Merge clang, llvm, lld, lldb, compiler-rt and libc++ 5.0.0 release.

MFC r309126 (by emaste):

  Correct lld llvm-tblgen dependency file name

MFC r309169:

  Get rid of separate Subversion mergeinfo properties for llvm-dwarfdump
  and llvm-lto.  The mergeinfo confuses Subversion enormously, and these
  directories will just use the mergeinfo for llvm itself.

MFC r312765:

  Pull in r276136 from upstream llvm trunk (by Wei Mi):

    Use ValueOffsetPair to enhance value reuse during SCEV expansion.

    In D12090, the ExprValueMap was added to reuse existing value during
    SCEV expansion. However, const folding and sext/zext distribution can
    make the reuse still difficult.

    A simplified case is: suppose we know S1 expands to V1 in
    ExprValueMap, and
      S1 = S2 + C_a
      S3 = S2 + C_b
    where C_a and C_b are different SCEVConstants. Then we'd like to
    expand S3 as V1 - C_a + C_b instead of expanding S2 literally. It is
    helpful when S2 is a complex SCEV expr and S2 has no entry in
    ExprValueMap, which is usually caused by the fact that S3 is
    generated from S1 after const folding.

    In order to do that, we represent ExprValueMap as a mapping from SCEV
    to ValueOffsetPair. We will save both S1->{V1, 0} and S2->{V1, C_a}
    into the ExprValueMap when we create SCEV for V1. When S3 is
    expanded, it will first expand S2 to V1 - C_a because of S2->{V1,
    C_a} in the map, then expand S3 to V1 - C_a + C_b.

    Differential Revision: https://reviews.llvm.org/D21313

  This should fix assertion failures when building OpenCV >= 3.1.

  PR:		215649

MFC r312831:

  Revert r312765 for now, since it causes assertions when building
  lang/spidermonkey24.

  Reported by:	antoine
  PR:		215649

MFC r316511 (by jhb):

  Add an implementation of __ffssi2() derived from __ffsdi2().

  Newer versions of GCC include an __ffssi2() symbol in libgcc and the
  compiler can emit calls to it in generated code.  This is true for at
  least GCC 6.2 when compiling world for mips and mips64.

  Reviewed by:	jmallett, dim
  Sponsored by:	DARPA / AFRL
  Differential Revision:	https://reviews.freebsd.org/D10086

MFC r318601 (by adrian):

  [libcompiler-rt] add bswapdi2/bswapsi2

  This is required for mips gcc 6.3 userland to build/run.

  Reviewed by:	emaste, dim
  Approved by:	emaste
  Differential Revision:	https://reviews.freebsd.org/D10838

MFC r318884 (by emaste):

  lldb: map TRAP_CAP to a trace trap

  In the absense of a more specific handler for TRAP_CAP (generated by
  ENOTCAPABLE or ECAPMODE while in capability mode) treat it as a trace
  trap.

  Example usage (testing the bug in PR219173):

  % proccontrol -m trapcap lldb usr.bin/hexdump/obj/hexdump -- -Cv -s 1 /bin/ls
  ...
  (lldb) run
  Process 12980 launching
  Process 12980 launched: '.../usr.bin/hexdump/obj/hexdump' (x86_64)
  Process 12980 stopped
  * thread #1, stop reason = trace
      frame #0: 0x0000004b80c65f1a libc.so.7`__sys_lseek + 10
  ...

  In the future we should have LLDB control the trapcap procctl itself
  (as it does with ASLR), as well as report a specific stop reason.
  This change eliminates an assertion failure from LLDB for now.

MFC r319796:

  Remove a few unneeded files from libllvm, libclang and liblldb.

MFC r319885 (by emaste):

  lld: ELF: Fix ICF crash on absolute symbol relocations.

  If two sections contained relocations to absolute symbols with the same
  value we would crash when trying to access their sections. Add a check that
  both symbols point to sections before accessing their sections, and treat
  absolute symbols as equal if their values are equal.

  Obtained from:	LLD commit r292578

MFC r319918:

  Revert r319796 for now, it can cause undefined references when linking
  in some circumstances.

  Reported by:	Shawn Webb <shawn.webb@hardenedbsd.org>

MFC r319957 (by emaste):

  lld: Add armelf emulation mode

  Obtained from:	LLD r305375

MFC r321369:

  Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
  5.0.0 (trunk r308421).  Upstream has branched for the 5.0.0 release,
  which should be in about a month.  Please report bugs and regressions,
  so we can get them into the release.

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

MFC r321420:

  Add a few more object files to liblldb, which should solve errors when
  linking the lldb executable in some cases.  In particular, when the
  -ffunction-sections -fdata-sections options are turned off, or
  ineffective.

  Reported by:	Shawn Webb, Mark Millard

MFC r321433:

  Cleanup stale Options.inc files from the previous libllvm build for
  clang 4.0.0.  Otherwise, these can get included before the two newly
  generated ones (which are different) for clang 5.0.0.

  Reported by:	Mark Millard

MFC r321439 (by bdrewery):

  Move llvm Options.inc hack from r321433 for NO_CLEAN to lib/clang/libllvm.

  The files are only ever generated to .OBJDIR, not to WORLDTMP (as a
  sysroot) and are only ever included from a compilation.  So using
  a beforebuild target here removes the file before the compilation
  tries to include it.

MFC r321664:

  Pull in r308891 from upstream llvm trunk (by Benjamin Kramer):

    [CodeGenPrepare] Cut off FindAllMemoryUses if there are too many uses.

