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, 598 insertions, 430 deletions

diff --git a/contrib/llvm/lib/IR/Attributes.cpp b/contrib/llvm/lib/IR/Attributes.cpp
index 1ec53cf..8f2e641 100644
--- a/contrib/llvm/lib/IR/Attributes.cpp
+++ b/contrib/llvm/lib/IR/Attributes.cpp
@@ -1,4 +1,4 @@
-//===-- Attributes.cpp - Implement AttributesList -------------------------===//
+//===- Attributes.cpp - Implement AttributesList --------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -9,23 +9,40 @@
 //
 // \file
 // \brief This file implements the Attribute, AttributeImpl, AttrBuilder,
-// AttributeSetImpl, and AttributeSet classes.
+// AttributeListImpl, and AttributeList classes.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/IR/Attributes.h"
-#include "llvm/IR/Function.h"
 #include "AttributeImpl.h"
 #include "LLVMContextImpl.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/FoldingSet.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Type.h"
-#include "llvm/Support/Atomic.h"
+#include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
-#include "llvm/Support/ManagedStatic.h"
-#include "llvm/Support/Mutex.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/MathExtras.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
+#include <cassert>
+#include <climits>
+#include <cstddef>
+#include <cstdint>
+#include <limits>
+#include <map>
+#include <string>
+#include <tuple>
+#include <utility>
+
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//
@@ -300,6 +317,8 @@ std::string Attribute::getAsString(bool InAttrGrp) const {
     return "returns_twice";
   if (hasAttribute(Attribute::SExt))
     return "signext";
+  if (hasAttribute(Attribute::Speculatable))
+    return "speculatable";
   if (hasAttribute(Attribute::StackProtect))
     return "ssp";
   if (hasAttribute(Attribute::StackProtectReq))
@@ -411,9 +430,12 @@ bool Attribute::operator<(Attribute A) const {
 //===----------------------------------------------------------------------===//
 
 // Pin the vtables to this file.
-AttributeImpl::~AttributeImpl() {}
+AttributeImpl::~AttributeImpl() = default;
+
 void EnumAttributeImpl::anchor() {}
+
 void IntAttributeImpl::anchor() {}
+
 void StringAttributeImpl::anchor() {}
 
 bool AttributeImpl::hasAttribute(Attribute::AttrKind A) const {
@@ -473,9 +495,152 @@ bool AttributeImpl::operator<(const AttributeImpl &AI) const {
 }
 
 //===----------------------------------------------------------------------===//
+// AttributeSet Definition
+//===----------------------------------------------------------------------===//
+
+AttributeSet AttributeSet::get(LLVMContext &C, const AttrBuilder &B) {
+  return AttributeSet(AttributeSetNode::get(C, B));
+}
+
+AttributeSet AttributeSet::get(LLVMContext &C, ArrayRef<Attribute> Attrs) {
+  return AttributeSet(AttributeSetNode::get(C, Attrs));
+}
+
+AttributeSet AttributeSet::addAttribute(LLVMContext &C,
+                                        Attribute::AttrKind Kind) const {
+  if (hasAttribute(Kind)) return *this;
+  AttrBuilder B;
+  B.addAttribute(Kind);
+  return addAttributes(C, AttributeSet::get(C, B));
+}
+
+AttributeSet AttributeSet::addAttribute(LLVMContext &C, StringRef Kind,
+                                        StringRef Value) const {
+  AttrBuilder B;
+  B.addAttribute(Kind, Value);
+  return addAttributes(C, AttributeSet::get(C, B));
+}
+
+AttributeSet AttributeSet::addAttributes(LLVMContext &C,
+                                         const AttributeSet AS) const {
+  if (!hasAttributes())
+    return AS;
+
+  if (!AS.hasAttributes())
+    return *this;
+
+  AttrBuilder B(AS);
+  for (Attribute I : *this)
+    B.addAttribute(I);
+
+ return get(C, B);
+}
+
+AttributeSet AttributeSet::removeAttribute(LLVMContext &C,
+                                             Attribute::AttrKind Kind) const {
+  if (!hasAttribute(Kind)) return *this;
+  AttrBuilder B;
+  B.addAttribute(Kind);
+  return removeAttributes(C, B);
+}
+
+AttributeSet AttributeSet::removeAttribute(LLVMContext &C,
+                                             StringRef Kind) const {
+  if (!hasAttribute(Kind)) return *this;
+  AttrBuilder B;
+  B.addAttribute(Kind);
+  return removeAttributes(C, B);
+}
+
+AttributeSet AttributeSet::removeAttributes(LLVMContext &C,
+                                              const AttrBuilder &Attrs) const {
+
+  // FIXME it is not obvious how this should work for alignment.
+  // For now, say we can't pass in alignment, which no current use does.
+  assert(!Attrs.hasAlignmentAttr() && "Attempt to change alignment!");
+
+  AttrBuilder B(*this);
+  B.remove(Attrs);
+  return get(C, B);
+}
+
+unsigned AttributeSet::getNumAttributes() const {
+  return SetNode ? SetNode->getNumAttributes() : 0;
+}
+
+bool AttributeSet::hasAttribute(Attribute::AttrKind Kind) const {
+  return SetNode ? SetNode->hasAttribute(Kind) : false;
+}
+
+bool AttributeSet::hasAttribute(StringRef Kind) const {
+  return SetNode ? SetNode->hasAttribute(Kind) : false;
+}
+
+Attribute AttributeSet::getAttribute(Attribute::AttrKind Kind) const {
+  return SetNode ? SetNode->getAttribute(Kind) : Attribute();
+}
+
+Attribute AttributeSet::getAttribute(StringRef Kind) const {
+  return SetNode ? SetNode->getAttribute(Kind) : Attribute();
+}
+
+unsigned AttributeSet::getAlignment() const {
+  return SetNode ? SetNode->getAlignment() : 0;
+}
+
+unsigned AttributeSet::getStackAlignment() const {
+  return SetNode ? SetNode->getStackAlignment() : 0;
+}
+
+uint64_t AttributeSet::getDereferenceableBytes() const {
+  return SetNode ? SetNode->getDereferenceableBytes() : 0;
+}
+
+uint64_t AttributeSet::getDereferenceableOrNullBytes() const {
+  return SetNode ? SetNode->getDereferenceableOrNullBytes() : 0;
+}
+
+std::pair<unsigned, Optional<unsigned>> AttributeSet::getAllocSizeArgs() const {
+  return SetNode ? SetNode->getAllocSizeArgs()
+                 : std::pair<unsigned, Optional<unsigned>>(0, 0);
+}
+
+std::string AttributeSet::getAsString(bool InAttrGrp) const {
+  return SetNode ? SetNode->getAsString(InAttrGrp) : "";
+}
+
+AttributeSet::iterator AttributeSet::begin() const {
+  return SetNode ? SetNode->begin() : nullptr;
+}
+
+AttributeSet::iterator AttributeSet::end() const {
+  return SetNode ? SetNode->end() : nullptr;
+}
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+LLVM_DUMP_METHOD void AttributeSet::dump() const {
+  dbgs() << "AS =\n";
+    dbgs() << "  { ";
+    dbgs() << getAsString(true) << " }\n";
+}
+#endif
+
+//===----------------------------------------------------------------------===//
 // AttributeSetNode Definition
 //===----------------------------------------------------------------------===//
 
