/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp

Bug Summary

File:	lib/Transforms/InstCombine/InstCombineAddSub.cpp
Warning:	line 209, column 33 The expression is an uninitialized value. The computed value will also be garbage
Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name InstCombineAddSub.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-eagerly-assume -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-7/lib/clang/7.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/lib/Transforms/InstCombine -I /build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine -I /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/include -I /build/llvm-toolchain-snapshot-7~svn338205/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward -internal-isystem /usr/include/clang/7.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-7/lib/clang/7.0.0/include -internal-externc-isystem /usr/lib/gcc/x86_64-linux-gnu/8/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/lib/Transforms/InstCombine -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-07-29-043837-17923-1 -x c++ /build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp -faddrsig
1//===- InstCombineAddSub.cpp ------------------------------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the visit functions for add, fadd, sub, and fsub.
11//
12//===----------------------------------------------------------------------===//

14#include "InstCombineInternal.h"
15#include "llvm/ADT/APFloat.h"
16#include "llvm/ADT/APInt.h"
17#include "llvm/ADT/STLExtras.h"
18#include "llvm/ADT/SmallVector.h"
19#include "llvm/Analysis/InstructionSimplify.h"
20#include "llvm/Analysis/ValueTracking.h"
21#include "llvm/IR/Constant.h"
22#include "llvm/IR/Constants.h"
23#include "llvm/IR/InstrTypes.h"
24#include "llvm/IR/Instruction.h"
25#include "llvm/IR/Instructions.h"
26#include "llvm/IR/Operator.h"
27#include "llvm/IR/PatternMatch.h"
28#include "llvm/IR/Type.h"
29#include "llvm/IR/Value.h"
30#include "llvm/Support/AlignOf.h"
31#include "llvm/Support/Casting.h"
32#include "llvm/Support/KnownBits.h"
33#include <cassert>
34#include <utility>

36using namespace llvm;
37using namespace PatternMatch;

39#define DEBUG_TYPE"instcombine" "instcombine"

41namespace {

/// Class representing coefficient of floating-point addend.
/// This class needs to be highly efficient, which is especially true for
/// the constructor. As of I write this comment, the cost of the default
/// constructor is merely 4-byte-store-zero (Assuming compiler is able to
/// perform write-merging).
///
class FAddendCoef {
public:
  // The constructor has to initialize a APFloat, which is unnecessary for
  // most addends which have coefficient either 1 or -1. So, the constructor
  // is expensive. In order to avoid the cost of the constructor, we should
  // reuse some instances whenever possible. The pre-created instances
  // FAddCombine::Add[0-5] embodies this idea.
  FAddendCoef() = default;
  ~FAddendCoef();

  // If possible, don't define operator+/operator- etc because these
  // operators inevitably call FAddendCoef's constructor which is not cheap.
  void operator=(const FAddendCoef &A);
  void operator+=(const FAddendCoef &A);
  void operator*=(const FAddendCoef &S);

  void set(short C) {
    assert(!insaneIntVal(C) && "Insane coefficient")(static_cast <bool> (!insaneIntVal(C) && "Insane coefficient"
) ? void (0) : __assert_fail ("!insaneIntVal(C) && \"Insane coefficient\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 66, __extension__ __PRETTY_FUNCTION__));
    IsFp = false; IntVal = C;
  }

  void set(const APFloat& C);

  void negate();

  bool isZero() const { return isInt() ? !IntVal : getFpVal().isZero(); }
  Value *getValue(Type *) const;

  bool isOne() const { return isInt() && IntVal == 1; }
  bool isTwo() const { return isInt() && IntVal == 2; }
  bool isMinusOne() const { return isInt() && IntVal == -1; }
  bool isMinusTwo() const { return isInt() && IntVal == -2; }

private:
  bool insaneIntVal(int V) { return V > 4 || V < -4; }

  APFloat *getFpValPtr()
    { return reinterpret_cast<APFloat *>(&FpValBuf.buffer[0]); }

  const APFloat *getFpValPtr() const
    { return reinterpret_cast<const APFloat *>(&FpValBuf.buffer[0]); }

  const APFloat &getFpVal() const {
    assert(IsFp && BufHasFpVal && "Incorret state")(static_cast <bool> (IsFp && BufHasFpVal &&
 "Incorret state") ? void (0) : __assert_fail ("IsFp && BufHasFpVal && \"Incorret state\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 92, __extension__ __PRETTY_FUNCTION__));
    return *getFpValPtr();
  }

  APFloat &getFpVal() {
    assert(IsFp && BufHasFpVal && "Incorret state")(static_cast <bool> (IsFp && BufHasFpVal &&
 "Incorret state") ? void (0) : __assert_fail ("IsFp && BufHasFpVal && \"Incorret state\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 97, __extension__ __PRETTY_FUNCTION__));
    return *getFpValPtr();
  }

  bool isInt() const { return !IsFp; }

  // If the coefficient is represented by an integer, promote it to a
  // floating point.
  void convertToFpType(const fltSemantics &Sem);

  // Construct an APFloat from a signed integer.
  // TODO: We should get rid of this function when APFloat can be constructed
  //       from an *SIGNED* integer.
  APFloat createAPFloatFromInt(const fltSemantics &Sem, int Val);

  bool IsFp = false;

  // True iff FpValBuf contains an instance of APFloat.
  bool BufHasFpVal = false;

  // The integer coefficient of an individual addend is either 1 or -1,
  // and we try to simplify at most 4 addends from neighboring at most
  // two instructions. So the range of <IntVal> falls in [-4, 4]. APInt
  // is overkill of this end.
  short IntVal = 0;

  AlignedCharArrayUnion<APFloat> FpValBuf;
};

/// FAddend is used to represent floating-point addend. An addend is
/// represented as <C, V>, where the V is a symbolic value, and C is a
/// constant coefficient. A constant addend is represented as <C, 0>.
class FAddend {
public:
  FAddend() = default;

  void operator+=(const FAddend &T) {
    assert((Val == T.Val) && "Symbolic-values disagree")(static_cast <bool> ((Val == T.Val) && "Symbolic-values disagree"
) ? void (0) : __assert_fail ("(Val == T.Val) && \"Symbolic-values disagree\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 134, __extension__ __PRETTY_FUNCTION__));
    Coeff += T.Coeff;
  }

  Value *getSymVal() const { return Val; }
  const FAddendCoef &getCoef() const { return Coeff; }

  bool isConstant() const { return Val == nullptr; }
  bool isZero() const { return Coeff.isZero(); }

  void set(short Coefficient, Value *V) {
    Coeff.set(Coefficient);
    Val = V;
  }
  void set(const APFloat &Coefficient, Value *V) {
    Coeff.set(Coefficient);
    Val = V;
  }
  void set(const ConstantFP *Coefficient, Value *V) {
    Coeff.set(Coefficient->getValueAPF());
    Val = V;
  }

  void negate() { Coeff.negate(); }

  /// Drill down the U-D chain one step to find the definition of V, and
  /// try to break the definition into one or two addends.
  static unsigned drillValueDownOneStep(Value* V, FAddend &A0, FAddend &A1);

  /// Similar to FAddend::drillDownOneStep() except that the value being
  /// splitted is the addend itself.
  unsigned drillAddendDownOneStep(FAddend &Addend0, FAddend &Addend1) const;

private:
  void Scale(const FAddendCoef& ScaleAmt) { Coeff *= ScaleAmt; }

  // This addend has the value of "Coeff * Val".
  Value *Val = nullptr;
  FAddendCoef Coeff;
};

/// FAddCombine is the class for optimizing an unsafe fadd/fsub along
/// with its neighboring at most two instructions.
///
class FAddCombine {
public:
  FAddCombine(InstCombiner::BuilderTy &B) : Builder(B) {}
18
←
Returning without writing to 'this->CreateInstrNum'→

  Value *simplify(Instruction *FAdd);

private:
  using AddendVect = SmallVector<const FAddend *, 4>;

  Value *simplifyFAdd(AddendVect& V, unsigned InstrQuota);

  Value *performFactorization(Instruction *I);

  /// Convert given addend to a Value
  Value *createAddendVal(const FAddend &A, bool& NeedNeg);

  /// Return the number of instructions needed to emit the N-ary addition.
  unsigned calcInstrNumber(const AddendVect& Vect);

  Value *createFSub(Value *Opnd0, Value *Opnd1);
  Value *createFAdd(Value *Opnd0, Value *Opnd1);
  Value *createFMul(Value *Opnd0, Value *Opnd1);
  Value *createFDiv(Value *Opnd0, Value *Opnd1);
  Value *createFNeg(Value *V);
  Value *createNaryFAdd(const AddendVect& Opnds, unsigned InstrQuota);
  void createInstPostProc(Instruction *NewInst, bool NoNumber = false);

   // Debugging stuff are clustered here.
  #ifndef NDEBUG
    unsigned CreateInstrNum;
    void initCreateInstNum() { CreateInstrNum = 0; }
    void incCreateInstNum() { CreateInstrNum++; }
50
←
The expression is an uninitialized value. The computed value will also be garbage
  #else
    void initCreateInstNum() {}
    void incCreateInstNum() {}
  #endif

  InstCombiner::BuilderTy &Builder;
  Instruction *Instr = nullptr;
};

219} // end anonymous namespace

221//===----------------------------------------------------------------------===//
222//
223// Implementation of
224//    {FAddendCoef, FAddend, FAddition, FAddCombine}.
225//
226//===----------------------------------------------------------------------===//
227FAddendCoef::~FAddendCoef() {
if (BufHasFpVal)
  getFpValPtr()->~APFloat();
230}

232void FAddendCoef::set(const APFloat& C) {
APFloat *P = getFpValPtr();

if (isInt()) {
  // As the buffer is meanless byte stream, we cannot call
  // APFloat::operator=().
  new(P) APFloat(C);
} else
  *P = C;

IsFp = BufHasFpVal = true;
243}

245void FAddendCoef::convertToFpType(const fltSemantics &Sem) {
if (!isInt())
  return;

APFloat *P = getFpValPtr();
if (IntVal > 0)
  new(P) APFloat(Sem, IntVal);
else {
  new(P) APFloat(Sem, 0 - IntVal);
  P->changeSign();
}
IsFp = BufHasFpVal = true;
257}

