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

MFC r309142 (by emaste):

Add WITH_LLD_AS_LD build knob

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

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

Sponsored by:	The FreeBSD Foundation

MFC r310840:

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

Move llvm-objdump from CLANG_EXTRAS to installed by default

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

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

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

MFC r312855 (by emaste):

Rename LLD_AS_LD to LLD_IS_LD, for consistency with CLANG_IS_CC

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

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

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

Reviewed by:	emaste, dim

MFC r314152 (by jkim):

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

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

Reviewed by:	dim

MFC r314564:

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

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

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

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

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

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

MFC r314708:

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

  [SCEV] limit recursion depth of CompareSCEVComplexity

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

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

  Reviewers: sanjoy

  Subscribers: mzolotukhin, tstellarAMD, llvm-commits

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

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

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

Reported by:	mjg

MFC r314795:

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

  [SCEV] limit recursion depth of CompareSCEVComplexity

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

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

  Reviewers: sanjoy

  Subscribers: mzolotukhin, tstellarAMD, llvm-commits

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

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

  [SCEV] Decrease the recursion threshold for CompareValueComplexity

  Fixes PR32142.

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

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

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

Unbreak ARMv6 world.

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

MFC r315016:

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

Relnotes:	yes

MFC r316005:

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

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

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

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

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

  Reviewers: weimingz, rengolin, compnerd

  Subscribers: aemerson, dim

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

Discussed with:	mmel

1 files changed, 571 insertions, 0 deletions

diff --git a/contrib/llvm/lib/Transforms/Utils/LibCallsShrinkWrap.cpp b/contrib/llvm/lib/Transforms/Utils/LibCallsShrinkWrap.cpp
new file mode 100644
index 0000000..d97cd75
--- /dev/null
+++ b/contrib/llvm/lib/Transforms/Utils/LibCallsShrinkWrap.cpp
@@ -0,0 +1,571 @@
+//===-- LibCallsShrinkWrap.cpp ----------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass shrink-wraps a call to function if the result is not used.
+// The call can set errno but is otherwise side effect free. For example:
+//    sqrt(val);
+//  is transformed to
+//    if (val < 0)
+//      sqrt(val);
+//  Even if the result of library call is not being used, the compiler cannot