+AttributeSetNode::AttributeSetNode(ArrayRef<Attribute> Attrs)
+    : AvailableAttrs(0), NumAttrs(Attrs.size()) {
+  // There's memory after the node where we can store the entries in.
+  std::copy(Attrs.begin(), Attrs.end(), getTrailingObjects<Attribute>());
+
+  for (Attribute I : *this) {
+    if (!I.isStringAttribute()) {
+      AvailableAttrs |= ((uint64_t)1) << I.getKindAsEnum();
+    }
+  }
+}
+
 AttributeSetNode *AttributeSetNode::get(LLVMContext &C,
                                         ArrayRef<Attribute> Attrs) {
   if (Attrs.empty())
@@ -504,10 +669,52 @@ AttributeSetNode *AttributeSetNode::get(LLVMContext &C,
     pImpl->AttrsSetNodes.InsertNode(PA, InsertPoint);
   }
 
-  // Return the AttributesListNode that we found or created.
+  // Return the AttributeSetNode that we found or created.
   return PA;
 }
 
+AttributeSetNode *AttributeSetNode::get(LLVMContext &C, const AttrBuilder &B) {
+  // Add target-independent attributes.
+  SmallVector<Attribute, 8> Attrs;
+  for (Attribute::AttrKind Kind = Attribute::None;
+       Kind != Attribute::EndAttrKinds; Kind = Attribute::AttrKind(Kind + 1)) {
+    if (!B.contains(Kind))
+      continue;
+
+    Attribute Attr;
+    switch (Kind) {
+    case Attribute::Alignment:
+      Attr = Attribute::getWithAlignment(C, B.getAlignment());
+      break;
+    case Attribute::StackAlignment:
+      Attr = Attribute::getWithStackAlignment(C, B.getStackAlignment());
+      break;
+    case Attribute::Dereferenceable:
+      Attr = Attribute::getWithDereferenceableBytes(
+          C, B.getDereferenceableBytes());
+      break;
+    case Attribute::DereferenceableOrNull:
+      Attr = Attribute::getWithDereferenceableOrNullBytes(
+          C, B.getDereferenceableOrNullBytes());
+      break;
+    case Attribute::AllocSize: {
+      auto A = B.getAllocSizeArgs();
+      Attr = Attribute::getWithAllocSizeArgs(C, A.first, A.second);
+      break;
+    }
+    default:
+      Attr = Attribute::get(C, Kind);
+    }
+    Attrs.push_back(Attr);
+  }
+
+  // Add target-dependent (string) attributes.
+  for (const auto &TDA : B.td_attrs())
+    Attrs.emplace_back(Attribute::get(C, TDA.first, TDA.second));
+
+  return get(C, Attrs);
+}
+
 bool AttributeSetNode::hasAttribute(StringRef Kind) const {
   for (Attribute I : *this)
     if (I.hasAttribute(Kind))
@@ -578,46 +785,91 @@ std::string AttributeSetNode::getAsString(bool InAttrGrp) const {
 }
 
 //===----------------------------------------------------------------------===//
-// AttributeSetImpl Definition
+// AttributeListImpl Definition
 //===----------------------------------------------------------------------===//
 
-LLVM_DUMP_METHOD void AttributeSetImpl::dump() const {
-  AttributeSet(const_cast<AttributeSetImpl *>(this)).dump();
+/// Map from AttributeList index to the internal array index. Adding one works:
+///   FunctionIndex: ~0U -> 0
+///   ReturnIndex:    0  -> 1
+///   FirstArgIndex: 1.. -> 2..
+static constexpr unsigned attrIdxToArrayIdx(unsigned Index) {
+  // MSVC warns about '~0U + 1' wrapping around when this is called on
+  // FunctionIndex, so cast to int first.
+  return static_cast<int>(Index) + 1;
+}
+
+AttributeListImpl::AttributeListImpl(LLVMContext &C,
+                                     ArrayRef<AttributeSet> Sets)
+    : AvailableFunctionAttrs(0), Context(C), NumAttrSets(Sets.size()) {
+  assert(!Sets.empty() && "pointless AttributeListImpl");
+
+  // There's memory after the node where we can store the entries in.
+  std::copy(Sets.begin(), Sets.end(), getTrailingObjects<AttributeSet>());
+
+  // Initialize AvailableFunctionAttrs summary bitset.
+  static_assert(Attribute::EndAttrKinds <=
+                    sizeof(AvailableFunctionAttrs) * CHAR_BIT,
+                "Too many attributes");
+  static_assert(attrIdxToArrayIdx(AttributeList::FunctionIndex) == 0U,
+                "function should be stored in slot 0");
+  for (Attribute I : Sets[0]) {
+    if (!I.isStringAttribute())
+      AvailableFunctionAttrs |= 1ULL << I.getKindAsEnum();
+  }
 }
 
+void AttributeListImpl::Profile(FoldingSetNodeID &ID) const {
+  Profile(ID, makeArrayRef(begin(), end()));
+}
+
+void AttributeListImpl::Profile(FoldingSetNodeID &ID,
+                                ArrayRef<AttributeSet> Sets) {
+  for (const auto &Set : Sets)
+    ID.AddPointer(Set.SetNode);
+}
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+LLVM_DUMP_METHOD void AttributeListImpl::dump() const {
+  AttributeList(const_cast<AttributeListImpl *>(this)).dump();
+}
+#endif
+
 //===----------------------------------------------------------------------===//
-// AttributeSet Construction and Mutation Methods
+// AttributeList Construction and Mutation Methods
 //===----------------------------------------------------------------------===//
 
-AttributeSet
-AttributeSet::getImpl(LLVMContext &C,
-                      ArrayRef<std::pair<unsigned, AttributeSetNode*> > Attrs) {
+AttributeList AttributeList::getImpl(LLVMContext &C,
+                                     ArrayRef<AttributeSet> AttrSets) {
+  assert(!AttrSets.empty() && "pointless AttributeListImpl");
+
   LLVMContextImpl *pImpl = C.pImpl;
   FoldingSetNodeID ID;
-  AttributeSetImpl::Profile(ID, Attrs);
+  AttributeListImpl::Profile(ID, AttrSets);
 
   void *InsertPoint;
-  AttributeSetImpl *PA = pImpl->AttrsLists.FindNodeOrInsertPos(ID, InsertPoint);
+  AttributeListImpl *PA =
+      pImpl->AttrsLists.FindNodeOrInsertPos(ID, InsertPoint);
 
   // If we didn't find any existing attributes of the same shape then
   // create a new one and insert it.
   if (!PA) {
-    // Coallocate entries after the AttributeSetImpl itself.
+    // Coallocate entries after the AttributeListImpl itself.
     void *Mem = ::operator new(
-        AttributeSetImpl::totalSizeToAlloc<IndexAttrPair>(Attrs.size()));
-    PA = new (Mem) AttributeSetImpl(C, Attrs);
+        AttributeListImpl::totalSizeToAlloc<AttributeSet>(AttrSets.size()));
+    PA = new (Mem) AttributeListImpl(C, AttrSets);
     pImpl->AttrsLists.InsertNode(PA, InsertPoint);
   }
 
   // Return the AttributesList that we found or created.
-  return AttributeSet(PA);
+  return AttributeList(PA);
 }
 
