-
+//===- Reassociate.cpp - Reassociate binary expressions -------------------===//
//
// The LLVM Compiler Infrastructure
//
//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "reassociate"
#include "llvm/Transforms/Scalar.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Function.h"
-#include "llvm/IRBuilder.h"
-#include "llvm/Instructions.h"
-#include "llvm/IntrinsicInst.h"
-#include "llvm/Pass.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
-#include "llvm/Assembly/Writer.h"
-#include "llvm/Support/CFG.h"
+#include "llvm/Analysis/GlobalsModRef.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/ValueHandle.h"
+#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Support/ValueHandle.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/Local.h"
#include <algorithm>
-#include <deque>
-#include <set>
using namespace llvm;
+#define DEBUG_TYPE "reassociate"
+
STATISTIC(NumChanged, "Number of insts reassociated");
STATISTIC(NumAnnihil, "Number of expr tree annihilated");
STATISTIC(NumFactor , "Number of multiplies factored");
}
#ifndef NDEBUG
-/// PrintOps - Print out the expression identified in the Ops list.
+/// Print out the expression identified in the Ops list.
///
static void PrintOps(Instruction *I, const SmallVectorImpl<ValueEntry> &Ops) {
Module *M = I->getParent()->getParent()->getParent();
<< *Ops[0].Op->getType() << '\t';
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
dbgs() << "[ ";
- WriteAsOperand(dbgs(), Ops[i].Op, false, M);
+ Ops[i].Op->printAsOperand(dbgs(), false, M);
dbgs() << ", #" << Ops[i].Rank << "] ";
}
}
}
};
};
-}
-
-namespace {
-
- class Reassociate;
-
- class isInstDeadFunc {
- public:
- bool operator() (Instruction* I) {
- return isInstructionTriviallyDead(I);
- }
- };
- class RmInstCallBackFunc {
- Reassociate *reassoc_;
- public:
- RmInstCallBackFunc(Reassociate* ra): reassoc_(ra) {}
- inline void operator() (Instruction*);
- };
-
- // The worklist has following traits:
- // - it is pretty much a dequeue.
- // - has "set" semantic, meaning all elements in the worklist are distinct.
- // - efficient in-place element removal (by replacing the element with
- // invalid value 0).
- //
- class RedoWorklist {
+ /// Utility class representing a non-constant Xor-operand. We classify
+ /// non-constant Xor-Operands into two categories:
+ /// C1) The operand is in the form "X & C", where C is a constant and C != ~0
+ /// C2)
+ /// C2.1) The operand is in the form of "X | C", where C is a non-zero
+ /// constant.
+ /// C2.2) Any operand E which doesn't fall into C1 and C2.1, we view this
+ /// operand as "E | 0"
+ class XorOpnd {
public:
- typedef AssertingVH<Instruction> value_type;
- typedef std::set<value_type> set_type;
- typedef std::deque<value_type> deque_type;
- // caller cannot modify element via iterator, hence constant.
- typedef deque_type::const_iterator iterator;
- typedef deque_type::const_iterator const_iterator;
- typedef deque_type::size_type size_type;
-
- RedoWorklist() {}
-
- bool empty() const {
- return deque_.empty();
- }
-
- size_type size() const {
- return deque_.size();
- }
-
- // return true iff X is in the worklist
- bool found(const value_type &X) {
- return set_.find(X) != set_.end();
- }
-
- iterator begin() {
- return deque_.begin();
- }
-
- const_iterator begin() const {
- return deque_.begin();
- }
-
- iterator end() {
- return deque_.end();
- }
-
- const_iterator end() const {
- return deque_.end();
- }
-
- const value_type &back() const {
- assert(!empty() && "worklist is empty");
- return deque_.back();
- }
-
- // If element X is already in the worklist, do nothing but return false;
- // otherwise, append X to the worklist and return true.
- //
- bool push_back(const value_type &X) {
- bool result = set_.insert(X).second;
- if (result)
- deque_.push_back(X);
- return result;
- }
-
- // insert() is the alias of push_back()
- bool insert(const value_type &X) {
- return push_back(X);
- }
-
- void clear() {
- set_.clear();
- deque_.clear();
- }
-
- void pop_back() {
- assert(!empty() && "worklist is empty");
- set_.erase(back());
- deque_.pop_back();
- }
-
- value_type pop_back_val() {
- value_type Ret = back();
- pop_back();
- return Ret;
- }
-
- const value_type &front() const {
- assert(!empty() && "worklist is empty");
- return deque_.front();
- }
-
- void pop_front() {
- assert(!empty() && "worklist is empty");
- set_.erase(front());
- deque_.pop_front();
- }
-
- value_type pop_front_val() {
- value_type Ret = front();
- pop_front();
- return Ret;
- }
-
- // Remove an element from the worklist. Return true iff the element was
- // in the worklist.
- bool remove(const value_type& X);
-
- template <typename pred, typename call_back_func>
- int inplace_remove(pred p, call_back_func cb);
-
- template <typename pred, typename call_back_func>
- int inplace_rremove(pred p, call_back_func cb);
-
- void append(RedoWorklist&);
-
+ XorOpnd(Value *V);
+
+ bool isInvalid() const { return SymbolicPart == nullptr; }
+ bool isOrExpr() const { return isOr; }
+ Value *getValue() const { return OrigVal; }
+ Value *getSymbolicPart() const { return SymbolicPart; }
+ unsigned getSymbolicRank() const { return SymbolicRank; }
+ const APInt &getConstPart() const { return ConstPart; }
+
+ void Invalidate() { SymbolicPart = OrigVal = nullptr; }
+ void setSymbolicRank(unsigned R) { SymbolicRank = R; }
+
+ // Sort the XorOpnd-Pointer in ascending order of symbolic-value-rank.
+ // The purpose is twofold:
+ // 1) Cluster together the operands sharing the same symbolic-value.
+ // 2) Operand having smaller symbolic-value-rank is permuted earlier, which
+ // could potentially shorten crital path, and expose more loop-invariants.
+ // Note that values' rank are basically defined in RPO order (FIXME).
+ // So, if Rank(X) < Rank(Y) < Rank(Z), it means X is defined earlier
+ // than Y which is defined earlier than Z. Permute "x | 1", "Y & 2",
+ // "z" in the order of X-Y-Z is better than any other orders.
+ struct PtrSortFunctor {
+ bool operator()(XorOpnd * const &LHS, XorOpnd * const &RHS) {
+ return LHS->getSymbolicRank() < RHS->getSymbolicRank();
+ }
+ };
private:
- set_type set_;
- deque_type deque_;
+ Value *OrigVal;
+ Value *SymbolicPart;
+ APInt ConstPart;
+ unsigned SymbolicRank;
+ bool isOr;
};
+}
+namespace {
class Reassociate : public FunctionPass {
- friend class RmInstCallBackFunc;
-
DenseMap<BasicBlock*, unsigned> RankMap;
DenseMap<AssertingVH<Value>, unsigned> ValueRankMap;
- RedoWorklist RedoInsts;
- RedoWorklist TmpRedoInsts;
+ SetVector<AssertingVH<Instruction> > RedoInsts;
bool MadeChange;
public:
static char ID; // Pass identification, replacement for typeid
initializeReassociatePass(*PassRegistry::getPassRegistry());
}
- bool runOnFunction(Function &F);
+ bool runOnFunction(Function &F) override;
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
+ AU.addPreserved<GlobalsAAWrapperPass>();
}
private:
void BuildRankMap(Function &F);
unsigned getRank(Value *V);
+ void canonicalizeOperands(Instruction *I);
void ReassociateExpression(BinaryOperator *I);
void RewriteExprTree(BinaryOperator *I, SmallVectorImpl<ValueEntry> &Ops);
Value *OptimizeExpression(BinaryOperator *I,
SmallVectorImpl<ValueEntry> &Ops);
Value *OptimizeAdd(Instruction *I, SmallVectorImpl<ValueEntry> &Ops);
+ Value *OptimizeXor(Instruction *I, SmallVectorImpl<ValueEntry> &Ops);
+ bool CombineXorOpnd(Instruction *I, XorOpnd *Opnd1, APInt &ConstOpnd,
+ Value *&Res);
+ bool CombineXorOpnd(Instruction *I, XorOpnd *Opnd1, XorOpnd *Opnd2,
+ APInt &ConstOpnd, Value *&Res);
bool collectMultiplyFactors(SmallVectorImpl<ValueEntry> &Ops,
SmallVectorImpl<Factor> &Factors);
Value *buildMinimalMultiplyDAG(IRBuilder<> &Builder,
SmallVectorImpl<Factor> &Factors);
- void removeNegFromMulOps(SmallVectorImpl<ValueEntry> &Ops);
Value *OptimizeMul(BinaryOperator *I, SmallVectorImpl<ValueEntry> &Ops);
Value *RemoveFactorFromExpression(Value *V, Value *Factor);
void EraseInst(Instruction *I);
- void EraseInstCallBack(Instruction *I);
- void EraseAllDeadInst();
void OptimizeInst(Instruction *I);
+ Instruction *canonicalizeNegConstExpr(Instruction *I);
};
}
+XorOpnd::XorOpnd(Value *V) {
+ assert(!isa<ConstantInt>(V) && "No ConstantInt");
+ OrigVal = V;
+ Instruction *I = dyn_cast<Instruction>(V);
+ SymbolicRank = 0;
+
+ if (I && (I->getOpcode() == Instruction::Or ||
+ I->getOpcode() == Instruction::And)) {
+ Value *V0 = I->getOperand(0);
+ Value *V1 = I->getOperand(1);
+ if (isa<ConstantInt>(V0))
+ std::swap(V0, V1);
+
+ if (ConstantInt *C = dyn_cast<ConstantInt>(V1)) {
+ ConstPart = C->getValue();
+ SymbolicPart = V0;
+ isOr = (I->getOpcode() == Instruction::Or);
+ return;
+ }
+ }
+
+ // view the operand as "V | 0"
+ SymbolicPart = V;
+ ConstPart = APInt::getNullValue(V->getType()->getIntegerBitWidth());
+ isOr = true;
+}
+
char Reassociate::ID = 0;
INITIALIZE_PASS(Reassociate, "reassociate",
"Reassociate expressions", false, false)
// Public interface to the Reassociate pass
FunctionPass *llvm::createReassociatePass() { return new Reassociate(); }
-/// isReassociableOp - Return true if V is an instruction of the specified
-/// opcode and if it only has one use.