+//  safely delete the call because the function can set errno on error
+//  conditions.
+//  Note in many functions, the error condition solely depends on the incoming
+//  parameter. In this optimization, we can generate the condition can lead to
+//  the errno to shrink-wrap the call. Since the chances of hitting the error
+//  condition is low, the runtime call is effectively eliminated.
+//
+//  These partially dead calls are usually results of C++ abstraction penalty
+//  exposed by inlining.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/LibCallsShrinkWrap.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/GlobalsModRef.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/InstVisitor.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/MDBuilder.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "libcalls-shrinkwrap"
+
+STATISTIC(NumWrappedOneCond, "Number of One-Condition Wrappers Inserted");
+STATISTIC(NumWrappedTwoCond, "Number of Two-Condition Wrappers Inserted");
+
+static cl::opt<bool> LibCallsShrinkWrapDoDomainError(
+    "libcalls-shrinkwrap-domain-error", cl::init(true), cl::Hidden,
+    cl::desc("Perform shrink-wrap on lib calls with domain errors"));
+static cl::opt<bool> LibCallsShrinkWrapDoRangeError(
+    "libcalls-shrinkwrap-range-error", cl::init(true), cl::Hidden,
+    cl::desc("Perform shrink-wrap on lib calls with range errors"));
+static cl::opt<bool> LibCallsShrinkWrapDoPoleError(
+    "libcalls-shrinkwrap-pole-error", cl::init(true), cl::Hidden,
+    cl::desc("Perform shrink-wrap on lib calls with pole errors"));
+
+namespace {
+class LibCallsShrinkWrapLegacyPass : public FunctionPass {
+public:
+  static char ID; // Pass identification, replacement for typeid
+  explicit LibCallsShrinkWrapLegacyPass() : FunctionPass(ID) {
+    initializeLibCallsShrinkWrapLegacyPassPass(
+        *PassRegistry::getPassRegistry());
+  }
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+  bool runOnFunction(Function &F) override;
+};
+}
+
+char LibCallsShrinkWrapLegacyPass::ID = 0;
+INITIALIZE_PASS_BEGIN(LibCallsShrinkWrapLegacyPass, "libcalls-shrinkwrap",
+                      "Conditionally eliminate dead library calls", false,
+                      false)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_END(LibCallsShrinkWrapLegacyPass, "libcalls-shrinkwrap",
+                    "Conditionally eliminate dead library calls", false, false)
+
+namespace {
+class LibCallsShrinkWrap : public InstVisitor<LibCallsShrinkWrap> {
+public:
+  LibCallsShrinkWrap(const TargetLibraryInfo &TLI) : TLI(TLI), Changed(false){};
+  bool isChanged() const { return Changed; }
+  void visitCallInst(CallInst &CI) { checkCandidate(CI); }
+  void perform() {
+    for (auto &CI : WorkList) {
+      DEBUG(dbgs() << "CDCE calls: " << CI->getCalledFunction()->getName()
+                   << "\n");
+      if (perform(CI)) {
+        Changed = true;
+        DEBUG(dbgs() << "Transformed\n");
+      }
+    }
+  }
+
+private:
+  bool perform(CallInst *CI);
+  void checkCandidate(CallInst &CI);
+  void shrinkWrapCI(CallInst *CI, Value *Cond);
+  bool performCallDomainErrorOnly(CallInst *CI, const LibFunc::Func &Func);
+  bool performCallErrors(CallInst *CI, const LibFunc::Func &Func);
+  bool performCallRangeErrorOnly(CallInst *CI, const LibFunc::Func &Func);
+  Value *generateOneRangeCond(CallInst *CI, const LibFunc::Func &Func);
+  Value *generateTwoRangeCond(CallInst *CI, const LibFunc::Func &Func);
+  Value *generateCondForPow(CallInst *CI, const LibFunc::Func &Func);
+
+  // Create an OR of two conditions.
+  Value *createOrCond(CallInst *CI, CmpInst::Predicate Cmp, float Val,
+                      CmpInst::Predicate Cmp2, float Val2) {
+    IRBuilder<> BBBuilder(CI);
+    Value *Arg = CI->getArgOperand(0);
+    auto Cond2 = createCond(BBBuilder, Arg, Cmp2, Val2);