    This avoids excessive compile time. The case I'm looking at is
    Function.cpp from an old version of LLVM that still had the giant
    memcmp string matcher in it. Before r308322 this compiled in about 2
    minutes, after it, clang takes infinite* time to compile it. With
    this patch we're at 5 min, which is still bad but this is a
    pathological case.

    The cut off at 20 uses was chosen by looking at other cut-offs in LLVM
    for user scanning. It's probably too high, but does the job and is
    very unlikely to regress anything.

    Fixes PR33900.

    * I'm impatient and aborted after 15 minutes, on the bug report it was
      killed after 2h.

  Pull in r308986 from upstream llvm trunk (by Simon Pilgrim):

    [X86][CGP] Reduce memcmp() expansion to 2 load pairs (PR33914)

    D35067/rL308322 attempted to support up to 4 load pairs for memcmp
    inlining which resulted in regressions for some optimized libc memcmp
    implementations (PR33914).

    Until we can match these more optimal cases, this patch reduces the
    memcmp expansion to a maximum of 2 load pairs (which matches what we
    do for -Os).

    This patch should be considered for the 5.0.0 release branch as well

    Differential Revision: https://reviews.llvm.org/D35830

  These fix a hang (or extremely long compile time) when building older
  LLVM ports.

  Reported by:    antoine
  PR:             219139

MFC r321719:

  Pull in r309503 from upstream clang trunk (by Richard Smith):

    PR33902: Invalidate line number cache when adding more text to
    existing buffer.

    This led to crashes as the line number cache would report a bogus
    line number for a line of code, and we'd try to find a nonexistent
    column within the line when printing diagnostics.

  This fixes an assertion when building the graphics/champlain port.

  Reported by:	antoine, kwm
  PR:		219139

MFC r321723:

  Upgrade our copies of clang, llvm, lld and lldb to r309439 from the
  upstream release_50 branch.  This is just after upstream's 5.0.0-rc1.

MFC r322320:

  Upgrade our copies of clang, llvm and libc++ to r310316 from the
  upstream release_50 branch.

MFC r322326 (by emaste):

  lldb: Make i386-*-freebsd expression work on JIT path

  * Enable i386 ABI creation for freebsd
  * Added an extra argument in ABISysV_i386::PrepareTrivialCall for mmap
    syscall
  * Unlike linux, the last argument of mmap is actually 64-bit(off_t).
    This requires us to push an additional word for the higher order bits.
  * Prior to this change, ktrace dump will show mmap failures due to
    invalid argument coming from the 6th mmap argument.

  Submitted by:	Karnajit Wangkhem
  Differential Revision:	https://reviews.llvm.org/D34776

MFC r322360 (by emaste):

  lldb: Report inferior signals as signals, not exceptions, on FreeBSD

  This is the FreeBSD equivalent of LLVM r238549.

  This serves 2 purposes:

  * LLDB should handle inferior process signals SIGSEGV/SIGILL/SIGBUS/
    SIGFPE the way it is suppose to be handled. Prior to this fix these
    signals will neither create a coredump, nor exit from the debugger
    or work for signal handling scenario.
  * eInvalidCrashReason need not report "unknown crash reason" if we have
    a valid si_signo

  llvm.org/pr23699

  Patch by Karnajit Wangkhem

  Differential Revision:  https://reviews.llvm.org/D35223

  Submitted by:	Karnajit Wangkhem
  Obtained from:	LLVM r310591

MFC r322474 (by emaste):

  lld: Add `-z muldefs` option.

  Obtained from:	LLVM r310757

MFC r322740:

  Upgrade our copies of clang, llvm, lld and libc++ to r311219 from the
  upstream release_50 branch.

MFC r322855:

  Upgrade our copies of clang, llvm, lldb and compiler-rt to r311606 from
  the upstream release_50 branch.

  As of this version, lib/msun's trig test should also work correctly
  again (see bug 220989 for more information).

  PR:		220989

MFC r323112:

  Upgrade our copies of clang, llvm, lldb and compiler-rt to r312293 from
  the upstream release_50 branch.  This corresponds to 5.0.0 rc4.

  As of this version, the cad/stepcode port should now compile in a more
  reasonable time on i386 (see bug 221836 for more information).

  PR:		221836

MFC r323245:

  Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
  5.0.0 release (upstream r312559).

  Release notes for llvm, clang and lld will be available here soon:
  <http://releases.llvm.org/5.0.0/docs/ReleaseNotes.html>
  <http://releases.llvm.org/5.0.0/tools/clang/docs/ReleaseNotes.html>
  <http://releases.llvm.org/5.0.0/tools/lld/docs/ReleaseNotes.html>

  Relnotes:	yes

(cherry picked from commit 12cd91cf4c6b96a24427c0de5374916f2808d263)

1 files changed, 283 insertions, 218 deletions

diff --git a/contrib/llvm/lib/CodeGen/ScheduleDAG.cpp b/contrib/llvm/lib/CodeGen/ScheduleDAG.cpp
index 427d952..5e95f76 100644
--- a/contrib/llvm/lib/CodeGen/ScheduleDAG.cpp
+++ b/contrib/llvm/lib/CodeGen/ScheduleDAG.cpp
@@ -1,4 +1,4 @@
-//===---- ScheduleDAG.cpp - Implement the ScheduleDAG class ---------------===//
+//===- ScheduleDAG.cpp - Implement the ScheduleDAG class ------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -7,22 +7,32 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This implements the ScheduleDAG class, which is a base class used by
-// scheduling implementation classes.
+/// \file Implements the ScheduleDAG class, which is a base class used by
+/// scheduling implementation classes.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/ScheduleDAG.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/ScheduleHazardRecognizer.h"
 #include "llvm/CodeGen/SelectionDAGNodes.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetSubtargetInfo.h"
-#include <climits>
+#include <algorithm>
+#include <cassert>
+#include <iterator>
+#include <limits>
+#include <utility>
+#include <vector>
+
 using namespace llvm;
 