+/// Return true if V is an instruction of the specified opcode and if it
+/// only has one use.
static BinaryOperator *isReassociableOp(Value *V, unsigned Opcode) {
if (V->hasOneUse() && isa<Instruction>(V) &&
- cast<Instruction>(V)->getOpcode() == Opcode)
+ cast<Instruction>(V)->getOpcode() == Opcode &&
+ (!isa<FPMathOperator>(V) ||
+ cast<Instruction>(V)->hasUnsafeAlgebra()))
return cast<BinaryOperator>(V);
- return 0;
-}
-
-static bool isUnmovableInstruction(Instruction *I) {
- if (I->getOpcode() == Instruction::PHI ||
- I->getOpcode() == Instruction::LandingPad ||
- I->getOpcode() == Instruction::Alloca ||
- I->getOpcode() == Instruction::Load ||
- I->getOpcode() == Instruction::Invoke ||
- (I->getOpcode() == Instruction::Call &&
- !isa<DbgInfoIntrinsic>(I)) ||
- I->getOpcode() == Instruction::UDiv ||
- I->getOpcode() == Instruction::SDiv ||
- I->getOpcode() == Instruction::FDiv ||
- I->getOpcode() == Instruction::URem ||
- I->getOpcode() == Instruction::SRem ||
- I->getOpcode() == Instruction::FRem)
- return true;
- return false;
-}
-
-inline void RmInstCallBackFunc::operator() (Instruction* I) {
- reassoc_->EraseInstCallBack(I);
-}
-
-// Remove an item from the worklist. Return true iff the element was
-// in the worklist.
-bool RedoWorklist::remove(const value_type& X) {
- if (set_.erase(X)) {
- deque_type::iterator I = std::find(deque_.begin(), deque_.end(), X);
- assert(I != deque_.end() && "Can not find element");
- deque_.erase(I);
- return true;
- }
- return false;
+ return nullptr;
}
-// Forward go through each element e, calling p(e) to tell if e should be
-// removed or not; if p(e) = true, then e will be replaced with NULL to
-// indicate it is removed from the worklist, and functor cb will be
-// called for further processing on e. The functors should not invalidate
-// the iterator by inserting or deleteing element to and from the worklist.
-//
-// Returns the number of instruction being deleted.
-template <typename pred, typename call_back_func>
-int RedoWorklist::inplace_remove(pred p, call_back_func cb) {
- int cnt = 0;
- for (typename deque_type::iterator iter = deque_.begin(),
- iter_e = deque_.end(); iter != iter_e; iter++) {
- value_type &element = *iter;
- if (p(element) && set_.erase(element)) {
- Instruction* t = element;
- element.~value_type();
- new (&element) value_type(NULL);
- cb(t);
- cnt ++;
- }
- }
- return cnt;
-}
-
-// inplace_rremove() is the same as inplace_remove() except that elements
-// are visited in backward order.
-template <typename pred, typename call_back_func>
-int RedoWorklist::inplace_rremove(pred p, call_back_func cb) {
- int cnt = 0;
- for (typename deque_type::reverse_iterator iter = deque_.rbegin(),
- iter_e = deque_.rend(); iter != iter_e; iter++) {
- value_type &element = *iter;
- if (p(element) && set_.erase(element)) {
- Instruction* t = element;
- element.~value_type();
- new (&element) value_type(NULL);
- cb(t);
- cnt ++;
- }
- }
- return cnt;
-}
-
-void RedoWorklist::append(RedoWorklist& that) {
- deque_type &that_deque = that.deque_;
-
- while (!that_deque.empty()) {
- push_back(that_deque.front());
- that_deque.pop_front();
- }
- that.clear();
+static BinaryOperator *isReassociableOp(Value *V, unsigned Opcode1,
+ unsigned Opcode2) {
+ if (V->hasOneUse() && isa<Instruction>(V) &&
+ (cast<Instruction>(V)->getOpcode() == Opcode1 ||
+ cast<Instruction>(V)->getOpcode() == Opcode2) &&
+ (!isa<FPMathOperator>(V) ||
+ cast<Instruction>(V)->hasUnsafeAlgebra()))
+ return cast<BinaryOperator>(V);
+ return nullptr;
}
void Reassociate::BuildRankMap(Function &F) {
unsigned i = 2;
- // Assign distinct ranks to function arguments
- for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
+ // Assign distinct ranks to function arguments.
+ for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I) {
ValueRankMap[&*I] = ++i;
+ DEBUG(dbgs() << "Calculated Rank[" << I->getName() << "] = " << i << "\n");
+ }
ReversePostOrderTraversal<Function*> RPOT(&F);
for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
// we cannot move. This ensures that the ranks for these instructions are
// all different in the block.
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
- if (isUnmovableInstruction(I))
+ if (mayBeMemoryDependent(*I))
ValueRankMap[&*I] = ++BBRank;
}
}
unsigned Reassociate::getRank(Value *V) {
Instruction *I = dyn_cast<Instruction>(V);
- if (I == 0) {
+ if (!I) {
if (isa<Argument>(V)) return ValueRankMap[V]; // Function argument.
return 0; // Otherwise it's a global or constant, rank 0.
}
// If this is a not or neg instruction, do not count it for rank. This
// assures us that X and ~X will have the same rank.
- if (!I->getType()->isIntegerTy() ||
- (!BinaryOperator::isNot(I) && !BinaryOperator::isNeg(I)))
+ if (!BinaryOperator::isNot(I) && !BinaryOperator::isNeg(I) &&
+ !BinaryOperator::isFNeg(I))
++Rank;
- //DEBUG(dbgs() << "Calculated Rank[" << V->getName() << "] = "
- // << Rank << "\n");
+ DEBUG(dbgs() << "Calculated Rank[" << V->getName() << "] = " << Rank << "\n");
return ValueRankMap[I] = Rank;
}
-/// LowerNegateToMultiply - Replace 0-X with X*-1.
-///
+// Canonicalize constants to RHS. Otherwise, sort the operands by rank.
+void Reassociate::canonicalizeOperands(Instruction *I) {
+ assert(isa<BinaryOperator>(I) && "Expected binary operator.");
+ assert(I->isCommutative() && "Expected commutative operator.");
+
+ Value *LHS = I->getOperand(0);
+ Value *RHS = I->getOperand(1);
+ unsigned LHSRank = getRank(LHS);
+ unsigned RHSRank = getRank(RHS);
+
+ if (isa<Constant>(RHS))
+ return;
+
+ if (isa<Constant>(LHS) || RHSRank < LHSRank)
+ cast<BinaryOperator>(I)->swapOperands();
+}
+
+static BinaryOperator *CreateAdd(Value *S1, Value *S2, const Twine &Name,
+ Instruction *InsertBefore, Value *FlagsOp) {
+ if (S1->getType()->isIntOrIntVectorTy())
+ return BinaryOperator::CreateAdd(S1, S2, Name, InsertBefore);
+ else {
+ BinaryOperator *Res =
+ BinaryOperator::CreateFAdd(S1, S2, Name, InsertBefore);
+ Res->setFastMathFlags(cast<FPMathOperator>(FlagsOp)->getFastMathFlags());
+ return Res;
+ }
+}
+
+static BinaryOperator *CreateMul(Value *S1, Value *S2, const Twine &Name,
+ Instruction *InsertBefore, Value *FlagsOp) {
+ if (S1->getType()->isIntOrIntVectorTy())
+ return BinaryOperator::CreateMul(S1, S2, Name, InsertBefore);
+ else {
+ BinaryOperator *Res =
+ BinaryOperator::CreateFMul(S1, S2, Name, InsertBefore);
+ Res->setFastMathFlags(cast<FPMathOperator>(FlagsOp)->getFastMathFlags());
+ return Res;
+ }
+}
+
+static BinaryOperator *CreateNeg(Value *S1, const Twine &Name,
+ Instruction *InsertBefore, Value *FlagsOp) {
+ if (S1->getType()->isIntOrIntVectorTy())
+ return BinaryOperator::CreateNeg(S1, Name, InsertBefore);
+ else {
+ BinaryOperator *Res = BinaryOperator::CreateFNeg(S1, Name, InsertBefore);
+ Res->setFastMathFlags(cast<FPMathOperator>(FlagsOp)->getFastMathFlags());
+ return Res;
+ }
+}
+
+/// Replace 0-X with X*-1.
static BinaryOperator *LowerNegateToMultiply(Instruction *Neg) {
- Constant *Cst = Constant::getAllOnesValue(Neg->getType());
+ Type *Ty = Neg->getType();
+ Constant *NegOne = Ty->isIntOrIntVectorTy() ?
+ ConstantInt::getAllOnesValue(Ty) : ConstantFP::get(Ty, -1.0);
- BinaryOperator *Res =
- BinaryOperator::CreateMul(Neg->getOperand(1), Cst, "",Neg);
- Neg->setOperand(1, Constant::getNullValue(Neg->getType())); // Drop use of op.
+ BinaryOperator *Res = CreateMul(Neg->getOperand(1), NegOne, "", Neg, Neg);
+ Neg->setOperand(1, Constant::getNullValue(Ty)); // Drop use of op.
Res->takeName(Neg);
Neg->replaceAllUsesWith(Res);
Res->setDebugLoc(Neg->getDebugLoc());
return Res;
}
-/// CarmichaelShift - Returns k such that lambda(2^Bitwidth) = 2^k, where lambda
-/// is the Carmichael function. This means that x^(2^k) === 1 mod 2^Bitwidth for
+/// Returns k such that lambda(2^Bitwidth) = 2^k, where lambda is the Carmichael
+/// function. This means that x^(2^k) === 1 mod 2^Bitwidth for
/// every odd x, i.e. x^(2^k) = 1 for every odd x in Bitwidth-bit arithmetic.
/// Note that 0 <= k < Bitwidth, and if Bitwidth > 3 then x^(2^k) = 0 for every
/// even x in Bitwidth-bit arithmetic.
return Bitwidth - 2;
}
-/// IncorporateWeight - Add the extra weight 'RHS' to the existing weight 'LHS',
+/// Add the extra weight 'RHS' to the existing weight 'LHS',
/// reducing the combined weight using any special properties of the operation.
/// The existing weight LHS represents the computation X op X op ... op X where
/// X occurs LHS times. The combined weight represents X op X op ... op X with
LHS = 0; // 1 + 1 === 0 modulo 2.
return;
}
- if (Opcode == Instruction::Add) {
+ if (Opcode == Instruction::Add || Opcode == Instruction::FAdd) {
// TODO: Reduce the weight by exploiting nsw/nuw?
LHS += RHS;
return;
}
- assert(Opcode == Instruction::Mul && "Unknown associative operation!");
+ assert((Opcode == Instruction::Mul || Opcode == Instruction::FMul) &&
+ "Unknown associative operation!");
unsigned Bitwidth = LHS.getBitWidth();
// If CM is the Carmichael number then a weight W satisfying W >= CM+Bitwidth
// can be replaced with W-CM. That's because x^W=x^(W-CM) for every Bitwidth
}
}
-/// EvaluateRepeatedConstant - Compute C op C op ... op C where the constant C
-/// is repeated Weight times.
-static Constant *EvaluateRepeatedConstant(unsigned Opcode, Constant *C,
- APInt Weight) {
- // For addition the result can be efficiently computed as the product of the
- // constant and the weight.
