Update clang, llvm, lld, lldb, compiler-rt and libc++ to 4.0.0 release:

MFC r309142 (by emaste):

Add WITH_LLD_AS_LD build knob

If set it installs LLD as /usr/bin/ld.  LLD (as of version 3.9) is not
capable of linking the world and kernel, but can self-host and link many
substantial applications. GNU ld continues to be used for the world and
kernel build, regardless of how this knob is set.

It is on by default for arm64, and off for all other CPU architectures.

Sponsored by:	The FreeBSD Foundation

MFC r310840:

Reapply 310775, now it also builds correctly if lldb is disabled:

Move llvm-objdump from CLANG_EXTRAS to installed by default

We currently install three tools from binutils 2.17.50: as, ld, and
objdump. Work is underway to migrate to a permissively-licensed
tool-chain, with one goal being the retirement of binutils 2.17.50.

LLVM's llvm-objdump is intended to be compatible with GNU objdump
although it is currently missing some options and may have formatting
differences. Enable it by default for testing and further investigation.
It may later be changed to install as /usr/bin/objdump, it becomes a
fully viable replacement.

Reviewed by:	emaste
Differential Revision:	https://reviews.freebsd.org/D8879

MFC r312855 (by emaste):

Rename LLD_AS_LD to LLD_IS_LD, for consistency with CLANG_IS_CC

Reported by:	Dan McGregor <dan.mcgregor usask.ca>

MFC r313559 | glebius | 2017-02-10 18:34:48 +0100 (Fri, 10 Feb 2017) | 5 lines

Don't check struct rtentry on FreeBSD, it is an internal kernel structure.
On other systems it may be API structure for SIOCADDRT/SIOCDELRT.

Reviewed by:	emaste, dim

MFC r314152 (by jkim):

Remove an assembler flag, which is redundant since r309124.  The upstream
took care of it by introducing a macro NO_EXEC_STACK_DIRECTIVE.

http://llvm.org/viewvc/llvm-project?rev=273500&view=rev

Reviewed by:	dim

MFC r314564:

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
4.0.0 (branches/release_40 296509).  The release will follow soon.

Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.

Also note that as of 4.0.0, lld should be able to link the base system
on amd64 and aarch64.  See the WITH_LLD_IS_LLD setting in src.conf(5).
Though please be aware that this is work in progress.

Release notes for llvm, clang and lld will be available here:
<http://releases.llvm.org/4.0.0/docs/ReleaseNotes.html>
<http://releases.llvm.org/4.0.0/tools/clang/docs/ReleaseNotes.html>
<http://releases.llvm.org/4.0.0/tools/lld/docs/ReleaseNotes.html>

Thanks to Ed Maste, Jan Beich, Antoine Brodin and Eric Fiselier for
their help.

Relnotes:	yes
Exp-run:	antoine
PR:		215969, 216008

MFC r314708:

For now, revert r287232 from upstream llvm trunk (by Daniil Fukalov):

  [SCEV] limit recursion depth of CompareSCEVComplexity

  Summary:
  CompareSCEVComplexity goes too deep (50+ on a quite a big unrolled
  loop) and runs almost infinite time.

  Added cache of "equal" SCEV pairs to earlier cutoff of further
  estimation. Recursion depth limit was also introduced as a parameter.

  Reviewers: sanjoy

  Subscribers: mzolotukhin, tstellarAMD, llvm-commits

  Differential Revision: https://reviews.llvm.org/D26389

This commit is the cause of excessive compile times on skein_block.c
(and possibly other files) during kernel builds on amd64.

We never saw the problematic behavior described in this upstream commit,
so for now it is better to revert it.  An upstream bug has been filed
here: https://bugs.llvm.org/show_bug.cgi?id=32142

Reported by:	mjg

MFC r314795:

Reapply r287232 from upstream llvm trunk (by Daniil Fukalov):

  [SCEV] limit recursion depth of CompareSCEVComplexity

  Summary:
  CompareSCEVComplexity goes too deep (50+ on a quite a big unrolled
  loop) and runs almost infinite time.

  Added cache of "equal" SCEV pairs to earlier cutoff of further
  estimation. Recursion depth limit was also introduced as a parameter.

  Reviewers: sanjoy

  Subscribers: mzolotukhin, tstellarAMD, llvm-commits

  Differential Revision: https://reviews.llvm.org/D26389

Pull in r296992 from upstream llvm trunk (by Sanjoy Das):

  [SCEV] Decrease the recursion threshold for CompareValueComplexity

  Fixes PR32142.

  r287232 accidentally increased the recursion threshold for
  CompareValueComplexity from 2 to 32.  This change reverses that
  change by introducing a separate flag for CompareValueComplexity's
  threshold.

The latter revision fixes the excessive compile times for skein_block.c.