-AttributeSet AttributeSet::get(LLVMContext &C,
-                               ArrayRef<std::pair<unsigned, Attribute> > Attrs){
+AttributeList
+AttributeList::get(LLVMContext &C,
+                   ArrayRef<std::pair<unsigned, Attribute>> Attrs) {
   // If there are no attributes then return a null AttributesList pointer.
   if (Attrs.empty())
-    return AttributeSet();
+    return AttributeList();
 
   assert(std::is_sorted(Attrs.begin(), Attrs.end(),
                         [](const std::pair<unsigned, Attribute> &LHS,
@@ -632,8 +884,8 @@ AttributeSet AttributeSet::get(LLVMContext &C,
 
   // Create a vector if (unsigned, AttributeSetNode*) pairs from the attributes
   // list.
-  SmallVector<std::pair<unsigned, AttributeSetNode*>, 8> AttrPairVec;
-  for (ArrayRef<std::pair<unsigned, Attribute> >::iterator I = Attrs.begin(),
+  SmallVector<std::pair<unsigned, AttributeSet>, 8> AttrPairVec;
+  for (ArrayRef<std::pair<unsigned, Attribute>>::iterator I = Attrs.begin(),
          E = Attrs.end(); I != E; ) {
     unsigned Index = I->first;
     SmallVector<Attribute, 4> AttrVec;
@@ -642,514 +894,427 @@ AttributeSet AttributeSet::get(LLVMContext &C,
       ++I;
     }
 
-    AttrPairVec.emplace_back(Index, AttributeSetNode::get(C, AttrVec));
+    AttrPairVec.emplace_back(Index, AttributeSet::get(C, AttrVec));
   }
 
-  return getImpl(C, AttrPairVec);
+  return get(C, AttrPairVec);
 }
 
-AttributeSet AttributeSet::get(LLVMContext &C,
-                               ArrayRef<std::pair<unsigned,
-                                                  AttributeSetNode*> > Attrs) {
+AttributeList
+AttributeList::get(LLVMContext &C,
+                   ArrayRef<std::pair<unsigned, AttributeSet>> Attrs) {
   // If there are no attributes then return a null AttributesList pointer.
   if (Attrs.empty())
-    return AttributeSet();
+    return AttributeList();
 
-  return getImpl(C, Attrs);
-}
+  assert(std::is_sorted(Attrs.begin(), Attrs.end(),
+                        [](const std::pair<unsigned, AttributeSet> &LHS,
+                           const std::pair<unsigned, AttributeSet> &RHS) {
+                          return LHS.first < RHS.first;
+                        }) &&
+         "Misordered Attributes list!");
+  assert(none_of(Attrs,
+                 [](const std::pair<unsigned, AttributeSet> &Pair) {
+                   return !Pair.second.hasAttributes();
+                 }) &&
+         "Pointless attribute!");
 
-AttributeSet AttributeSet::get(LLVMContext &C, unsigned Index,
-                               const AttrBuilder &B) {
-  if (!B.hasAttributes())
-    return AttributeSet();
+  unsigned MaxIndex = Attrs.back().first;
 
-  // Add target-independent attributes.
-  SmallVector<std::pair<unsigned, Attribute>, 8> Attrs;
-  for (Attribute::AttrKind Kind = Attribute::None;
-       Kind != Attribute::EndAttrKinds; Kind = Attribute::AttrKind(Kind + 1)) {
-    if (!B.contains(Kind))
-      continue;
+  SmallVector<AttributeSet, 4> AttrVec(attrIdxToArrayIdx(MaxIndex) + 1);
+  for (auto Pair : Attrs)
+    AttrVec[attrIdxToArrayIdx(Pair.first)] = Pair.second;
 
-    Attribute Attr;
-    switch (Kind) {
-    case Attribute::Alignment:
-      Attr = Attribute::getWithAlignment(C, B.getAlignment());
-      break;
-    case Attribute::StackAlignment:
-      Attr = Attribute::getWithStackAlignment(C, B.getStackAlignment());
-      break;
-    case Attribute::Dereferenceable:
-      Attr = Attribute::getWithDereferenceableBytes(
-          C, B.getDereferenceableBytes());
-      break;
-    case Attribute::DereferenceableOrNull:
-      Attr = Attribute::getWithDereferenceableOrNullBytes(
-          C, B.getDereferenceableOrNullBytes());
-      break;
-    case Attribute::AllocSize: {
-      auto A = B.getAllocSizeArgs();
-      Attr = Attribute::getWithAllocSizeArgs(C, A.first, A.second);
+  return getImpl(C, AttrVec);
+}
+
+AttributeList AttributeList::get(LLVMContext &C, AttributeSet FnAttrs,
+                                 AttributeSet RetAttrs,
+                                 ArrayRef<AttributeSet> ArgAttrs) {
+  // Scan from the end to find the last argument with attributes.  Most
+  // arguments don't have attributes, so it's nice if we can have fewer unique
+  // AttributeListImpls by dropping empty attribute sets at the end of the list.
+  unsigned NumSets = 0;
+  for (size_t I = ArgAttrs.size(); I != 0; --I) {
+    if (ArgAttrs[I - 1].hasAttributes()) {
+      NumSets = I + 2;
       break;
     }
-    default:
-      Attr = Attribute::get(C, Kind);
-    }
-    Attrs.emplace_back(Index, Attr);
+  }
+  if (NumSets == 0) {
+    // Check function and return attributes if we didn't have argument
+    // attributes.
+    if (RetAttrs.hasAttributes())
+      NumSets = 2;
+    else if (FnAttrs.hasAttributes())
+      NumSets = 1;
   }
 
-  // Add target-dependent (string) attributes.
-  for (const auto &TDA : B.td_attrs())
-    Attrs.emplace_back(Index, Attribute::get(C, TDA.first, TDA.second));
+  // If all attribute sets were empty, we can use the empty attribute list.
+  if (NumSets == 0)
+    return AttributeList();
+
+  SmallVector<AttributeSet, 8> AttrSets;
+  AttrSets.reserve(NumSets);
+  // If we have any attributes, we always have function attributes.
+  AttrSets.push_back(FnAttrs);
+  if (NumSets > 1)
+    AttrSets.push_back(RetAttrs);
+  if (NumSets > 2) {
+    // Drop the empty argument attribute sets at the end.
+    ArgAttrs = ArgAttrs.take_front(NumSets - 2);
+    AttrSets.insert(AttrSets.end(), ArgAttrs.begin(), ArgAttrs.end());
+  }
 
-  return get(C, Attrs);
+  return getImpl(C, AttrSets);
 }
 
-AttributeSet AttributeSet::get(LLVMContext &C, unsigned Index,
-                               ArrayRef<Attribute::AttrKind> Kinds) {
+AttributeList AttributeList::get(LLVMContext &C, unsigned Index,
+                                 const AttrBuilder &B) {
+  if (!B.hasAttributes())
+    return AttributeList();
+  Index = attrIdxToArrayIdx(Index);
+  SmallVector<AttributeSet, 8> AttrSets(Index + 1);
+  AttrSets[Index] = AttributeSet::get(C, B);
+  return getImpl(C, AttrSets);
+}
+
+AttributeList AttributeList::get(LLVMContext &C, unsigned Index,
+                                 ArrayRef<Attribute::AttrKind> Kinds) {
   SmallVector<std::pair<unsigned, Attribute>, 8> Attrs;
   for (Attribute::AttrKind K : Kinds)
     Attrs.emplace_back(Index, Attribute::get(C, K));
   return get(C, Attrs);
 }
 