 #define DEBUG_TYPE "pre-RA-sched"
@@ -33,58 +43,87 @@ static cl::opt<bool> StressSchedOpt(
   cl::desc("Stress test instruction scheduling"));
 #endif
 
-void SchedulingPriorityQueue::anchor() { }
+void SchedulingPriorityQueue::anchor() {}
 
 ScheduleDAG::ScheduleDAG(MachineFunction &mf)
     : TM(mf.getTarget()), TII(mf.getSubtarget().getInstrInfo()),
       TRI(mf.getSubtarget().getRegisterInfo()), MF(mf),
-      MRI(mf.getRegInfo()), EntrySU(), ExitSU() {
+      MRI(mf.getRegInfo()) {
 #ifndef NDEBUG
   StressSched = StressSchedOpt;
 #endif
 }
 
-ScheduleDAG::~ScheduleDAG() {}
+ScheduleDAG::~ScheduleDAG() = default;
 
-/// Clear the DAG state (e.g. between scheduling regions).
 void ScheduleDAG::clearDAG() {
   SUnits.clear();
   EntrySU = SUnit();
   ExitSU = SUnit();
 }
 
-/// getInstrDesc helper to handle SDNodes.
 const MCInstrDesc *ScheduleDAG::getNodeDesc(const SDNode *Node) const {
   if (!Node || !Node->isMachineOpcode()) return nullptr;
   return &TII->get(Node->getMachineOpcode());
 }
 
-/// addPred - This adds the specified edge as a pred of the current node if
-/// not already.  It also adds the current node as a successor of the
-/// specified node.
+LLVM_DUMP_METHOD
+raw_ostream &SDep::print(raw_ostream &OS, const TargetRegisterInfo *TRI) const {
+  switch (getKind()) {
+  case Data:   OS << "Data"; break;
+  case Anti:   OS << "Anti"; break;
+  case Output: OS << "Out "; break;
+  case Order:  OS << "Ord "; break;
+  }
+
+  switch (getKind()) {
+  case Data:
+    OS << " Latency=" << getLatency();
+    if (TRI && isAssignedRegDep())
+      OS << " Reg=" << PrintReg(getReg(), TRI);
+    break;
+  case Anti:
+  case Output:
+    OS << " Latency=" << getLatency();
+    break;
+  case Order:
+    OS << " Latency=" << getLatency();
+    switch(Contents.OrdKind) {
+    case Barrier:      OS << " Barrier"; break;
+    case MayAliasMem:
+    case MustAliasMem: OS << " Memory"; break;
+    case Artificial:   OS << " Artificial"; break;
+    case Weak:         OS << " Weak"; break;
+    case Cluster:      OS << " Cluster"; break;
+    }
+    break;
+  }
+
+  return OS;
+}
+
 bool SUnit::addPred(const SDep &D, bool Required) {
   // If this node already has this dependence, don't add a redundant one.
-  for (SmallVectorImpl<SDep>::iterator I = Preds.begin(), E = Preds.end();
-         I != E; ++I) {
+  for (SDep &PredDep : Preds) {
     // Zero-latency weak edges may be added purely for heuristic ordering. Don't
     // add them if another kind of edge already exists.
-    if (!Required && I->getSUnit() == D.getSUnit())
+    if (!Required && PredDep.getSUnit() == D.getSUnit())
       return false;
-    if (I->overlaps(D)) {
-      // Extend the latency if needed. Equivalent to removePred(I) + addPred(D).
-      if (I->getLatency() < D.getLatency()) {
-        SUnit *PredSU = I->getSUnit();
+    if (PredDep.overlaps(D)) {
+      // Extend the latency if needed. Equivalent to
+      // removePred(PredDep) + addPred(D).
+      if (PredDep.getLatency() < D.getLatency()) {
+        SUnit *PredSU = PredDep.getSUnit();
         // Find the corresponding successor in N.
-        SDep ForwardD = *I;
+        SDep ForwardD = PredDep;
         ForwardD.setSUnit(this);
-        for (SmallVectorImpl<SDep>::iterator II = PredSU->Succs.begin(),
-               EE = PredSU->Succs.end(); II != EE; ++II) {
-          if (*II == ForwardD) {
-            II->setLatency(D.getLatency());
+        for (SDep &SuccDep : PredSU->Succs) {
+          if (SuccDep == ForwardD) {
+            SuccDep.setLatency(D.getLatency());
             break;
           }
         }
-        I->setLatency(D.getLatency());
+        PredDep.setLatency(D.getLatency());
       }
       return false;
     }
@@ -95,8 +134,10 @@ bool SUnit::addPred(const SDep &D, bool Required) {
   SUnit *N = D.getSUnit();
   // Update the bookkeeping.
   if (D.getKind() == SDep::Data) {
-    assert(NumPreds < UINT_MAX && "NumPreds will overflow!");
-    assert(N->NumSuccs < UINT_MAX && "NumSuccs will overflow!");
+    assert(NumPreds < std::numeric_limits<unsigned>::max() &&
+           "NumPreds will overflow!");
+    assert(N->NumSuccs < std::numeric_limits<unsigned>::max() &&
+           "NumSuccs will overflow!");
     ++NumPreds;
     ++N->NumSuccs;
   }
@@ -105,7 +146,8 @@ bool SUnit::addPred(const SDep &D, bool Required) {
       ++WeakPredsLeft;
     }
     else {
-      assert(NumPredsLeft < UINT_MAX && "NumPredsLeft will overflow!");
+      assert(NumPredsLeft < std::numeric_limits<unsigned>::max() &&
+             "NumPredsLeft will overflow!");
       ++NumPredsLeft;
     }
   }
@@ -114,7 +156,8 @@ bool SUnit::addPred(const SDep &D, bool Required) {
       ++N->WeakSuccsLeft;
     }
     else {
-      assert(N->NumSuccsLeft < UINT_MAX && "NumSuccsLeft will overflow!");
+      assert(N->NumSuccsLeft < std::numeric_limits<unsigned>::max() &&
+             "NumSuccsLeft will overflow!");
       ++N->NumSuccsLeft;
     }
   }
@@ -127,51 +170,46 @@ bool SUnit::addPred(const SDep &D, bool Required) {
   return true;
 }
 