259APFloat FAddendCoef::createAPFloatFromInt(const fltSemantics &Sem, int Val) {
if (Val >= 0)
  return APFloat(Sem, Val);

APFloat T(Sem, 0 - Val);
T.changeSign();

return T;
267}

269void FAddendCoef::operator=(const FAddendCoef &That) {
if (That.isInt())
  set(That.IntVal);
else
  set(That.getFpVal());
274}

276void FAddendCoef::operator+=(const FAddendCoef &That) {
enum APFloat::roundingMode RndMode = APFloat::rmNearestTiesToEven;
if (isInt() == That.isInt()) {
  if (isInt())
    IntVal += That.IntVal;
  else
    getFpVal().add(That.getFpVal(), RndMode);
  return;
}

if (isInt()) {
  const APFloat &T = That.getFpVal();
  convertToFpType(T.getSemantics());
  getFpVal().add(T, RndMode);
  return;
}

APFloat &T = getFpVal();
T.add(createAPFloatFromInt(T.getSemantics(), That.IntVal), RndMode);
295}

297void FAddendCoef::operator*=(const FAddendCoef &That) {
if (That.isOne())
  return;

if (That.isMinusOne()) {
  negate();
  return;
}

if (isInt() && That.isInt()) {
  int Res = IntVal * (int)That.IntVal;
  assert(!insaneIntVal(Res) && "Insane int value")(static_cast <bool> (!insaneIntVal(Res) && "Insane int value"
) ? void (0) : __assert_fail ("!insaneIntVal(Res) && \"Insane int value\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 308, __extension__ __PRETTY_FUNCTION__));
  IntVal = Res;
  return;
}

const fltSemantics &Semantic =
  isInt() ? That.getFpVal().getSemantics() : getFpVal().getSemantics();

if (isInt())
  convertToFpType(Semantic);
APFloat &F0 = getFpVal();

if (That.isInt())
  F0.multiply(createAPFloatFromInt(Semantic, That.IntVal),
              APFloat::rmNearestTiesToEven);
else
  F0.multiply(That.getFpVal(), APFloat::rmNearestTiesToEven);
325}

327void FAddendCoef::negate() {
if (isInt())
  IntVal = 0 - IntVal;
else
  getFpVal().changeSign();
332}

334Value *FAddendCoef::getValue(Type *Ty) const {
return isInt() ?
  ConstantFP::get(Ty, float(IntVal)) :
  ConstantFP::get(Ty->getContext(), getFpVal());
338}

340// The definition of <Val>     Addends
341// =========================================
342//  A + B                     <1, A>, <1,B>
343//  A - B                     <1, A>, <1,B>
344//  0 - B                     <-1, B>
345//  C * A,                    <C, A>
346//  A + C                     <1, A> <C, NULL>
347//  0 +/- 0                   <0, NULL> (corner case)
348//
349// Legend: A and B are not constant, C is constant
350unsigned FAddend::drillValueDownOneStep
(Value *Val, FAddend &Addend0, FAddend &Addend1) {
Instruction *I = nullptr;
if (!Val || !(I = dyn_cast<Instruction>(Val)))
  return 0;

unsigned Opcode = I->getOpcode();

if (Opcode == Instruction::FAdd || Opcode == Instruction::FSub) {
  ConstantFP *C0, *C1;
  Value *Opnd0 = I->getOperand(0);
  Value *Opnd1 = I->getOperand(1);
  if ((C0 = dyn_cast<ConstantFP>(Opnd0)) && C0->isZero())
    Opnd0 = nullptr;

  if ((C1 = dyn_cast<ConstantFP>(Opnd1)) && C1->isZero())
    Opnd1 = nullptr;

  if (Opnd0) {
    if (!C0)
      Addend0.set(1, Opnd0);
    else
      Addend0.set(C0, nullptr);
  }

  if (Opnd1) {
    FAddend &Addend = Opnd0 ? Addend1 : Addend0;
    if (!C1)
      Addend.set(1, Opnd1);
    else
      Addend.set(C1, nullptr);
    if (Opcode == Instruction::FSub)
      Addend.negate();
  }

  if (Opnd0 || Opnd1)
    return Opnd0 && Opnd1 ? 2 : 1;

  // Both operands are zero. Weird!
  Addend0.set(APFloat(C0->getValueAPF().getSemantics()), nullptr);
  return 1;
}

if (I->getOpcode() == Instruction::FMul) {
  Value *V0 = I->getOperand(0);
  Value *V1 = I->getOperand(1);
  if (ConstantFP *C = dyn_cast<ConstantFP>(V0)) {
    Addend0.set(C, V1);
    return 1;
  }

  if (ConstantFP *C = dyn_cast<ConstantFP>(V1)) {
    Addend0.set(C, V0);
    return 1;
  }
}

return 0;
408}

410// Try to break *this* addend into two addends. e.g. Suppose this addend is
411// <2.3, V>, and V = X + Y, by calling this function, we obtain two addends,
412// i.e. <2.3, X> and <2.3, Y>.
413unsigned FAddend::drillAddendDownOneStep
(FAddend &Addend0, FAddend &Addend1) const {
if (isConstant())
  return 0;

unsigned BreakNum = FAddend::drillValueDownOneStep(Val, Addend0, Addend1);
if (!BreakNum || Coeff.isOne())
  return BreakNum;

Addend0.Scale(Coeff);

if (BreakNum == 2)
  Addend1.Scale(Coeff);

return BreakNum;
428}

430// Try to perform following optimization on the input instruction I. Return the
431// simplified expression if was successful; otherwise, return 0.
432//
433//   Instruction "I" is                Simplified into
434// -------------------------------------------------------
435//   (x * y) +/- (x * z)               x * (y +/- z)
436//   (y / x) +/- (z / x)               (y +/- z) / x
437Value *FAddCombine::performFactorization(Instruction *I) {
assert((I->getOpcode() == Instruction::FAdd ||(static_cast <bool> ((I->getOpcode() == Instruction::
FAdd || I->getOpcode() == Instruction::FSub) && "Expect add/sub"
) ? void (0) : __assert_fail ("(I->getOpcode() == Instruction::FAdd || I->getOpcode() == Instruction::FSub) && \"Expect add/sub\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 439, __extension__ __PRETTY_FUNCTION__))
        I->getOpcode() == Instruction::FSub) && "Expect add/sub")(static_cast <bool> ((I->getOpcode() == Instruction::
FAdd || I->getOpcode() == Instruction::FSub) && "Expect add/sub"
) ? void (0) : __assert_fail ("(I->getOpcode() == Instruction::FAdd || I->getOpcode() == Instruction::FSub) && \"Expect add/sub\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 439, __extension__ __PRETTY_FUNCTION__));

Instruction *I0 = dyn_cast<Instruction>(I->getOperand(0));
Instruction *I1 = dyn_cast<Instruction>(I->getOperand(1));

if (!I0 || !I1 || I0->getOpcode() != I1->getOpcode())
28
←
Assuming 'I0' is non-null→
29
←
Assuming 'I1' is non-null→
30
←
Assuming the condition is false→
31
←
Taking false branch→
  return nullptr;

bool isMpy = false;
if (I0->getOpcode() == Instruction::FMul)
32
←
Assuming the condition is false→
33
←
Taking false branch→
  isMpy = true;
else if (I0->getOpcode() != Instruction::FDiv)
34
←
Assuming the condition is false→
35
←
Taking false branch→
  return nullptr;

Value *Opnd0_0 = I0->getOperand(0);
Value *Opnd0_1 = I0->getOperand(1);
Value *Opnd1_0 = I1->getOperand(0);
Value *Opnd1_1 = I1->getOperand(1);

//  Input Instr I       Factor   AddSub0  AddSub1
//  ----------------------------------------------
// (x*y) +/- (x*z)        x        y         z
// (y/x) +/- (z/x)        x        y         z
Value *Factor = nullptr;
Value *AddSub0 = nullptr, *AddSub1 = nullptr;

if (isMpy) {
36
←
Taking false branch→
  if (Opnd0_0 == Opnd1_0 || Opnd0_0 == Opnd1_1)
    Factor = Opnd0_0;
  else if (Opnd0_1 == Opnd1_0 || Opnd0_1 == Opnd1_1)
    Factor = Opnd0_1;

  if (Factor) {
    AddSub0 = (Factor == Opnd0_0) ? Opnd0_1 : Opnd0_0;
    AddSub1 = (Factor == Opnd1_0) ? Opnd1_1 : Opnd1_0;
  }
} else if (Opnd0_1 == Opnd1_1) {
37
←
Assuming 'Opnd0_1' is equal to 'Opnd1_1'→
38
←
Taking true branch→
  Factor = Opnd0_1;
  AddSub0 = Opnd0_0;
  AddSub1 = Opnd1_0;
}

if (!Factor)
39
←
Assuming 'Factor' is non-null→
40
←
Taking false branch→
  return nullptr;

FastMathFlags Flags;
Flags.setFast();
if (I0) Flags &= I->getFastMathFlags();
41
←
Taking true branch→
if (I1) Flags &= I->getFastMathFlags();
42
←
Taking true branch→

// Create expression "NewAddSub = AddSub0 +/- AddsSub1"
Value *NewAddSub = (I->getOpcode() == Instruction::FAdd) ?
43
←
'?' condition is false→
                    createFAdd(AddSub0, AddSub1) :
                    createFSub(AddSub0, AddSub1);
44
←
Calling 'FAddCombine::createFSub'→
if (ConstantFP *CFP = dyn_cast<ConstantFP>(NewAddSub)) {
  const APFloat &F = CFP->getValueAPF();
  if (!F.isNormal())
    return nullptr;
} else if (Instruction *II = dyn_cast<Instruction>(NewAddSub))
  II->setFastMathFlags(Flags);

if (isMpy) {
  Value *RI = createFMul(Factor, NewAddSub);
  if (Instruction *II = dyn_cast<Instruction>(RI))
    II->setFastMathFlags(Flags);
  return RI;
}

Value *RI = createFDiv(NewAddSub, Factor);
if (Instruction *II = dyn_cast<Instruction>(RI))
  II->setFastMathFlags(Flags);
return RI;
511}