-AttributeSet AttributeSet::get(LLVMContext &C, unsigned Index,
-                               ArrayRef<StringRef> Kinds) {
+AttributeList AttributeList::get(LLVMContext &C, unsigned Index,
+                                 ArrayRef<StringRef> Kinds) {
   SmallVector<std::pair<unsigned, Attribute>, 8> Attrs;
   for (StringRef K : Kinds)
     Attrs.emplace_back(Index, Attribute::get(C, K));
   return get(C, Attrs);
 }
 
-AttributeSet AttributeSet::get(LLVMContext &C, ArrayRef<AttributeSet> Attrs) {
-  if (Attrs.empty()) return AttributeSet();
-  if (Attrs.size() == 1) return Attrs[0];
-
-  SmallVector<std::pair<unsigned, AttributeSetNode*>, 8> AttrNodeVec;
-  AttributeSetImpl *A0 = Attrs[0].pImpl;
-  if (A0)
-    AttrNodeVec.append(A0->getNode(0), A0->getNode(A0->getNumSlots()));
-  // Copy all attributes from Attrs into AttrNodeVec while keeping AttrNodeVec
-  // ordered by index.  Because we know that each list in Attrs is ordered by
-  // index we only need to merge each successive list in rather than doing a
-  // full sort.
-  for (unsigned I = 1, E = Attrs.size(); I != E; ++I) {
-    AttributeSetImpl *AS = Attrs[I].pImpl;
-    if (!AS) continue;
-    SmallVector<std::pair<unsigned, AttributeSetNode *>, 8>::iterator
-      ANVI = AttrNodeVec.begin(), ANVE;
-    for (const IndexAttrPair *AI = AS->getNode(0),
-                             *AE = AS->getNode(AS->getNumSlots());
-         AI != AE; ++AI) {
-      ANVE = AttrNodeVec.end();
-      while (ANVI != ANVE && ANVI->first <= AI->first)
-        ++ANVI;
-      ANVI = AttrNodeVec.insert(ANVI, *AI) + 1;
-    }
+AttributeList AttributeList::get(LLVMContext &C,
+                                 ArrayRef<AttributeList> Attrs) {
+  if (Attrs.empty())
+    return AttributeList();
+  if (Attrs.size() == 1)
+    return Attrs[0];
+
+  unsigned MaxSize = 0;
+  for (AttributeList List : Attrs)
+    MaxSize = std::max(MaxSize, List.getNumAttrSets());
+
+  // If every list was empty, there is no point in merging the lists.
+  if (MaxSize == 0)
+    return AttributeList();
+
+  SmallVector<AttributeSet, 8> NewAttrSets(MaxSize);
+  for (unsigned I = 0; I < MaxSize; ++I) {
+    AttrBuilder CurBuilder;
+    for (AttributeList List : Attrs)
+      CurBuilder.merge(List.getAttributes(I - 1));
+    NewAttrSets[I] = AttributeSet::get(C, CurBuilder);
   }
 
-  return getImpl(C, AttrNodeVec);
+  return getImpl(C, NewAttrSets);
 }
 
-AttributeSet AttributeSet::addAttribute(LLVMContext &C, unsigned Index,
-                                        Attribute::AttrKind Kind) const {
+AttributeList AttributeList::addAttribute(LLVMContext &C, unsigned Index,
+                                          Attribute::AttrKind Kind) const {
   if (hasAttribute(Index, Kind)) return *this;
-  return addAttributes(C, Index, AttributeSet::get(C, Index, Kind));
+  AttrBuilder B;
+  B.addAttribute(Kind);
+  return addAttributes(C, Index, B);
 }
 
-AttributeSet AttributeSet::addAttribute(LLVMContext &C, unsigned Index,
-                                        StringRef Kind, StringRef Value) const {
-  llvm::AttrBuilder B;
+AttributeList AttributeList::addAttribute(LLVMContext &C, unsigned Index,
+                                          StringRef Kind,
+                                          StringRef Value) const {
+  AttrBuilder B;
   B.addAttribute(Kind, Value);
-  return addAttributes(C, Index, AttributeSet::get(C, Index, B));
+  return addAttributes(C, Index, B);
 }
 
-AttributeSet AttributeSet::addAttribute(LLVMContext &C,
-                                        ArrayRef<unsigned> Indices,
-                                        Attribute A) const {
-  unsigned I = 0, E = pImpl ? pImpl->getNumSlots() : 0;
-  auto IdxI = Indices.begin(), IdxE = Indices.end();
-  SmallVector<AttributeSet, 4> AttrSet;
-
-  while (I != E && IdxI != IdxE) {
-    if (getSlotIndex(I) < *IdxI)
-      AttrSet.emplace_back(getSlotAttributes(I++));
-    else if (getSlotIndex(I) > *IdxI)
-      AttrSet.emplace_back(AttributeSet::get(C, std::make_pair(*IdxI++, A)));
-    else {
-      AttrBuilder B(getSlotAttributes(I), *IdxI);
-      B.addAttribute(A);
-      AttrSet.emplace_back(AttributeSet::get(C, *IdxI, B));
-      ++I;
-      ++IdxI;
-    }
-  }
-
-  while (I != E)
-    AttrSet.emplace_back(getSlotAttributes(I++));
-
-  while (IdxI != IdxE)
-    AttrSet.emplace_back(AttributeSet::get(C, std::make_pair(*IdxI++, A)));
-
-  return get(C, AttrSet);
+AttributeList AttributeList::addAttribute(LLVMContext &C, unsigned Index,
+                                          Attribute A) const {
+  AttrBuilder B;
+  B.addAttribute(A);
+  return addAttributes(C, Index, B);
 }
 
-AttributeSet AttributeSet::addAttributes(LLVMContext &C, unsigned Index,
-                                         AttributeSet Attrs) const {
-  if (!pImpl) return Attrs;
-  if (!Attrs.pImpl) return *this;
+AttributeList AttributeList::addAttributes(LLVMContext &C, unsigned Index,
+                                           const AttrBuilder &B) const {
+  if (!B.hasAttributes())
+    return *this;
+
+  if (!pImpl)
+    return AttributeList::get(C, {{Index, AttributeSet::get(C, B)}});
 
 #ifndef NDEBUG
   // FIXME it is not obvious how this should work for alignment. For now, say
   // we can't change a known alignment.
-  unsigned OldAlign = getParamAlignment(Index);
-  unsigned NewAlign = Attrs.getParamAlignment(Index);
+  unsigned OldAlign = getAttributes(Index).getAlignment();
+  unsigned NewAlign = B.getAlignment();
   assert((!OldAlign || !NewAlign || OldAlign == NewAlign) &&
          "Attempt to change alignment!");
 #endif
 