-/// removePred - This removes the specified edge as a pred of the current
-/// node if it exists.  It also removes the current node as a successor of
-/// the specified node.
 void SUnit::removePred(const SDep &D) {
   // Find the matching predecessor.
-  for (SmallVectorImpl<SDep>::iterator I = Preds.begin(), E = Preds.end();
-         I != E; ++I)
-    if (*I == D) {
-      // Find the corresponding successor in N.
-      SDep P = D;
-      P.setSUnit(this);
-      SUnit *N = D.getSUnit();
-      SmallVectorImpl<SDep>::iterator Succ = find(N->Succs, P);
-      assert(Succ != N->Succs.end() && "Mismatching preds / succs lists!");
-      N->Succs.erase(Succ);
-      Preds.erase(I);
-      // Update the bookkeeping.
-      if (P.getKind() == SDep::Data) {
-        assert(NumPreds > 0 && "NumPreds will underflow!");
-        assert(N->NumSuccs > 0 && "NumSuccs will underflow!");
-        --NumPreds;
-        --N->NumSuccs;
-      }
-      if (!N->isScheduled) {
-        if (D.isWeak())
-          --WeakPredsLeft;
-        else {
-          assert(NumPredsLeft > 0 && "NumPredsLeft will underflow!");
-          --NumPredsLeft;
-        }
-      }
-      if (!isScheduled) {
-        if (D.isWeak())
-          --N->WeakSuccsLeft;
-        else {
-          assert(N->NumSuccsLeft > 0 && "NumSuccsLeft will underflow!");
-          --N->NumSuccsLeft;
-        }
-      }
-      if (P.getLatency() != 0) {
-        this->setDepthDirty();
-        N->setHeightDirty();
-      }
-      return;
+  SmallVectorImpl<SDep>::iterator I = llvm::find(Preds, D);
+  if (I == Preds.end())
+    return;
+  // Find the corresponding successor in N.
+  SDep P = D;
+  P.setSUnit(this);
+  SUnit *N = D.getSUnit();
+  SmallVectorImpl<SDep>::iterator Succ = llvm::find(N->Succs, P);
+  assert(Succ != N->Succs.end() && "Mismatching preds / succs lists!");
+  N->Succs.erase(Succ);
+  Preds.erase(I);
+  // Update the bookkeeping.
+  if (P.getKind() == SDep::Data) {
+    assert(NumPreds > 0 && "NumPreds will underflow!");
+    assert(N->NumSuccs > 0 && "NumSuccs will underflow!");
+    --NumPreds;
+    --N->NumSuccs;
+  }
+  if (!N->isScheduled) {
+    if (D.isWeak())
+      --WeakPredsLeft;
+    else {
+      assert(NumPredsLeft > 0 && "NumPredsLeft will underflow!");
+      --NumPredsLeft;
     }
+  }
+  if (!isScheduled) {
+    if (D.isWeak())
+      --N->WeakSuccsLeft;
+    else {
+      assert(N->NumSuccsLeft > 0 && "NumSuccsLeft will underflow!");
+      --N->NumSuccsLeft;
+    }
+  }
+  if (P.getLatency() != 0) {
+    this->setDepthDirty();
+    N->setHeightDirty();
+  }
 }
 
 void SUnit::setDepthDirty() {
@@ -181,9 +219,8 @@ void SUnit::setDepthDirty() {
   do {
     SUnit *SU = WorkList.pop_back_val();
     SU->isDepthCurrent = false;
-    for (SUnit::const_succ_iterator I = SU->Succs.begin(),
-         E = SU->Succs.end(); I != E; ++I) {
-      SUnit *SuccSU = I->getSUnit();
+    for (SDep &SuccDep : SU->Succs) {
+      SUnit *SuccSU = SuccDep.getSUnit();
       if (SuccSU->isDepthCurrent)
         WorkList.push_back(SuccSU);
     }
@@ -197,18 +234,14 @@ void SUnit::setHeightDirty() {
   do {
     SUnit *SU = WorkList.pop_back_val();
     SU->isHeightCurrent = false;
-    for (SUnit::const_pred_iterator I = SU->Preds.begin(),
-         E = SU->Preds.end(); I != E; ++I) {
-      SUnit *PredSU = I->getSUnit();
+    for (SDep &PredDep : SU->Preds) {
+      SUnit *PredSU = PredDep.getSUnit();
       if (PredSU->isHeightCurrent)
         WorkList.push_back(PredSU);
     }
   } while (!WorkList.empty());
 }
 