513Value *FAddCombine::simplify(Instruction *I) {
assert(I->hasAllowReassoc() && I->hasNoSignedZeros() &&(static_cast <bool> (I->hasAllowReassoc() &&
 I->hasNoSignedZeros() && "Expected 'reassoc'+'nsz' instruction"
) ? void (0) : __assert_fail ("I->hasAllowReassoc() && I->hasNoSignedZeros() && \"Expected 'reassoc'+'nsz' instruction\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 515, __extension__ __PRETTY_FUNCTION__))
       "Expected 'reassoc'+'nsz' instruction")(static_cast <bool> (I->hasAllowReassoc() &&
 I->hasNoSignedZeros() && "Expected 'reassoc'+'nsz' instruction"
) ? void (0) : __assert_fail ("I->hasAllowReassoc() && I->hasNoSignedZeros() && \"Expected 'reassoc'+'nsz' instruction\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 515, __extension__ __PRETTY_FUNCTION__));

// Currently we are not able to handle vector type.
if (I->getType()->isVectorTy())
21
←
Taking false branch→
  return nullptr;

assert((I->getOpcode() == Instruction::FAdd ||(static_cast <bool> ((I->getOpcode() == Instruction::
FAdd || I->getOpcode() == Instruction::FSub) && "Expect add/sub"
) ? void (0) : __assert_fail ("(I->getOpcode() == Instruction::FAdd || I->getOpcode() == Instruction::FSub) && \"Expect add/sub\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 522, __extension__ __PRETTY_FUNCTION__))
        I->getOpcode() == Instruction::FSub) && "Expect add/sub")(static_cast <bool> ((I->getOpcode() == Instruction::
FAdd || I->getOpcode() == Instruction::FSub) && "Expect add/sub"
) ? void (0) : __assert_fail ("(I->getOpcode() == Instruction::FAdd || I->getOpcode() == Instruction::FSub) && \"Expect add/sub\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 522, __extension__ __PRETTY_FUNCTION__));

// Save the instruction before calling other member-functions.
Instr = I;

FAddend Opnd0, Opnd1, Opnd0_0, Opnd0_1, Opnd1_0, Opnd1_1;

unsigned OpndNum = FAddend::drillValueDownOneStep(I, Opnd0, Opnd1);

// Step 1: Expand the 1st addend into Opnd0_0 and Opnd0_1.
unsigned Opnd0_ExpNum = 0;
unsigned Opnd1_ExpNum = 0;

if (!Opnd0.isConstant())
22
←
Taking true branch→
  Opnd0_ExpNum = Opnd0.drillAddendDownOneStep(Opnd0_0, Opnd0_1);

// Step 2: Expand the 2nd addend into Opnd1_0 and Opnd1_1.
if (OpndNum == 2 && !Opnd1.isConstant())
23
←
Taking true branch→
  Opnd1_ExpNum = Opnd1.drillAddendDownOneStep(Opnd1_0, Opnd1_1);

// Step 3: Try to optimize Opnd0_0 + Opnd0_1 + Opnd1_0 + Opnd1_1
if (Opnd0_ExpNum && Opnd1_ExpNum) {
  AddendVect AllOpnds;
  AllOpnds.push_back(&Opnd0_0);
  AllOpnds.push_back(&Opnd1_0);
  if (Opnd0_ExpNum == 2)
    AllOpnds.push_back(&Opnd0_1);
  if (Opnd1_ExpNum == 2)
    AllOpnds.push_back(&Opnd1_1);

  // Compute instruction quota. We should save at least one instruction.
  unsigned InstQuota = 0;

  Value *V0 = I->getOperand(0);
  Value *V1 = I->getOperand(1);
  InstQuota = ((!isa<Constant>(V0) && V0->hasOneUse()) &&
               (!isa<Constant>(V1) && V1->hasOneUse())) ? 2 : 1;

  if (Value *R = simplifyFAdd(AllOpnds, InstQuota))
    return R;
}

if (OpndNum != 2) {
24
←
Taking false branch→
  // The input instruction is : "I=0.0 +/- V". If the "V" were able to be
  // splitted into two addends, say "V = X - Y", the instruction would have
  // been optimized into "I = Y - X" in the previous steps.
  //
  const FAddendCoef &CE = Opnd0.getCoef();
  return CE.isOne() ? Opnd0.getSymVal() : nullptr;
}

// step 4: Try to optimize Opnd0 + Opnd1_0 [+ Opnd1_1]
if (Opnd1_ExpNum) {
25
←
Taking false branch→
  AddendVect AllOpnds;
  AllOpnds.push_back(&Opnd0);
  AllOpnds.push_back(&Opnd1_0);
  if (Opnd1_ExpNum == 2)
    AllOpnds.push_back(&Opnd1_1);

  if (Value *R = simplifyFAdd(AllOpnds, 1))
    return R;
}

// step 5: Try to optimize Opnd1 + Opnd0_0 [+ Opnd0_1]
if (Opnd0_ExpNum) {
26
←
Taking false branch→
  AddendVect AllOpnds;
  AllOpnds.push_back(&Opnd1);
  AllOpnds.push_back(&Opnd0_0);
  if (Opnd0_ExpNum == 2)
    AllOpnds.push_back(&Opnd0_1);

  if (Value *R = simplifyFAdd(AllOpnds, 1))
    return R;
}

// step 6: Try factorization as the last resort,
return performFactorization(I);
27
←
Calling 'FAddCombine::performFactorization'→
599}

601Value *FAddCombine::simplifyFAdd(AddendVect& Addends, unsigned InstrQuota) {
unsigned AddendNum = Addends.size();
assert(AddendNum <= 4 && "Too many addends")(static_cast <bool> (AddendNum <= 4 && "Too many addends"
) ? void (0) : __assert_fail ("AddendNum <= 4 && \"Too many addends\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 603, __extension__ __PRETTY_FUNCTION__));

// For saving intermediate results;
unsigned NextTmpIdx = 0;
FAddend TmpResult[3];

// Points to the constant addend of the resulting simplified expression.
// If the resulting expr has constant-addend, this constant-addend is
// desirable to reside at the top of the resulting expression tree. Placing
// constant close to supper-expr(s) will potentially reveal some optimization
// opportunities in super-expr(s).
const FAddend *ConstAdd = nullptr;

// Simplified addends are placed <SimpVect>.
AddendVect SimpVect;

// The outer loop works on one symbolic-value at a time. Suppose the input
// addends are : <a1, x>, <b1, y>, <a2, x>, <c1, z>, <b2, y>, ...
// The symbolic-values will be processed in this order: x, y, z.
for (unsigned SymIdx = 0; SymIdx < AddendNum; SymIdx++) {

  const FAddend *ThisAddend = Addends[SymIdx];
  if (!ThisAddend) {
    // This addend was processed before.
    continue;
  }

  Value *Val = ThisAddend->getSymVal();
  unsigned StartIdx = SimpVect.size();
  SimpVect.push_back(ThisAddend);

  // The inner loop collects addends sharing same symbolic-value, and these
  // addends will be later on folded into a single addend. Following above
  // example, if the symbolic value "y" is being processed, the inner loop
  // will collect two addends "<b1,y>" and "<b2,Y>". These two addends will
  // be later on folded into "<b1+b2, y>".
  for (unsigned SameSymIdx = SymIdx + 1;
       SameSymIdx < AddendNum; SameSymIdx++) {
    const FAddend *T = Addends[SameSymIdx];
    if (T && T->getSymVal() == Val) {
      // Set null such that next iteration of the outer loop will not process
      // this addend again.
      Addends[SameSymIdx] = nullptr;
      SimpVect.push_back(T);
    }
  }

  // If multiple addends share same symbolic value, fold them together.
  if (StartIdx + 1 != SimpVect.size()) {
    FAddend &R = TmpResult[NextTmpIdx ++];
    R = *SimpVect[StartIdx];
    for (unsigned Idx = StartIdx + 1; Idx < SimpVect.size(); Idx++)
      R += *SimpVect[Idx];

    // Pop all addends being folded and push the resulting folded addend.
    SimpVect.resize(StartIdx);
    if (Val) {
      if (!R.isZero()) {
        SimpVect.push_back(&R);
      }
    } else {
      // Don't push constant addend at this time. It will be the last element
      // of <SimpVect>.
      ConstAdd = &R;
    }
  }
}

assert((NextTmpIdx <= array_lengthof(TmpResult) + 1) &&(static_cast <bool> ((NextTmpIdx <= array_lengthof(TmpResult
) + 1) && "out-of-bound access") ? void (0) : __assert_fail
 ("(NextTmpIdx <= array_lengthof(TmpResult) + 1) && \"out-of-bound access\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 672, __extension__ __PRETTY_FUNCTION__))
       "out-of-bound access")(static_cast <bool> ((NextTmpIdx <= array_lengthof(TmpResult
) + 1) && "out-of-bound access") ? void (0) : __assert_fail
 ("(NextTmpIdx <= array_lengthof(TmpResult) + 1) && \"out-of-bound access\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 672, __extension__ __PRETTY_FUNCTION__));

if (ConstAdd)
  SimpVect.push_back(ConstAdd);

Value *Result;
if (!SimpVect.empty())
  Result = createNaryFAdd(SimpVect, InstrQuota);
else {
  // The addition is folded to 0.0.
  Result = ConstantFP::get(Instr->getType(), 0.0);
}

return Result;
686}

688Value *FAddCombine::createNaryFAdd
(const AddendVect &Opnds, unsigned InstrQuota) {
assert(!Opnds.empty() && "Expect at least one addend")(static_cast <bool> (!Opnds.empty() && "Expect at least one addend"
) ? void (0) : __assert_fail ("!Opnds.empty() && \"Expect at least one addend\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 690, __extension__ __PRETTY_FUNCTION__));

// Step 1: Check if the # of instructions needed exceeds the quota.

unsigned InstrNeeded = calcInstrNumber(Opnds);
if (InstrNeeded > InstrQuota)
  return nullptr;

initCreateInstNum();

// step 2: Emit the N-ary addition.
// Note that at most three instructions are involved in Fadd-InstCombine: the
// addition in question, and at most two neighboring instructions.
// The resulting optimized addition should have at least one less instruction
// than the original addition expression tree. This implies that the resulting
// N-ary addition has at most two instructions, and we don't need to worry
// about tree-height when constructing the N-ary addition.