+    auto Cond1 = createCond(BBBuilder, Arg, Cmp, Val);
+    return BBBuilder.CreateOr(Cond1, Cond2);
+  }
+
+  // Create a single condition using IRBuilder.
+  Value *createCond(IRBuilder<> &BBBuilder, Value *Arg, CmpInst::Predicate Cmp,
+                    float Val) {
+    Constant *V = ConstantFP::get(BBBuilder.getContext(), APFloat(Val));
+    if (!Arg->getType()->isFloatTy())
+      V = ConstantExpr::getFPExtend(V, Arg->getType());
+    return BBBuilder.CreateFCmp(Cmp, Arg, V);
+  }
+
+  // Create a single condition.
+  Value *createCond(CallInst *CI, CmpInst::Predicate Cmp, float Val) {
+    IRBuilder<> BBBuilder(CI);
+    Value *Arg = CI->getArgOperand(0);
+    return createCond(BBBuilder, Arg, Cmp, Val);
+  }
+
+  const TargetLibraryInfo &TLI;
+  SmallVector<CallInst *, 16> WorkList;
+  bool Changed;
+};
+} // end anonymous namespace
+
+// Perform the transformation to calls with errno set by domain error.
+bool LibCallsShrinkWrap::performCallDomainErrorOnly(CallInst *CI,
+                                                    const LibFunc::Func &Func) {
+  Value *Cond = nullptr;
+
+  switch (Func) {
+  case LibFunc::acos:  // DomainError: (x < -1 || x > 1)
+  case LibFunc::acosf: // Same as acos
+  case LibFunc::acosl: // Same as acos
+  case LibFunc::asin:  // DomainError: (x < -1 || x > 1)
+  case LibFunc::asinf: // Same as asin
+  case LibFunc::asinl: // Same as asin
+  {
+    ++NumWrappedTwoCond;
+    Cond = createOrCond(CI, CmpInst::FCMP_OLT, -1.0f, CmpInst::FCMP_OGT, 1.0f);
+    break;
+  }
+  case LibFunc::cos:  // DomainError: (x == +inf || x == -inf)
+  case LibFunc::cosf: // Same as cos
+  case LibFunc::cosl: // Same as cos
+  case LibFunc::sin:  // DomainError: (x == +inf || x == -inf)
+  case LibFunc::sinf: // Same as sin
+  case LibFunc::sinl: // Same as sin
+  {
+    ++NumWrappedTwoCond;
+    Cond = createOrCond(CI, CmpInst::FCMP_OEQ, INFINITY, CmpInst::FCMP_OEQ,
+                        -INFINITY);
+    break;
+  }
+  case LibFunc::acosh:  // DomainError: (x < 1)
+  case LibFunc::acoshf: // Same as acosh
+  case LibFunc::acoshl: // Same as acosh
+  {
+    ++NumWrappedOneCond;
+    Cond = createCond(CI, CmpInst::FCMP_OLT, 1.0f);
+    break;
+  }
+  case LibFunc::sqrt:  // DomainError: (x < 0)
+  case LibFunc::sqrtf: // Same as sqrt
+  case LibFunc::sqrtl: // Same as sqrt
+  {
+    ++NumWrappedOneCond;
+    Cond = createCond(CI, CmpInst::FCMP_OLT, 0.0f);
+    break;
+  }
+  default:
+    return false;
+  }
+  shrinkWrapCI(CI, Cond);
+  return true;
+}
+
+// Perform the transformation to calls with errno set by range error.
+bool LibCallsShrinkWrap::performCallRangeErrorOnly(CallInst *CI,
+                                                   const LibFunc::Func &Func) {
+  Value *Cond = nullptr;
+
+  switch (Func) {
+  case LibFunc::cosh:
+  case LibFunc::coshf:
+  case LibFunc::coshl:
+  case LibFunc::exp:
+  case LibFunc::expf:
+  case LibFunc::expl:
+  case LibFunc::exp10:
+  case LibFunc::exp10f:
+  case LibFunc::exp10l:
+  case LibFunc::exp2:
+  case LibFunc::exp2f:
+  case LibFunc::exp2l:
+  case LibFunc::sinh:
+  case LibFunc::sinhf:
+  case LibFunc::sinhl: {
+    Cond = generateTwoRangeCond(CI, Func);
+    break;
+  }
+  case LibFunc::expm1:  // RangeError: (709, inf)
+  case LibFunc::expm1f: // RangeError: (88, inf)
+  case LibFunc::expm1l: // RangeError: (11356, inf)
+  {
+    Cond = generateOneRangeCond(CI, Func);
+    break;
+  }
+  default:
+    return false;
+  }
+  shrinkWrapCI(CI, Cond);
+  return true;
+}
+
+// Perform the transformation to calls with errno set by combination of errors.
+bool LibCallsShrinkWrap::performCallErrors(CallInst *CI,
+                                           const LibFunc::Func &Func) {
+  Value *Cond = nullptr;
+
+  switch (Func) {
+  case LibFunc::atanh:  // DomainError: (x < -1 || x > 1)
