[llvm] 9f48a16 - Revert "[DBG][OPT] Attempt to salvage or undef debug info when removing trivially deletable instructions in the Reassociate Expression pass."
Tom Weaver via llvm-commits
llvm-commits at lists.llvm.org
Mon Nov 11 06:13:49 PST 2019
Author: Tom Weaver
Date: 2019-11-11T14:13:33Z
New Revision: 9f48a160dd3fd56314cfbbe74c56e09aaab11566
URL: https://github.com/llvm/llvm-project/commit/9f48a160dd3fd56314cfbbe74c56e09aaab11566
DIFF: https://github.com/llvm/llvm-project/commit/9f48a160dd3fd56314cfbbe74c56e09aaab11566.diff
LOG: Revert "[DBG][OPT] Attempt to salvage or undef debug info when removing trivially deletable instructions in the Reassociate Expression pass."
This reverts commit 1984a27db58e9053371ab6d6dc288c81c8a071ac.
Added:
Modified:
Removed:
llvm/lib/Transforms/Scalar/Reassociate.cpp.rej
llvm/test/Transforms/Reassociate/reassociate_salvages_debug_info.ll
llvm/test/Transforms/Reassociate/undef_intrinsics_when_deleting_instructions.ll
################################################################################
diff --git a/llvm/lib/Transforms/Scalar/Reassociate.cpp.rej b/llvm/lib/Transforms/Scalar/Reassociate.cpp.rej
deleted file mode 100644
index 83c547675403..000000000000
--- a/llvm/lib/Transforms/Scalar/Reassociate.cpp.rej
+++ /dev/null
@@ -1,2506 +0,0 @@
---- llvm/lib/Transforms/Scalar/Reassociate.cpp
-+++ llvm/lib/Transforms/Scalar/Reassociate.cpp
-@@ -1,2501 +1,2503 @@
- //===- Reassociate.cpp - Reassociate binary expressions -------------------===//
- //
- // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
- // See https://llvm.org/LICENSE.txt for license information.
- // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
- //
- //===----------------------------------------------------------------------===//
- //
- // This pass reassociates commutative expressions in an order that is designed
- // to promote better constant propagation, GCSE, LICM, PRE, etc.
- //
- // For example: 4 + (x + 5) -> x + (4 + 5)
- //
- // In the implementation of this algorithm, constants are assigned rank = 0,
- // function arguments are rank = 1, and other values are assigned ranks
- // corresponding to the reverse post order traversal of current function
- // (starting at 2), which effectively gives values in deep loops higher rank
- // than values not in loops.
- //
- //===----------------------------------------------------------------------===//
-
- #include "llvm/Transforms/Scalar/Reassociate.h"
- #include "llvm/ADT/APFloat.h"
- #include "llvm/ADT/APInt.h"
- #include "llvm/ADT/DenseMap.h"
- #include "llvm/ADT/PostOrderIterator.h"
- #include "llvm/ADT/SetVector.h"
- #include "llvm/ADT/SmallPtrSet.h"
- #include "llvm/ADT/SmallSet.h"
- #include "llvm/ADT/SmallVector.h"
- #include "llvm/ADT/Statistic.h"
- #include "llvm/Analysis/GlobalsModRef.h"
- #include "llvm/Transforms/Utils/Local.h"
- #include "llvm/Analysis/ValueTracking.h"
- #include "llvm/IR/Argument.h"
- #include "llvm/IR/BasicBlock.h"
- #include "llvm/IR/CFG.h"
- #include "llvm/IR/Constant.h"
- #include "llvm/IR/Constants.h"
- #include "llvm/IR/Function.h"
- #include "llvm/IR/IRBuilder.h"
- #include "llvm/IR/InstrTypes.h"
- #include "llvm/IR/Instruction.h"
- #include "llvm/IR/Instructions.h"
- #include "llvm/IR/IntrinsicInst.h"
- #include "llvm/IR/Operator.h"
- #include "llvm/IR/PassManager.h"
- #include "llvm/IR/PatternMatch.h"
- #include "llvm/IR/Type.h"
- #include "llvm/IR/User.h"
- #include "llvm/IR/Value.h"
- #include "llvm/IR/ValueHandle.h"
- #include "llvm/Pass.h"
- #include "llvm/Support/Casting.h"
- #include "llvm/Support/Debug.h"
- #include "llvm/Support/ErrorHandling.h"
- #include "llvm/Support/raw_ostream.h"
- #include "llvm/Transforms/Scalar.h"
- #include <algorithm>
- #include <cassert>
- #include <utility>
-
- using namespace llvm;
- using namespace reassociate;
- using namespace PatternMatch;
-
- #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
- /// Print out the expression identified in the Ops list.