-/// setDepthToAtLeast - Update this node's successors to reflect the
-/// fact that this node's depth just increased.
-///
 void SUnit::setDepthToAtLeast(unsigned NewDepth) {
   if (NewDepth <= getDepth())
     return;
@@ -217,9 +250,6 @@ void SUnit::setDepthToAtLeast(unsigned NewDepth) {
   isDepthCurrent = true;
 }
 
-/// setHeightToAtLeast - Update this node's predecessors to reflect the
-/// fact that this node's height just increased.
-///
 void SUnit::setHeightToAtLeast(unsigned NewHeight) {
   if (NewHeight <= getHeight())
     return;
@@ -228,8 +258,7 @@ void SUnit::setHeightToAtLeast(unsigned NewHeight) {
   isHeightCurrent = true;
 }
 
-/// ComputeDepth - Calculate the maximal path from the node to the exit.
-///
+/// Calculates the maximal path from the node to the exit.
 void SUnit::ComputeDepth() {
   SmallVector<SUnit*, 8> WorkList;
   WorkList.push_back(this);
@@ -238,12 +267,11 @@ void SUnit::ComputeDepth() {
 
     bool Done = true;
     unsigned MaxPredDepth = 0;
-    for (SUnit::const_pred_iterator I = Cur->Preds.begin(),
-         E = Cur->Preds.end(); I != E; ++I) {
-      SUnit *PredSU = I->getSUnit();
+    for (const SDep &PredDep : Cur->Preds) {
+      SUnit *PredSU = PredDep.getSUnit();
       if (PredSU->isDepthCurrent)
         MaxPredDepth = std::max(MaxPredDepth,
-                                PredSU->Depth + I->getLatency());
+                                PredSU->Depth + PredDep.getLatency());
       else {
         Done = false;
         WorkList.push_back(PredSU);
@@ -261,8 +289,7 @@ void SUnit::ComputeDepth() {
   } while (!WorkList.empty());
 }
 
-/// ComputeHeight - Calculate the maximal path from the node to the entry.
-///
+/// Calculates the maximal path from the node to the entry.
 void SUnit::ComputeHeight() {
   SmallVector<SUnit*, 8> WorkList;
   WorkList.push_back(this);
@@ -271,12 +298,11 @@ void SUnit::ComputeHeight() {
 
     bool Done = true;
     unsigned MaxSuccHeight = 0;
-    for (SUnit::const_succ_iterator I = Cur->Succs.begin(),
-         E = Cur->Succs.end(); I != E; ++I) {
-      SUnit *SuccSU = I->getSUnit();
+    for (const SDep &SuccDep : Cur->Succs) {
+      SUnit *SuccSU = SuccDep.getSUnit();
       if (SuccSU->isHeightCurrent)
         MaxSuccHeight = std::max(MaxSuccHeight,
-                                 SuccSU->Height + I->getLatency());
+                                 SuccSU->Height + SuccDep.getLatency());
       else {
         Done = false;
         WorkList.push_back(SuccSU);
@@ -310,24 +336,31 @@ void SUnit::biasCriticalPath() {
 }
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-void SUnit::print(raw_ostream &OS, const ScheduleDAG *DAG) const {
-  if (this == &DAG->ExitSU)
-    OS << "ExitSU";
-  else if (this == &DAG->EntrySU)
+LLVM_DUMP_METHOD
+raw_ostream &SUnit::print(raw_ostream &OS,
+                          const SUnit *Entry, const SUnit *Exit) const {
+  if (this == Entry)
     OS << "EntrySU";
+  else if (this == Exit)
+    OS << "ExitSU";
   else
     OS << "SU(" << NodeNum << ")";
+  return OS;
+}
+
+LLVM_DUMP_METHOD
+raw_ostream &SUnit::print(raw_ostream &OS, const ScheduleDAG *G) const {
+  return print(OS, &G->EntrySU, &G->ExitSU);
 }
 
-/// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
-/// a group of nodes flagged together.
+LLVM_DUMP_METHOD
 void SUnit::dump(const ScheduleDAG *G) const {
   print(dbgs(), G);
   dbgs() << ": ";
   G->dumpNode(this);
 }
 
-void SUnit::dumpAll(const ScheduleDAG *G) const {
+LLVM_DUMP_METHOD void SUnit::dumpAll(const ScheduleDAG *G) const {
   dump(G);
 
   dbgs() << "  # preds left       : " << NumPredsLeft << "\n";
@@ -343,89 +376,62 @@ void SUnit::dumpAll(const ScheduleDAG *G) const {
 