-  // Add the attribute slots before the one we're trying to add.
-  SmallVector<AttributeSet, 4> AttrSet;
-  uint64_t NumAttrs = pImpl->getNumSlots();
-  AttributeSet AS;
-  uint64_t LastIndex = 0;
-  for (unsigned I = 0, E = NumAttrs; I != E; ++I) {
-    if (getSlotIndex(I) >= Index) {
-      if (getSlotIndex(I) == Index) AS = getSlotAttributes(LastIndex++);
-      break;
-    }
-    LastIndex = I + 1;
-    AttrSet.push_back(getSlotAttributes(I));
-  }
+  Index = attrIdxToArrayIdx(Index);
+  SmallVector<AttributeSet, 4> AttrSets(this->begin(), this->end());
+  if (Index >= AttrSets.size())
+    AttrSets.resize(Index + 1);
 
-  // Now add the attribute into the correct slot. There may already be an
-  // AttributeSet there.
-  AttrBuilder B(AS, Index);
+  AttrBuilder Merged(AttrSets[Index]);
+  Merged.merge(B);
+  AttrSets[Index] = AttributeSet::get(C, Merged);
 
-  for (unsigned I = 0, E = Attrs.pImpl->getNumSlots(); I != E; ++I)
-    if (Attrs.getSlotIndex(I) == Index) {
-      for (AttributeSetImpl::iterator II = Attrs.pImpl->begin(I),
-             IE = Attrs.pImpl->end(I); II != IE; ++II)
-        B.addAttribute(*II);
-      break;
-    }
+  return getImpl(C, AttrSets);
+}
 
-  AttrSet.push_back(AttributeSet::get(C, Index, B));
+AttributeList AttributeList::addParamAttribute(LLVMContext &C,
+                                               ArrayRef<unsigned> ArgNos,
+                                               Attribute A) const {
+  assert(std::is_sorted(ArgNos.begin(), ArgNos.end()));
 
-  // Add the remaining attribute slots.
-  for (unsigned I = LastIndex, E = NumAttrs; I < E; ++I)
-    AttrSet.push_back(getSlotAttributes(I));
+  SmallVector<AttributeSet, 4> AttrSets(this->begin(), this->end());
+  unsigned MaxIndex = attrIdxToArrayIdx(ArgNos.back() + FirstArgIndex);
+  if (MaxIndex >= AttrSets.size())
+    AttrSets.resize(MaxIndex + 1);
 
-  return get(C, AttrSet);
+  for (unsigned ArgNo : ArgNos) {
+    unsigned Index = attrIdxToArrayIdx(ArgNo + FirstArgIndex);
+    AttrBuilder B(AttrSets[Index]);
+    B.addAttribute(A);
+    AttrSets[Index] = AttributeSet::get(C, B);
+  }
+
+  return getImpl(C, AttrSets);
 }
 
-AttributeSet AttributeSet::removeAttribute(LLVMContext &C, unsigned Index,
-                                           Attribute::AttrKind Kind) const {
+AttributeList AttributeList::removeAttribute(LLVMContext &C, unsigned Index,
+                                             Attribute::AttrKind Kind) const {
   if (!hasAttribute(Index, Kind)) return *this;
-  return removeAttributes(C, Index, AttributeSet::get(C, Index, Kind));
+  AttrBuilder B;
+  B.addAttribute(Kind);
+  return removeAttributes(C, Index, B);
 }
 
-AttributeSet AttributeSet::removeAttribute(LLVMContext &C, unsigned Index,
-                                           StringRef Kind) const {
+AttributeList AttributeList::removeAttribute(LLVMContext &C, unsigned Index,
+                                             StringRef Kind) const {
   if (!hasAttribute(Index, Kind)) return *this;
-  return removeAttributes(C, Index, AttributeSet::get(C, Index, Kind));
+  AttrBuilder B;
+  B.addAttribute(Kind);
+  return removeAttributes(C, Index, B);
 }
 
-AttributeSet AttributeSet::removeAttributes(LLVMContext &C, unsigned Index,
-                                            AttributeSet Attrs) const {
-  if (!pImpl) return AttributeSet();
-  if (!Attrs.pImpl) return *this;
+AttributeList
+AttributeList::removeAttributes(LLVMContext &C, unsigned Index,
+                                const AttrBuilder &AttrsToRemove) const {
+  if (!pImpl)
+    return AttributeList();
 
   // FIXME it is not obvious how this should work for alignment.
   // For now, say we can't pass in alignment, which no current use does.
-  assert(!Attrs.hasAttribute(Index, Attribute::Alignment) &&
-         "Attempt to change alignment!");
-
-  // Add the attribute slots before the one we're trying to add.
-  SmallVector<AttributeSet, 4> AttrSet;
-  uint64_t NumAttrs = pImpl->getNumSlots();
-  AttributeSet AS;
-  uint64_t LastIndex = 0;
-  for (unsigned I = 0, E = NumAttrs; I != E; ++I) {
-    if (getSlotIndex(I) >= Index) {
-      if (getSlotIndex(I) == Index) AS = getSlotAttributes(LastIndex++);
-      break;
-    }
-    LastIndex = I + 1;
-    AttrSet.push_back(getSlotAttributes(I));
-  }
-
-  // Now remove the attribute from the correct slot. There may already be an
-  // AttributeSet there.
-  AttrBuilder B(AS, Index);
-
-  for (unsigned I = 0, E = Attrs.pImpl->getNumSlots(); I != E; ++I)
-    if (Attrs.getSlotIndex(I) == Index) {
-      B.removeAttributes(Attrs.pImpl->getSlotAttributes(I), Index);
-      break;
-    }
+  assert(!AttrsToRemove.hasAlignmentAttr() && "Attempt to change alignment!");
 
-  AttrSet.push_back(AttributeSet::get(C, Index, B));
+  Index = attrIdxToArrayIdx(Index);
+  SmallVector<AttributeSet, 4> AttrSets(this->begin(), this->end());
+  if (Index >= AttrSets.size())
+    AttrSets.resize(Index + 1);
 
-  // Add the remaining attribute slots.
-  for (unsigned I = LastIndex, E = NumAttrs; I < E; ++I)
-    AttrSet.push_back(getSlotAttributes(I));
+  AttrBuilder B(AttrSets[Index]);
+  B.remove(AttrsToRemove);
+  AttrSets[Index] = AttributeSet::get(C, B);
 
-  return get(C, AttrSet);
+  return getImpl(C, AttrSets);
 }
 
-AttributeSet AttributeSet::removeAttributes(LLVMContext &C, unsigned Index,
-                                            const AttrBuilder &Attrs) const {
-  if (!pImpl) return AttributeSet();
-
-  // FIXME it is not obvious how this should work for alignment.
-  // For now, say we can't pass in alignment, which no current use does.
-  assert(!Attrs.hasAlignmentAttr() && "Attempt to change alignment!");
-
-  // Add the attribute slots before the one we're trying to add.
-  SmallVector<AttributeSet, 4> AttrSet;
-  uint64_t NumAttrs = pImpl->getNumSlots();
-  AttributeSet AS;
-  uint64_t LastIndex = 0;
-  for (unsigned I = 0, E = NumAttrs; I != E; ++I) {
-    if (getSlotIndex(I) >= Index) {
-      if (getSlotIndex(I) == Index) AS = getSlotAttributes(LastIndex++);
-      break;
-    }
-    LastIndex = I + 1;
-    AttrSet.push_back(getSlotAttributes(I));
-  }
-
-  // Now remove the attribute from the correct slot. There may already be an
-  // AttributeSet there.
-  AttrBuilder B(AS, Index);
-  B.remove(Attrs);
-
-  AttrSet.push_back(AttributeSet::get(C, Index, B));
-
-  // Add the remaining attribute slots.
-  for (unsigned I = LastIndex, E = NumAttrs; I < E; ++I)
-    AttrSet.push_back(getSlotAttributes(I));
-
-  return get(C, AttrSet);
+AttributeList AttributeList::removeAttributes(LLVMContext &C,
+                                              unsigned WithoutIndex) const {
+  if (!pImpl)
+    return AttributeList();
+  WithoutIndex = attrIdxToArrayIdx(WithoutIndex);
+  if (WithoutIndex >= getNumAttrSets())
+    return *this;
+  SmallVector<AttributeSet, 4> AttrSets(this->begin(), this->end());
+  AttrSets[WithoutIndex] = AttributeSet();
+  return getImpl(C, AttrSets);
 }
 