- static void PrintOps(Instruction *I, const SmallVectorImpl<ValueEntry> &Ops) {
- Module *M = I->getModule();
- dbgs() << Instruction::getOpcodeName(I->getOpcode()) << " "
- << *Ops[0].Op->getType() << '\t';
- for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
- dbgs() << "[ ";
- Ops[i].Op->printAsOperand(dbgs(), false, M);
- dbgs() << ", #" << Ops[i].Rank << "] ";
- }
- }
- #endif
-
- /// 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 llvm::reassociate::XorOpnd {
- public:
- 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; }
-
- private:
- Value *OrigVal;
- Value *SymbolicPart;
- APInt ConstPart;
- unsigned SymbolicRank;
- bool isOr;
- };
-
- 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);
- const APInt *C;
- if (match(V0, m_APInt(C)))
- std::swap(V0, V1);
-
- if (match(V1, m_APInt(C))) {
- ConstPart = *C;
- SymbolicPart = V0;
- isOr = (I->getOpcode() == Instruction::Or);
- return;
- }
- }
-
- // view the operand as "V | 0"
- SymbolicPart = V;
- ConstPart = APInt::getNullValue(V->getType()->getScalarSizeInBits());
- isOr = true;
- }
-
- /// 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) {
- auto *I = dyn_cast<Instruction>(V);
- if (I && I->hasOneUse() && I->getOpcode() == Opcode)
- if (!isa<FPMathOperator>(I) || I->isFast())
- return cast<BinaryOperator>(I);
- return nullptr;
- }
-
- static BinaryOperator *isReassociableOp(Value *V, unsigned Opcode1,
- unsigned Opcode2) {
- auto *I = dyn_cast<Instruction>(V);
- if (I && I->hasOneUse() &&
- (I->getOpcode() == Opcode1 || I->getOpcode() == Opcode2))
- if (!isa<FPMathOperator>(I) || I->isFast())
- return cast<BinaryOperator>(I);
- return nullptr;
- }
-
- void ReassociatePass::BuildRankMap(Function &F,
- ReversePostOrderTraversal<Function*> &RPOT) {
- unsigned Rank = 2;
-
- // Assign distinct ranks to function arguments.
- for (auto &Arg : F.args()) {
- ValueRankMap[&Arg] = ++Rank;
- LLVM_DEBUG(dbgs() << "Calculated Rank[" << Arg.getName() << "] = " << Rank
- << "\n");
- }
-
- // Traverse basic blocks in ReversePostOrder
- for (BasicBlock *BB : RPOT) {
- unsigned BBRank = RankMap[BB] = ++Rank << 16;
-
- // Walk the basic block, adding precomputed ranks for any instructions that
- // we cannot move. This ensures that the ranks for these instructions are
- // all
diff erent in the block.
- for (Instruction &I : *BB)
- if (mayBeMemoryDependent(I))
- ValueRankMap[&I] = ++BBRank;
- }
- }
-
- unsigned ReassociatePass::getRank(Value *V) {
- Instruction *I = dyn_cast<Instruction>(V);
- if (!I) {
- if (isa<Argument>(V)) return ValueRankMap[V]; // Function argument.
- return 0; // Otherwise it's a global or constant, rank 0.
- }
-
- if (unsigned Rank = ValueRankMap[I])
- return Rank; // Rank already known?
-
- // If this is an expression, return the 1+MAX(rank(LHS), rank(RHS)) so that
- // we can reassociate expressions for code motion! Since we do not recurse
- // for PHI nodes, we cannot have infinite recursion here, because there
- // cannot be loops in the value graph that do not go through PHI nodes.
- unsigned Rank = 0, MaxRank = RankMap[I->getParent()];
- for (unsigned i = 0, e = I->getNumOperands(); i != e && Rank != MaxRank; ++i)
- Rank = std::max(Rank, getRank(I->getOperand(i)));
-
- // 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 (!match(I, m_Not(m_Value())) && !match(I, m_Neg(m_Value())) &&
- !match(I, m_FNeg(m_Value())))
- ++Rank;
-
- LLVM_DEBUG(dbgs() << "Calculated Rank[" << V->getName() << "] = " << Rank
- << "\n");
-
- return ValueRankMap[I] = Rank;
- }
-
- // Canonicalize constants to RHS. Otherwise, sort the operands by rank.
- void ReassociatePass::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);
- if (LHS == RHS || isa<Constant>(RHS))
- return;
- if (isa<Constant>(LHS) || getRank(RHS) < getRank(LHS))
- 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) {
- assert((isa<UnaryOperator>(Neg) || isa<BinaryOperator>(Neg)) &&
- "Expected a Negate!");
- // FIXME: It's not safe to lower a unary FNeg into a FMul by -1.0.
- unsigned OpNo = isa<BinaryOperator>(Neg) ? 1 : 0;
- Type *Ty = Neg->getType();
- Constant *NegOne = Ty->isIntOrIntVectorTy() ?
- ConstantInt::getAllOnesValue(Ty) : ConstantFP::get(Ty, -1.0);
-
- BinaryOperator *Res = CreateMul(Neg->getOperand(OpNo), NegOne, "", Neg, Neg);
- Neg->setOperand(OpNo, Constant::getNullValue(Ty)); // Drop use of op.
- Res->takeName(Neg);
- Neg->replaceAllUsesWith(Res);
- Res->setDebugLoc(Neg->getDebugLoc());
- return Res;
- }
-
- /// 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.
- static unsigned CarmichaelShift(unsigned Bitwidth) {
- if (Bitwidth < 3)
- return Bitwidth - 1;
- return Bitwidth - 2;
- }
-
- /// 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
- /// X occurring LHS + RHS times. If op is "Xor" for example then the combined
- /// operation is equivalent to X if LHS + RHS is odd, or 0 if LHS + RHS is even;
- /// the routine returns 1 in LHS in the first case, and 0 in LHS in the second.
- static void IncorporateWeight(APInt &LHS, const APInt &RHS, unsigned Opcode) {
- // If we were working with infinite precision arithmetic then the combined
- // weight would be LHS + RHS. But we are using finite precision arithmetic,
- // and the APInt sum LHS + RHS may not be correct if it wraps (it is correct
- // for nilpotent operations and addition, but not for idempotent operations
- // and multiplication), so it is important to correctly reduce the combined
- // weight back into range if wrapping would be wrong.
-
- // If RHS is zero then the weight didn't change.
- if (RHS.isMinValue())
- return;
- // If LHS is zero then the combined weight is RHS.
- if (LHS.isMinValue()) {
- LHS = RHS;
- return;
- }
- // From this point on we know that neither LHS nor RHS is zero.
-
- if (Instruction::isIdempotent(Opcode)) {
- // Idempotent means X op X === X, so any non-zero weight is equivalent to a
- // weight of 1. Keeping weights at zero or one also means that wrapping is
- // not a problem.
