = UndefReads.back().second;
+    }
+  }
 }
 
 // A hard instruction only works in one domain. All input registers will be
@@ -549,7 +619,7 @@ void ExeDepsFix::visitSoftInstr(MachineInstr *mi, unsigned mask) {
         // Is it possible to use this collapsed register for free?
         if (dv->isCollapsed()) {
           // Restrict available domains to the ones in common with the operand.
-          // If there are no common domains, we must pay the cross-domain 
+          // If there are no common domains, we must pay the cross-domain
           // penalty for this operand.
           if (common) available = common;
         } else if (common)
@@ -564,7 +634,7 @@ void ExeDepsFix::visitSoftInstr(MachineInstr *mi, unsigned mask) {
 
   // If the collapsed operands force a single domain, propagate the collapse.
   if (isPowerOf2_32(available)) {
-    unsigned domain = CountTrailingZeros_32(available);
+    unsigned domain = countTrailingZeros(available);
     TII->setExecutionDomain(mi, domain);
     visitHardInstr(mi, domain);
     return;
@@ -573,7 +643,7 @@ void ExeDepsFix::visitSoftInstr(MachineInstr *mi, unsigned mask) {
   // Kill off any remaining uses that don't match available, and build a list of
   // incoming DomainValues that we want to merge.
   SmallVector<LiveReg, 4> Regs;
-  for (SmallVector<int, 4>::iterator i=used.begin(), e=used.end(); i!=e; ++i) {
+  for (SmallVectorImpl<int>::iterator i=used.begin(), e=used.end(); i!=e; ++i) {
     int rx = *i;
     const LiveReg &LR = LiveRegs[rx];
     // This useless DomainValue could have been missed above.
@@ -583,7 +653,7 @@ void ExeDepsFix::visitSoftInstr(MachineInstr *mi, unsigned mask) {
     }
     // Sorted insertion.
     bool Inserted = false;
-    for (SmallVector<LiveReg, 4>::iterator i = Regs.begin(), e = Regs.end();
+    for (SmallVectorImpl<LiveReg>::iterator i = Regs.begin(), e = Regs.end();
            i != e && !Inserted; ++i) {
       if (LR.Def < i->Def) {
         Inserted = true;
@@ -614,7 +684,7 @@ void ExeDepsFix::visitSoftInstr(MachineInstr *mi, unsigned mask) {
       continue;
 
     // If latest didn't merge, it is useless now. Kill all registers using it.
-    for (SmallVector<int,4>::iterator i=used.begin(), e=used.end(); i != e; ++i)
+    for (SmallVectorImpl<int>::iterator i=used.begin(), e=used.end(); i!=e; ++i)
       if (LiveRegs[*i].Value == Latest)
         kill(*i);
   }
@@ -686,6 +756,7 @@ bool ExeDepsFix::runOnMachineFunction(MachineFunction &mf) {
     for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
         ++I)
       visitInstr(I);
+    processUndefReads(MBB);
     leaveBasicBlock(MBB);
   }
 
@@ -698,6 +769,7 @@ bool ExeDepsFix::runOnMachineFunction(MachineFunction &mf) {
         ++I)
       if (!I->isDebugValue())
         processDefs(I, false);
+    processUndefReads(MBB);
     leaveBasicBlock(MBB);
   }
 
@@ -713,6 +785,7 @@ bool ExeDepsFix::runOnMachineFunction(MachineFunction &mf) {
     delete[] FI->second;
   }
   LiveOuts.clear();
+  UndefReads.clear();
   Avail.clear();
   Allocator.DestroyAll();