+                        // PoleError:   (x == -1 || x == 1)
+                        // Overall Cond: (x <= -1 || x >= 1)
+  case LibFunc::atanhf: // Same as atanh
+  case LibFunc::atanhl: // Same as atanh
+  {
+    if (!LibCallsShrinkWrapDoDomainError || !LibCallsShrinkWrapDoPoleError)
+      return false;
+    ++NumWrappedTwoCond;
+    Cond = createOrCond(CI, CmpInst::FCMP_OLE, -1.0f, CmpInst::FCMP_OGE, 1.0f);
+    break;
+  }
+  case LibFunc::log:    // DomainError: (x < 0)
+                        // PoleError:   (x == 0)
+                        // Overall Cond: (x <= 0)
+  case LibFunc::logf:   // Same as log
+  case LibFunc::logl:   // Same as log
+  case LibFunc::log10:  // Same as log
+  case LibFunc::log10f: // Same as log
+  case LibFunc::log10l: // Same as log
+  case LibFunc::log2:   // Same as log
+  case LibFunc::log2f:  // Same as log
+  case LibFunc::log2l:  // Same as log
+  case LibFunc::logb:   // Same as log
+  case LibFunc::logbf:  // Same as log
+  case LibFunc::logbl:  // Same as log
+  {
+    if (!LibCallsShrinkWrapDoDomainError || !LibCallsShrinkWrapDoPoleError)
+      return false;
+    ++NumWrappedOneCond;
+    Cond = createCond(CI, CmpInst::FCMP_OLE, 0.0f);
+    break;
+  }
+  case LibFunc::log1p:  // DomainError: (x < -1)
+                        // PoleError:   (x == -1)
+                        // Overall Cond: (x <= -1)
+  case LibFunc::log1pf: // Same as log1p
+  case LibFunc::log1pl: // Same as log1p
+  {
+    if (!LibCallsShrinkWrapDoDomainError || !LibCallsShrinkWrapDoPoleError)
+      return false;
+    ++NumWrappedOneCond;
+    Cond = createCond(CI, CmpInst::FCMP_OLE, -1.0f);
+    break;
+  }
+  case LibFunc::pow: // DomainError: x < 0 and y is noninteger
+                     // PoleError:   x == 0 and y < 0
+                     // RangeError:  overflow or underflow
+  case LibFunc::powf:
+  case LibFunc::powl: {
+    if (!LibCallsShrinkWrapDoDomainError || !LibCallsShrinkWrapDoPoleError ||
+        !LibCallsShrinkWrapDoRangeError)
+      return false;
+    Cond = generateCondForPow(CI, Func);
+    if (Cond == nullptr)
+      return false;
+    break;
+  }
+  default:
+    return false;
+  }
+  assert(Cond && "performCallErrors should not see an empty condition");
+  shrinkWrapCI(CI, Cond);
+  return true;
+}
+
+// Checks if CI is a candidate for shrinkwrapping and put it into work list if
+// true.
+void LibCallsShrinkWrap::checkCandidate(CallInst &CI) {
+  if (CI.isNoBuiltin())
+    return;
+  // A possible improvement is to handle the calls with the return value being
+  // used. If there is API for fast libcall implementation without setting
+  // errno, we can use the same framework to direct/wrap the call to the fast
+  // API in the error free path, and leave the original call in the slow path.
+  if (!CI.use_empty())
+    return;
+
+  LibFunc::Func Func;
+  Function *Callee = CI.getCalledFunction();
+  if (!Callee)
+    return;
+  if (!TLI.getLibFunc(*Callee, Func) || !TLI.has(Func))
+    return;
+
+  if (CI.getNumArgOperands() == 0)
+    return;
+  // TODO: Handle long double in other formats.
+  Type *ArgType = CI.getArgOperand(0)->getType();
+  if (!(ArgType->isFloatTy() || ArgType->isDoubleTy() ||
+        ArgType->isX86_FP80Ty()))
+    return;
+
+  WorkList.push_back(&CI);
+}
+
+// Generate the upper bound condition for RangeError.
+Value *LibCallsShrinkWrap::generateOneRangeCond(CallInst *CI,
+                                                const LibFunc::Func &Func) {
+  float UpperBound;
+  switch (Func) {
+  case LibFunc::expm1: // RangeError: (709, inf)
+    UpperBound = 709.0f;
+    break;
+  case LibFunc::expm1f: // RangeError: (88, inf)
+    UpperBound = 88.0f;
+    break;
+  case LibFunc::expm1l: // RangeError: (11356, inf)
+    UpperBound = 11356.0f;
+    break;
+  default:
+    llvm_unreachable("Should be reach here");