- assert(LHS == 1 && RHS == 1 && "Weights not reduced!");
- return; // Return a weight of 1.
- }
- if (Instruction::isNilpotent(Opcode)) {
- // Nilpotent means X op X === 0, so reduce weights modulo 2.
- assert(LHS == 1 && RHS == 1 && "Weights not reduced!");
- LHS = 0; // 1 + 1 === 0 modulo 2.
- return;
- }
- if (Opcode == Instruction::Add || Opcode == Instruction::FAdd) {
- // TODO: Reduce the weight by exploiting nsw/nuw?
- LHS += RHS;
- return;
- }
-
- 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
- // bit number x, since either x is odd in which case x^CM = 1, or x is even in
- // which case both x^W and x^(W - CM) are zero. By subtracting off multiples
- // of CM like this weights can always be reduced to the range [0, CM+Bitwidth)
- // which by a happy accident means that they can always be represented using
- // Bitwidth bits.
- // TODO: Reduce the weight by exploiting nsw/nuw? (Could do much better than
- // the Carmichael number).
- if (Bitwidth > 3) {
- /// CM - The value of Carmichael's lambda function.
- APInt CM = APInt::getOneBitSet(Bitwidth, CarmichaelShift(Bitwidth));
- // Any weight W >= Threshold can be replaced with W - CM.
- APInt Threshold = CM + Bitwidth;
- assert(LHS.ult(Threshold) && RHS.ult(Threshold) && "Weights not reduced!");
- // For Bitwidth 4 or more the following sum does not overflow.
- LHS += RHS;
- while (LHS.uge(Threshold))
- LHS -= CM;
- } else {
- // To avoid problems with overflow do everything the same as above but using
- // a larger type.
- unsigned CM = 1U << CarmichaelShift(Bitwidth);
- unsigned Threshold = CM + Bitwidth;
- assert(LHS.getZExtValue() < Threshold && RHS.getZExtValue() < Threshold &&
- "Weights not reduced!");
- unsigned Total = LHS.getZExtValue() + RHS.getZExtValue();
- while (Total >= Threshold)
- Total -= CM;
- LHS = Total;
- }
- }
-
- using RepeatedValue = std::pair<Value*, APInt>;
-
- /// 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[1].first op Ops[1].first op ... Ops[1].first) <- Ops[1].second times
- /// op
- /// ...
- /// 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.
- ///
- /// 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'
- /// to something completely
diff erent. Thus if the routine returns 'true' then
- /// you MUST either replace I with a new expression computed from the Ops array,
- /// or use RewriteExprTree to put the values back in.
- ///
- /// A leaf node is either not a binary operation of the same kind as the root
- /// node 'I' (i.e. is not a binary operator at all, or is, but with a
diff erent
- /// opcode), or is the same kind of binary operator but has a use which either
- /// does not belong to the expression, or does belong to the expression but is
- /// a leaf node. Every leaf node has at least one use that is a non-leaf node
- /// of the expression, while for non-leaf nodes (except for the root 'I') every
- /// use is a non-leaf node of the expression.
- ///
- /// For example:
- /// expression graph node names
- ///
- /// + | I
- /// / \ |
- /// + + | A, B
- /// / \ / \ |
- /// * + * | C, D, E
- /// / \ / \ / \ |
- /// + * | F, G
- ///
- /// The leaf nodes are C, E, F and G. The Ops array will contain (maybe not in
- /// that order) (C, 1), (E, 1), (F, 2), (G, 2).
- ///
- /// The expression is maximal: if some instruction is a binary operator of the
- /// same kind as 'I', and all of its uses are non-leaf nodes of the expression,
- /// then the instruction also belongs to the expression, is not a leaf node of
- /// it, and its operands also belong to the expression (but may be leaf nodes).
- ///
- /// NOTE: This routine will set operands of non-leaf non-root nodes to undef in
- /// order to ensure that every non-root node in the expression has *exactly one*
- /// use by a non-leaf node of the expression. This destruction means that the
- /// caller MUST either replace 'I' with a new expression or use something like
- /// RewriteExprTree to put the values back in if the routine indicates that it
- /// made a change by returning 'true'.
- ///
- /// In the above example either the right operand of A or the left operand of B
- /// will be replaced by undef. If it is B's operand then this gives:
- ///
- /// + | I
- /// / \ |
- /// + + | A, B - operand of B replaced with undef
- /// / \ \ |
- /// * + * | C, D, E
- /// / \ / \ / \ |
- /// + * | F, G
- ///
- /// Note that such undef operands can only be reached by passing through 'I'.
- /// For example, if you visit operands recursively starting from a leaf node
- /// then you will never see such an undef operand unless you get back to 'I',
- /// which requires passing through a phi node.
- ///
- /// Note that this routine may also mutate binary operators of the wrong type
- /// that have all uses inside the expression (i.e. only used by non-leaf nodes
- /// of the expression) if it can turn them into binary operators of the right
- /// type and thus make the expression bigger.
- static bool LinearizeExprTree(Instruction *I,
- SmallVectorImpl<RepeatedValue> &Ops) {
- assert((isa<UnaryOperator>(I) || isa<BinaryOperator>(I)) &&
- "Expected a UnaryOperator or BinaryOperator!");
- LLVM_DEBUG(dbgs() << "LINEARIZE: " << *I << '\n');
- unsigned Bitwidth = I->getType()->getScalarType()->getPrimitiveSizeInBits();
- unsigned Opcode = I->getOpcode();
- assert(I->isAssociative() && I->isCommutative() &&
- "Expected an associative and commutative operation!");
-
- // 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
- // the number of times that operand occurs in the linearized expression).
- // For example, if I = X + A, where X = A + B, then I, X and B have weight 1
- // while A has weight two.