-AttributeSet AttributeSet::addDereferenceableAttr(LLVMContext &C, unsigned Index,
-                                                  uint64_t Bytes) const {
-  llvm::AttrBuilder B;
+AttributeList AttributeList::addDereferenceableAttr(LLVMContext &C,
+                                                    unsigned Index,
+                                                    uint64_t Bytes) const {
+  AttrBuilder B;
   B.addDereferenceableAttr(Bytes);
-  return addAttributes(C, Index, AttributeSet::get(C, Index, B));
+  return addAttributes(C, Index, B);
 }
 
-AttributeSet AttributeSet::addDereferenceableOrNullAttr(LLVMContext &C,
-                                                        unsigned Index,
-                                                        uint64_t Bytes) const {
-  llvm::AttrBuilder B;
+AttributeList
+AttributeList::addDereferenceableOrNullAttr(LLVMContext &C, unsigned Index,
+                                            uint64_t Bytes) const {
+  AttrBuilder B;
   B.addDereferenceableOrNullAttr(Bytes);
-  return addAttributes(C, Index, AttributeSet::get(C, Index, B));
+  return addAttributes(C, Index, B);
 }
 
-AttributeSet
-AttributeSet::addAllocSizeAttr(LLVMContext &C, unsigned Index,
-                               unsigned ElemSizeArg,
-                               const Optional<unsigned> &NumElemsArg) {
-  llvm::AttrBuilder B;
+AttributeList
+AttributeList::addAllocSizeAttr(LLVMContext &C, unsigned Index,
+                                unsigned ElemSizeArg,
+                                const Optional<unsigned> &NumElemsArg) {
+  AttrBuilder B;
   B.addAllocSizeAttr(ElemSizeArg, NumElemsArg);
-  return addAttributes(C, Index, AttributeSet::get(C, Index, B));
+  return addAttributes(C, Index, B);
 }
 
 //===----------------------------------------------------------------------===//
-// AttributeSet Accessor Methods
+// AttributeList Accessor Methods
 //===----------------------------------------------------------------------===//
 
-LLVMContext &AttributeSet::getContext() const {
-  return pImpl->getContext();
-}
+LLVMContext &AttributeList::getContext() const { return pImpl->getContext(); }
 
-AttributeSet AttributeSet::getParamAttributes(unsigned Index) const {
-  return pImpl && hasAttributes(Index) ?
-    AttributeSet::get(pImpl->getContext(),
-                      ArrayRef<std::pair<unsigned, AttributeSetNode*> >(
-                        std::make_pair(Index, getAttributes(Index)))) :
-    AttributeSet();
+AttributeSet AttributeList::getParamAttributes(unsigned ArgNo) const {
+  return getAttributes(ArgNo + FirstArgIndex);
 }
 
-AttributeSet AttributeSet::getRetAttributes() const {
-  return pImpl && hasAttributes(ReturnIndex) ?
-    AttributeSet::get(pImpl->getContext(),
-                      ArrayRef<std::pair<unsigned, AttributeSetNode*> >(
-                        std::make_pair(ReturnIndex,
-                                       getAttributes(ReturnIndex)))) :
-    AttributeSet();
+AttributeSet AttributeList::getRetAttributes() const {
+  return getAttributes(ReturnIndex);
 }
 
-AttributeSet AttributeSet::getFnAttributes() const {
-  return pImpl && hasAttributes(FunctionIndex) ?
-    AttributeSet::get(pImpl->getContext(),
-                      ArrayRef<std::pair<unsigned, AttributeSetNode*> >(
-                        std::make_pair(FunctionIndex,
-                                       getAttributes(FunctionIndex)))) :
-    AttributeSet();
+AttributeSet AttributeList::getFnAttributes() const {
+  return getAttributes(FunctionIndex);
 }
 
-bool AttributeSet::hasAttribute(unsigned Index, Attribute::AttrKind Kind) const{
-  AttributeSetNode *ASN = getAttributes(Index);
-  return ASN && ASN->hasAttribute(Kind);
+bool AttributeList::hasAttribute(unsigned Index,
+                                 Attribute::AttrKind Kind) const {
+  return getAttributes(Index).hasAttribute(Kind);
 }
 
-bool AttributeSet::hasAttribute(unsigned Index, StringRef Kind) const {
-  AttributeSetNode *ASN = getAttributes(Index);
-  return ASN && ASN->hasAttribute(Kind);
+bool AttributeList::hasAttribute(unsigned Index, StringRef Kind) const {
+  return getAttributes(Index).hasAttribute(Kind);
 }
 
-bool AttributeSet::hasAttributes(unsigned Index) const {
-  AttributeSetNode *ASN = getAttributes(Index);
-  return ASN && ASN->hasAttributes();
+bool AttributeList::hasAttributes(unsigned Index) const {
+  return getAttributes(Index).hasAttributes();
 }
 
-bool AttributeSet::hasFnAttribute(Attribute::AttrKind Kind) const {
+bool AttributeList::hasFnAttribute(Attribute::AttrKind Kind) const {
   return pImpl && pImpl->hasFnAttribute(Kind);
 }
 
-bool AttributeSet::hasFnAttribute(StringRef Kind) const {
-  return hasAttribute(AttributeSet::FunctionIndex, Kind);
+bool AttributeList::hasFnAttribute(StringRef Kind) const {
+  return hasAttribute(AttributeList::FunctionIndex, Kind);
+}
+
+bool AttributeList::hasParamAttribute(unsigned ArgNo,
+                                      Attribute::AttrKind Kind) const {
+  return hasAttribute(ArgNo + FirstArgIndex, Kind);
 }
 
-bool AttributeSet::hasAttrSomewhere(Attribute::AttrKind Attr,
-                                    unsigned *Index) const {
+bool AttributeList::hasAttrSomewhere(Attribute::AttrKind Attr,
+                                     unsigned *Index) const {
   if (!pImpl) return false;
 