Value *LastVal = nullptr;
bool LastValNeedNeg = false;

// Iterate the addends, creating fadd/fsub using adjacent two addends.
for (const FAddend *Opnd : Opnds) {
  bool NeedNeg;
  Value *V = createAddendVal(*Opnd, NeedNeg);
  if (!LastVal) {
    LastVal = V;
    LastValNeedNeg = NeedNeg;
    continue;
  }

  if (LastValNeedNeg == NeedNeg) {
    LastVal = createFAdd(LastVal, V);
    continue;
  }

  if (LastValNeedNeg)
    LastVal = createFSub(V, LastVal);
  else
    LastVal = createFSub(LastVal, V);

  LastValNeedNeg = false;
}

if (LastValNeedNeg) {
  LastVal = createFNeg(LastVal);
}

738#ifndef NDEBUG
assert(CreateInstrNum == InstrNeeded &&(static_cast <bool> (CreateInstrNum == InstrNeeded &&
 "Inconsistent in instruction numbers") ? void (0) : __assert_fail
 ("CreateInstrNum == InstrNeeded && \"Inconsistent in instruction numbers\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 740, __extension__ __PRETTY_FUNCTION__))
       "Inconsistent in instruction numbers")(static_cast <bool> (CreateInstrNum == InstrNeeded &&
 "Inconsistent in instruction numbers") ? void (0) : __assert_fail
 ("CreateInstrNum == InstrNeeded && \"Inconsistent in instruction numbers\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 740, __extension__ __PRETTY_FUNCTION__));
741#endif

return LastVal;
744}

746Value *FAddCombine::createFSub(Value *Opnd0, Value *Opnd1) {
Value *V = Builder.CreateFSub(Opnd0, Opnd1);
if (Instruction *I = dyn_cast<Instruction>(V))
45
←
Assuming 'I' is non-null→
46
←
Taking true branch→
  createInstPostProc(I);
47
←
Calling 'FAddCombine::createInstPostProc'→
return V;
751}

753Value *FAddCombine::createFNeg(Value *V) {
Value *Zero = cast<Value>(ConstantFP::getZeroValueForNegation(V->getType()));
Value *NewV = createFSub(Zero, V);
if (Instruction *I = dyn_cast<Instruction>(NewV))
  createInstPostProc(I, true); // fneg's don't receive instruction numbers.
return NewV;
759}

761Value *FAddCombine::createFAdd(Value *Opnd0, Value *Opnd1) {
Value *V = Builder.CreateFAdd(Opnd0, Opnd1);
if (Instruction *I = dyn_cast<Instruction>(V))
  createInstPostProc(I);
return V;
766}

768Value *FAddCombine::createFMul(Value *Opnd0, Value *Opnd1) {
Value *V = Builder.CreateFMul(Opnd0, Opnd1);
if (Instruction *I = dyn_cast<Instruction>(V))
  createInstPostProc(I);
return V;
773}

775Value *FAddCombine::createFDiv(Value *Opnd0, Value *Opnd1) {
Value *V = Builder.CreateFDiv(Opnd0, Opnd1);
if (Instruction *I = dyn_cast<Instruction>(V))
  createInstPostProc(I);
return V;
780}

782void FAddCombine::createInstPostProc(Instruction *NewInstr, bool NoNumber) {
NewInstr->setDebugLoc(Instr->getDebugLoc());

// Keep track of the number of instruction created.
if (!NoNumber)
48
←
Taking true branch→
  incCreateInstNum();
49
←
Calling 'FAddCombine::incCreateInstNum'→

// Propagate fast-math flags
NewInstr->setFastMathFlags(Instr->getFastMathFlags());
791}

793// Return the number of instruction needed to emit the N-ary addition.
794// NOTE: Keep this function in sync with createAddendVal().
795unsigned FAddCombine::calcInstrNumber(const AddendVect &Opnds) {
unsigned OpndNum = Opnds.size();
unsigned InstrNeeded = OpndNum - 1;

// The number of addends in the form of "(-1)*x".
unsigned NegOpndNum = 0;

// Adjust the number of instructions needed to emit the N-ary add.
for (const FAddend *Opnd : Opnds) {
  if (Opnd->isConstant())
    continue;

  // The constant check above is really for a few special constant
  // coefficients.
  if (isa<UndefValue>(Opnd->getSymVal()))
    continue;

  const FAddendCoef &CE = Opnd->getCoef();
  if (CE.isMinusOne() || CE.isMinusTwo())
    NegOpndNum++;

  // Let the addend be "c * x". If "c == +/-1", the value of the addend
  // is immediately available; otherwise, it needs exactly one instruction
  // to evaluate the value.
  if (!CE.isMinusOne() && !CE.isOne())
    InstrNeeded++;
}
if (NegOpndNum == OpndNum)
  InstrNeeded++;
return InstrNeeded;
825}

827// Input Addend        Value           NeedNeg(output)
828// ================================================================
829// Constant C          C               false
830// <+/-1, V>           V               coefficient is -1
831// <2/-2, V>          "fadd V, V"      coefficient is -2
832// <C, V>             "fmul V, C"      false
833//
834// NOTE: Keep this function in sync with FAddCombine::calcInstrNumber.
835Value *FAddCombine::createAddendVal(const FAddend &Opnd, bool &NeedNeg) {
const FAddendCoef &Coeff = Opnd.getCoef();

if (Opnd.isConstant()) {
  NeedNeg = false;
  return Coeff.getValue(Instr->getType());
}

Value *OpndVal = Opnd.getSymVal();

if (Coeff.isMinusOne() || Coeff.isOne()) {
  NeedNeg = Coeff.isMinusOne();
  return OpndVal;
}

if (Coeff.isTwo() || Coeff.isMinusTwo()) {
  NeedNeg = Coeff.isMinusTwo();
  return createFAdd(OpndVal, OpndVal);
}

NeedNeg = false;
return createFMul(OpndVal, Coeff.getValue(Instr->getType()));
857}

859// Checks if any operand is negative and we can convert add to sub.
860// This function checks for following negative patterns
861//   ADD(XOR(OR(Z, NOT(C)), C)), 1) == NEG(AND(Z, C))
862//   ADD(XOR(AND(Z, C), C), 1) == NEG(OR(Z, ~C))
863//   XOR(AND(Z, C), (C + 1)) == NEG(OR(Z, ~C)) if C is even
864static Value *checkForNegativeOperand(BinaryOperator &I,
                                    InstCombiner::BuilderTy &Builder) {
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);

// This function creates 2 instructions to replace ADD, we need at least one
// of LHS or RHS to have one use to ensure benefit in transform.
if (!LHS->hasOneUse() && !RHS->hasOneUse())
  return nullptr;

Value *X = nullptr, *Y = nullptr, *Z = nullptr;
const APInt *C1 = nullptr, *C2 = nullptr;

// if ONE is on other side, swap
if (match(RHS, m_Add(m_Value(X), m_One())))
  std::swap(LHS, RHS);

if (match(LHS, m_Add(m_Value(X), m_One()))) {
  // if XOR on other side, swap
  if (match(RHS, m_Xor(m_Value(Y), m_APInt(C1))))
    std::swap(X, RHS);

  if (match(X, m_Xor(m_Value(Y), m_APInt(C1)))) {
    // X = XOR(Y, C1), Y = OR(Z, C2), C2 = NOT(C1) ==> X == NOT(AND(Z, C1))
    // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, AND(Z, C1))
    if (match(Y, m_Or(m_Value(Z), m_APInt(C2))) && (*C2 == ~(*C1))) {
      Value *NewAnd = Builder.CreateAnd(Z, *C1);
      return Builder.CreateSub(RHS, NewAnd, "sub");
    } else if (match(Y, m_And(m_Value(Z), m_APInt(C2))) && (*C1 == *C2)) {
      // X = XOR(Y, C1), Y = AND(Z, C2), C2 == C1 ==> X == NOT(OR(Z, ~C1))
      // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, OR(Z, ~C1))
      Value *NewOr = Builder.CreateOr(Z, ~(*C1));
      return Builder.CreateSub(RHS, NewOr, "sub");
    }
  }
}

// Restore LHS and RHS
LHS = I.getOperand(0);
RHS = I.getOperand(1);

// if XOR is on other side, swap
if (match(RHS, m_Xor(m_Value(Y), m_APInt(C1))))
  std::swap(LHS, RHS);

// C2 is ODD
// LHS = XOR(Y, C1), Y = AND(Z, C2), C1 == (C2 + 1) => LHS == NEG(OR(Z, ~C2))
// ADD(LHS, RHS) == SUB(RHS, OR(Z, ~C2))
if (match(LHS, m_Xor(m_Value(Y), m_APInt(C1))))
  if (C1->countTrailingZeros() == 0)
    if (match(Y, m_And(m_Value(Z), m_APInt(C2))) && *C1 == (*C2 + 1)) {
      Value *NewOr = Builder.CreateOr(Z, ~(*C2));
      return Builder.CreateSub(RHS, NewOr, "sub");
    }
return nullptr;
918}

920Instruction *InstCombiner::foldAddWithConstant(BinaryOperator &Add) {
Value *Op0 = Add.getOperand(0), *Op1 = Add.getOperand(1);
Constant *Op1C;
if (!match(Op1, m_Constant(Op1C)))
  return nullptr;

if (Instruction *NV = foldBinOpIntoSelectOrPhi(Add))
  return NV;

Value *X, *Y;

// add (sub X, Y), -1 --> add (not Y), X
if (match(Op0, m_OneUse(m_Sub(m_Value(X), m_Value(Y)))) &&
    match(Op1, m_AllOnes()))
  return BinaryOperator::CreateAdd(Builder.CreateNot(Y), X);

// zext(bool) + C -> bool ? C + 1 : C
if (match(Op0, m_ZExt(m_Value(X))) &&
    X->getType()->getScalarSizeInBits() == 1)
  return SelectInst::Create(X, AddOne(Op1C), Op1);

// ~X + C --> (C-1) - X
if (match(Op0, m_Not(m_Value(X))))
  return BinaryOperator::CreateSub(SubOne(Op1C), X);

const APInt *C;
if (!match(Op1, m_APInt(C)))
  return nullptr;

if (C->isSignMask()) {
  // If wrapping is not allowed, then the addition must set the sign bit:
  // X + (signmask) --> X | signmask
  if (Add.hasNoSignedWrap() || Add.hasNoUnsignedWrap())
    return BinaryOperator::CreateOr(Op0, Op1);