-
- // Worklist of non-leaf nodes (their operands are in the expression too) along
- // with their weights, representing a certain number of paths to the operator.
- // If an operator occurs in the worklist multiple times then we found multiple
- // ways to get to it.
- SmallVector<std::pair<Instruction*, APInt>, 8> Worklist; // (Op, Weight)
- Worklist.push_back(std::make_pair(I, APInt(Bitwidth, 1)));
- 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
- // some uses that are not inside the expression. For example, in I = X + X,
- // X = A + B, the value X has two uses (by I) that are in the expression. If
- // X has any other uses, for example in a return instruction, then we consider
- // X to be a leaf, and won't analyze it further. When we first visit a value,
- // if it has more than one use then at first we conservatively consider it to
- // be a leaf. Later, as the expression is explored, we may discover some more
- // uses of the value from inside the expression. If all uses turn out to be
- // from within the expression (and the value is a binary operator of the right
- // kind) then the value is no longer considered to be a leaf, and its operands
- // are explored.
-
- // Leaves - Keeps track of the set of putative leaves as well as the number of
- // paths to each leaf seen so far.
- using LeafMap = DenseMap<Value *, APInt>;
- LeafMap Leaves; // Leaf -> Total weight so far.
- SmallVector<Value *, 8> LeafOrder; // Ensure deterministic leaf output order.
-
- #ifndef NDEBUG
- SmallPtrSet<Value *, 8> Visited; // For sanity checking the iteration scheme.
- #endif
- while (!Worklist.empty()) {
- std::pair<Instruction*, APInt> P = Worklist.pop_back_val();
- I = P.first; // We examine the operands of this binary operator.
-
- for (unsigned OpIdx = 0; OpIdx < I->getNumOperands(); ++OpIdx) { // Visit operands.
- Value *Op = I->getOperand(OpIdx);
- APInt Weight = P.second; // Number of paths to this operand.
- LLVM_DEBUG(dbgs() << "OPERAND: " << *Op << " (" << Weight << ")\n");
- assert(!Op->use_empty() && "No uses, so how did we get to it?!");
-
- // 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).second && "Not first visit!");
- LLVM_DEBUG(dbgs() << "DIRECT ADD: " << *Op << " (" << Weight << ")\n");
- Worklist.push_back(std::make_pair(BO, Weight));
- continue;
- }
-
- // Appears to be a leaf. Is the operand already in the set of leaves?
- 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).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.
- LLVM_DEBUG(dbgs()
- << "ADD USES LEAF: " << *Op << " (" << Weight << ")\n");
- LeafOrder.push_back(Op);
- Leaves[Op] = Weight;
- continue;
- }
- // No uses outside the expression, try morphing it.
- } else {
- // Already in the leaf map.
- assert(It != Leaves.end() && Visited.count(Op) &&
- "In leaf map but not visited!");
-
- // Update the number of paths to the leaf.
- IncorporateWeight(It->second, Weight, Opcode);
-
- #if 0 // TODO: Re-enable once PR13021 is fixed.
- // The leaf already has one use from inside the expression. As we want
- // 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()));
- 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
- // to the expression, then no longer consider it to be a leaf and add
- // its operands to the expression.
- if (BinaryOperator *BO = isReassociableOp(Op, Opcode)) {
- LLVM_DEBUG(dbgs() << "UNLEAF: " << *Op << " (" << It->second << ")\n");
- Worklist.push_back(std::make_pair(BO, It->second));
- Leaves.erase(It);
- continue;
- }
- #endif
-
- // If we still have uses that are not accounted for by the expression
- // then it is not safe to modify the value.
- if (!Op->hasOneUse())
- continue;
-
- // No uses outside the expression, try morphing it.
- Weight = It->second;
- Leaves.erase(It); // Since the value may be morphed below.
- }
-
- // At this point we have a value which, first of all, is not a binary
- // expression of the right kind, and secondly, is only used inside the
- // 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
- || (isa<FPMathOperator>(Op) &&
- !cast<Instruction>(Op)->isFast())) &&
- "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.
- if (Instruction *Tmp = dyn_cast<Instruction>(Op))
- if ((Opcode == Instruction::Mul && match(Tmp, m_Neg(m_Value()))) ||
- (Opcode == Instruction::FMul && match(Tmp, m_FNeg(m_Value())))) {
- LLVM_DEBUG(dbgs()
- << "MORPH LEAF: " << *Op << " (" << Weight << ") TO ");
- Tmp = LowerNegateToMultiply(Tmp);
- LLVM_DEBUG(dbgs() << *Tmp << '\n');
- Worklist.push_back(std::make_pair(Tmp, Weight));
- Changed = true;
- continue;
- }
-
- // Failed to morph into an expression of the right type. This really is
- // a leaf.
- LLVM_DEBUG(dbgs() << "ADD LEAF: " << *Op << " (" << Weight << ")\n");
- assert(!isReassociableOp(Op, Opcode) && "Value was morphed?");
- LeafOrder.push_back(Op);
- Leaves[Op] = Weight;
- }
- }
-
- // The leaves, repeated according to their weights, represent the linearized
- // form of the expression.
- for (unsigned i = 0, e = LeafOrder.size(); i != e; ++i) {
- Value *V = LeafOrder[i];
- LeafMap::iterator It = Leaves.find(V);
- if (It == Leaves.end())
- // Node initially thought to be a leaf wasn't.
- continue;
- assert(!isReassociableOp(V, Opcode) && "Shouldn't be a leaf!");
- APInt Weight = It->second;
- if (Weight.isMinValue())
- // Leaf already output or weight reduction eliminated it.
- continue;
- // Ensure the leaf is only output once.