- if (Opcode == Instruction::Add)
- return ConstantExpr::getMul(C, ConstantInt::get(C->getContext(), Weight));
-
- // The weight might be huge, so compute by repeated squaring to ensure that
- // compile time is proportional to the logarithm of the weight.
- Constant *Result = 0;
- Constant *Power = C; // Successively C, C op C, (C op C) op (C op C) etc.
- // Visit the bits in Weight.
- while (Weight != 0) {
- // If the current bit in Weight is non-zero do Result = Result op Power.
- if (Weight[0])
- Result = Result ? ConstantExpr::get(Opcode, Result, Power) : Power;
- // Move on to the next bit if any more are non-zero.
- Weight = Weight.lshr(1);
- if (Weight.isMinValue())
- break;
- // Square the power.
- Power = ConstantExpr::get(Opcode, Power, Power);
- }
-
- assert(Result && "Only positive weights supported!");
- return Result;
-}
-
typedef std::pair<Value*, APInt> RepeatedValue;
-/// LinearizeExprTree - Given an associative binary expression, return the leaf
+/// Given an associative binary expression, return the leaf
/// nodes in Ops along with their weights (how many times the leaf occurs). The
/// original expression is the same as
/// (Ops[0].first op Ops[0].first op ... Ops[0].first) <- Ops[0].second times
/// op
/// (Ops[N].first op Ops[N].first op ... Ops[N].first) <- Ops[N].second times
///
-/// Note that the values Ops[0].first, ..., Ops[N].first are all distinct, and
-/// they are all non-constant except possibly for the last one, which if it is
-/// constant will have weight one (Ops[N].second === 1).
+/// Note that the values Ops[0].first, ..., Ops[N].first are all distinct.
///
/// This routine may modify the function, in which case it returns 'true'. The
/// changes it makes may well be destructive, changing the value computed by 'I'
DEBUG(dbgs() << "LINEARIZE: " << *I << '\n');
unsigned Bitwidth = I->getType()->getScalarType()->getPrimitiveSizeInBits();
unsigned Opcode = I->getOpcode();
- assert(Instruction::isAssociative(Opcode) &&
- Instruction::isCommutative(Opcode) &&
+ assert(I->isAssociative() && I->isCommutative() &&
"Expected an associative and commutative operation!");
- // If we see an absorbing element then the entire expression must be equal to
- // it. For example, if this is a multiplication expression and zero occurs as
- // an operand somewhere in it then the result of the expression must be zero.
- Constant *Absorber = ConstantExpr::getBinOpAbsorber(Opcode, I->getType());
// Visit all operands of the expression, keeping track of their weight (the
// number of paths from the expression root to the operand, or if you like
// ways to get to it.
SmallVector<std::pair<BinaryOperator*, APInt>, 8> Worklist; // (Op, Weight)
Worklist.push_back(std::make_pair(I, APInt(Bitwidth, 1)));
- bool MadeChange = false;
+ bool Changed = false;
// Leaves of the expression are values that either aren't the right kind of
// operation (eg: a constant, or a multiply in an add tree), or are, but have
DEBUG(dbgs() << "OPERAND: " << *Op << " (" << Weight << ")\n");
assert(!Op->use_empty() && "No uses, so how did we get to it?!");
- // If the expression contains an absorbing element then there is no need
- // to analyze it further: it must evaluate to the absorbing element.
- if (Op == Absorber && !Weight.isMinValue()) {
- Ops.push_back(std::make_pair(Absorber, APInt(Bitwidth, 1)));
- return MadeChange;
- }
-
// If this is a binary operation of the right kind with only one use then
// add its operands to the expression.
if (BinaryOperator *BO = isReassociableOp(Op, Opcode)) {
- assert(Visited.insert(Op) && "Not first visit!");
+ assert(Visited.insert(Op).second && "Not first visit!");
DEBUG(dbgs() << "DIRECT ADD: " << *Op << " (" << Weight << ")\n");
Worklist.push_back(std::make_pair(BO, Weight));
continue;
LeafMap::iterator It = Leaves.find(Op);
if (It == Leaves.end()) {
// Not in the leaf map. Must be the first time we saw this operand.
- assert(Visited.insert(Op) && "Not first visit!");
+ assert(Visited.insert(Op).second && "Not first visit!");
if (!Op->hasOneUse()) {
// This value has uses not accounted for by the expression, so it is
// not safe to modify. Mark it as being a leaf.
// exactly one such use, drop this new use of the leaf.
assert(!Op->hasOneUse() && "Only one use, but we got here twice!");
I->setOperand(OpIdx, UndefValue::get(I->getType()));
- MadeChange = true;
+ Changed = true;
// If the leaf is a binary operation of the right kind and we now see
// that its multiple original uses were in fact all by nodes belonging
// expression. This means that it can safely be modified. See if we
// can usefully morph it into an expression of the right kind.
assert((!isa<Instruction>(Op) ||
- cast<Instruction>(Op)->getOpcode() != Opcode) &&
+ cast<Instruction>(Op)->getOpcode() != Opcode
+ || (isa<FPMathOperator>(Op) &&
+ !cast<Instruction>(Op)->hasUnsafeAlgebra())) &&
"Should have been handled above!");
assert(Op->hasOneUse() && "Has uses outside the expression tree!");
// If this is a multiply expression, turn any internal negations into
// multiplies by -1 so they can be reassociated.
- BinaryOperator *BO = dyn_cast<BinaryOperator>(Op);
- if (Opcode == Instruction::Mul && BO && BinaryOperator::isNeg(BO)) {
- DEBUG(dbgs() << "MORPH LEAF: " << *Op << " (" << Weight << ") TO ");
- BO = LowerNegateToMultiply(BO);
- DEBUG(dbgs() << *BO << 'n');
- Worklist.push_back(std::make_pair(BO, Weight));
- MadeChange = true;
- continue;
- }
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op))
+ if ((Opcode == Instruction::Mul && BinaryOperator::isNeg(BO)) ||
+ (Opcode == Instruction::FMul && BinaryOperator::isFNeg(BO))) {
+ DEBUG(dbgs() << "MORPH LEAF: " << *Op << " (" << Weight << ") TO ");
+ BO = LowerNegateToMultiply(BO);
+ DEBUG(dbgs() << *BO << '\n');
+ Worklist.push_back(std::make_pair(BO, Weight));
+ Changed = true;
+ continue;
+ }
// Failed to morph into an expression of the right type. This really is
// a leaf.
// The leaves, repeated according to their weights, represent the linearized
// form of the expression.
- Constant *Cst = 0; // Accumulate constants here.
for (unsigned i = 0, e = LeafOrder.size(); i != e; ++i) {
Value *V = LeafOrder[i];
LeafMap::iterator It = Leaves.find(V);
continue;
// Ensure the leaf is only output once.
It->second = 0;
- // Glob all constants together into Cst.
- if (Constant *C = dyn_cast<Constant>(V)) {
- C = EvaluateRepeatedConstant(Opcode, C, Weight);
- Cst = Cst ? ConstantExpr::get(Opcode, Cst, C) : C;
- continue;
- }
- // Add non-constant
Ops.push_back(std::make_pair(V, Weight));
}
- // Add any constants back into Ops, all globbed together and reduced to having
- // weight 1 for the convenience of users.
- Constant *Identity = ConstantExpr::getBinOpIdentity(Opcode, I->getType());
- if (Cst && Cst != Identity) {
- // If combining multiple constants resulted in the absorber then the entire
- // expression must evaluate to the absorber.
- if (Cst == Absorber)
- Ops.clear();
- Ops.push_back(std::make_pair(Cst, APInt(Bitwidth, 1)));
- }
-
// For nilpotent operations or addition there may be no operands, for example
// because the expression was "X xor X" or consisted of 2^Bitwidth additions:
// in both cases the weight reduces to 0 causing the value to be skipped.
if (Ops.empty()) {
+ Constant *Identity = ConstantExpr::getBinOpIdentity(Opcode, I->getType());
assert(Identity && "Associative operation without identity!");
- Ops.push_back(std::make_pair(Identity, APInt(Bitwidth, 1)));
+ Ops.emplace_back(Identity, APInt(Bitwidth, 1));
}
- return MadeChange;
+ return Changed;
}
-// RewriteExprTree - Now that the operands for this expression tree are
-// linearized and optimized, emit them in-order.
+/// Now that the operands for this expression tree are
+/// linearized and optimized, emit them in-order.
void Reassociate::RewriteExprTree(BinaryOperator *I,
SmallVectorImpl<ValueEntry> &Ops) {
assert(Ops.size() > 1 && "Single values should be used directly!");
- // Since our optimizations never increase the number of operations, the new
- // expression can always be written by reusing the existing binary operators
+ // Since our optimizations should never increase the number of operations, the
+ // new expression can usually be written reusing the existing binary operators
// from the original expression tree, without creating any new instructions,
// though the rewritten expression may have a completely different topology.
// We take care to not change anything if the new expression will be the same
unsigned Opcode = I->getOpcode();
BinaryOperator *Op = I;
+ /// NotRewritable - The operands being written will be the leaves of the new
+ /// expression and must not be used as inner nodes (via NodesToRewrite) by
+ /// mistake. Inner nodes are always reassociable, and usually leaves are not
+ /// (if they were they would have been incorporated into the expression and so
+ /// would not be leaves), so most of the time there is no danger of this. But
+ /// in rare cases a leaf may become reassociable if an optimization kills uses
+ /// of it, or it may momentarily become reassociable during rewriting (below)
+ /// due it being removed as an operand of one of its uses. Ensure that misuse
+ /// of leaf nodes as inner nodes cannot occur by remembering all of the future
+ /// leaves and refusing to reuse any of them as inner nodes.
+ SmallPtrSet<Value*, 8> NotRewritable;
+ for (unsigned i = 0, e = Ops.size(); i != e; ++i)
+ NotRewritable.insert(Ops[i].Op);
+
// ExpressionChanged - Non-null if the rewritten expression differs from the
// original in some non-trivial way, requiring the clearing of optional flags.
// Flags are cleared from the operator in ExpressionChanged up to I inclusive.
- BinaryOperator *ExpressionChanged = 0;
+ BinaryOperator *ExpressionChanged = nullptr;
for (unsigned i = 0; ; ++i) {
// The last operation (which comes earliest in the IR) is special as both
// operands will come from Ops, rather than just one with the other being
// the old operands with the new ones.
DEBUG(dbgs() << "RA: " << *Op << '\n');
if (NewLHS != OldLHS) {
- if (BinaryOperator *BO = isReassociableOp(OldLHS, Opcode))
+ BinaryOperator *BO = isReassociableOp(OldLHS, Opcode);
+ if (BO && !NotRewritable.count(BO))
NodesToRewrite.push_back(BO);
Op->setOperand(0, NewLHS);
}
if (NewRHS != OldRHS) {
- if (BinaryOperator *BO = isReassociableOp(OldRHS, Opcode))
+ BinaryOperator *BO = isReassociableOp(OldRHS, Opcode);
+ if (BO && !NotRewritable.count(BO))
NodesToRewrite.push_back(BO);
Op->setOperand(1, NewRHS);
}
Op->swapOperands();
} else {
// Overwrite with the new right-hand side.