MFC r314907 | mmel | 2017-03-08 12:40:27 +0100 (Wed, 08 Mar 2017) | 7 lines

Unbreak ARMv6 world.

The new compiler_rt library imported with clang 4.0.0 have several fatal
issues (non-functional __udivsi3 for example) with ARM specific instrict
functions. As temporary workaround, until upstream solve these problems,
disable all thumb[1][2] related feature.

MFC r315016:

Update clang, llvm, lld, lldb, compiler-rt and libc++ to 4.0.0 release.
We were already very close to the last release candidate, so this is a
pretty minor update.

Relnotes:	yes

MFC r316005:

Revert r314907, and pull in r298713 from upstream compiler-rt trunk (by
Weiming Zhao):

  builtins: Select correct code fragments when compiling for Thumb1/Thum2/ARM ISA.

  Summary:
  Value of __ARM_ARCH_ISA_THUMB isn't based on the actual compilation
  mode (-mthumb, -marm), it reflect's capability of given CPU.

  Due to this:
   - use  __tbumb__ and __thumb2__ insteand of __ARM_ARCH_ISA_THUMB
   - use '.thumb' directive consistently  in all affected files
   - decorate all thumb functions using
     DEFINE_COMPILERRT_THUMB_FUNCTION()

  ---------
  Note: This patch doesn't fix broken Thumb1 variant of __udivsi3 !

  Reviewers: weimingz, rengolin, compnerd

  Subscribers: aemerson, dim

  Differential Revision: https://reviews.llvm.org/D30938

Discussed with:	mmel

1 files changed, 72 insertions, 22 deletions

diff --git a/contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp b/contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp
index 566b8d5..32c57e3 100644
--- a/contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp
+++ b/contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp
@@ -26,6 +26,7 @@
 #include "llvm/CodeGen/LivePhysRegs.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RegisterClassInfo.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
@@ -137,6 +138,7 @@ class ExeDepsFix : public MachineFunctionPass {
   MachineFunction *MF;
   const TargetInstrInfo *TII;
   const TargetRegisterInfo *TRI;
+  RegisterClassInfo RegClassInfo;
   std::vector<SmallVector<int, 1>> AliasMap;
   const unsigned NumRegs;
   LiveReg *LiveRegs;
@@ -170,12 +172,10 @@ public:
 
   MachineFunctionProperties getRequiredProperties() const override {
     return MachineFunctionProperties().set(
-        MachineFunctionProperties::Property::AllVRegsAllocated);
+        MachineFunctionProperties::Property::NoVRegs);
   }
 
-  const char *getPassName() const override {
-    return "Execution dependency fix";
-  }
+  StringRef getPassName() const override { return "Execution dependency fix"; }
 
 private:
   iterator_range<SmallVectorImpl<int>::const_iterator>
@@ -203,6 +203,8 @@ private:
   void processDefs(MachineInstr*, bool Kill);
   void visitSoftInstr(MachineInstr*, unsigned mask);
   void visitHardInstr(MachineInstr*, unsigned domain);
+  void pickBestRegisterForUndef(MachineInstr *MI, unsigned OpIdx,
+                                unsigned Pref);
   bool shouldBreakDependence(MachineInstr*, unsigned OpIdx, unsigned Pref);
   void processUndefReads(MachineBasicBlock*);
 };
@@ -473,6 +475,60 @@ void ExeDepsFix::visitInstr(MachineInstr *MI) {
   processDefs(MI, !DomP.first);
 }
 