+  }
+
+  ++NumWrappedOneCond;
+  return createCond(CI, CmpInst::FCMP_OGT, UpperBound);
+}
+
+// Generate the lower and upper bound condition for RangeError.
+Value *LibCallsShrinkWrap::generateTwoRangeCond(CallInst *CI,
+                                                const LibFunc::Func &Func) {
+  float UpperBound, LowerBound;
+  switch (Func) {
+  case LibFunc::cosh: // RangeError: (x < -710 || x > 710)
+  case LibFunc::sinh: // Same as cosh
+    LowerBound = -710.0f;
+    UpperBound = 710.0f;
+    break;
+  case LibFunc::coshf: // RangeError: (x < -89 || x > 89)
+  case LibFunc::sinhf: // Same as coshf
+    LowerBound = -89.0f;
+    UpperBound = 89.0f;
+    break;
+  case LibFunc::coshl: // RangeError: (x < -11357 || x > 11357)
+  case LibFunc::sinhl: // Same as coshl
+    LowerBound = -11357.0f;
+    UpperBound = 11357.0f;
+    break;
+  case LibFunc::exp: // RangeError: (x < -745 || x > 709)
+    LowerBound = -745.0f;
+    UpperBound = 709.0f;
+    break;
+  case LibFunc::expf: // RangeError: (x < -103 || x > 88)
+    LowerBound = -103.0f;
+    UpperBound = 88.0f;
+    break;
+  case LibFunc::expl: // RangeError: (x < -11399 || x > 11356)
+    LowerBound = -11399.0f;
+    UpperBound = 11356.0f;
+    break;
+  case LibFunc::exp10: // RangeError: (x < -323 || x > 308)
+    LowerBound = -323.0f;
+    UpperBound = 308.0f;
+    break;
+  case LibFunc::exp10f: // RangeError: (x < -45 || x > 38)
+    LowerBound = -45.0f;
+    UpperBound = 38.0f;
+    break;
+  case LibFunc::exp10l: // RangeError: (x < -4950 || x > 4932)
+    LowerBound = -4950.0f;
+    UpperBound = 4932.0f;
+    break;
+  case LibFunc::exp2: // RangeError: (x < -1074 || x > 1023)
+    LowerBound = -1074.0f;
+    UpperBound = 1023.0f;
+    break;
+  case LibFunc::exp2f: // RangeError: (x < -149 || x > 127)
+    LowerBound = -149.0f;
+    UpperBound = 127.0f;
+    break;
+  case LibFunc::exp2l: // RangeError: (x < -16445 || x > 11383)
+    LowerBound = -16445.0f;
+    UpperBound = 11383.0f;
+    break;
+  default:
+    llvm_unreachable("Should be reach here");
+  }
+
+  ++NumWrappedTwoCond;
+  return createOrCond(CI, CmpInst::FCMP_OGT, UpperBound, CmpInst::FCMP_OLT,
+                      LowerBound);
+}
+
+// For pow(x,y), We only handle the following cases:
+// (1) x is a constant && (x >= 1) && (x < MaxUInt8)
+//     Cond is: (y > 127)
+// (2) x is a value coming from an integer type.
+//   (2.1) if x's bit_size == 8
+//         Cond: (x <= 0 || y > 128)
+//   (2.2) if x's bit_size is 16
+//         Cond: (x <= 0 || y > 64)
+//   (2.3) if x's bit_size is 32
+//         Cond: (x <= 0 || y > 32)
+// Support for powl(x,y) and powf(x,y) are TBD.
+//
+// Note that condition can be more conservative than the actual condition
+// (i.e. we might invoke the calls that will not set the errno.).
+//
+Value *LibCallsShrinkWrap::generateCondForPow(CallInst *CI,
+                                              const LibFunc::Func &Func) {
+  // FIXME: LibFunc::powf and powl TBD.
+  if (Func != LibFunc::pow) {
+    DEBUG(dbgs() << "Not handled powf() and powl()\n");
+    return nullptr;
+  }
+
+  Value *Base = CI->getArgOperand(0);
+  Value *Exp = CI->getArgOperand(1);
+  IRBuilder<> BBBuilder(CI);
+
+  // Constant Base case.
+  if (ConstantFP *CF = dyn_cast<ConstantFP>(Base)) {
+    double D = CF->getValueAPF().convertToDouble();
+    if (D < 1.0f || D > APInt::getMaxValue(8).getZExtValue()) {
+      DEBUG(dbgs() << "Not handled pow(): constant base out of range\n");
+      return nullptr;
+    }
+
+    ++NumWrappedOneCond;
+    Constant *V = ConstantFP::get(CI->getContext(), APFloat(127.0f));
+    if (!Exp->getType()->isFloatTy())
+      V = ConstantExpr::getFPExtend(V, Exp->getType());
+    return BBBuilder.CreateFCmp(CmpInst::FCMP_OGT, Exp, V);
+  }
+
+  // If the Base value coming from an integer type.