-  for (unsigned I = 0, E = pImpl->getNumSlots(); I != E; ++I)
-    for (AttributeSetImpl::iterator II = pImpl->begin(I),
-           IE = pImpl->end(I); II != IE; ++II)
-      if (II->hasAttribute(Attr)) {
-        if (Index) *Index = pImpl->getSlotIndex(I);
-        return true;
-      }
+  for (unsigned I = index_begin(), E = index_end(); I != E; ++I) {
+    if (hasAttribute(I, Attr)) {
+      if (Index)
+        *Index = I;
+      return true;
+    }
+  }
 
   return false;
 }
 
-Attribute AttributeSet::getAttribute(unsigned Index,
-                                     Attribute::AttrKind Kind) const {
-  AttributeSetNode *ASN = getAttributes(Index);
-  return ASN ? ASN->getAttribute(Kind) : Attribute();
+Attribute AttributeList::getAttribute(unsigned Index,
+                                      Attribute::AttrKind Kind) const {
+  return getAttributes(Index).getAttribute(Kind);
 }
 
-Attribute AttributeSet::getAttribute(unsigned Index,
-                                     StringRef Kind) const {
-  AttributeSetNode *ASN = getAttributes(Index);
-  return ASN ? ASN->getAttribute(Kind) : Attribute();
+Attribute AttributeList::getAttribute(unsigned Index, StringRef Kind) const {
+  return getAttributes(Index).getAttribute(Kind);
 }
 
-unsigned AttributeSet::getParamAlignment(unsigned Index) const {
-  AttributeSetNode *ASN = getAttributes(Index);
-  return ASN ? ASN->getAlignment() : 0;
+unsigned AttributeList::getRetAlignment() const {
+  return getAttributes(ReturnIndex).getAlignment();
 }
 
-unsigned AttributeSet::getStackAlignment(unsigned Index) const {
-  AttributeSetNode *ASN = getAttributes(Index);
-  return ASN ? ASN->getStackAlignment() : 0;
+unsigned AttributeList::getParamAlignment(unsigned ArgNo) const {
+  return getAttributes(ArgNo + FirstArgIndex).getAlignment();
 }
 
-uint64_t AttributeSet::getDereferenceableBytes(unsigned Index) const {
-  AttributeSetNode *ASN = getAttributes(Index);
-  return ASN ? ASN->getDereferenceableBytes() : 0;
+unsigned AttributeList::getStackAlignment(unsigned Index) const {
+  return getAttributes(Index).getStackAlignment();
 }
 
-uint64_t AttributeSet::getDereferenceableOrNullBytes(unsigned Index) const {
-  AttributeSetNode *ASN = getAttributes(Index);
-  return ASN ? ASN->getDereferenceableOrNullBytes() : 0;
+uint64_t AttributeList::getDereferenceableBytes(unsigned Index) const {
+  return getAttributes(Index).getDereferenceableBytes();
 }
 
-std::pair<unsigned, Optional<unsigned>>
-AttributeSet::getAllocSizeArgs(unsigned Index) const {
-  AttributeSetNode *ASN = getAttributes(Index);
-  return ASN ? ASN->getAllocSizeArgs() : std::make_pair(0u, Optional<unsigned>(0u));
+uint64_t AttributeList::getDereferenceableOrNullBytes(unsigned Index) const {
+  return getAttributes(Index).getDereferenceableOrNullBytes();
 }
 
-std::string AttributeSet::getAsString(unsigned Index, bool InAttrGrp) const {
-  AttributeSetNode *ASN = getAttributes(Index);
-  return ASN ? ASN->getAsString(InAttrGrp) : std::string("");
+std::pair<unsigned, Optional<unsigned>>
+AttributeList::getAllocSizeArgs(unsigned Index) const {
+  return getAttributes(Index).getAllocSizeArgs();
 }
 
-AttributeSetNode *AttributeSet::getAttributes(unsigned Index) const {
-  if (!pImpl) return nullptr;
-
-  // Loop through to find the attribute node we want.
-  for (unsigned I = 0, E = pImpl->getNumSlots(); I != E; ++I)
-    if (pImpl->getSlotIndex(I) == Index)
-      return pImpl->getSlotNode(I);
+std::string AttributeList::getAsString(unsigned Index, bool InAttrGrp) const {
+  return getAttributes(Index).getAsString(InAttrGrp);
+}
 
-  return nullptr;
+AttributeSet AttributeList::getAttributes(unsigned Index) const {
+  Index = attrIdxToArrayIdx(Index);
+  if (!pImpl || Index >= getNumAttrSets())
+    return AttributeSet();
+  return pImpl->begin()[Index];
 }
 
-AttributeSet::iterator AttributeSet::begin(unsigned Slot) const {
-  if (!pImpl)
-    return ArrayRef<Attribute>().begin();
-  return pImpl->begin(Slot);
+AttributeList::iterator AttributeList::begin() const {
+  return pImpl ? pImpl->begin() : nullptr;
 }
 
-AttributeSet::iterator AttributeSet::end(unsigned Slot) const {
-  if (!pImpl)
-    return ArrayRef<Attribute>().end();
-  return pImpl->end(Slot);
+AttributeList::iterator AttributeList::end() const {
+  return pImpl ? pImpl->end() : nullptr;
 }
 
 //===----------------------------------------------------------------------===//
-// AttributeSet Introspection Methods
+// AttributeList Introspection Methods
 //===----------------------------------------------------------------------===//
 
-unsigned AttributeSet::getNumSlots() const {
-  return pImpl ? pImpl->getNumSlots() : 0;
+unsigned AttributeList::getNumAttrSets() const {
+  return pImpl ? pImpl->NumAttrSets : 0;
 }
 
-unsigned AttributeSet::getSlotIndex(unsigned Slot) const {
-  assert(pImpl && Slot < pImpl->getNumSlots() &&
-         "Slot # out of range!");
-  return pImpl->getSlotIndex(Slot);
-}
-
-AttributeSet AttributeSet::getSlotAttributes(unsigned Slot) const {
-  assert(pImpl && Slot < pImpl->getNumSlots() &&
-         "Slot # out of range!");
-  return pImpl->getSlotAttributes(Slot);
-}
-
-LLVM_DUMP_METHOD void AttributeSet::dump() const {
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+LLVM_DUMP_METHOD void AttributeList::dump() const {
   dbgs() << "PAL[\n";
 
-  for (unsigned i = 0, e = getNumSlots(); i < e; ++i) {
-    uint64_t Index = getSlotIndex(i);
-    dbgs() << "  { ";
-    if (Index == ~0U)
-      dbgs() << "~0U";
-    else
-      dbgs() << Index;
-    dbgs() << " => " << getAsString(Index) << " }\n";
+  for (unsigned i = index_begin(), e = index_end(); i != e; ++i) {
+    if (getAttributes(i).hasAttributes())
+      dbgs() << "  { " << i << " => " << getAsString(i) << " }\n";
   }
 
   dbgs() << "]\n";
 }
+#endif
 
 //===----------------------------------------------------------------------===//
 // AttrBuilder Method Implementations
 //===----------------------------------------------------------------------===//
 
-AttrBuilder::AttrBuilder(AttributeSet AS, unsigned Index)
-    : Attrs(0), Alignment(0), StackAlignment(0), DerefBytes(0),
-      DerefOrNullBytes(0), AllocSizeArgs(0) {
-  AttributeSetImpl *pImpl = AS.pImpl;
-  if (!pImpl) return;
-
-  for (unsigned I = 0, E = pImpl->getNumSlots(); I != E; ++I) {
-    if (pImpl->getSlotIndex(I) != Index) continue;
-
-    for (AttributeSetImpl::iterator II = pImpl->begin(I),
-           IE = pImpl->end(I); II != IE; ++II)
-      addAttribute(*II);
+// FIXME: Remove this ctor, use AttributeSet.
+AttrBuilder::AttrBuilder(AttributeList AL, unsigned Index) {
+  AttributeSet AS = AL.getAttributes(Index);
+  for (const Attribute &A : AS)
+    addAttribute(A);
+}
 