- if (BinaryOperator *BO = isReassociableOp(Op->getOperand(1), Opcode))
+ BinaryOperator *BO = isReassociableOp(Op->getOperand(1), Opcode);
+ if (BO && !NotRewritable.count(BO))
NodesToRewrite.push_back(BO);
Op->setOperand(1, NewRHS);
ExpressionChanged = Op;
// Now deal with the left-hand side. If this is already an operation node
// from the original expression then just rewrite the rest of the expression
// into it.
- if (BinaryOperator *BO = isReassociableOp(Op->getOperand(0), Opcode)) {
+ BinaryOperator *BO = isReassociableOp(Op->getOperand(0), Opcode);
+ if (BO && !NotRewritable.count(BO)) {
Op = BO;
continue;
}
Constant *Undef = UndefValue::get(I->getType());
NewOp = BinaryOperator::Create(Instruction::BinaryOps(Opcode),
Undef, Undef, "", I);
+ if (NewOp->getType()->isFPOrFPVectorTy())
+ NewOp->setFastMathFlags(I->getFastMathFlags());
} else {
NewOp = NodesToRewrite.pop_back_val();
}
// expression tree is dominated by all of Ops.
if (ExpressionChanged)
do {
- ExpressionChanged->clearSubclassOptionalData();
+ // Preserve FastMathFlags.
+ if (isa<FPMathOperator>(I)) {
+ FastMathFlags Flags = I->getFastMathFlags();
+ ExpressionChanged->clearSubclassOptionalData();
+ ExpressionChanged->setFastMathFlags(Flags);
+ } else
+ ExpressionChanged->clearSubclassOptionalData();
+
if (ExpressionChanged == I)
break;
ExpressionChanged->moveBefore(I);
- ExpressionChanged = cast<BinaryOperator>(*ExpressionChanged->use_begin());
+ ExpressionChanged = cast<BinaryOperator>(*ExpressionChanged->user_begin());
} while (1);
// Throw away any left over nodes from the original expression.
RedoInsts.insert(NodesToRewrite[i]);
}
-/// NegateValue - Insert instructions before the instruction pointed to by BI,
+/// Insert instructions before the instruction pointed to by BI,
/// that computes the negative version of the value specified. The negative
/// version of the value is returned, and BI is left pointing at the instruction
/// that should be processed next by the reassociation pass.
static Value *NegateValue(Value *V, Instruction *BI) {
- if (Constant *C = dyn_cast<Constant>(V))
+ if (Constant *C = dyn_cast<Constant>(V)) {
+ if (C->getType()->isFPOrFPVectorTy()) {
+ return ConstantExpr::getFNeg(C);
+ }
return ConstantExpr::getNeg(C);
+ }
+
// We are trying to expose opportunity for reassociation. One of the things
// that we want to do to achieve this is to push a negation as deep into an
// the constants. We assume that instcombine will clean up the mess later if
// we introduce tons of unnecessary negation instructions.
//
- if (BinaryOperator *I = isReassociableOp(V, Instruction::Add)) {
+ if (BinaryOperator *I =
+ isReassociableOp(V, Instruction::Add, Instruction::FAdd)) {
// Push the negates through the add.
I->setOperand(0, NegateValue(I->getOperand(0), BI));
I->setOperand(1, NegateValue(I->getOperand(1), BI));
+ if (I->getOpcode() == Instruction::Add) {
+ I->setHasNoUnsignedWrap(false);
+ I->setHasNoSignedWrap(false);
+ }
// We must move the add instruction here, because the neg instructions do
// not dominate the old add instruction in general. By moving it, we are
// Okay, we need to materialize a negated version of V with an instruction.
// Scan the use lists of V to see if we have one already.
- for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
- User *U = *UI;
- if (!BinaryOperator::isNeg(U)) continue;
+ for (User *U : V->users()) {
+ if (!BinaryOperator::isNeg(U) && !BinaryOperator::isFNeg(U))
+ continue;
// We found one! Now we have to make sure that the definition dominates
// this use. We do this by moving it to the entry block (if it is a
if (Instruction *InstInput = dyn_cast<Instruction>(V)) {
if (InvokeInst *II = dyn_cast<InvokeInst>(InstInput)) {
InsertPt = II->getNormalDest()->begin();
+ } else if (auto *CPI = dyn_cast<CatchPadInst>(InstInput)) {
+ InsertPt = CPI->getNormalDest()->begin();
} else {
InsertPt = InstInput;
++InsertPt;
InsertPt = TheNeg->getParent()->getParent()->getEntryBlock().begin();
}
TheNeg->moveBefore(InsertPt);
+ if (TheNeg->getOpcode() == Instruction::Sub) {
+ TheNeg->setHasNoUnsignedWrap(false);
+ TheNeg->setHasNoSignedWrap(false);
+ } else {
+ TheNeg->andIRFlags(BI);
+ }
return TheNeg;
}
// Insert a 'neg' instruction that subtracts the value from zero to get the
// negation.
- return BinaryOperator::CreateNeg(V, V->getName() + ".neg", BI);
+ return CreateNeg(V, V->getName() + ".neg", BI, BI);
}
-/// ShouldBreakUpSubtract - Return true if we should break up this subtract of
-/// X-Y into (X + -Y).
+/// Return true if we should break up this subtract of X-Y into (X + -Y).
static bool ShouldBreakUpSubtract(Instruction *Sub) {
// If this is a negation, we can't split it up!
- if (BinaryOperator::isNeg(Sub))
+ if (BinaryOperator::isNeg(Sub) || BinaryOperator::isFNeg(Sub))
+ return false;
+
+ // Don't breakup X - undef.
+ if (isa<UndefValue>(Sub->getOperand(1)))
return false;
// Don't bother to break this up unless either the LHS is an associable add or
// subtract or if this is only used by one.
- if (isReassociableOp(Sub->getOperand(0), Instruction::Add) ||
- isReassociableOp(Sub->getOperand(0), Instruction::Sub))
+ Value *V0 = Sub->getOperand(0);
+ if (isReassociableOp(V0, Instruction::Add, Instruction::FAdd) ||
+ isReassociableOp(V0, Instruction::Sub, Instruction::FSub))
return true;
- if (isReassociableOp(Sub->getOperand(1), Instruction::Add) ||
- isReassociableOp(Sub->getOperand(1), Instruction::Sub))
+ Value *V1 = Sub->getOperand(1);
+ if (isReassociableOp(V1, Instruction::Add, Instruction::FAdd) ||
+ isReassociableOp(V1, Instruction::Sub, Instruction::FSub))
return true;
+ Value *VB = Sub->user_back();
if (Sub->hasOneUse() &&
- (isReassociableOp(Sub->use_back(), Instruction::Add) ||
- isReassociableOp(Sub->use_back(), Instruction::Sub)))
+ (isReassociableOp(VB, Instruction::Add, Instruction::FAdd) ||
+ isReassociableOp(VB, Instruction::Sub, Instruction::FSub)))
return true;
return false;
}
-/// BreakUpSubtract - If we have (X-Y), and if either X is an add, or if this is
-/// only used by an add, transform this into (X+(0-Y)) to promote better
-/// reassociation.
+/// If we have (X-Y), and if either X is an add, or if this is only used by an
+/// add, transform this into (X+(0-Y)) to promote better reassociation.
static BinaryOperator *BreakUpSubtract(Instruction *Sub) {
// Convert a subtract into an add and a neg instruction. This allows sub
// instructions to be commuted with other add instructions.
// and set it as the RHS of the add instruction we just made.
//
Value *NegVal = NegateValue(Sub->getOperand(1), Sub);
- BinaryOperator *New =
- BinaryOperator::CreateAdd(Sub->getOperand(0), NegVal, "", Sub);
+ BinaryOperator *New = CreateAdd(Sub->getOperand(0), NegVal, "", Sub, Sub);
Sub->setOperand(0, Constant::getNullValue(Sub->getType())); // Drop use of op.
Sub->setOperand(1, Constant::getNullValue(Sub->getType())); // Drop use of op.
New->takeName(Sub);
return New;
}
-/// ConvertShiftToMul - If this is a shift of a reassociable multiply or is used
-/// by one, change this into a multiply by a constant to assist with further
-/// reassociation.
+/// If this is a shift of a reassociable multiply or is used by one, change
+/// this into a multiply by a constant to assist with further reassociation.
static BinaryOperator *ConvertShiftToMul(Instruction *Shl) {
Constant *MulCst = ConstantInt::get(Shl->getType(), 1);
MulCst = ConstantExpr::getShl(MulCst, cast<Constant>(Shl->getOperand(1)));
BinaryOperator::CreateMul(Shl->getOperand(0), MulCst, "", Shl);
Shl->setOperand(0, UndefValue::get(Shl->getType())); // Drop use of op.
Mul->takeName(Shl);
+
+ // Everyone now refers to the mul instruction.
Shl->replaceAllUsesWith(Mul);
Mul->setDebugLoc(Shl->getDebugLoc());
+
+ // We can safely preserve the nuw flag in all cases. It's also safe to turn a
+ // nuw nsw shl into a nuw nsw mul. However, nsw in isolation requires special
+ // handling.
+ bool NSW = cast<BinaryOperator>(Shl)->hasNoSignedWrap();
+ bool NUW = cast<BinaryOperator>(Shl)->hasNoUnsignedWrap();
+ if (NSW && NUW)
+ Mul->setHasNoSignedWrap(true);
+ Mul->setHasNoUnsignedWrap(NUW);
return Mul;
}
-/// FindInOperandList - Scan backwards and forwards among values with the same
-/// rank as element i to see if X exists. If X does not exist, return i. This
-/// is useful when scanning for 'x' when we see '-x' because they both get the
-/// same rank.
+/// Scan backwards and forwards among values with the same rank as element i
+/// to see if X exists. If X does not exist, return i. This is useful when
+/// scanning for 'x' when we see '-x' because they both get the same rank.
static unsigned FindInOperandList(SmallVectorImpl<ValueEntry> &Ops, unsigned i,
Value *X) {
unsigned XRank = Ops[i].Rank;
unsigned e = Ops.size();
- for (unsigned j = i+1; j != e && Ops[j].Rank == XRank; ++j)
+ for (unsigned j = i+1; j != e && Ops[j].Rank == XRank; ++j) {
if (Ops[j].Op == X)
return j;
+ if (Instruction *I1 = dyn_cast<Instruction>(Ops[j].Op))
+ if (Instruction *I2 = dyn_cast<Instruction>(X))
+ if (I1->isIdenticalTo(I2))
+ return j;
+ }
// Scan backwards.