  // If wrapping is allowed, then the addition flips the sign bit of LHS:
  // X + (signmask) --> X ^ signmask
  return BinaryOperator::CreateXor(Op0, Op1);
}

// Is this add the last step in a convoluted sext?
// add(zext(xor i16 X, -32768), -32768) --> sext X
Type *Ty = Add.getType();
const APInt *C2;
if (match(Op0, m_ZExt(m_Xor(m_Value(X), m_APInt(C2)))) &&
    C2->isMinSignedValue() && C2->sext(Ty->getScalarSizeInBits()) == *C)
  return CastInst::Create(Instruction::SExt, X, Ty);

// (add (zext (add nuw X, C2)), C) --> (zext (add nuw X, C2 + C))
if (match(Op0, m_OneUse(m_ZExt(m_NUWAdd(m_Value(X), m_APInt(C2))))) &&
    C->isNegative() && C->sge(-C2->sext(C->getBitWidth()))) {
  Constant *NewC =
      ConstantInt::get(X->getType(), *C2 + C->trunc(C2->getBitWidth()));
  return new ZExtInst(Builder.CreateNUWAdd(X, NewC), Ty);
}

if (C->isOneValue() && Op0->hasOneUse()) {
  // add (sext i1 X), 1 --> zext (not X)
  // TODO: The smallest IR representation is (select X, 0, 1), and that would
  // not require the one-use check. But we need to remove a transform in
  // visitSelect and make sure that IR value tracking for select is equal or
  // better than for these ops.
  if (match(Op0, m_SExt(m_Value(X))) &&
      X->getType()->getScalarSizeInBits() == 1)
    return new ZExtInst(Builder.CreateNot(X), Ty);

  // Shifts and add used to flip and mask off the low bit:
  // add (ashr (shl i32 X, 31), 31), 1 --> and (not X), 1
  const APInt *C3;
  if (match(Op0, m_AShr(m_Shl(m_Value(X), m_APInt(C2)), m_APInt(C3))) &&
      C2 == C3 && *C2 == Ty->getScalarSizeInBits() - 1) {
    Value *NotX = Builder.CreateNot(X);
    return BinaryOperator::CreateAnd(NotX, ConstantInt::get(Ty, 1));
  }
}

return nullptr;
997}

999// Matches multiplication expression Op * C where C is a constant. Returns the
1000// constant value in C and the other operand in Op. Returns true if such a
1001// match is found.
1002static bool MatchMul(Value *E, Value *&Op, APInt &C) {
const APInt *AI;
if (match(E, m_Mul(m_Value(Op), m_APInt(AI)))) {
  C = *AI;
  return true;
}
if (match(E, m_Shl(m_Value(Op), m_APInt(AI)))) {
  C = APInt(AI->getBitWidth(), 1);
  C <<= *AI;
  return true;
}
return false;
1014}

1016// Matches remainder expression Op % C where C is a constant. Returns the
1017// constant value in C and the other operand in Op. Returns the signedness of
1018// the remainder operation in IsSigned. Returns true if such a match is
1019// found.
1020static bool MatchRem(Value *E, Value *&Op, APInt &C, bool &IsSigned) {
const APInt *AI;
IsSigned = false;
if (match(E, m_SRem(m_Value(Op), m_APInt(AI)))) {
  IsSigned = true;
  C = *AI;
  return true;
}
if (match(E, m_URem(m_Value(Op), m_APInt(AI)))) {
  C = *AI;
  return true;
}
if (match(E, m_And(m_Value(Op), m_APInt(AI))) && (*AI + 1).isPowerOf2()) {
  C = *AI + 1;
  return true;
}
return false;
1037}

1039// Matches division expression Op / C with the given signedness as indicated
1040// by IsSigned, where C is a constant. Returns the constant value in C and the
1041// other operand in Op. Returns true if such a match is found.
1042static bool MatchDiv(Value *E, Value *&Op, APInt &C, bool IsSigned) {
const APInt *AI;
if (IsSigned && match(E, m_SDiv(m_Value(Op), m_APInt(AI)))) {
  C = *AI;
  return true;
}
if (!IsSigned) {
  if (match(E, m_UDiv(m_Value(Op), m_APInt(AI)))) {
    C = *AI;
    return true;
  }
  if (match(E, m_LShr(m_Value(Op), m_APInt(AI)))) {
    C = APInt(AI->getBitWidth(), 1);
    C <<= *AI;
    return true;
  }
}
return false;
1060}

1062// Returns whether C0 * C1 with the given signedness overflows.
1063static bool MulWillOverflow(APInt &C0, APInt &C1, bool IsSigned) {
bool overflow;
if (IsSigned)
  (void)C0.smul_ov(C1, overflow);
else
  (void)C0.umul_ov(C1, overflow);
return overflow;
1070}

1072// Simplifies X % C0 + (( X / C0 ) % C1) * C0 to X % (C0 * C1), where (C0 * C1)
1073// does not overflow.
1074Value *InstCombiner::SimplifyAddWithRemainder(BinaryOperator &I) {
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
Value *X, *MulOpV;
APInt C0, MulOpC;
bool IsSigned;
// Match I = X % C0 + MulOpV * C0
if (((MatchRem(LHS, X, C0, IsSigned) && MatchMul(RHS, MulOpV, MulOpC)) ||
     (MatchRem(RHS, X, C0, IsSigned) && MatchMul(LHS, MulOpV, MulOpC))) &&
    C0 == MulOpC) {
  Value *RemOpV;
  APInt C1;
  bool Rem2IsSigned;
  // Match MulOpC = RemOpV % C1
  if (MatchRem(MulOpV, RemOpV, C1, Rem2IsSigned) &&
      IsSigned == Rem2IsSigned) {
    Value *DivOpV;
    APInt DivOpC;
    // Match RemOpV = X / C0
    if (MatchDiv(RemOpV, DivOpV, DivOpC, IsSigned) && X == DivOpV &&
        C0 == DivOpC && !MulWillOverflow(C0, C1, IsSigned)) {
      Value *NewDivisor =
          ConstantInt::get(X->getType()->getContext(), C0 * C1);
      return IsSigned ? Builder.CreateSRem(X, NewDivisor, "srem")
                      : Builder.CreateURem(X, NewDivisor, "urem");
    }
  }
}

return nullptr;
1103}

1105/// Fold
1106///   (1 << NBits) - 1
1107/// Into:
1108///   ~(-(1 << NBits))
1109/// Because a 'not' is better for bit-tracking analysis and other transforms
1110/// than an 'add'. The new shl is always nsw, and is nuw if old `and` was.
1111static Instruction *canonicalizeLowbitMask(BinaryOperator &I,
                                         InstCombiner::BuilderTy &Builder) {
Value *NBits;
if (!match(&I, m_Add(m_OneUse(m_Shl(m_One(), m_Value(NBits))), m_AllOnes())))
  return nullptr;

Constant *MinusOne = Constant::getAllOnesValue(NBits->getType());
Value *NotMask = Builder.CreateShl(MinusOne, NBits, "notmask");
// Be wary of constant folding.
if (auto *BOp = dyn_cast<BinaryOperator>(NotMask)) {
  // Always NSW. But NUW propagates from `add`.
  BOp->setHasNoSignedWrap();
  BOp->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
}

return BinaryOperator::CreateNot(NotMask, I.getName());
1127}

1129Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
if (Value *V = SimplifyAddInst(I.getOperand(0), I.getOperand(1),
                               I.hasNoSignedWrap(), I.hasNoUnsignedWrap(),
                               SQ.getWithInstruction(&I)))
  return replaceInstUsesWith(I, V);

if (SimplifyAssociativeOrCommutative(I))
  return &I;

if (Instruction *X = foldShuffledBinop(I))
  return X;

// (A*B)+(A*C) -> A*(B+C) etc
if (Value *V = SimplifyUsingDistributiveLaws(I))
  return replaceInstUsesWith(I, V);

if (Instruction *X = foldAddWithConstant(I))
  return X;

// FIXME: This should be moved into the above helper function to allow these
// transforms for general constant or constant splat vectors.
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
Type *Ty = I.getType();
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
  Value *XorLHS = nullptr; ConstantInt *XorRHS = nullptr;
  if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
    unsigned TySizeBits = Ty->getScalarSizeInBits();
    const APInt &RHSVal = CI->getValue();
    unsigned ExtendAmt = 0;
    // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
    // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
    if (XorRHS->getValue() == -RHSVal) {
      if (RHSVal.isPowerOf2())
        ExtendAmt = TySizeBits - RHSVal.logBase2() - 1;
      else if (XorRHS->getValue().isPowerOf2())
        ExtendAmt = TySizeBits - XorRHS->getValue().logBase2() - 1;
    }

    if (ExtendAmt) {
      APInt Mask = APInt::getHighBitsSet(TySizeBits, ExtendAmt);
      if (!MaskedValueIsZero(XorLHS, Mask, 0, &I))
        ExtendAmt = 0;
    }

    if (ExtendAmt) {
      Constant *ShAmt = ConstantInt::get(Ty, ExtendAmt);
      Value *NewShl = Builder.CreateShl(XorLHS, ShAmt, "sext");
      return BinaryOperator::CreateAShr(NewShl, ShAmt);
    }

    // If this is a xor that was canonicalized from a sub, turn it back into
    // a sub and fuse this add with it.
    if (LHS->hasOneUse() && (XorRHS->getValue()+1).isPowerOf2()) {
      KnownBits LHSKnown = computeKnownBits(XorLHS, 0, &I);
      if ((XorRHS->getValue() | LHSKnown.Zero).isAllOnesValue())
        return BinaryOperator::CreateSub(ConstantExpr::getAdd(XorRHS, CI),
                                         XorLHS);
    }
    // (X + signmask) + C could have gotten canonicalized to (X^signmask) + C,
    // transform them into (X + (signmask ^ C))
    if (XorRHS->getValue().isSignMask())
      return BinaryOperator::CreateAdd(XorLHS,
                                       ConstantExpr::getXor(XorRHS, CI));
  }
}

if (Ty->isIntOrIntVectorTy(1))
  return BinaryOperator::CreateXor(LHS, RHS);