- It->second = 0;
- Ops.push_back(std::make_pair(V, Weight));
- }
-
- // 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.emplace_back(Identity, APInt(Bitwidth, 1));
- }
-
- return Changed;
- }
-
- /// Now that the operands for this expression tree are
- /// linearized and optimized, emit them in-order.
- void ReassociatePass::RewriteExprTree(BinaryOperator *I,
- SmallVectorImpl<ValueEntry> &Ops) {
- assert(Ops.size() > 1 && "Single values should be used directly!");
-
- // 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
diff erent topology.
- // We take care to not change anything if the new expression will be the same
- // as the original. If more than trivial changes (like commuting operands)
- // were made then we are obliged to clear out any optional subclass data like
- // nsw flags.
-
- /// NodesToRewrite - Nodes from the original expression available for writing
- /// the new expression into.
- SmallVector<BinaryOperator*, 8> NodesToRewrite;
- 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
diff ers 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 = 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
- // a subexpression.
- if (i+2 == Ops.size()) {
- Value *NewLHS = Ops[i].Op;
- Value *NewRHS = Ops[i+1].Op;
- Value *OldLHS = Op->getOperand(0);
- Value *OldRHS = Op->getOperand(1);
-
- if (NewLHS == OldLHS && NewRHS == OldRHS)
- // Nothing changed, leave it alone.
- break;
-
- if (NewLHS == OldRHS && NewRHS == OldLHS) {
- // The order of the operands was reversed. Swap them.
- LLVM_DEBUG(dbgs() << "RA: " << *Op << '\n');
- Op->swapOperands();
- LLVM_DEBUG(dbgs() << "TO: " << *Op << '\n');
- MadeChange = true;
- ++NumChanged;
- break;
- }
-
- // The new operation
diff ers non-trivially from the original. Overwrite
- // the old operands with the new ones.
- LLVM_DEBUG(dbgs() << "RA: " << *Op << '\n');
- if (NewLHS != OldLHS) {
- BinaryOperator *BO = isReassociableOp(OldLHS, Opcode);
- if (BO && !NotRewritable.count(BO))
- NodesToRewrite.push_back(BO);
- Op->setOperand(0, NewLHS);
- }
- if (NewRHS != OldRHS) {
- BinaryOperator *BO = isReassociableOp(OldRHS, Opcode);
- if (BO && !NotRewritable.count(BO))
- NodesToRewrite.push_back(BO);
- Op->setOperand(1, NewRHS);
- }
- LLVM_DEBUG(dbgs() << "TO: " << *Op << '\n');
-
- ExpressionChanged = Op;
- MadeChange = true;
- ++NumChanged;
-
- break;
- }
-
- // Not the last operation. The left-hand side will be a sub-expression
- // while the right-hand side will be the current element of Ops.
- Value *NewRHS = Ops[i].Op;
- if (NewRHS != Op->getOperand(1)) {
- LLVM_DEBUG(dbgs() << "RA: " << *Op << '\n');
- if (NewRHS == Op->getOperand(0)) {
- // The new right-hand side was already present as the left operand. If
- // we are lucky then swapping the operands will sort out both of them.
- Op->swapOperands();
- } else {
- // Overwrite with the new right-hand side.
- BinaryOperator *BO = isReassociableOp(Op->getOperand(1), Opcode);
- if (BO && !NotRewritable.count(BO))
- NodesToRewrite.push_back(BO);
- Op->setOperand(1, NewRHS);
- ExpressionChanged = Op;
- }
- LLVM_DEBUG(dbgs() << "TO: " << *Op << '\n');
- MadeChange = true;
- ++NumChanged;
- }
-
- // 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.
- BinaryOperator *BO = isReassociableOp(Op->getOperand(0), Opcode);
- if (BO && !NotRewritable.count(BO)) {
- Op = BO;
- continue;
- }
-
- // Otherwise, grab a spare node from the original expression and use that as
- // the left-hand side. If there are no nodes left then the optimizers made
- // an expression with more nodes than the original! This usually means that
- // they did something stupid but it might mean that the problem was just too
- // hard (finding the mimimal number of multiplications needed to realize a
- // multiplication expression is NP-complete). Whatever the reason, smart or
- // stupid, create a new node if there are none left.
- BinaryOperator *NewOp;
- if (NodesToRewrite.empty()) {
- 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();
- }
-
- LLVM_DEBUG(dbgs() << "RA: " << *Op << '\n');
- Op->setOperand(0, NewOp);
- LLVM_DEBUG(dbgs() << "TO: " << *Op << '\n');
- ExpressionChanged = Op;
- MadeChange = true;
- ++NumChanged;
- Op = NewOp;
- }
-
- // If the expression changed non-trivially then clear out all subclass data
- // starting from the operator specified in ExpressionChanged, and compactify
- // the operators to just before the expression root to guarantee that the
- // expression tree is dominated by all of Ops.
- if (ExpressionChanged)
- do {
- // Preserve FastMathFlags.
- if (isa<FPMathOperator>(I)) {
- FastMathFlags Flags = I->getFastMathFlags();
- ExpressionChanged->clearSubclassOptionalData();
- ExpressionChanged->setFastMathFlags(Flags);
- } else
- ExpressionChanged->clearSubclassOptionalData();
-
- if (ExpressionChanged == I)
- break;
-
- // Discard any debug info related to the expressions that has changed (we
- // can leave debug infor related to the root, since the result of the
- // expression tree should be the same even after reassociation).
- replaceDbgUsesWithUndef(ExpressionChanged);
-
- ExpressionChanged->moveBefore(I);
- ExpressionChanged = cast<BinaryOperator>(*ExpressionChanged->user_begin());
- } while (true);
-
- // Throw away any left over nodes from the original expression.
- for (unsigned i = 0, e = NodesToRewrite.size(); i != e; ++i)
- RedoInsts.insert(NodesToRewrite[i]);
- }
-
- /// 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.