- for (unsigned j = i-1; j != ~0U && Ops[j].Rank == XRank; --j)
+ for (unsigned j = i-1; j != ~0U && Ops[j].Rank == XRank; --j) {
if (Ops[j].Op == X)
return j;
+ if (Instruction *I1 = dyn_cast<Instruction>(Ops[j].Op))
+ if (Instruction *I2 = dyn_cast<Instruction>(X))
+ if (I1->isIdenticalTo(I2))
+ return j;
+ }
return i;
}
-/// EmitAddTreeOfValues - Emit a tree of add instructions, summing Ops together
+/// Emit a tree of add instructions, summing Ops together
/// and returning the result. Insert the tree before I.
static Value *EmitAddTreeOfValues(Instruction *I,
SmallVectorImpl<WeakVH> &Ops){
Value *V1 = Ops.back();
Ops.pop_back();
Value *V2 = EmitAddTreeOfValues(I, Ops);
- return BinaryOperator::CreateAdd(V2, V1, "tmp", I);
+ return CreateAdd(V2, V1, "tmp", I, I);
}
-/// RemoveFactorFromExpression - If V is an expression tree that is a
-/// multiplication sequence, and if this sequence contains a multiply by Factor,
+/// If V is an expression tree that is a multiplication sequence,
+/// and if this sequence contains a multiply by Factor,
/// remove Factor from the tree and return the new tree.
Value *Reassociate::RemoveFactorFromExpression(Value *V, Value *Factor) {
- BinaryOperator *BO = isReassociableOp(V, Instruction::Mul);
- if (!BO) return 0;
+ BinaryOperator *BO = isReassociableOp(V, Instruction::Mul, Instruction::FMul);
+ if (!BO)
+ return nullptr;
SmallVector<RepeatedValue, 8> Tree;
MadeChange |= LinearizeExprTree(BO, Tree);
}
// If this is a negative version of this factor, remove it.
- if (ConstantInt *FC1 = dyn_cast<ConstantInt>(Factor))
+ if (ConstantInt *FC1 = dyn_cast<ConstantInt>(Factor)) {
if (ConstantInt *FC2 = dyn_cast<ConstantInt>(Factors[i].Op))
if (FC1->getValue() == -FC2->getValue()) {
FoundFactor = NeedsNegate = true;
Factors.erase(Factors.begin()+i);
break;
}
+ } else if (ConstantFP *FC1 = dyn_cast<ConstantFP>(Factor)) {
+ if (ConstantFP *FC2 = dyn_cast<ConstantFP>(Factors[i].Op)) {
+ APFloat F1(FC1->getValueAPF());
+ APFloat F2(FC2->getValueAPF());
+ F2.changeSign();
+ if (F1.compare(F2) == APFloat::cmpEqual) {
+ FoundFactor = NeedsNegate = true;
+ Factors.erase(Factors.begin() + i);
+ break;
+ }
+ }
+ }
}
if (!FoundFactor) {
// Make sure to restore the operands to the expression tree.
RewriteExprTree(BO, Factors);
- return 0;
+ return nullptr;
}
BasicBlock::iterator InsertPt = BO; ++InsertPt;
}
if (NeedsNegate)
- V = BinaryOperator::CreateNeg(V, "neg", InsertPt);
+ V = CreateNeg(V, "neg", InsertPt, BO);
return V;
}
-/// FindSingleUseMultiplyFactors - If V is a single-use multiply, recursively
-/// add its operands as factors, otherwise add V to the list of factors.
+/// If V is a single-use multiply, recursively add its operands as factors,
+/// otherwise add V to the list of factors.
///
/// Ops is the top-level list of add operands we're trying to factor.
static void FindSingleUseMultiplyFactors(Value *V,
SmallVectorImpl<Value*> &Factors,
const SmallVectorImpl<ValueEntry> &Ops) {
- BinaryOperator *BO = isReassociableOp(V, Instruction::Mul);
+ BinaryOperator *BO = isReassociableOp(V, Instruction::Mul, Instruction::FMul);
if (!BO) {
Factors.push_back(V);
return;
FindSingleUseMultiplyFactors(BO->getOperand(0), Factors, Ops);
}
-/// OptimizeAndOrXor - Optimize a series of operands to an 'and', 'or', or 'xor'
-/// instruction. This optimizes based on identities. If it can be reduced to
-/// a single Value, it is returned, otherwise the Ops list is mutated as
-/// necessary.
+/// Optimize a series of operands to an 'and', 'or', or 'xor' instruction.
+/// This optimizes based on identities. If it can be reduced to a single Value,
+/// it is returned, otherwise the Ops list is mutated as necessary.
static Value *OptimizeAndOrXor(unsigned Opcode,
SmallVectorImpl<ValueEntry> &Ops) {
// Scan the operand lists looking for X and ~X pairs, along with X,X pairs.
++NumAnnihil;
}
}
- return 0;
+ return nullptr;
+}
+
+/// Helper funciton of CombineXorOpnd(). It creates a bitwise-and
+/// instruction with the given two operands, and return the resulting
+/// instruction. There are two special cases: 1) if the constant operand is 0,
+/// it will return NULL. 2) if the constant is ~0, the symbolic operand will
+/// be returned.
+static Value *createAndInstr(Instruction *InsertBefore, Value *Opnd,
+ const APInt &ConstOpnd) {
+ if (ConstOpnd != 0) {
+ if (!ConstOpnd.isAllOnesValue()) {
+ LLVMContext &Ctx = Opnd->getType()->getContext();
+ Instruction *I;
+ I = BinaryOperator::CreateAnd(Opnd, ConstantInt::get(Ctx, ConstOpnd),
+ "and.ra", InsertBefore);
+ I->setDebugLoc(InsertBefore->getDebugLoc());
+ return I;
+ }
+ return Opnd;
+ }
+ return nullptr;
+}
+
+// Helper function of OptimizeXor(). It tries to simplify "Opnd1 ^ ConstOpnd"
+// into "R ^ C", where C would be 0, and R is a symbolic value.
+//
+// If it was successful, true is returned, and the "R" and "C" is returned
+// via "Res" and "ConstOpnd", respectively; otherwise, false is returned,
+// and both "Res" and "ConstOpnd" remain unchanged.
+//
+bool Reassociate::CombineXorOpnd(Instruction *I, XorOpnd *Opnd1,
+ APInt &ConstOpnd, Value *&Res) {
+ // Xor-Rule 1: (x | c1) ^ c2 = (x | c1) ^ (c1 ^ c1) ^ c2
+ // = ((x | c1) ^ c1) ^ (c1 ^ c2)
+ // = (x & ~c1) ^ (c1 ^ c2)
+ // It is useful only when c1 == c2.
+ if (Opnd1->isOrExpr() && Opnd1->getConstPart() != 0) {
+ if (!Opnd1->getValue()->hasOneUse())
+ return false;
+
+ const APInt &C1 = Opnd1->getConstPart();
+ if (C1 != ConstOpnd)
+ return false;
+
+ Value *X = Opnd1->getSymbolicPart();
+ Res = createAndInstr(I, X, ~C1);
+ // ConstOpnd was C2, now C1 ^ C2.
+ ConstOpnd ^= C1;
+
+ if (Instruction *T = dyn_cast<Instruction>(Opnd1->getValue()))
+ RedoInsts.insert(T);
+ return true;
+ }
+ return false;
+}
+
+
+// Helper function of OptimizeXor(). It tries to simplify
+// "Opnd1 ^ Opnd2 ^ ConstOpnd" into "R ^ C", where C would be 0, and R is a
+// symbolic value.
+//
+// If it was successful, true is returned, and the "R" and "C" is returned
+// via "Res" and "ConstOpnd", respectively (If the entire expression is
+// evaluated to a constant, the Res is set to NULL); otherwise, false is
+// returned, and both "Res" and "ConstOpnd" remain unchanged.
+bool Reassociate::CombineXorOpnd(Instruction *I, XorOpnd *Opnd1, XorOpnd *Opnd2,
+ APInt &ConstOpnd, Value *&Res) {
+ Value *X = Opnd1->getSymbolicPart();
+ if (X != Opnd2->getSymbolicPart())
+ return false;
+
+ // This many instruction become dead.(At least "Opnd1 ^ Opnd2" will die.)
+ int DeadInstNum = 1;
+ if (Opnd1->getValue()->hasOneUse())
+ DeadInstNum++;
+ if (Opnd2->getValue()->hasOneUse())
+ DeadInstNum++;
+
+ // Xor-Rule 2:
+ // (x | c1) ^ (x & c2)
+ // = (x|c1) ^ (x&c2) ^ (c1 ^ c1) = ((x|c1) ^ c1) ^ (x & c2) ^ c1
+ // = (x & ~c1) ^ (x & c2) ^ c1 // Xor-Rule 1
+ // = (x & c3) ^ c1, where c3 = ~c1 ^ c2 // Xor-rule 3
+ //
+ if (Opnd1->isOrExpr() != Opnd2->isOrExpr()) {
+ if (Opnd2->isOrExpr())
+ std::swap(Opnd1, Opnd2);
+
+ const APInt &C1 = Opnd1->getConstPart();
+ const APInt &C2 = Opnd2->getConstPart();
+ APInt C3((~C1) ^ C2);
+
+ // Do not increase code size!
+ if (C3 != 0 && !C3.isAllOnesValue()) {
+ int NewInstNum = ConstOpnd != 0 ? 1 : 2;
+ if (NewInstNum > DeadInstNum)
+ return false;
+ }
+
+ Res = createAndInstr(I, X, C3);
+ ConstOpnd ^= C1;
+
+ } else if (Opnd1->isOrExpr()) {
+ // Xor-Rule 3: (x | c1) ^ (x | c2) = (x & c3) ^ c3 where c3 = c1 ^ c2
+ //
+ const APInt &C1 = Opnd1->getConstPart();
+ const APInt &C2 = Opnd2->getConstPart();
+ APInt C3 = C1 ^ C2;
+
+ // Do not increase code size
+ if (C3 != 0 && !C3.isAllOnesValue()) {
+ int NewInstNum = ConstOpnd != 0 ? 1 : 2;
+ if (NewInstNum > DeadInstNum)
+ return false;
+ }
+
+ Res = createAndInstr(I, X, C3);
+ ConstOpnd ^= C3;
+ } else {
+ // Xor-Rule 4: (x & c1) ^ (x & c2) = (x & (c1^c2))
+ //
+ const APInt &C1 = Opnd1->getConstPart();
+ const APInt &C2 = Opnd2->getConstPart();
+ APInt C3 = C1 ^ C2;
+ Res = createAndInstr(I, X, C3);
+ }
+
+ // Put the original operands in the Redo list; hope they will be deleted
+ // as dead code.