// X + X --> X << 1
if (LHS == RHS) {
  auto *Shl = BinaryOperator::CreateShl(LHS, ConstantInt::get(Ty, 1));
  Shl->setHasNoSignedWrap(I.hasNoSignedWrap());
  Shl->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
  return Shl;
}

Value *A, *B;
if (match(LHS, m_Neg(m_Value(A)))) {
  // -A + -B --> -(A + B)
  if (match(RHS, m_Neg(m_Value(B))))
    return BinaryOperator::CreateNeg(Builder.CreateAdd(A, B));

  // -A + B --> B - A
  return BinaryOperator::CreateSub(RHS, A);
}

// A + -B  -->  A - B
if (match(RHS, m_Neg(m_Value(B))))
  return BinaryOperator::CreateSub(LHS, B);

if (Value *V = checkForNegativeOperand(I, Builder))
  return replaceInstUsesWith(I, V);

// (A + 1) + ~B --> A - B
// ~B + (A + 1) --> A - B
if (match(&I, m_c_BinOp(m_Add(m_Value(A), m_One()), m_Not(m_Value(B)))))
  return BinaryOperator::CreateSub(A, B);

// X % C0 + (( X / C0 ) % C1) * C0 => X % (C0 * C1)
if (Value *V = SimplifyAddWithRemainder(I)) return replaceInstUsesWith(I, V);

// A+B --> A|B iff A and B have no bits set in common.
if (haveNoCommonBitsSet(LHS, RHS, DL, &AC, &I, &DT))
  return BinaryOperator::CreateOr(LHS, RHS);

// FIXME: We already did a check for ConstantInt RHS above this.
// FIXME: Is this pattern covered by another fold? No regression tests fail on
// removal.
if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
  // (X & FF00) + xx00  -> (X+xx00) & FF00
  Value *X;
  ConstantInt *C2;
  if (LHS->hasOneUse() &&
      match(LHS, m_And(m_Value(X), m_ConstantInt(C2))) &&
      CRHS->getValue() == (CRHS->getValue() & C2->getValue())) {
    // See if all bits from the first bit set in the Add RHS up are included
    // in the mask.  First, get the rightmost bit.
    const APInt &AddRHSV = CRHS->getValue();

    // Form a mask of all bits from the lowest bit added through the top.
    APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));

    // See if the and mask includes all of these bits.
    APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());

    if (AddRHSHighBits == AddRHSHighBitsAnd) {
      // Okay, the xform is safe.  Insert the new add pronto.
      Value *NewAdd = Builder.CreateAdd(X, CRHS, LHS->getName());
      return BinaryOperator::CreateAnd(NewAdd, C2);
    }
  }
}

// add (select X 0 (sub n A)) A  -->  select X A n
{
  SelectInst *SI = dyn_cast<SelectInst>(LHS);
  Value *A = RHS;
  if (!SI) {
    SI = dyn_cast<SelectInst>(RHS);
    A = LHS;
  }
  if (SI && SI->hasOneUse()) {
    Value *TV = SI->getTrueValue();
    Value *FV = SI->getFalseValue();
    Value *N;

    // Can we fold the add into the argument of the select?
    // We check both true and false select arguments for a matching subtract.
    if (match(FV, m_Zero()) && match(TV, m_Sub(m_Value(N), m_Specific(A))))
      // Fold the add into the true select value.
      return SelectInst::Create(SI->getCondition(), N, A);

    if (match(TV, m_Zero()) && match(FV, m_Sub(m_Value(N), m_Specific(A))))
      // Fold the add into the false select value.
      return SelectInst::Create(SI->getCondition(), A, N);
  }
}

// Check for (add (sext x), y), see if we can merge this into an
// integer add followed by a sext.
if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) {
  // (add (sext x), cst) --> (sext (add x, cst'))
  if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
    if (LHSConv->hasOneUse()) {
      Constant *CI =
          ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
      if (ConstantExpr::getSExt(CI, Ty) == RHSC &&
          willNotOverflowSignedAdd(LHSConv->getOperand(0), CI, I)) {
        // Insert the new, smaller add.
        Value *NewAdd =
            Builder.CreateNSWAdd(LHSConv->getOperand(0), CI, "addconv");
        return new SExtInst(NewAdd, Ty);
      }
    }
  }

  // (add (sext x), (sext y)) --> (sext (add int x, y))
  if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) {
    // Only do this if x/y have the same type, if at least one of them has a
    // single use (so we don't increase the number of sexts), and if the
    // integer add will not overflow.
    if (LHSConv->getOperand(0)->getType() ==
            RHSConv->getOperand(0)->getType() &&
        (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
        willNotOverflowSignedAdd(LHSConv->getOperand(0),
                                 RHSConv->getOperand(0), I)) {
      // Insert the new integer add.
      Value *NewAdd = Builder.CreateNSWAdd(LHSConv->getOperand(0),
                                           RHSConv->getOperand(0), "addconv");
      return new SExtInst(NewAdd, Ty);
    }
  }
}

// Check for (add (zext x), y), see if we can merge this into an
// integer add followed by a zext.
if (auto *LHSConv = dyn_cast<ZExtInst>(LHS)) {
  // (add (zext x), cst) --> (zext (add x, cst'))
  if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
    if (LHSConv->hasOneUse()) {
      Constant *CI =
          ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
      if (ConstantExpr::getZExt(CI, Ty) == RHSC &&
          willNotOverflowUnsignedAdd(LHSConv->getOperand(0), CI, I)) {
        // Insert the new, smaller add.
        Value *NewAdd =
            Builder.CreateNUWAdd(LHSConv->getOperand(0), CI, "addconv");
        return new ZExtInst(NewAdd, Ty);
      }
    }
  }

  // (add (zext x), (zext y)) --> (zext (add int x, y))
  if (auto *RHSConv = dyn_cast<ZExtInst>(RHS)) {
    // Only do this if x/y have the same type, if at least one of them has a
    // single use (so we don't increase the number of zexts), and if the
    // integer add will not overflow.
    if (LHSConv->getOperand(0)->getType() ==
            RHSConv->getOperand(0)->getType() &&
        (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
        willNotOverflowUnsignedAdd(LHSConv->getOperand(0),
                                   RHSConv->getOperand(0), I)) {
      // Insert the new integer add.
      Value *NewAdd = Builder.CreateNUWAdd(
          LHSConv->getOperand(0), RHSConv->getOperand(0), "addconv");
      return new ZExtInst(NewAdd, Ty);
    }
  }
}

// (add (xor A, B) (and A, B)) --> (or A, B)
// (add (and A, B) (xor A, B)) --> (or A, B)
if (match(&I, m_c_BinOp(m_Xor(m_Value(A), m_Value(B)),
                        m_c_And(m_Deferred(A), m_Deferred(B)))))
  return BinaryOperator::CreateOr(A, B);

// (add (or A, B) (and A, B)) --> (add A, B)
// (add (and A, B) (or A, B)) --> (add A, B)
if (match(&I, m_c_BinOp(m_Or(m_Value(A), m_Value(B)),
                        m_c_And(m_Deferred(A), m_Deferred(B))))) {
  I.setOperand(0, A);
  I.setOperand(1, B);
  return &I;
}

// TODO(jingyue): Consider willNotOverflowSignedAdd and
// willNotOverflowUnsignedAdd to reduce the number of invocations of
// computeKnownBits.
bool Changed = false;
if (!I.hasNoSignedWrap() && willNotOverflowSignedAdd(LHS, RHS, I)) {
  Changed = true;
  I.setHasNoSignedWrap(true);
}
if (!I.hasNoUnsignedWrap() && willNotOverflowUnsignedAdd(LHS, RHS, I)) {
  Changed = true;
  I.setHasNoUnsignedWrap(true);
}

if (Instruction *V = canonicalizeLowbitMask(I, Builder))
  return V;

return Changed ? &I : nullptr;
1392}

1394Instruction *InstCombiner::visitFAdd(BinaryOperator &I) {
if (Value *V = SimplifyFAddInst(I.getOperand(0), I.getOperand(1),
1
Assuming 'V' is null→
2
←
Taking false branch→
                                I.getFastMathFlags(),
                                SQ.getWithInstruction(&I)))
  return replaceInstUsesWith(I, V);

if (SimplifyAssociativeOrCommutative(I))
3
←
Assuming the condition is false→
4
←
Taking false branch→
  return &I;

if (Instruction *X = foldShuffledBinop(I))
5
←
Assuming 'X' is null→
6
←
Taking false branch→
  return X;

if (Instruction *FoldedFAdd = foldBinOpIntoSelectOrPhi(I))
7
←
Assuming 'FoldedFAdd' is null→
8
←
Taking false branch→
  return FoldedFAdd;

Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
Value *X;
// (-X) + Y --> Y - X
if (match(LHS, m_FNeg(m_Value(X))))
9
←
Taking false branch→
  return BinaryOperator::CreateFSubFMF(RHS, X, &I);
// Y + (-X) --> Y - X
if (match(RHS, m_FNeg(m_Value(X))))
10
←
Taking false branch→
  return BinaryOperator::CreateFSubFMF(LHS, X, &I);

// Check for (fadd double (sitofp x), y), see if we can merge this into an
// integer add followed by a promotion.
if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) {
11
←
Taking false branch→
  Value *LHSIntVal = LHSConv->getOperand(0);
  Type *FPType = LHSConv->getType();

  // TODO: This check is overly conservative. In many cases known bits
  // analysis can tell us that the result of the addition has less significant
  // bits than the integer type can hold.
  auto IsValidPromotion = [](Type *FTy, Type *ITy) {
    Type *FScalarTy = FTy->getScalarType();
    Type *IScalarTy = ITy->getScalarType();

    // Do we have enough bits in the significand to represent the result of
    // the integer addition?
    unsigned MaxRepresentableBits =
        APFloat::semanticsPrecision(FScalarTy->getFltSemantics());
    return IScalarTy->getIntegerBitWidth() <= MaxRepresentableBits;
  };