- /// Also add intermediate instructions to the redo list that are modified while
- /// pushing the negates through adds. These will be revisited to see if
- /// additional opportunities have been exposed.
- static Value *NegateValue(Value *V, Instruction *BI,
- ReassociatePass::OrderedSet &ToRedo) {
- if (auto *C = dyn_cast<Constant>(V))
- return C->getType()->isFPOrFPVectorTy() ? ConstantExpr::getFNeg(C) :
- 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
- // expression chain as possible, to expose the add instructions. In practice,
- // this means that we turn this:
- // X = -(A+12+C+D) into X = -A + -12 + -C + -D = -12 + -A + -C + -D
- // so that later, a: Y = 12+X could get reassociated with the -12 to eliminate
- // 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, Instruction::FAdd)) {
- // Push the negates through the add.
- I->setOperand(0, NegateValue(I->getOperand(0), BI, ToRedo));
- I->setOperand(1, NegateValue(I->getOperand(1), BI, ToRedo));
- 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
- // assured that the neg instructions we just inserted dominate the
- // instruction we are about to insert after them.
- //
- I->moveBefore(BI);
- I->setName(I->getName()+".neg");
-
- // Add the intermediate negates to the redo list as processing them later
- // could expose more reassociating opportunities.
- ToRedo.insert(I);
- return I;
- }
-
- // 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 (User *U : V->users()) {
- if (!match(U, m_Neg(m_Value())) && !match(U, m_FNeg(m_Value())))
- 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
- // non-instruction value) or right after the definition. These negates will
- // be zapped by reassociate later, so we don't need much finesse here.
- Instruction *TheNeg = cast<Instruction>(U);
-
- // Verify that the negate is in this function, V might be a constant expr.
- if (TheNeg->getParent()->getParent() != BI->getParent()->getParent())
- continue;
-
- bool FoundCatchSwitch = false;
-
- BasicBlock::iterator InsertPt;
- if (Instruction *InstInput = dyn_cast<Instruction>(V)) {
- if (InvokeInst *II = dyn_cast<InvokeInst>(InstInput)) {
- InsertPt = II->getNormalDest()->begin();
- } else {
- InsertPt = ++InstInput->getIterator();
- }
-
- const BasicBlock *BB = InsertPt->getParent();
-
- // Make sure we don't move anything before PHIs or exception
- // handling pads.
- while (InsertPt != BB->end() && (isa<PHINode>(InsertPt) ||
- InsertPt->isEHPad())) {
- if (isa<CatchSwitchInst>(InsertPt))
- // A catchswitch cannot have anything in the block except
- // itself and PHIs. We'll bail out below.
- FoundCatchSwitch = true;
- ++InsertPt;
- }
- } else {
- InsertPt = TheNeg->getParent()->getParent()->getEntryBlock().begin();
- }
-
- // We found a catchswitch in the block where we want to move the
- // neg. We cannot move anything into that block. Bail and just
- // create the neg before BI, as if we hadn't found an existing
- // neg.
- if (FoundCatchSwitch)
- break;
-
- TheNeg->moveBefore(&*InsertPt);
- if (TheNeg->getOpcode() == Instruction::Sub) {
- TheNeg->setHasNoUnsignedWrap(false);
- TheNeg->setHasNoSignedWrap(false);
- } else {
- TheNeg->andIRFlags(BI);
- }
- ToRedo.insert(TheNeg);
- return TheNeg;
- }
-
- // Insert a 'neg' instruction that subtracts the value from zero to get the
- // negation.
- BinaryOperator *NewNeg = CreateNeg(V, V->getName() + ".neg", BI, BI);
- ToRedo.insert(NewNeg);
- return NewNeg;
- }
-
- /// 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 (match(Sub, m_Neg(m_Value())) || match(Sub, m_FNeg(m_Value())))
- 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.
- Value *V0 = Sub->getOperand(0);
- if (isReassociableOp(V0, Instruction::Add, Instruction::FAdd) ||
- isReassociableOp(V0, Instruction::Sub, Instruction::FSub))
- return true;
- 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(VB, Instruction::Add, Instruction::FAdd) ||
- isReassociableOp(VB, Instruction::Sub, Instruction::FSub)))
- return true;
-
- return false;
- }
-
- /// 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,
- ReassociatePass::OrderedSet &ToRedo) {
- // Convert a subtract into an add and a neg instruction. This allows sub
- // instructions to be commuted with other add instructions.
- //
- // Calculate the negative value of Operand 1 of the sub instruction,
- // and set it as the RHS of the add instruction we just made.
- Value *NegVal = NegateValue(Sub->getOperand(1), Sub, ToRedo);
- 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);
-
- // Everyone now refers to the add instruction.
- Sub->replaceAllUsesWith(New);
- New->setDebugLoc(Sub->getDebugLoc());
-
- LLVM_DEBUG(dbgs() << "Negated: " << *New << '\n');
- return New;
- }
-
- /// 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 *Mul =
- 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;
- }
-
- /// 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(const 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) {
- 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) {
- 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;
- }
-
- /// Emit a tree of add instructions, summing Ops together
- /// and returning the result. Insert the tree before I.