   if (Preds.size() != 0) {
     dbgs() << "  Predecessors:\n";
-    for (SUnit::const_succ_iterator I = Preds.begin(), E = Preds.end();
-         I != E; ++I) {
-      dbgs() << "   ";
-      switch (I->getKind()) {
-      case SDep::Data:   dbgs() << "data "; break;
-      case SDep::Anti:   dbgs() << "anti "; break;
-      case SDep::Output: dbgs() << "out  "; break;
-      case SDep::Order:  dbgs() << "ord  "; break;
-      }
-      I->getSUnit()->print(dbgs(), G);
-      if (I->isArtificial())
-        dbgs() << " *";
-      dbgs() << ": Latency=" << I->getLatency();
-      if (I->isAssignedRegDep())
-        dbgs() << " Reg=" << PrintReg(I->getReg(), G->TRI);
-      dbgs() << "\n";
+    for (const SDep &Dep : Preds) {
+      dbgs() << "    ";
+      Dep.getSUnit()->print(dbgs(), G); dbgs() << ": ";
+      Dep.print(dbgs(), G->TRI); dbgs() << '\n';
     }
   }
   if (Succs.size() != 0) {
     dbgs() << "  Successors:\n";
-    for (SUnit::const_succ_iterator I = Succs.begin(), E = Succs.end();
-         I != E; ++I) {
-      dbgs() << "   ";
-      switch (I->getKind()) {
-      case SDep::Data:   dbgs() << "data "; break;
-      case SDep::Anti:   dbgs() << "anti "; break;
-      case SDep::Output: dbgs() << "out  "; break;
-      case SDep::Order:  dbgs() << "ord  "; break;
-      }
-      I->getSUnit()->print(dbgs(), G);
-      if (I->isArtificial())
-        dbgs() << " *";
-      dbgs() << ": Latency=" << I->getLatency();
-      if (I->isAssignedRegDep())
-        dbgs() << " Reg=" << PrintReg(I->getReg(), G->TRI);
-      dbgs() << "\n";
+    for (const SDep &Dep : Succs) {
+      dbgs() << "    ";
+      Dep.getSUnit()->print(dbgs(), G); dbgs() << ": ";
+      Dep.print(dbgs(), G->TRI); dbgs() << '\n';
     }
   }
 }
 #endif
 
 #ifndef NDEBUG
-/// VerifyScheduledDAG - Verify that all SUnits were scheduled and that
-/// their state is consistent. Return the number of scheduled nodes.
-///
 unsigned ScheduleDAG::VerifyScheduledDAG(bool isBottomUp) {
   bool AnyNotSched = false;
   unsigned DeadNodes = 0;
-  for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
-    if (!SUnits[i].isScheduled) {
-      if (SUnits[i].NumPreds == 0 && SUnits[i].NumSuccs == 0) {
+  for (const SUnit &SUnit : SUnits) {
+    if (!SUnit.isScheduled) {
+      if (SUnit.NumPreds == 0 && SUnit.NumSuccs == 0) {
         ++DeadNodes;
         continue;
       }
       if (!AnyNotSched)
         dbgs() << "*** Scheduling failed! ***\n";
-      SUnits[i].dump(this);
+      SUnit.dump(this);
       dbgs() << "has not been scheduled!\n";
       AnyNotSched = true;
     }
-    if (SUnits[i].isScheduled &&
-        (isBottomUp ? SUnits[i].getHeight() : SUnits[i].getDepth()) >
-          unsigned(INT_MAX)) {
+    if (SUnit.isScheduled &&
+        (isBottomUp ? SUnit.getHeight() : SUnit.getDepth()) >
+          unsigned(std::numeric_limits<int>::max())) {
       if (!AnyNotSched)
         dbgs() << "*** Scheduling failed! ***\n";
-      SUnits[i].dump(this);
+      SUnit.dump(this);
       dbgs() << "has an unexpected "
            << (isBottomUp ? "Height" : "Depth") << " value!\n";
       AnyNotSched = true;
     }
     if (isBottomUp) {
-      if (SUnits[i].NumSuccsLeft != 0) {
+      if (SUnit.NumSuccsLeft != 0) {
         if (!AnyNotSched)
           dbgs() << "*** Scheduling failed! ***\n";
-        SUnits[i].dump(this);
+        SUnit.dump(this);
         dbgs() << "has successors left!\n";
         AnyNotSched = true;
       }
     } else {
-      if (SUnits[i].NumPredsLeft != 0) {
+      if (SUnit.NumPredsLeft != 0) {
         if (!AnyNotSched)
           dbgs() << "*** Scheduling failed! ***\n";
-        SUnits[i].dump(this);
+        SUnit.dump(this);
         dbgs() << "has predecessors left!\n";
         AnyNotSched = true;
       }
@@ -436,36 +442,33 @@ unsigned ScheduleDAG::VerifyScheduledDAG(bool isBottomUp) {
 }
 #endif
 