  // (fadd double (sitofp x), fpcst) --> (sitofp (add int x, intcst))
  // ... if the constant fits in the integer value.  This is useful for things
  // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer
  // requires a constant pool load, and generally allows the add to be better
  // instcombined.
  if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS))
    if (IsValidPromotion(FPType, LHSIntVal->getType())) {
      Constant *CI =
        ConstantExpr::getFPToSI(CFP, LHSIntVal->getType());
      if (LHSConv->hasOneUse() &&
          ConstantExpr::getSIToFP(CI, I.getType()) == CFP &&
          willNotOverflowSignedAdd(LHSIntVal, CI, I)) {
        // Insert the new integer add.
        Value *NewAdd = Builder.CreateNSWAdd(LHSIntVal, CI, "addconv");
        return new SIToFPInst(NewAdd, I.getType());
      }
    }

  // (fadd double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))
  if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) {
    Value *RHSIntVal = RHSConv->getOperand(0);
    // It's enough to check LHS types only because we require int types to
    // be the same for this transform.
    if (IsValidPromotion(FPType, LHSIntVal->getType())) {
      // Only do this if x/y have the same type, if at least one of them has a
      // single use (so we don't increase the number of int->fp conversions),
      // and if the integer add will not overflow.
      if (LHSIntVal->getType() == RHSIntVal->getType() &&
          (LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
          willNotOverflowSignedAdd(LHSIntVal, RHSIntVal, I)) {
        // Insert the new integer add.
        Value *NewAdd = Builder.CreateNSWAdd(LHSIntVal, RHSIntVal, "addconv");
        return new SIToFPInst(NewAdd, I.getType());
      }
    }
  }
}

// Handle specials cases for FAdd with selects feeding the operation
if (Value *V = SimplifySelectsFeedingBinaryOp(I, LHS, RHS))
12
←
Assuming 'V' is null→
13
←
Taking false branch→
  return replaceInstUsesWith(I, V);

if (I.hasAllowReassoc() && I.hasNoSignedZeros()) {
14
←
Assuming the condition is true→
15
←
Assuming the condition is true→
16
←
Taking true branch→
  if (Value *V = FAddCombine(Builder).simplify(&I))
17
←
Calling constructor for 'FAddCombine'→
19
←
Returning from constructor for 'FAddCombine'→
20
←
Calling 'FAddCombine::simplify'→
    return replaceInstUsesWith(I, V);
}

return nullptr;
1486}

1488/// Optimize pointer differences into the same array into a size.  Consider:
1489///  &A[10] - &A[0]: we should compile this to "10".  LHS/RHS are the pointer
1490/// operands to the ptrtoint instructions for the LHS/RHS of the subtract.
1491Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS,
                                             Type *Ty) {
// If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize
// this.
bool Swapped = false;
GEPOperator *GEP1 = nullptr, *GEP2 = nullptr;

// For now we require one side to be the base pointer "A" or a constant
// GEP derived from it.
if (GEPOperator *LHSGEP = dyn_cast<GEPOperator>(LHS)) {
  // (gep X, ...) - X
  if (LHSGEP->getOperand(0) == RHS) {
    GEP1 = LHSGEP;
    Swapped = false;
  } else if (GEPOperator *RHSGEP = dyn_cast<GEPOperator>(RHS)) {
    // (gep X, ...) - (gep X, ...)
    if (LHSGEP->getOperand(0)->stripPointerCasts() ==
          RHSGEP->getOperand(0)->stripPointerCasts()) {
      GEP2 = RHSGEP;
      GEP1 = LHSGEP;
      Swapped = false;
    }
  }
}

if (GEPOperator *RHSGEP = dyn_cast<GEPOperator>(RHS)) {
  // X - (gep X, ...)
  if (RHSGEP->getOperand(0) == LHS) {
    GEP1 = RHSGEP;
    Swapped = true;
  } else if (GEPOperator *LHSGEP = dyn_cast<GEPOperator>(LHS)) {
    // (gep X, ...) - (gep X, ...)
    if (RHSGEP->getOperand(0)->stripPointerCasts() ==
          LHSGEP->getOperand(0)->stripPointerCasts()) {
      GEP2 = LHSGEP;
      GEP1 = RHSGEP;
      Swapped = true;
    }
  }
}

if (!GEP1)
  // No GEP found.
  return nullptr;

if (GEP2) {
  // (gep X, ...) - (gep X, ...)
  //
  // Avoid duplicating the arithmetic if there are more than one non-constant
  // indices between the two GEPs and either GEP has a non-constant index and
  // multiple users. If zero non-constant index, the result is a constant and
  // there is no duplication. If one non-constant index, the result is an add
  // or sub with a constant, which is no larger than the original code, and
  // there's no duplicated arithmetic, even if either GEP has multiple
  // users. If more than one non-constant indices combined, as long as the GEP
  // with at least one non-constant index doesn't have multiple users, there
  // is no duplication.
  unsigned NumNonConstantIndices1 = GEP1->countNonConstantIndices();
  unsigned NumNonConstantIndices2 = GEP2->countNonConstantIndices();
  if (NumNonConstantIndices1 + NumNonConstantIndices2 > 1 &&
      ((NumNonConstantIndices1 > 0 && !GEP1->hasOneUse()) ||
       (NumNonConstantIndices2 > 0 && !GEP2->hasOneUse()))) {
    return nullptr;
  }
}

// Emit the offset of the GEP and an intptr_t.
Value *Result = EmitGEPOffset(GEP1);

// If we had a constant expression GEP on the other side offsetting the
// pointer, subtract it from the offset we have.
if (GEP2) {
  Value *Offset = EmitGEPOffset(GEP2);
  Result = Builder.CreateSub(Result, Offset);
}

// If we have p - gep(p, ...)  then we have to negate the result.
if (Swapped)
  Result = Builder.CreateNeg(Result, "diff.neg");

return Builder.CreateIntCast(Result, Ty, true);
1572}

1574Instruction *InstCombiner::visitSub(BinaryOperator &I) {
if (Value *V = SimplifySubInst(I.getOperand(0), I.getOperand(1),
                               I.hasNoSignedWrap(), I.hasNoUnsignedWrap(),
                               SQ.getWithInstruction(&I)))
  return replaceInstUsesWith(I, V);

if (Instruction *X = foldShuffledBinop(I))
  return X;

// (A*B)-(A*C) -> A*(B-C) etc
if (Value *V = SimplifyUsingDistributiveLaws(I))
  return replaceInstUsesWith(I, V);

// If this is a 'B = x-(-A)', change to B = x+A.
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Value *V = dyn_castNegVal(Op1)) {
  BinaryOperator *Res = BinaryOperator::CreateAdd(Op0, V);

  if (const auto *BO = dyn_cast<BinaryOperator>(Op1)) {
    assert(BO->getOpcode() == Instruction::Sub &&(static_cast <bool> (BO->getOpcode() == Instruction::
Sub && "Expected a subtraction operator!") ? void (0)
 : __assert_fail ("BO->getOpcode() == Instruction::Sub && \"Expected a subtraction operator!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 1594, __extension__ __PRETTY_FUNCTION__))
           "Expected a subtraction operator!")(static_cast <bool> (BO->getOpcode() == Instruction::
Sub && "Expected a subtraction operator!") ? void (0)
 : __assert_fail ("BO->getOpcode() == Instruction::Sub && \"Expected a subtraction operator!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/Transforms/InstCombine/InstCombineAddSub.cpp"
, 1594, __extension__ __PRETTY_FUNCTION__));
    if (BO->hasNoSignedWrap() && I.hasNoSignedWrap())
      Res->setHasNoSignedWrap(true);
  } else {
    if (cast<Constant>(Op1)->isNotMinSignedValue() && I.hasNoSignedWrap())
      Res->setHasNoSignedWrap(true);
  }

  return Res;
}

if (I.getType()->isIntOrIntVectorTy(1))
  return BinaryOperator::CreateXor(Op0, Op1);

// Replace (-1 - A) with (~A).
if (match(Op0, m_AllOnes()))
  return BinaryOperator::CreateNot(Op1);

// (~X) - (~Y) --> Y - X
Value *X, *Y;
if (match(Op0, m_Not(m_Value(X))) && match(Op1, m_Not(m_Value(Y))))
  return BinaryOperator::CreateSub(Y, X);

if (Constant *C = dyn_cast<Constant>(Op0)) {
  bool IsNegate = match(C, m_ZeroInt());
  Value *X;
  if (match(Op1, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) {
    // 0 - (zext bool) --> sext bool
    // C - (zext bool) --> bool ? C - 1 : C
    if (IsNegate)
      return CastInst::CreateSExtOrBitCast(X, I.getType());
    return SelectInst::Create(X, SubOne(C), C);
  }
  if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) {
    // 0 - (sext bool) --> zext bool
    // C - (sext bool) --> bool ? C + 1 : C
    if (IsNegate)
      return CastInst::CreateZExtOrBitCast(X, I.getType());
    return SelectInst::Create(X, AddOne(C), C);
  }

  // C - ~X == X + (1+C)
  if (match(Op1, m_Not(m_Value(X))))
    return BinaryOperator::CreateAdd(X, AddOne(C));

  // Try to fold constant sub into select arguments.
  if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
    if (Instruction *R = FoldOpIntoSelect(I, SI))
      return R;

  // Try to fold constant sub into PHI values.
  if (PHINode *PN = dyn_cast<PHINode>(Op1))
    if (Instruction *R = foldOpIntoPhi(I, PN))
      return R;

  // C-(X+C2) --> (C-C2)-X
  Constant *C2;
  if (match(Op1, m_Add(m_Value(X), m_Constant(C2))))
    return BinaryOperator::CreateSub(ConstantExpr::getSub(C, C2), X);
}

const APInt *Op0C;
if (match(Op0, m_APInt(Op0C))) {
  unsigned BitWidth = I.getType()->getScalarSizeInBits();