- static Value *EmitAddTreeOfValues(Instruction *I,
- SmallVectorImpl<WeakTrackingVH> &Ops) {
- if (Ops.size() == 1) return Ops.back();
-
- Value *V1 = Ops.back();
- Ops.pop_back();
- Value *V2 = EmitAddTreeOfValues(I, Ops);
- return CreateAdd(V2, V1, "reass.add", I, I);
- }
-
- /// 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 *ReassociatePass::RemoveFactorFromExpression(Value *V, Value *Factor) {
- BinaryOperator *BO = isReassociableOp(V, Instruction::Mul, Instruction::FMul);
- if (!BO)
- return nullptr;
-
- SmallVector<RepeatedValue, 8> Tree;
- MadeChange |= LinearizeExprTree(BO, Tree);
- SmallVector<ValueEntry, 8> Factors;
- Factors.reserve(Tree.size());
- for (unsigned i = 0, e = Tree.size(); i != e; ++i) {
- RepeatedValue E = Tree[i];
- Factors.append(E.second.getZExtValue(),
- ValueEntry(getRank(E.first), E.first));
- }
-
- bool FoundFactor = false;
- bool NeedsNegate = false;
- for (unsigned i = 0, e = Factors.size(); i != e; ++i) {
- if (Factors[i].Op == Factor) {
- FoundFactor = true;
- Factors.erase(Factors.begin()+i);
- break;
- }
-
- // If this is a negative version of this factor, remove it.
- 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)) {
- const 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 nullptr;
- }
-
- BasicBlock::iterator InsertPt = ++BO->getIterator();
-
- // If this was just a single multiply, remove the multiply and return the only
- // remaining operand.
- if (Factors.size() == 1) {
- RedoInsts.insert(BO);
- V = Factors[0].Op;
- } else {
- RewriteExprTree(BO, Factors);
- V = BO;
- }
-
- if (NeedsNegate)
- V = CreateNeg(V, "neg", &*InsertPt, BO);
-
- return V;
- }
-
- /// 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) {
- BinaryOperator *BO = isReassociableOp(V, Instruction::Mul, Instruction::FMul);
- if (!BO) {
- Factors.push_back(V);
- return;
- }
-
- // Otherwise, add the LHS and RHS to the list of factors.
- FindSingleUseMultiplyFactors(BO->getOperand(1), Factors);
- FindSingleUseMultiplyFactors(BO->getOperand(0), Factors);
- }
-
- /// 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.
- // If we find any, we can simplify the expression. X&~X == 0, X|~X == -1.
- for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
- // First, check for X and ~X in the operand list.
- assert(i < Ops.size());
- Value *X;
- if (match(Ops[i].Op, m_Not(m_Value(X)))) { // Cannot occur for ^.
- unsigned FoundX = FindInOperandList(Ops, i, X);
- if (FoundX != i) {
- if (Opcode == Instruction::And) // ...&X&~X = 0
- return Constant::getNullValue(X->getType());
-
- if (Opcode == Instruction::Or) // ...|X|~X = -1
- return Constant::getAllOnesValue(X->getType());
- }
- }
-
- // Next, check for duplicate pairs of values, which we assume are next to
- // each other, due to our sorting criteria.
- assert(i < Ops.size());
- if (i+1 != Ops.size() && Ops[i+1].Op == Ops[i].Op) {
- if (Opcode == Instruction::And || Opcode == Instruction::Or) {
- // Drop duplicate values for And and Or.
- Ops.erase(Ops.begin()+i);
- --i; --e;
- ++NumAnnihil;
- continue;
- }
-
- // Drop pairs of values for Xor.
- assert(Opcode == Instruction::Xor);
- if (e == 2)
- return Constant::getNullValue(Ops[0].Op->getType());
-
- // Y ^ X^X -> Y
- Ops.erase(Ops.begin()+i, Ops.begin()+i+2);
- i -= 1; e -= 2;
- ++NumAnnihil;
- }
- }
- return nullptr;
- }
-
- /// Helper function 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.isNullValue())
- return nullptr;
-
- if (ConstOpnd.isAllOnesValue())
- return Opnd;
-
- Instruction *I = BinaryOperator::CreateAnd(
- Opnd, ConstantInt::get(Opnd->getType(), ConstOpnd), "and.ra",
- InsertBefore);
- I->setDebugLoc(InsertBefore->getDebugLoc());
- return I;
- }
-
- // 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 ReassociatePass::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().isNullValue())
- return false;
-
- 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;
- }
-
- // 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 ReassociatePass::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.isNullValue() && !C3.isAllOnesValue()) {
- int NewInstNum = ConstOpnd.getBoolValue() ? 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.isNullValue() && !C3.isAllOnesValue()) {
- int NewInstNum = ConstOpnd.getBoolValue() ? 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 *ReassociatePass::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->getScalarSizeInBits(), 0);
-
- // Step 1: Convert ValueEntry to XorOpnd
- for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
- Value *V = Ops[i].Op;
- const APInt *C;
- // TODO: Support non-splat vectors.
- if (match(V, m_APInt(C))) {
- ConstOpnd ^= *C;
- } else {
- XorOpnd O(V);
- O.setSymbolicRank(getRank(O.getSymbolicPart()));
- Opnds.push_back(O);
- }
- }
-
- // 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").
- //
- // 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.
- llvm::stable_sort(OpndPtrs, [](XorOpnd *LHS, XorOpnd *RHS) {
- return LHS->getSymbolicRank() < RHS->getSymbolicRank();
- });
-
- // 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.isNullValue() &&
- 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.isNullValue()) {
- Value *C = ConstantInt::get(Ty, ConstOpnd);
- ValueEntry VE(getRank(C), C);
- Ops.push_back(VE);
- }
- unsigned Sz = Ops.size();
- if (Sz == 1)
- return Ops.back().Op;
- if (Sz == 0) {
- assert(ConstOpnd.isNullValue());
- return ConstantInt::get(Ty, ConstOpnd);
- }
- }
-
- return nullptr;
- }
-
- /// 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 *ReassociatePass::OptimizeAdd(Instruction *I,
- SmallVectorImpl<ValueEntry> &Ops) {
- // Scan the operand lists looking for X and -X pairs. If we find any, we
- // 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.