+  Instruction *I = dyn_cast<Instruction>(Base);
+  if (!I) {
+    DEBUG(dbgs() << "Not handled pow(): FP type base\n");
+    return nullptr;
+  }
+  unsigned Opcode = I->getOpcode();
+  if (Opcode == Instruction::UIToFP || Opcode == Instruction::SIToFP) {
+    unsigned BW = I->getOperand(0)->getType()->getPrimitiveSizeInBits();
+    float UpperV = 0.0f;
+    if (BW == 8)
+      UpperV = 128.0f;
+    else if (BW == 16)
+      UpperV = 64.0f;
+    else if (BW == 32)
+      UpperV = 32.0f;
+    else {
+      DEBUG(dbgs() << "Not handled pow(): type too wide\n");
+      return nullptr;
+    }
+
+    ++NumWrappedTwoCond;
+    Constant *V = ConstantFP::get(CI->getContext(), APFloat(UpperV));
+    Constant *V0 = ConstantFP::get(CI->getContext(), APFloat(0.0f));
+    if (!Exp->getType()->isFloatTy())
+      V = ConstantExpr::getFPExtend(V, Exp->getType());
+    if (!Base->getType()->isFloatTy())
+      V0 = ConstantExpr::getFPExtend(V0, Exp->getType());
+
+    Value *Cond = BBBuilder.CreateFCmp(CmpInst::FCMP_OGT, Exp, V);
+    Value *Cond0 = BBBuilder.CreateFCmp(CmpInst::FCMP_OLE, Base, V0);
+    return BBBuilder.CreateOr(Cond0, Cond);
+  }
+  DEBUG(dbgs() << "Not handled pow(): base not from integer convert\n");
+  return nullptr;
+}
+
+// Wrap conditions that can potentially generate errno to the library call.
+void LibCallsShrinkWrap::shrinkWrapCI(CallInst *CI, Value *Cond) {
+  assert(Cond != nullptr && "hrinkWrapCI is not expecting an empty call inst");
+  MDNode *BranchWeights =
+      MDBuilder(CI->getContext()).createBranchWeights(1, 2000);
+  TerminatorInst *NewInst =
+      SplitBlockAndInsertIfThen(Cond, CI, false, BranchWeights);
+  BasicBlock *CallBB = NewInst->getParent();
+  CallBB->setName("cdce.call");
+  CallBB->getSingleSuccessor()->setName("cdce.end");
+  CI->removeFromParent();
+  CallBB->getInstList().insert(CallBB->getFirstInsertionPt(), CI);
+  DEBUG(dbgs() << "== Basic Block After ==");
+  DEBUG(dbgs() << *CallBB->getSinglePredecessor() << *CallBB
+               << *CallBB->getSingleSuccessor() << "\n");
+}
+
+// Perform the transformation to a single candidate.
+bool LibCallsShrinkWrap::perform(CallInst *CI) {
+  LibFunc::Func Func;
+  Function *Callee = CI->getCalledFunction();
+  assert(Callee && "perform() should apply to a non-empty callee");
+  TLI.getLibFunc(*Callee, Func);
+  assert(Func && "perform() is not expecting an empty function");
+
+  if (LibCallsShrinkWrapDoDomainError && performCallDomainErrorOnly(CI, Func))
+    return true;
+
+  if (LibCallsShrinkWrapDoRangeError && performCallRangeErrorOnly(CI, Func))
+    return true;
+
+  return performCallErrors(CI, Func);
+}
+
+void LibCallsShrinkWrapLegacyPass::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.addPreserved<GlobalsAAWrapperPass>();
+  AU.addRequired<TargetLibraryInfoWrapperPass>();
+}
+
+static bool runImpl(Function &F, const TargetLibraryInfo &TLI) {
+  if (F.hasFnAttribute(Attribute::OptimizeForSize))
+    return false;
+  LibCallsShrinkWrap CCDCE(TLI);
+  CCDCE.visit(F);
+  CCDCE.perform();
+  return CCDCE.isChanged();
+}
+
+bool LibCallsShrinkWrapLegacyPass::runOnFunction(Function &F) {
+  auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+  return runImpl(F, TLI);
+}
+
+namespace llvm {
+char &LibCallsShrinkWrapPassID = LibCallsShrinkWrapLegacyPass::ID;
+
+// Public interface to LibCallsShrinkWrap pass.
+FunctionPass *createLibCallsShrinkWrapPass() {
+  return new LibCallsShrinkWrapLegacyPass();
+}
+
+PreservedAnalyses LibCallsShrinkWrapPass::run(Function &F,
+                                              FunctionAnalysisManager &FAM) {
+  auto &TLI = FAM.getResult<TargetLibraryAnalysis>(F);
+  bool Changed = runImpl(F, TLI);
+  if (!Changed)
+    return PreservedAnalyses::all();
+  auto PA = PreservedAnalyses();
+  PA.preserve<GlobalsAA>();
+  return PA;
+}
+}