-    break;
-  }
+AttrBuilder::AttrBuilder(AttributeSet AS) {
+  for (const Attribute &A : AS)
+    addAttribute(A);
 }
 
 void AttrBuilder::clear() {
@@ -1213,26 +1378,8 @@ AttrBuilder &AttrBuilder::removeAttribute(Attribute::AttrKind Val) {
   return *this;
 }
 
-AttrBuilder &AttrBuilder::removeAttributes(AttributeSet A, uint64_t Index) {
-  unsigned Slot = ~0U;
-  for (unsigned I = 0, E = A.getNumSlots(); I != E; ++I)
-    if (A.getSlotIndex(I) == Index) {
-      Slot = I;
-      break;
-    }
-
-  assert(Slot != ~0U && "Couldn't find index in AttributeSet!");
-
-  for (AttributeSet::iterator I = A.begin(Slot), E = A.end(Slot); I != E; ++I) {
-    Attribute Attr = *I;
-    if (Attr.isEnumAttribute() || Attr.isIntAttribute()) {
-      removeAttribute(Attr.getKindAsEnum());
-    } else {
-      assert(Attr.isStringAttribute() && "Invalid attribute type!");
-      removeAttribute(Attr.getKindAsString());
-    }
-  }
-
+AttrBuilder &AttrBuilder::removeAttributes(AttributeList A, uint64_t Index) {
+  remove(A.getAttributes(Index));
   return *this;
 }
 
@@ -1359,7 +1506,7 @@ bool AttrBuilder::overlaps(const AttrBuilder &B) const {
     return true;
 
   // Then check if any target dependent ones do.
-  for (auto I : td_attrs())
+  for (const auto &I : td_attrs())
     if (B.contains(I.first))
       return true;
 
@@ -1374,24 +1521,16 @@ bool AttrBuilder::hasAttributes() const {
   return !Attrs.none() || !TargetDepAttrs.empty();
 }
 
-bool AttrBuilder::hasAttributes(AttributeSet A, uint64_t Index) const {
-  unsigned Slot = ~0U;
-  for (unsigned I = 0, E = A.getNumSlots(); I != E; ++I)
-    if (A.getSlotIndex(I) == Index) {
-      Slot = I;
-      break;
-    }
+bool AttrBuilder::hasAttributes(AttributeList AL, uint64_t Index) const {
+  AttributeSet AS = AL.getAttributes(Index);
 
-  assert(Slot != ~0U && "Couldn't find the index!");
-
-  for (AttributeSet::iterator I = A.begin(Slot), E = A.end(Slot); I != E; ++I) {
-    Attribute Attr = *I;
+  for (Attribute Attr : AS) {
     if (Attr.isEnumAttribute() || Attr.isIntAttribute()) {
-      if (Attrs[I->getKindAsEnum()])
+      if (contains(Attr.getKindAsEnum()))
         return true;
     } else {
       assert(Attr.isStringAttribute() && "Invalid attribute kind!");
-      return TargetDepAttrs.find(Attr.getKindAsString())!=TargetDepAttrs.end();
+      return contains(Attr.getKindAsString());
     }
   }
 
@@ -1481,20 +1620,17 @@ static void adjustCallerSSPLevel(Function &Caller, const Function &Callee) {
   // If upgrading the SSP attribute, clear out the old SSP Attributes first.
   // Having multiple SSP attributes doesn't actually hurt, but it adds useless
   // clutter to the IR.
-  AttrBuilder B;
-  B.addAttribute(Attribute::StackProtect)
-    .addAttribute(Attribute::StackProtectStrong)
-    .addAttribute(Attribute::StackProtectReq);
-  AttributeSet OldSSPAttr = AttributeSet::get(Caller.getContext(),
-                                              AttributeSet::FunctionIndex,
-                                              B);
+  AttrBuilder OldSSPAttr;
+  OldSSPAttr.addAttribute(Attribute::StackProtect)
+      .addAttribute(Attribute::StackProtectStrong)
+      .addAttribute(Attribute::StackProtectReq);
 
   if (Callee.hasFnAttribute(Attribute::StackProtectReq)) {
-    Caller.removeAttributes(AttributeSet::FunctionIndex, OldSSPAttr);
+    Caller.removeAttributes(AttributeList::FunctionIndex, OldSSPAttr);
     Caller.addFnAttr(Attribute::StackProtectReq);
   } else if (Callee.hasFnAttribute(Attribute::StackProtectStrong) &&
              !Caller.hasFnAttribute(Attribute::StackProtectReq)) {
-    Caller.removeAttributes(AttributeSet::FunctionIndex, OldSSPAttr);
+    Caller.removeAttributes(AttributeList::FunctionIndex, OldSSPAttr);
     Caller.addFnAttr(Attribute::StackProtectStrong);
   } else if (Callee.hasFnAttribute(Attribute::StackProtect) &&
              !Caller.hasFnAttribute(Attribute::StackProtectReq) &&
@@ -1502,6 +1638,39 @@ static void adjustCallerSSPLevel(Function &Caller, const Function &Callee) {
     Caller.addFnAttr(Attribute::StackProtect);
 }
 
+/// \brief If the inlined function required stack probes, then ensure that
+/// the calling function has those too.
+static void adjustCallerStackProbes(Function &Caller, const Function &Callee) {
+  if (!Caller.hasFnAttribute("probe-stack") &&
+      Callee.hasFnAttribute("probe-stack")) {
+    Caller.addFnAttr(Callee.getFnAttribute("probe-stack"));
+  }
+}
+
+/// \brief If the inlined function defines the size of guard region
+/// on the stack, then ensure that the calling function defines a guard region
+/// that is no larger.
+static void
+adjustCallerStackProbeSize(Function &Caller, const Function &Callee) {
+  if (Callee.hasFnAttribute("stack-probe-size")) {
+    uint64_t CalleeStackProbeSize;
+    Callee.getFnAttribute("stack-probe-size")
+          .getValueAsString()
+          .getAsInteger(0, CalleeStackProbeSize);
+    if (Caller.hasFnAttribute("stack-probe-size")) {
+      uint64_t CallerStackProbeSize;
+      Caller.getFnAttribute("stack-probe-size")
+            .getValueAsString()
+            .getAsInteger(0, CallerStackProbeSize);
+      if (CallerStackProbeSize > CalleeStackProbeSize) {
+        Caller.addFnAttr(Callee.getFnAttribute("stack-probe-size"));
+      }
+    } else {
+      Caller.addFnAttr(Callee.getFnAttribute("stack-probe-size"));
+    }
+  }
+}
+
 #define GET_ATTR_COMPAT_FUNC
 #include "AttributesCompatFunc.inc"
 
@@ -1510,7 +1679,6 @@ bool AttributeFuncs::areInlineCompatible(const Function &Caller,
   return hasCompatibleFnAttrs(Caller, Callee);
 }
 
-
 void AttributeFuncs::mergeAttributesForInlining(Function &Caller,
                                                 const Function &Callee) {
   mergeFnAttrs(Caller, Callee);