+ if (Instruction *T = dyn_cast<Instruction>(Opnd1->getValue()))
+ RedoInsts.insert(T);
+ if (Instruction *T = dyn_cast<Instruction>(Opnd2->getValue()))
+ RedoInsts.insert(T);
+
+ return true;
+}
+
+/// Optimize a series of operands to an 'xor' instruction. If it can be reduced
+/// to a single Value, it is returned, otherwise the Ops list is mutated as
+/// necessary.
+Value *Reassociate::OptimizeXor(Instruction *I,
+ SmallVectorImpl<ValueEntry> &Ops) {
+ if (Value *V = OptimizeAndOrXor(Instruction::Xor, Ops))
+ return V;
+
+ if (Ops.size() == 1)
+ return nullptr;
+
+ SmallVector<XorOpnd, 8> Opnds;
+ SmallVector<XorOpnd*, 8> OpndPtrs;
+ Type *Ty = Ops[0].Op->getType();
+ APInt ConstOpnd(Ty->getIntegerBitWidth(), 0);
+
+ // Step 1: Convert ValueEntry to XorOpnd
+ for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
+ Value *V = Ops[i].Op;
+ if (!isa<ConstantInt>(V)) {
+ XorOpnd O(V);
+ O.setSymbolicRank(getRank(O.getSymbolicPart()));
+ Opnds.push_back(O);
+ } else
+ ConstOpnd ^= cast<ConstantInt>(V)->getValue();
+ }
+
+ // NOTE: From this point on, do *NOT* add/delete element to/from "Opnds".
+ // It would otherwise invalidate the "Opnds"'s iterator, and hence invalidate
+ // the "OpndPtrs" as well. For the similar reason, do not fuse this loop
+ // with the previous loop --- the iterator of the "Opnds" may be invalidated
+ // when new elements are added to the vector.
+ for (unsigned i = 0, e = Opnds.size(); i != e; ++i)
+ OpndPtrs.push_back(&Opnds[i]);
+
+ // Step 2: Sort the Xor-Operands in a way such that the operands containing
+ // the same symbolic value cluster together. For instance, the input operand
+ // sequence ("x | 123", "y & 456", "x & 789") will be sorted into:
+ // ("x | 123", "x & 789", "y & 456").
+ std::stable_sort(OpndPtrs.begin(), OpndPtrs.end(), XorOpnd::PtrSortFunctor());
+
+ // Step 3: Combine adjacent operands
+ XorOpnd *PrevOpnd = nullptr;
+ bool Changed = false;
+ for (unsigned i = 0, e = Opnds.size(); i < e; i++) {
+ XorOpnd *CurrOpnd = OpndPtrs[i];
+ // The combined value
+ Value *CV;
+
+ // Step 3.1: Try simplifying "CurrOpnd ^ ConstOpnd"
+ if (ConstOpnd != 0 && CombineXorOpnd(I, CurrOpnd, ConstOpnd, CV)) {
+ Changed = true;
+ if (CV)
+ *CurrOpnd = XorOpnd(CV);
+ else {
+ CurrOpnd->Invalidate();
+ continue;
+ }
+ }
+
+ if (!PrevOpnd || CurrOpnd->getSymbolicPart() != PrevOpnd->getSymbolicPart()) {
+ PrevOpnd = CurrOpnd;
+ continue;
+ }
+
+ // step 3.2: When previous and current operands share the same symbolic
+ // value, try to simplify "PrevOpnd ^ CurrOpnd ^ ConstOpnd"
+ //
+ if (CombineXorOpnd(I, CurrOpnd, PrevOpnd, ConstOpnd, CV)) {
+ // Remove previous operand
+ PrevOpnd->Invalidate();
+ if (CV) {
+ *CurrOpnd = XorOpnd(CV);
+ PrevOpnd = CurrOpnd;
+ } else {
+ CurrOpnd->Invalidate();
+ PrevOpnd = nullptr;
+ }
+ Changed = true;
+ }
+ }
+
+ // Step 4: Reassemble the Ops
+ if (Changed) {
+ Ops.clear();
+ for (unsigned int i = 0, e = Opnds.size(); i < e; i++) {
+ XorOpnd &O = Opnds[i];
+ if (O.isInvalid())
+ continue;
+ ValueEntry VE(getRank(O.getValue()), O.getValue());
+ Ops.push_back(VE);
+ }
+ if (ConstOpnd != 0) {
+ Value *C = ConstantInt::get(Ty->getContext(), ConstOpnd);
+ ValueEntry VE(getRank(C), C);
+ Ops.push_back(VE);
+ }
+ int Sz = Ops.size();
+ if (Sz == 1)
+ return Ops.back().Op;
+ else if (Sz == 0) {
+ assert(ConstOpnd == 0);
+ return ConstantInt::get(Ty->getContext(), ConstOpnd);
+ }
+ }
+
+ return nullptr;
}
-/// OptimizeAdd - Optimize a series of operands to an 'add' instruction. This
+/// Optimize a series of operands to an 'add' instruction. This
/// optimizes based on identities. If it can be reduced to a single Value, it
/// is returned, otherwise the Ops list is mutated as necessary.
Value *Reassociate::OptimizeAdd(Instruction *I,
SmallVectorImpl<ValueEntry> &Ops) {
// Scan the operand lists looking for X and -X pairs. If we find any, we
- // can simplify the expression. X+-X == 0. While we're at it, scan for any
+ // can simplify expressions like X+-X == 0 and X+~X ==-1. While we're at it,
+ // scan for any
// duplicates. We want to canonicalize Y+Y+Y+Z -> 3*Y+Z.
- //
- // TODO: We could handle "X + ~X" -> "-1" if we wanted, since "-X = ~X+1".
- //
+
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
Value *TheOp = Ops[i].Op;
// Check to see if we've seen this operand before. If so, we factor all
++NumFound;
} while (i != Ops.size() && Ops[i].Op == TheOp);
- DEBUG(errs() << "\nFACTORING [" << NumFound << "]: " << *TheOp << '\n');
+ DEBUG(dbgs() << "\nFACTORING [" << NumFound << "]: " << *TheOp << '\n');
++NumFactor;
// Insert a new multiply.
- Value *Mul = ConstantInt::get(cast<IntegerType>(I->getType()), NumFound);
- Mul = BinaryOperator::CreateMul(TheOp, Mul, "factor", I);
+ Type *Ty = TheOp->getType();
+ Constant *C = Ty->isIntOrIntVectorTy() ?
+ ConstantInt::get(Ty, NumFound) : ConstantFP::get(Ty, NumFound);
+ Instruction *Mul = CreateMul(TheOp, C, "factor", I, I);
// Now that we have inserted a multiply, optimize it. This allows us to
// handle cases that require multiple factoring steps, such as this:
// (X*2) + (X*2) + (X*2) -> (X*2)*3 -> X*6
- RedoInsts.insert(cast<Instruction>(Mul));
+ RedoInsts.insert(Mul);
// If every add operand was a duplicate, return the multiply.
if (Ops.empty())
continue;
}
- // Check for X and -X in the operand list.
- if (!BinaryOperator::isNeg(TheOp))
+ // Check for X and -X or X and ~X in the operand list.
+ if (!BinaryOperator::isNeg(TheOp) && !BinaryOperator::isFNeg(TheOp) &&
+ !BinaryOperator::isNot(TheOp))
continue;
- Value *X = BinaryOperator::getNegArgument(TheOp);
+ Value *X = nullptr;
+ if (BinaryOperator::isNeg(TheOp) || BinaryOperator::isFNeg(TheOp))
+ X = BinaryOperator::getNegArgument(TheOp);
+ else if (BinaryOperator::isNot(TheOp))
+ X = BinaryOperator::getNotArgument(TheOp);
+
unsigned FoundX = FindInOperandList(Ops, i, X);
if (FoundX == i)
continue;
// Remove X and -X from the operand list.
- if (Ops.size() == 2)
+ if (Ops.size() == 2 &&
+ (BinaryOperator::isNeg(TheOp) || BinaryOperator::isFNeg(TheOp)))
return Constant::getNullValue(X->getType());
+ // Remove X and ~X from the operand list.
+ if (Ops.size() == 2 && BinaryOperator::isNot(TheOp))
+ return Constant::getAllOnesValue(X->getType());
+
Ops.erase(Ops.begin()+i);
if (i < FoundX)
--FoundX;
++NumAnnihil;
--i; // Revisit element.
e -= 2; // Removed two elements.
+
+ // if X and ~X we append -1 to the operand list.
+ if (BinaryOperator::isNot(TheOp)) {
+ Value *V = Constant::getAllOnesValue(X->getType());
+ Ops.insert(Ops.end(), ValueEntry(getRank(V), V));
+ e += 1;
+ }
}
// Scan the operand list, checking to see if there are any common factors
// Keep track of each multiply we see, to avoid triggering on (X*4)+(X*4)
// where they are actually the same multiply.
unsigned MaxOcc = 0;
- Value *MaxOccVal = 0;
+ Value *MaxOccVal = nullptr;
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
- BinaryOperator *BOp = isReassociableOp(Ops[i].Op, Instruction::Mul);
+ BinaryOperator *BOp =
+ isReassociableOp(Ops[i].Op, Instruction::Mul, Instruction::FMul);
if (!BOp)
continue;
SmallPtrSet<Value*, 8> Duplicates;
for (unsigned i = 0, e = Factors.size(); i != e; ++i) {
Value *Factor = Factors[i];
- if (!Duplicates.insert(Factor)) continue;
+ if (!Duplicates.insert(Factor).second)
+ continue;
unsigned Occ = ++FactorOccurrences[Factor];
- if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factor; }
+ if (Occ > MaxOcc) {
+ MaxOcc = Occ;
+ MaxOccVal = Factor;
+ }
// If Factor is a negative constant, add the negated value as a factor
// because we can percolate the negate out. Watch for minint, which
// cannot be positivified.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Factor))
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Factor)) {
if (CI->isNegative() && !CI->isMinValue(true)) {
Factor = ConstantInt::get(CI->getContext(), -CI->getValue());
assert(!Duplicates.count(Factor) &&
"Shouldn't have two constant factors, missed a canonicalize");
-
unsigned Occ = ++FactorOccurrences[Factor];
- if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factor; }
+ if (Occ > MaxOcc) {
+ MaxOcc = Occ;
+ MaxOccVal = Factor;
+ }
+ }
+ } else if (ConstantFP *CF = dyn_cast<ConstantFP>(Factor)) {
+ if (CF->isNegative()) {
+ APFloat F(CF->getValueAPF());
+ F.changeSign();
+ Factor = ConstantFP::get(CF->getContext(), F);
+ assert(!Duplicates.count(Factor) &&
+ "Shouldn't have two constant factors, missed a canonicalize");
+ unsigned Occ = ++FactorOccurrences[Factor];
+ if (Occ > MaxOcc) {
+ MaxOcc = Occ;
+ MaxOccVal = Factor;
+ }
}
+ }
}
}
// If any factor occurred more than one time, we can pull it out.
if (MaxOcc > 1) {
- DEBUG(errs() << "\nFACTORING [" << MaxOcc << "]: " << *MaxOccVal << '\n');
+ DEBUG(dbgs() << "\nFACTORING [" << MaxOcc << "]: " << *MaxOccVal << '\n');
++NumFactor;
// Create a new instruction that uses the MaxOccVal twice. If we don't do
// this, we could otherwise run into situations where removing a factor
// from an expression will drop a use of maxocc, and this can cause
// RemoveFactorFromExpression on successive values to behave differently.