-/// InitDAGTopologicalSorting - create the initial topological
-/// ordering from the DAG to be scheduled.
-///
-/// The idea of the algorithm is taken from
-/// "Online algorithms for managing the topological order of
-/// a directed acyclic graph" by David J. Pearce and Paul H.J. Kelly
-/// This is the MNR algorithm, which was first introduced by
-/// A. Marchetti-Spaccamela, U. Nanni and H. Rohnert in
-/// "Maintaining a topological order under edge insertions".
-///
-/// Short description of the algorithm:
-///
-/// Topological ordering, ord, of a DAG maps each node to a topological
-/// index so that for all edges X->Y it is the case that ord(X) < ord(Y).
-///
-/// This means that if there is a path from the node X to the node Z,
-/// then ord(X) < ord(Z).
-///
-/// This property can be used to check for reachability of nodes:
-/// if Z is reachable from X, then an insertion of the edge Z->X would
-/// create a cycle.
-///
-/// The algorithm first computes a topological ordering for the DAG by
-/// initializing the Index2Node and Node2Index arrays and then tries to keep
-/// the ordering up-to-date after edge insertions by reordering the DAG.
-///
-/// On insertion of the edge X->Y, the algorithm first marks by calling DFS
-/// the nodes reachable from Y, and then shifts them using Shift to lie
-/// immediately after X in Index2Node.
 void ScheduleDAGTopologicalSort::InitDAGTopologicalSorting() {
+  // The idea of the algorithm is taken from
+  // "Online algorithms for managing the topological order of
+  // a directed acyclic graph" by David J. Pearce and Paul H.J. Kelly
+  // This is the MNR algorithm, which was first introduced by
+  // A. Marchetti-Spaccamela, U. Nanni and H. Rohnert in
+  // "Maintaining a topological order under edge insertions".
+  //
+  // Short description of the algorithm:
+  //
+  // Topological ordering, ord, of a DAG maps each node to a topological
+  // index so that for all edges X->Y it is the case that ord(X) < ord(Y).
+  //
+  // This means that if there is a path from the node X to the node Z,
+  // then ord(X) < ord(Z).
+  //
+  // This property can be used to check for reachability of nodes:
+  // if Z is reachable from X, then an insertion of the edge Z->X would
+  // create a cycle.
+  //
+  // The algorithm first computes a topological ordering for the DAG by
+  // initializing the Index2Node and Node2Index arrays and then tries to keep
+  // the ordering up-to-date after edge insertions by reordering the DAG.
+  //
+  // On insertion of the edge X->Y, the algorithm first marks by calling DFS
+  // the nodes reachable from Y, and then shifts them using Shift to lie
+  // immediately after X in Index2Node.
   unsigned DAGSize = SUnits.size();
   std::vector<SUnit*> WorkList;
   WorkList.reserve(DAGSize);
@@ -476,18 +479,17 @@ void ScheduleDAGTopologicalSort::InitDAGTopologicalSorting() {
   // Initialize the data structures.
   if (ExitSU)
     WorkList.push_back(ExitSU);
-  for (unsigned i = 0, e = DAGSize; i != e; ++i) {
-    SUnit *SU = &SUnits[i];
-    int NodeNum = SU->NodeNum;
-    unsigned Degree = SU->Succs.size();
+  for (SUnit &SU : SUnits) {
+    int NodeNum = SU.NodeNum;
+    unsigned Degree = SU.Succs.size();
     // Temporarily use the Node2Index array as scratch space for degree counts.
     Node2Index[NodeNum] = Degree;
 
     // Is it a node without dependencies?
     if (Degree == 0) {
-      assert(SU->Succs.empty() && "SUnit should have no successors");
+      assert(SU.Succs.empty() && "SUnit should have no successors");
       // Collect leaf nodes.
-      WorkList.push_back(SU);
+      WorkList.push_back(&SU);
     }
   }
 
@@ -497,9 +499,8 @@ void ScheduleDAGTopologicalSort::InitDAGTopologicalSorting() {
     WorkList.pop_back();
     if (SU->NodeNum < DAGSize)
       Allocate(SU->NodeNum, --Id);
-    for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
-         I != E; ++I) {
-      SUnit *SU = I->getSUnit();
+    for (const SDep &PredDep : SU->Preds) {
+      SUnit *SU = PredDep.getSUnit();
       if (SU->NodeNum < DAGSize && !--Node2Index[SU->NodeNum])
         // If all dependencies of the node are processed already,
         // then the node can be computed now.
@@ -511,19 +512,15 @@ void ScheduleDAGTopologicalSort::InitDAGTopologicalSorting() {
 
 #ifndef NDEBUG
   // Check correctness of the ordering
-  for (unsigned i = 0, e = DAGSize; i != e; ++i) {
-    SUnit *SU = &SUnits[i];
-    for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
-         I != E; ++I) {
-      assert(Node2Index[SU->NodeNum] > Node2Index[I->getSUnit()->NodeNum] &&
+  for (SUnit &SU : SUnits)  {
+    for (const SDep &PD : SU.Preds) {
+      assert(Node2Index[SU.NodeNum] > Node2Index[PD.getSUnit()->NodeNum] &&
       "Wrong topological sorting");
     }
   }
 #endif
 }
 
-/// AddPred - Updates the topological ordering to accommodate an edge
-/// to be added from SUnit X to SUnit Y.
 void ScheduleDAGTopologicalSort::AddPred(SUnit *Y, SUnit *X) {
   int UpperBound, LowerBound;
   LowerBound = Node2Index[Y->NodeNum];
@@ -540,16 +537,10 @@ void ScheduleDAGTopologicalSort::AddPred(SUnit *Y, SUnit *X) {
   }
 }
 
-/// RemovePred - Updates the topological ordering to accommodate an
-/// an edge to be removed from the specified node N from the predecessors
-/// of the current node M.
 void ScheduleDAGTopologicalSort::RemovePred(SUnit *M, SUnit *N) {
   // InitDAGTopologicalSorting();
 }
 