+/// \brief Helps avoid false dependencies on undef registers by updating the
+/// machine instructions' undef operand to use a register that the instruction
+/// is truly dependent on, or use a register with clearance higher than Pref.
+void ExeDepsFix::pickBestRegisterForUndef(MachineInstr *MI, unsigned OpIdx,
+                                          unsigned Pref) {
+  MachineOperand &MO = MI->getOperand(OpIdx);
+  assert(MO.isUndef() && "Expected undef machine operand");
+
+  unsigned OriginalReg = MO.getReg();
+
+  // Update only undef operands that are mapped to one register.
+  if (AliasMap[OriginalReg].size() != 1)
+    return;
+
+  // Get the undef operand's register class
+  const TargetRegisterClass *OpRC =
+      TII->getRegClass(MI->getDesc(), OpIdx, TRI, *MF);
+
+  // If the instruction has a true dependency, we can hide the false depdency
+  // behind it.
+  for (MachineOperand &CurrMO : MI->operands()) {
+    if (!CurrMO.isReg() || CurrMO.isDef() || CurrMO.isUndef() ||
+        !OpRC->contains(CurrMO.getReg()))
+      continue;
+    // We found a true dependency - replace the undef register with the true
+    // dependency.
+    MO.setReg(CurrMO.getReg());
+    return;
+  }
+
+  // Go over all registers in the register class and find the register with
+  // max clearance or clearance higher than Pref.
+  unsigned MaxClearance = 0;
+  unsigned MaxClearanceReg = OriginalReg;
+  ArrayRef<MCPhysReg> Order = RegClassInfo.getOrder(OpRC);
+  for (auto Reg : Order) {
+    assert(AliasMap[Reg].size() == 1 &&
+           "Reg is expected to be mapped to a single index");
+    int RCrx = *regIndices(Reg).begin();
+    unsigned Clearance = CurInstr - LiveRegs[RCrx].Def;
+    if (Clearance <= MaxClearance)
+      continue;
+    MaxClearance = Clearance;
+    MaxClearanceReg = Reg;
+
+    if (MaxClearance > Pref)
+      break;
+  }
+
+  // Update the operand if we found a register with better clearance.
+  if (MaxClearanceReg != OriginalReg)
+    MO.setReg(MaxClearanceReg);
+}
+
 /// \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,
@@ -510,6 +566,7 @@ void ExeDepsFix::processDefs(MachineInstr *MI, bool Kill) {
   unsigned OpNum;
   unsigned Pref = TII->getUndefRegClearance(*MI, OpNum, TRI);
   if (Pref) {
+    pickBestRegisterForUndef(MI, OpNum, Pref);
     if (shouldBreakDependence(MI, OpNum, Pref))
       UndefReads.push_back(std::make_pair(MI, OpNum));
   }
@@ -520,8 +577,6 @@ void ExeDepsFix::processDefs(MachineInstr *MI, bool Kill) {
     MachineOperand &MO = MI->getOperand(i);
     if (!MO.isReg())
       continue;
-    if (MO.isImplicit())
-      break;
     if (MO.isUse())
       continue;
     for (int rx : regIndices(MO.getReg())) {
@@ -557,7 +612,7 @@ void ExeDepsFix::processUndefReads(MachineBasicBlock *MBB) {
     return;
 
   // Collect this block's live out register units.
-  LiveRegSet.init(TRI);
+  LiveRegSet.init(*TRI);
   // We do not need to care about pristine registers as they are just preserved
   // but not actually used in the function.
   LiveRegSet.addLiveOutsNoPristines(*MBB);
@@ -652,9 +707,8 @@ 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 (SmallVectorImpl<int>::iterator i=used.begin(), e=used.end(); i!=e; ++i) {
-    int rx = *i;
+  SmallVector<const LiveReg *, 4> Regs;
+  for (int rx : used) {
     assert(LiveRegs && "no space allocated for live registers");
     const LiveReg &LR = LiveRegs[rx];
     // This useless DomainValue could have been missed above.
@@ -663,16 +717,11 @@ void ExeDepsFix::visitSoftInstr(MachineInstr *mi, unsigned mask) {
       continue;
     }
     // Sorted insertion.
-    bool Inserted = false;
-    for (SmallVectorImpl<LiveReg>::iterator i = Regs.begin(), e = Regs.end();
-           i != e && !Inserted; ++i) {
-      if (LR.Def < i->Def) {
-        Inserted = true;
-        Regs.insert(i, LR);
-      }
-    }
-    if (!Inserted)
-      Regs.push_back(LR);
+    auto I = std::upper_bound(Regs.begin(), Regs.end(), &LR,
+                              [](const LiveReg *LHS, const LiveReg *RHS) {
+                                return LHS->Def < RHS->Def;
+                              });
+    Regs.insert(I, &LR);
   }
 
   // doms are now sorted in order of appearance. Try to merge them all, giving
@@ -680,14 +729,14 @@ void ExeDepsFix::visitSoftInstr(MachineInstr *mi, unsigned mask) {
   DomainValue *dv = nullptr;
   while (!Regs.empty()) {
     if (!dv) {
-      dv = Regs.pop_back_val().Value;
+      dv = Regs.pop_back_val()->Value;
       // Force the first dv to match the current instruction.
       dv->AvailableDomains = dv->getCommonDomains(available);
       assert(dv->AvailableDomains && "Domain should have been filtered");
       continue;
     }
 
-    DomainValue *Latest = Regs.pop_back_val().Value;
+    DomainValue *Latest = Regs.pop_back_val()->Value;
     // Skip already merged values.
     if (Latest == dv || Latest->Next)
       continue;
@@ -731,6 +780,7 @@ bool ExeDepsFix::runOnMachineFunction(MachineFunction &mf) {
   MF = &mf;
   TII = MF->getSubtarget().getInstrInfo();
   TRI = MF->getSubtarget().getRegisterInfo();
+  RegClassInfo.runOnMachineFunction(mf);
   LiveRegs = nullptr;
   assert(NumRegs == RC->getNumRegs() && "Bad regclass");