- Instruction *DummyInst = BinaryOperator::CreateAdd(MaxOccVal, MaxOccVal);
+ Instruction *DummyInst =
+ I->getType()->isIntOrIntVectorTy()
+ ? BinaryOperator::CreateAdd(MaxOccVal, MaxOccVal)
+ : BinaryOperator::CreateFAdd(MaxOccVal, MaxOccVal);
+
SmallVector<WeakVH, 4> NewMulOps;
for (unsigned i = 0; i != Ops.size(); ++i) {
// Only try to remove factors from expressions we're allowed to.
- BinaryOperator *BOp = isReassociableOp(Ops[i].Op, Instruction::Mul);
+ BinaryOperator *BOp =
+ isReassociableOp(Ops[i].Op, Instruction::Mul, Instruction::FMul);
if (!BOp)
continue;
RedoInsts.insert(VI);
// Create the multiply.
- Instruction *V2 = BinaryOperator::CreateMul(V, MaxOccVal, "tmp", I);
+ Instruction *V2 = CreateMul(V, MaxOccVal, "tmp", I, I);
// Rerun associate on the multiply in case the inner expression turned into
// a multiply. We want to make sure that we keep things in canonical form.
Ops.insert(Ops.begin(), ValueEntry(getRank(V2), V2));
}
- return 0;
-}
-
-namespace {
- /// \brief Predicate tests whether a ValueEntry's op is in a map.
- struct IsValueInMap {
- const DenseMap<Value *, unsigned> ⤅
-
- IsValueInMap(const DenseMap<Value *, unsigned> &Map) : Map(Map) {}
-
- bool operator()(const ValueEntry &Entry) {
- return Map.find(Entry.Op) != Map.end();
- }
- };
+ return nullptr;
}
/// \brief Build up a vector of value/power pairs factoring a product.
// below our mininum of '4'.
assert(FactorPowerSum >= 4);
- std::sort(Factors.begin(), Factors.end(), Factor::PowerDescendingSorter());
+ std::stable_sort(Factors.begin(), Factors.end(), Factor::PowerDescendingSorter());
return true;
}
Value *LHS = Ops.pop_back_val();
do {
- LHS = Builder.CreateMul(LHS, Ops.pop_back_val());
+ if (LHS->getType()->isIntOrIntVectorTy())
+ LHS = Builder.CreateMul(LHS, Ops.pop_back_val());
+ else
+ LHS = Builder.CreateFMul(LHS, Ops.pop_back_val());
} while (!Ops.empty());
return LHS;
return V;
}
-// Multiply Ops may have some negation operators. This situation arises
-// when the negation operators have multiple uses, and LinearizeExprTree() has
-// to treat them as leaf operands. Before multiplication optimization begins,
-// get rid of the negations wherever possible.
-void Reassociate::removeNegFromMulOps(SmallVectorImpl<ValueEntry> &Ops) {
- int32_t NegIdx = -1;
-
- // loop over all elements except the last one
- for (int32_t Idx = 0, IdxEnd = Ops.size() - 1; Idx < IdxEnd; Idx++) {
- ValueEntry &VE = Ops[Idx];
- if (!BinaryOperator::isNeg(VE.Op))
- continue;
-
- if (NegIdx < 0) {
- NegIdx = Idx;
- continue;
- }
-
- // Find a pair of negation operators, say -X and -Y, change them to
- // X and Y respectively.
- ValueEntry &VEX = Ops[NegIdx];
- Value *OpX = cast<BinaryOperator>(VEX.Op)->getOperand(1);
- VEX.Op = OpX;
- VEX.Rank = getRank(OpX);
-
- Value *OpY = cast<BinaryOperator>(VE.Op)->getOperand(1);
- VE.Op = OpY;
- VE.Rank = getRank(OpY);
- NegIdx = -1;
- }
-
- if (NegIdx >= 0) {
- // We have visited odd number of negation operators so far.
- // Check if the last element is negation as well.
- ValueEntry &Last = Ops.back();
- Value *LastOp = Last.Op;
- if (!isa<ConstantInt>(LastOp) && !BinaryOperator::isNeg(LastOp))
- return;
-
- ValueEntry& PrevNeg = Ops[NegIdx];
- Value *Op = cast<BinaryOperator>(PrevNeg.Op)->getOperand(1);
- PrevNeg.Op = Op;
- PrevNeg.Rank = getRank(Op);
-
- if (isa<ConstantInt>(LastOp))
- Last.Op = ConstantExpr::getNeg(cast<Constant>(LastOp));
- else {
- LastOp = cast<BinaryOperator>(PrevNeg.Op)->getOperand(1);
- Last.Op = LastOp;
- Last.Rank = getRank(LastOp);
- }
- }
-}
-
Value *Reassociate::OptimizeMul(BinaryOperator *I,
SmallVectorImpl<ValueEntry> &Ops) {
-
- // Simplify the operands: (-x)*(-y) -> x*y, and (-x)*c -> x*(-c)
- removeNegFromMulOps(Ops);
-
// We can only optimize the multiplies when there is a chain of more than
// three, such that a balanced tree might require fewer total multiplies.
if (Ops.size() < 4)
- return 0;
+ return nullptr;
// Try to turn linear trees of multiplies without other uses of the
// intermediate stages into minimal multiply DAGs with perfect sub-expression
// re-use.
SmallVector<Factor, 4> Factors;
if (!collectMultiplyFactors(Ops, Factors))
- return 0; // All distinct factors, so nothing left for us to do.
+ return nullptr; // All distinct factors, so nothing left for us to do.
IRBuilder<> Builder(I);
Value *V = buildMinimalMultiplyDAG(Builder, Factors);
ValueEntry NewEntry = ValueEntry(getRank(V), V);
Ops.insert(std::lower_bound(Ops.begin(), Ops.end(), NewEntry), NewEntry);
- return 0;
+ return nullptr;
}
Value *Reassociate::OptimizeExpression(BinaryOperator *I,
SmallVectorImpl<ValueEntry> &Ops) {
// Now that we have the linearized expression tree, try to optimize it.
// Start by folding any constants that we found.
- if (Ops.size() == 1) return Ops[0].Op;
-
+ Constant *Cst = nullptr;
unsigned Opcode = I->getOpcode();
+ while (!Ops.empty() && isa<Constant>(Ops.back().Op)) {
+ Constant *C = cast<Constant>(Ops.pop_back_val().Op);
+ Cst = Cst ? ConstantExpr::get(Opcode, C, Cst) : C;
+ }
+ // If there was nothing but constants then we are done.
+ if (Ops.empty())
+ return Cst;
+
+ // Put the combined constant back at the end of the operand list, except if
+ // there is no point. For example, an add of 0 gets dropped here, while a
+ // multiplication by zero turns the whole expression into zero.
+ if (Cst && Cst != ConstantExpr::getBinOpIdentity(Opcode, I->getType())) {
+ if (Cst == ConstantExpr::getBinOpAbsorber(Opcode, I->getType()))
+ return Cst;
+ Ops.push_back(ValueEntry(0, Cst));
+ }
+
+ if (Ops.size() == 1) return Ops[0].Op;
// Handle destructive annihilation due to identities between elements in the
// argument list here.
default: break;
case Instruction::And:
case Instruction::Or:
- case Instruction::Xor:
if (Value *Result = OptimizeAndOrXor(Opcode, Ops))
return Result;
break;
+ case Instruction::Xor:
+ if (Value *Result = OptimizeXor(I, Ops))
+ return Result;
+ break;
+
case Instruction::Add:
+ case Instruction::FAdd:
if (Value *Result = OptimizeAdd(I, Ops))
return Result;
break;
case Instruction::Mul:
+ case Instruction::FMul:
if (Value *Result = OptimizeMul(I, Ops))
return Result;
break;
if (Ops.size() != NumOps)
return OptimizeExpression(I, Ops);
- return 0;
+ return nullptr;
}
-// EraseInstCallBack is a helper function of EraseInst which will be called to
-// delete an individual instruction, and it is also a callback funciton when
-// EraseAllDeadInst is called to delete all dead instruciton in the Redo
-// worklist (RedoInsts).
-//
-void Reassociate::EraseInstCallBack(Instruction *I) {
- DEBUG(dbgs() << "Erase instruction :" << *I << "\n");
+/// Zap the given instruction, adding interesting operands to the work list.
+void Reassociate::EraseInst(Instruction *I) {
assert(isInstructionTriviallyDead(I) && "Trivially dead instructions only!");
SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
// Erase the dead instruction.
ValueRankMap.erase(I);
+ RedoInsts.remove(I);
I->eraseFromParent();
// Optimize its operands.
SmallPtrSet<Instruction *, 8> Visited; // Detect self-referential nodes.
// If this is a node in an expression tree, climb to the expression root
// and add that since that's where optimization actually happens.
unsigned Opcode = Op->getOpcode();
- while (Op->hasOneUse() && Op->use_back()->getOpcode() == Opcode &&
- Visited.insert(Op))
- Op = Op->use_back();
-
- // The caller may be itearating the RedoInsts. Inserting a new element to
- // RedoInsts will invaidate the iterator. Instead, we temporally place the
- // new candidate to TmpRedoInsts. It is up to caller to combine
- // TmpRedoInsts and RedoInsts together.
- //
- if (!RedoInsts.found(Op))
- TmpRedoInsts.insert(Op);
+ while (Op->hasOneUse() && Op->user_back()->getOpcode() == Opcode &&
+ Visited.insert(Op).second)
+ Op = Op->user_back();
+ RedoInsts.insert(Op);
}
}
-/// EraseInst - Zap the given instruction, adding interesting operands to the
-/// work list.
-void Reassociate::EraseInst(Instruction *I) {
- RedoInsts.remove(I);
+// Canonicalize expressions of the following form:
+// x + (-Constant * y) -> x - (Constant * y)
+// x - (-Constant * y) -> x + (Constant * y)
+Instruction *Reassociate::canonicalizeNegConstExpr(Instruction *I) {
+ if (!I->hasOneUse() || I->getType()->isVectorTy())
+ return nullptr;
- // Since EraseInstCallBack() put new reassociation candidates to TmpRedoInsts
- // we need to copy the candidates back to RedoInsts.
- TmpRedoInsts.clear();
- EraseInstCallBack(I);
- RedoInsts.append(TmpRedoInsts);
-}
+ // Must be a fmul or fdiv instruction.