  // -(X >>u 31) -> (X >>s 31)
  // -(X >>s 31) -> (X >>u 31)
  if (Op0C->isNullValue()) {
    Value *X;
    const APInt *ShAmt;
    if (match(Op1, m_LShr(m_Value(X), m_APInt(ShAmt))) &&
        *ShAmt == BitWidth - 1) {
      Value *ShAmtOp = cast<Instruction>(Op1)->getOperand(1);
      return BinaryOperator::CreateAShr(X, ShAmtOp);
    }
    if (match(Op1, m_AShr(m_Value(X), m_APInt(ShAmt))) &&
        *ShAmt == BitWidth - 1) {
      Value *ShAmtOp = cast<Instruction>(Op1)->getOperand(1);
      return BinaryOperator::CreateLShr(X, ShAmtOp);
    }

    if (Op1->hasOneUse()) {
      Value *LHS, *RHS;
      SelectPatternFlavor SPF = matchSelectPattern(Op1, LHS, RHS).Flavor;
      if (SPF == SPF_ABS || SPF == SPF_NABS) {
        // This is a negate of an ABS/NABS pattern. Just swap the operands
        // of the select.
        SelectInst *SI = cast<SelectInst>(Op1);
        Value *TrueVal = SI->getTrueValue();
        Value *FalseVal = SI->getFalseValue();
        SI->setTrueValue(FalseVal);
        SI->setFalseValue(TrueVal);
        // Don't swap prof metadata, we didn't change the branch behavior.
        return replaceInstUsesWith(I, SI);
      }
    }
  }

  // Turn this into a xor if LHS is 2^n-1 and the remaining bits are known
  // zero.
  if (Op0C->isMask()) {
    KnownBits RHSKnown = computeKnownBits(Op1, 0, &I);
    if ((*Op0C | RHSKnown.Zero).isAllOnesValue())
      return BinaryOperator::CreateXor(Op1, Op0);
  }
}

{
  Value *Y;
  // X-(X+Y) == -Y    X-(Y+X) == -Y
  if (match(Op1, m_c_Add(m_Specific(Op0), m_Value(Y))))
    return BinaryOperator::CreateNeg(Y);

  // (X-Y)-X == -Y
  if (match(Op0, m_Sub(m_Specific(Op1), m_Value(Y))))
    return BinaryOperator::CreateNeg(Y);
}

// (sub (or A, B), (xor A, B)) --> (and A, B)
{
  Value *A, *B;
  if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
      match(Op0, m_c_Or(m_Specific(A), m_Specific(B))))
    return BinaryOperator::CreateAnd(A, B);
}

{
  Value *Y;
  // ((X | Y) - X) --> (~X & Y)
  if (match(Op0, m_OneUse(m_c_Or(m_Value(Y), m_Specific(Op1)))))
    return BinaryOperator::CreateAnd(
        Y, Builder.CreateNot(Op1, Op1->getName() + ".not"));
}

if (Op1->hasOneUse()) {
  Value *X = nullptr, *Y = nullptr, *Z = nullptr;
  Constant *C = nullptr;

  // (X - (Y - Z))  -->  (X + (Z - Y)).
  if (match(Op1, m_Sub(m_Value(Y), m_Value(Z))))
    return BinaryOperator::CreateAdd(Op0,
                                    Builder.CreateSub(Z, Y, Op1->getName()));

  // (X - (X & Y))   -->   (X & ~Y)
  if (match(Op1, m_c_And(m_Value(Y), m_Specific(Op0))))
    return BinaryOperator::CreateAnd(Op0,
                                Builder.CreateNot(Y, Y->getName() + ".not"));

  // 0 - (X sdiv C)  -> (X sdiv -C)  provided the negation doesn't overflow.
  if (match(Op1, m_SDiv(m_Value(X), m_Constant(C))) && match(Op0, m_Zero()) &&
      C->isNotMinSignedValue() && !C->isOneValue())
    return BinaryOperator::CreateSDiv(X, ConstantExpr::getNeg(C));

  // 0 - (X << Y)  -> (-X << Y)   when X is freely negatable.
  if (match(Op1, m_Shl(m_Value(X), m_Value(Y))) && match(Op0, m_Zero()))
    if (Value *XNeg = dyn_castNegVal(X))
      return BinaryOperator::CreateShl(XNeg, Y);

  // Subtracting -1/0 is the same as adding 1/0:
  // sub [nsw] Op0, sext(bool Y) -> add [nsw] Op0, zext(bool Y)
  // 'nuw' is dropped in favor of the canonical form.
  if (match(Op1, m_SExt(m_Value(Y))) &&
      Y->getType()->getScalarSizeInBits() == 1) {
    Value *Zext = Builder.CreateZExt(Y, I.getType());
    BinaryOperator *Add = BinaryOperator::CreateAdd(Op0, Zext);
    Add->setHasNoSignedWrap(I.hasNoSignedWrap());
    return Add;
  }

  // X - A*-B -> X + A*B
  // X - -A*B -> X + A*B
  Value *A, *B;
  Constant *CI;
  if (match(Op1, m_c_Mul(m_Value(A), m_Neg(m_Value(B)))))
    return BinaryOperator::CreateAdd(Op0, Builder.CreateMul(A, B));

  // X - A*CI -> X + A*-CI
  // No need to handle commuted multiply because multiply handling will
  // ensure constant will be move to the right hand side.
  if (match(Op1, m_Mul(m_Value(A), m_Constant(CI)))) {
    Value *NewMul = Builder.CreateMul(A, ConstantExpr::getNeg(CI));
    return BinaryOperator::CreateAdd(Op0, NewMul);
  }
}

// Optimize pointer differences into the same array into a size.  Consider:
//  &A[10] - &A[0]: we should compile this to "10".
Value *LHSOp, *RHSOp;
if (match(Op0, m_PtrToInt(m_Value(LHSOp))) &&
    match(Op1, m_PtrToInt(m_Value(RHSOp))))
  if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
    return replaceInstUsesWith(I, Res);

// trunc(p)-trunc(q) -> trunc(p-q)
if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) &&
    match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp)))))
  if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType()))
    return replaceInstUsesWith(I, Res);

// Canonicalize a shifty way to code absolute value to the common pattern.
// There are 2 potential commuted variants.
// We're relying on the fact that we only do this transform when the shift has
// exactly 2 uses and the xor has exactly 1 use (otherwise, we might increase
// instructions).
Value *A;
const APInt *ShAmt;
Type *Ty = I.getType();
if (match(Op1, m_AShr(m_Value(A), m_APInt(ShAmt))) &&
    Op1->hasNUses(2) && *ShAmt == Ty->getScalarSizeInBits() - 1 &&
    match(Op0, m_OneUse(m_c_Xor(m_Specific(A), m_Specific(Op1))))) {
  // B = ashr i32 A, 31 ; smear the sign bit
  // sub (xor A, B), B  ; flip bits if negative and subtract -1 (add 1)
  // --> (A < 0) ? -A : A
  Value *Cmp = Builder.CreateICmpSLT(A, ConstantInt::getNullValue(Ty));
  // Copy the nuw/nsw flags from the sub to the negate.
  Value *Neg = Builder.CreateNeg(A, "", I.hasNoUnsignedWrap(),
                                 I.hasNoSignedWrap());
  return SelectInst::Create(Cmp, Neg, A);
}

bool Changed = false;
if (!I.hasNoSignedWrap() && willNotOverflowSignedSub(Op0, Op1, I)) {
  Changed = true;
  I.setHasNoSignedWrap(true);
}
if (!I.hasNoUnsignedWrap() && willNotOverflowUnsignedSub(Op0, Op1, I)) {
  Changed = true;
  I.setHasNoUnsignedWrap(true);
}

return Changed ? &I : nullptr;
1825}

1827Instruction *InstCombiner::visitFSub(BinaryOperator &I) {
if (Value *V = SimplifyFSubInst(I.getOperand(0), I.getOperand(1),
                                I.getFastMathFlags(),
                                SQ.getWithInstruction(&I)))
  return replaceInstUsesWith(I, V);

if (Instruction *X = foldShuffledBinop(I))
  return X;

// Subtraction from -0.0 is the canonical form of fneg.
// fsub nsz 0, X ==> fsub nsz -0.0, X
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (I.hasNoSignedZeros() && match(Op0, m_PosZeroFP()))
  return BinaryOperator::CreateFNegFMF(Op1, &I);

// If Op0 is not -0.0 or we can ignore -0.0: Z - (X - Y) --> Z + (Y - X)
// Canonicalize to fadd to make analysis easier.
// This can also help codegen because fadd is commutative.
// Note that if this fsub was really an fneg, the fadd with -0.0 will get
// killed later. We still limit that particular transform with 'hasOneUse'
// because an fneg is assumed better/cheaper than a generic fsub.
Value *X, *Y;
if (I.hasNoSignedZeros() || CannotBeNegativeZero(Op0, SQ.TLI)) {
  if (match(Op1, m_OneUse(m_FSub(m_Value(X), m_Value(Y))))) {
    Value *NewSub = Builder.CreateFSubFMF(Y, X, &I);
    return BinaryOperator::CreateFAddFMF(Op0, NewSub, &I);
  }
}

if (isa<Constant>(Op0))
  if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
    if (Instruction *NV = FoldOpIntoSelect(I, SI))
      return NV;

// X - C --> X + (-C)
// But don't transform constant expressions because there's an inverse fold
// for X + (-Y) --> X - Y.
Constant *C;
if (match(Op1, m_Constant(C)) && !isa<ConstantExpr>(Op1))
  return BinaryOperator::CreateFAddFMF(Op0, ConstantExpr::getFNeg(C), &I);

// X - (-Y) --> X + Y
if (match(Op1, m_FNeg(m_Value(Y))))
  return BinaryOperator::CreateFAddFMF(Op0, Y, &I);

// Similar to above, but look through a cast of the negated value:
// X - (fptrunc(-Y)) --> X + fptrunc(Y)
if (match(Op1, m_OneUse(m_FPTrunc(m_FNeg(m_Value(Y)))))) {
  Value *TruncY = Builder.CreateFPTrunc(Y, I.getType());
  return BinaryOperator::CreateFAddFMF(Op0, TruncY, &I);
}
// X - (fpext(-Y)) --> X + fpext(Y)
if (match(Op1, m_OneUse(m_FPExt(m_FNeg(m_Value(Y)))))) {
  Value *ExtY = Builder.CreateFPExt(Y, I.getType());
  return BinaryOperator::CreateFAddFMF(Op0, ExtY, &I);
}

// Handle specials cases for FSub with selects feeding the operation
if (Value *V = SimplifySelectsFeedingBinaryOp(I, Op0, Op1))
  return replaceInstUsesWith(I, V);

if (I.hasAllowReassoc() && I.hasNoSignedZeros()) {
  if (Value *V = FAddCombine(Builder).simplify(&I))
    return replaceInstUsesWith(I, V);
}

return nullptr;
1894}