-/// DFS - Make a DFS traversal to mark all nodes reachable from SU and mark
-/// all nodes affected by the edge insertion. These nodes will later get new
-/// topological indexes by means of the Shift method.
 void ScheduleDAGTopologicalSort::DFS(const SUnit *SU, int UpperBound,
                                      bool &HasLoop) {
   std::vector<const SUnit*> WorkList;
@@ -560,8 +551,9 @@ void ScheduleDAGTopologicalSort::DFS(const SUnit *SU, int UpperBound,
     SU = WorkList.back();
     WorkList.pop_back();
     Visited.set(SU->NodeNum);
-    for (int I = SU->Succs.size()-1; I >= 0; --I) {
-      unsigned s = SU->Succs[I].getSUnit()->NodeNum;
+    for (const SDep &SuccDep
+         : make_range(SU->Succs.rbegin(), SU->Succs.rend())) {
+      unsigned s = SuccDep.getSUnit()->NodeNum;
       // Edges to non-SUnits are allowed but ignored (e.g. ExitSU).
       if (s >= Node2Index.size())
         continue;
@@ -571,14 +563,93 @@ void ScheduleDAGTopologicalSort::DFS(const SUnit *SU, int UpperBound,
       }
       // Visit successors if not already and in affected region.
       if (!Visited.test(s) && Node2Index[s] < UpperBound) {
-        WorkList.push_back(SU->Succs[I].getSUnit());
+        WorkList.push_back(SuccDep.getSUnit());
+      }
+    }
+  } while (!WorkList.empty());
+}
+
+std::vector<int> ScheduleDAGTopologicalSort::GetSubGraph(const SUnit &StartSU,
+                                                         const SUnit &TargetSU,
+                                                         bool &Success) {
+  std::vector<const SUnit*> WorkList;
+  int LowerBound = Node2Index[StartSU.NodeNum];
+  int UpperBound = Node2Index[TargetSU.NodeNum];
+  bool Found = false;
+  BitVector VisitedBack;
+  std::vector<int> Nodes;
+
+  if (LowerBound > UpperBound) {
+    Success = false;
+    return Nodes;
+  }
+
+  WorkList.reserve(SUnits.size());
+  Visited.reset();
+
+  // Starting from StartSU, visit all successors up
+  // to UpperBound.
+  WorkList.push_back(&StartSU);
+  do {
+    const SUnit *SU = WorkList.back();
+    WorkList.pop_back();
+    for (int I = SU->Succs.size()-1; I >= 0; --I) {
+      const SUnit *Succ = SU->Succs[I].getSUnit();
+      unsigned s = Succ->NodeNum;
+      // Edges to non-SUnits are allowed but ignored (e.g. ExitSU).
+      if (Succ->isBoundaryNode())
+        continue;
+      if (Node2Index[s] == UpperBound) {
+        Found = true;
+        continue;
+      }
+      // Visit successors if not already and in affected region.
+      if (!Visited.test(s) && Node2Index[s] < UpperBound) {
+        Visited.set(s);
+        WorkList.push_back(Succ);
+      }
+    }
+  } while (!WorkList.empty());
+
+  if (!Found) {
+    Success = false;
+    return Nodes;
+  }
+
+  WorkList.clear();
+  VisitedBack.resize(SUnits.size());
+  Found = false;
+
+  // Starting from TargetSU, visit all predecessors up
+  // to LowerBound. SUs that are visited by the two
+  // passes are added to Nodes.
+  WorkList.push_back(&TargetSU);
+  do {
+    const SUnit *SU = WorkList.back();
+    WorkList.pop_back();
+    for (int I = SU->Preds.size()-1; I >= 0; --I) {
+      const SUnit *Pred = SU->Preds[I].getSUnit();
+      unsigned s = Pred->NodeNum;
+      // Edges to non-SUnits are allowed but ignored (e.g. EntrySU).
+      if (Pred->isBoundaryNode())
+        continue;
+      if (Node2Index[s] == LowerBound) {
+        Found = true;
+        continue;
+      }
+      if (!VisitedBack.test(s) && Visited.test(s)) {
+        VisitedBack.set(s);
+        WorkList.push_back(Pred);
+        Nodes.push_back(s);
       }
     }
   } while (!WorkList.empty());
+
+  assert(Found && "Error in SUnit Graph!");
+  Success = true;
+  return Nodes;
 }
 
-/// Shift - Renumber the nodes so that the topological ordering is
-/// preserved.
 void ScheduleDAGTopologicalSort::Shift(BitVector& Visited, int LowerBound,
                                        int UpperBound) {
   std::vector<int> L;
@@ -598,28 +669,23 @@ void ScheduleDAGTopologicalSort::Shift(BitVector& Visited, int LowerBound,
     }
   }
 
-  for (unsigned j = 0; j < L.size(); ++j) {
-    Allocate(L[j], i - shift);
+  for (unsigned LI : L) {
+    Allocate(LI, i - shift);
     i = i + 1;
   }
 }
 
-
-/// WillCreateCycle - Returns true if adding an edge to TargetSU from SU will
-/// create a cycle. If so, it is not safe to call AddPred(TargetSU, SU).
 bool ScheduleDAGTopologicalSort::WillCreateCycle(SUnit *TargetSU, SUnit *SU) {
   // Is SU reachable from TargetSU via successor edges?
   if (IsReachable(SU, TargetSU))
     return true;
-  for (SUnit::pred_iterator
-         I = TargetSU->Preds.begin(), E = TargetSU->Preds.end(); I != E; ++I)
-    if (I->isAssignedRegDep() &&
-        IsReachable(SU, I->getSUnit()))
+  for (const SDep &PredDep : TargetSU->Preds)
+    if (PredDep.isAssignedRegDep() &&
+        IsReachable(SU, PredDep.getSUnit()))
       return true;
   return false;
 }
 
-/// IsReachable - Checks if SU is reachable from TargetSU.
 bool ScheduleDAGTopologicalSort::IsReachable(const SUnit *SU,
                                              const SUnit *TargetSU) {
   // If insertion of the edge SU->TargetSU would create a cycle
@@ -637,7 +703,6 @@ bool ScheduleDAGTopologicalSort::IsReachable(const SUnit *SU,
   return HasLoop;
 }
 
-/// Allocate - assign the topological index to the node n.
 void ScheduleDAGTopologicalSort::Allocate(int n, int index) {
   Node2Index[n] = index;
   Index2Node[index] = n;
@@ -647,4 +712,4 @@ ScheduleDAGTopologicalSort::
 ScheduleDAGTopologicalSort(std::vector<SUnit> &sunits, SUnit *exitsu)
   : SUnits(sunits), ExitSU(exitsu) {}
 
-ScheduleHazardRecognizer::~ScheduleHazardRecognizer() {}
+ScheduleHazardRecognizer::~ScheduleHazardRecognizer() = default;