+ unsigned Opcode = I->getOpcode();
+ if (Opcode != Instruction::FMul && Opcode != Instruction::FDiv)
+ return nullptr;
+
+ auto *C0 = dyn_cast<ConstantFP>(I->getOperand(0));
+ auto *C1 = dyn_cast<ConstantFP>(I->getOperand(1));
+
+ // Both operands are constant, let it get constant folded away.
+ if (C0 && C1)
+ return nullptr;
+
+ ConstantFP *CF = C0 ? C0 : C1;
+
+ // Must have one constant operand.
+ if (!CF)
+ return nullptr;
+
+ // Must be a negative ConstantFP.
+ if (!CF->isNegative())
+ return nullptr;
+
+ // User must be a binary operator with one or more uses.
+ Instruction *User = I->user_back();
+ if (!isa<BinaryOperator>(User) || !User->hasNUsesOrMore(1))
+ return nullptr;
+
+ unsigned UserOpcode = User->getOpcode();
+ if (UserOpcode != Instruction::FAdd && UserOpcode != Instruction::FSub)
+ return nullptr;
+
+ // Subtraction is not commutative. Explicitly, the following transform is
+ // not valid: (-Constant * y) - x -> x + (Constant * y)
+ if (!User->isCommutative() && User->getOperand(1) != I)
+ return nullptr;
+
+ // Change the sign of the constant.
+ APFloat Val = CF->getValueAPF();
+ Val.changeSign();
+ I->setOperand(C0 ? 0 : 1, ConstantFP::get(CF->getContext(), Val));
+
+ // Canonicalize I to RHS to simplify the next bit of logic. E.g.,
+ // ((-Const*y) + x) -> (x + (-Const*y)).
+ if (User->getOperand(0) == I && User->isCommutative())
+ cast<BinaryOperator>(User)->swapOperands();
+
+ Value *Op0 = User->getOperand(0);
+ Value *Op1 = User->getOperand(1);
+ BinaryOperator *NI;
+ switch (UserOpcode) {
+ default:
+ llvm_unreachable("Unexpected Opcode!");
+ case Instruction::FAdd:
+ NI = BinaryOperator::CreateFSub(Op0, Op1);
+ NI->setFastMathFlags(cast<FPMathOperator>(User)->getFastMathFlags());
+ break;
+ case Instruction::FSub:
+ NI = BinaryOperator::CreateFAdd(Op0, Op1);
+ NI->setFastMathFlags(cast<FPMathOperator>(User)->getFastMathFlags());
+ break;
+ }
-/// EraseAllDeadInst - Remove all dead instructions from the worklist.
-void Reassociate::EraseAllDeadInst() {
- TmpRedoInsts.clear();
- RedoInsts.inplace_rremove(isInstDeadFunc(), RmInstCallBackFunc(this));
- RedoInsts.append(TmpRedoInsts);
+ NI->insertBefore(User);
+ NI->setName(User->getName());
+ User->replaceAllUsesWith(NI);
+ NI->setDebugLoc(I->getDebugLoc());
+ RedoInsts.insert(I);
+ MadeChange = true;
+ return NI;
}
-/// OptimizeInst - Inspect and optimize the given instruction. Note that erasing
+/// Inspect and optimize the given instruction. Note that erasing
/// instructions is not allowed.
void Reassociate::OptimizeInst(Instruction *I) {
// Only consider operations that we understand.
if (!isa<BinaryOperator>(I))
return;
- DEBUG(dbgs() << "\n>Opt Instruction: " << *I << '\n');
-
- if (I->getOpcode() == Instruction::Shl &&
- isa<ConstantInt>(I->getOperand(1)))
+ if (I->getOpcode() == Instruction::Shl && isa<ConstantInt>(I->getOperand(1)))
// If an operand of this shift is a reassociable multiply, or if the shift
// is used by a reassociable multiply or add, turn into a multiply.
if (isReassociableOp(I->getOperand(0), Instruction::Mul) ||
(I->hasOneUse() &&
- (isReassociableOp(I->use_back(), Instruction::Mul) ||
- isReassociableOp(I->use_back(), Instruction::Add)))) {
+ (isReassociableOp(I->user_back(), Instruction::Mul) ||
+ isReassociableOp(I->user_back(), Instruction::Add)))) {
Instruction *NI = ConvertShiftToMul(I);
RedoInsts.insert(I);
MadeChange = true;
I = NI;
}
- // Floating point binary operators are not associative, but we can still
- // commute (some) of them, to canonicalize the order of their operands.
- // This can potentially expose more CSE opportunities, and makes writing
- // other transformations simpler.
- if ((I->getType()->isFloatingPointTy() || I->getType()->isVectorTy())) {
- // FAdd and FMul can be commuted.
- if (I->getOpcode() != Instruction::FMul &&
- I->getOpcode() != Instruction::FAdd)
- return;
+ // Canonicalize negative constants out of expressions.
+ if (Instruction *Res = canonicalizeNegConstExpr(I))
+ I = Res;
- Value *LHS = I->getOperand(0);
- Value *RHS = I->getOperand(1);
- unsigned LHSRank = getRank(LHS);
- unsigned RHSRank = getRank(RHS);
+ // Commute binary operators, to canonicalize the order of their operands.
+ // This can potentially expose more CSE opportunities, and makes writing other
+ // transformations simpler.
+ if (I->isCommutative())
+ canonicalizeOperands(I);
- // Sort the operands by rank.
- if (RHSRank < LHSRank) {
- I->setOperand(0, RHS);
- I->setOperand(1, LHS);
- }
+ // TODO: We should optimize vector Xor instructions, but they are
+ // currently unsupported.
+ if (I->getType()->isVectorTy() && I->getOpcode() == Instruction::Xor)
+ return;
+ // Don't optimize floating point instructions that don't have unsafe algebra.
+ if (I->getType()->isFloatingPointTy() && !I->hasUnsafeAlgebra())
return;
- }
// Do not reassociate boolean (i1) expressions. We want to preserve the
// original order of evaluation for short-circuited comparisons that
// and if this is not an inner node of a multiply tree.
if (isReassociableOp(I->getOperand(1), Instruction::Mul) &&
(!I->hasOneUse() ||
- !isReassociableOp(I->use_back(), Instruction::Mul))) {
+ !isReassociableOp(I->user_back(), Instruction::Mul))) {
+ Instruction *NI = LowerNegateToMultiply(I);
+ RedoInsts.insert(I);
+ MadeChange = true;
+ I = NI;
+ }
+ }
+ } else if (I->getOpcode() == Instruction::FSub) {
+ if (ShouldBreakUpSubtract(I)) {
+ Instruction *NI = BreakUpSubtract(I);
+ RedoInsts.insert(I);
+ MadeChange = true;
+ I = NI;
+ } else if (BinaryOperator::isFNeg(I)) {
+ // Otherwise, this is a negation. See if the operand is a multiply tree
+ // and if this is not an inner node of a multiply tree.
+ if (isReassociableOp(I->getOperand(1), Instruction::FMul) &&
+ (!I->hasOneUse() ||
+ !isReassociableOp(I->user_back(), Instruction::FMul))) {
Instruction *NI = LowerNegateToMultiply(I);
RedoInsts.insert(I);
MadeChange = true;
// If this is an interior node of a reassociable tree, ignore it until we
// get to the root of the tree, to avoid N^2 analysis.
unsigned Opcode = BO->getOpcode();
- if (BO->hasOneUse() && BO->use_back()->getOpcode() == Opcode)
+ if (BO->hasOneUse() && BO->user_back()->getOpcode() == Opcode)
return;
// If this is an add tree that is used by a sub instruction, ignore it
// until we process the subtract.
if (BO->hasOneUse() && BO->getOpcode() == Instruction::Add &&
- cast<Instruction>(BO->use_back())->getOpcode() == Instruction::Sub)
+ cast<Instruction>(BO->user_back())->getOpcode() == Instruction::Sub)
+ return;
+ if (BO->hasOneUse() && BO->getOpcode() == Instruction::FAdd &&
+ cast<Instruction>(BO->user_back())->getOpcode() == Instruction::FSub)
return;
ReassociateExpression(BO);
}
void Reassociate::ReassociateExpression(BinaryOperator *I) {
-
// First, walk the expression tree, linearizing the tree, collecting the
// operand information.
SmallVector<RepeatedValue, 8> Tree;
// the vector.
std::stable_sort(Ops.begin(), Ops.end());
- // OptimizeExpression - Now that we have the expression tree in a convenient
+ // Now that we have the expression tree in a convenient
// sorted form, optimize it globally if possible.
if (Value *V = OptimizeExpression(I, Ops)) {
if (V == I)
// this is a multiply tree used only by an add, and the immediate is a -1.
// In this case we reassociate to put the negation on the outside so that we
// can fold the negation into the add: (-X)*Y + Z -> Z-X*Y
- if (I->getOpcode() == Instruction::Mul && I->hasOneUse() &&
- cast<Instruction>(I->use_back())->getOpcode() == Instruction::Add &&
- isa<ConstantInt>(Ops.back().Op) &&
- cast<ConstantInt>(Ops.back().Op)->isAllOnesValue()) {
- ValueEntry Tmp = Ops.pop_back_val();
- Ops.insert(Ops.begin(), Tmp);
+ if (I->hasOneUse()) {
+ if (I->getOpcode() == Instruction::Mul &&
+ cast<Instruction>(I->user_back())->getOpcode() == Instruction::Add &&
+ isa<ConstantInt>(Ops.back().Op) &&
+ cast<ConstantInt>(Ops.back().Op)->isAllOnesValue()) {
+ ValueEntry Tmp = Ops.pop_back_val();
+ Ops.insert(Ops.begin(), Tmp);
+ } else if (I->getOpcode() == Instruction::FMul &&
+ cast<Instruction>(I->user_back())->getOpcode() ==
+ Instruction::FAdd &&
+ isa<ConstantFP>(Ops.back().Op) &&
+ cast<ConstantFP>(Ops.back().Op)->isExactlyValue(-1.0)) {
+ ValueEntry Tmp = Ops.pop_back_val();
+ Ops.insert(Ops.begin(), Tmp);
+ }
}
DEBUG(dbgs() << "RAOut:\t"; PrintOps(I, Ops); dbgs() << '\n');
}
bool Reassociate::runOnFunction(Function &F) {
+ if (skipOptnoneFunction(F))
+ return false;
+
// Calculate the rank map for F
BuildRankMap(F);
++II;
}
- DEBUG(dbgs() << "Process instructions in worklist\n");
- EraseAllDeadInst();
-
// If this produced extra instructions to optimize, handle them now.
while (!RedoInsts.empty()) {
- Instruction *I = RedoInsts.pop_front_val();
- if (!I)
- continue;
+ Instruction *I = RedoInsts.pop_back_val();
if (isInstructionTriviallyDead(I))
EraseInst(I);
else
projects / oota-llvm.git / blobdiff