-
- 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
- // instances of the operand together. Due to our sorting criteria, we know
- // that these need to be next to each other in the vector.
- if (i+1 != Ops.size() && Ops[i+1].Op == TheOp) {
- // Rescan the list, remove all instances of this operand from the expr.
- unsigned NumFound = 0;
- do {
- Ops.erase(Ops.begin()+i);
- ++NumFound;
- } while (i != Ops.size() && Ops[i].Op == TheOp);
-
- LLVM_DEBUG(dbgs() << "\nFACTORING [" << NumFound << "]: " << *TheOp
- << '\n');
- ++NumFactor;
-
- // Insert a new multiply.
- 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(Mul);
-
- // If every add operand was a duplicate, return the multiply.
- if (Ops.empty())
- return Mul;
-
- // Otherwise, we had some input that didn't have the dupe, such as
- // "A + A + B" -> "A*2 + B". Add the new multiply to the list of
- // things being added by this operation.
- Ops.insert(Ops.begin(), ValueEntry(getRank(Mul), Mul));
-
- --i;
- e = Ops.size();
- continue;
- }
-
- // Check for X and -X or X and ~X in the operand list.
- Value *X;
- if (!match(TheOp, m_Neg(m_Value(X))) && !match(TheOp, m_Not(m_Value(X))) &&
- !match(TheOp, m_FNeg(m_Value(X))))
- continue;
-
- unsigned FoundX = FindInOperandList(Ops, i, X);
- if (FoundX == i)
- continue;
-
- // Remove X and -X from the operand list.
- if (Ops.size() == 2 &&
- (match(TheOp, m_Neg(m_Value())) || match(TheOp, m_FNeg(m_Value()))))
- return Constant::getNullValue(X->getType());
-
- // Remove X and ~X from the operand list.
- if (Ops.size() == 2 && match(TheOp, m_Not(m_Value())))
- return Constant::getAllOnesValue(X->getType());
-
- Ops.erase(Ops.begin()+i);
- if (i < FoundX)
- --FoundX;
- else
- --i; // Need to back up an extra one.
- Ops.erase(Ops.begin()+FoundX);
- ++NumAnnihil;
- --i; // Revisit element.
- e -= 2; // Removed two elements.
-
- // if X and ~X we append -1 to the operand list.
- if (match(TheOp, m_Not(m_Value()))) {
- 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
- // between operands. Consider something like A*A+A*B*C+D. We would like to
- // reassociate this to A*(A+B*C)+D, which reduces the number of multiplies.
- // To efficiently find this, we count the number of times a factor occurs
- // for any ADD operands that are MULs.
- DenseMap<Value*, unsigned> FactorOccurrences;
-
- // 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 = nullptr;
- for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
- BinaryOperator *BOp =
- isReassociableOp(Ops[i].Op, Instruction::Mul, Instruction::FMul);
- if (!BOp)
- continue;
-
- // Compute all of the factors of this added value.
- SmallVector<Value*, 8> Factors;
- FindSingleUseMultiplyFactors(BOp, Factors);
- assert(Factors.size() > 1 && "Bad linearize!");
-
- // Add one to FactorOccurrences for each unique factor in this op.
- SmallPtrSet<Value*, 8> Duplicates;
- for (unsigned i = 0, e = Factors.size(); i != e; ++i) {
- Value *Factor = Factors[i];
- if (!Duplicates.insert(Factor).second)
- continue;
-
- unsigned Occ = ++FactorOccurrences[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 (CI->isNegative() && !CI->isMinValue(true)) {
- Factor = ConstantInt::get(CI->getContext(), -CI->getValue());
- if (!Duplicates.insert(Factor).second)
- continue;
- unsigned Occ = ++FactorOccurrences[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);
- if (!Duplicates.insert(Factor).second)
- continue;
- 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) {
- LLVM_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
diff erently.
- Instruction *DummyInst =
- I->getType()->isIntOrIntVectorTy()
- ? BinaryOperator::CreateAdd(MaxOccVal, MaxOccVal)
- : BinaryOperator::CreateFAdd(MaxOccVal, MaxOccVal);
-
- SmallVector<WeakTrackingVH, 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, Instruction::FMul);
- if (!BOp)
- continue;
-
- if (Value *V = RemoveFactorFromExpression(Ops[i].Op, MaxOccVal)) {
- // The factorized operand may occur several times. Convert them all in
- // one fell swoop.
- for (unsigned j = Ops.size(); j != i;) {
- --j;
- if (Ops[j].Op == Ops[i].Op) {
- NewMulOps.push_back(V);
- Ops.erase(Ops.begin()+j);
- }
- }
- --i;
- }
- }
-
- // No need for extra uses anymore.
- DummyInst->deleteValue();
-
- unsigned NumAddedValues = NewMulOps.size();
- Value *V = EmitAddTreeOfValues(I, NewMulOps);
-
- // Now that we have inserted the add tree, optimize it. This allows us to
- // handle cases that require multiple factoring steps, such as this:
- // A*A*B + A*A*C --> A*(A*B+A*C) --> A*(A*(B+C))
- assert(NumAddedValues > 1 && "Each occurrence should contribute a value");
- (void)NumAddedValues;
- if (Instruction *VI = dyn_cast<Instruction>(V))
- RedoInsts.insert(VI);
-
- // Create the multiply.
- Instruction *V2 = CreateMul(V, MaxOccVal, "reass.mul", 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.
- RedoInsts.insert(V2);
-
- // If every add operand included the factor (e.g. "A*B + A*C"), then the
- // entire result expression is just the multiply "A*(B+C)".
- if (Ops.empty())
- return V2;
-
- // Otherwise, we had some input that didn't have the factor, such as
- // "A*B + A*C + D" -> "A*(B+C) + D". Add the new multiply to the list of
- // things being added by this operation.
- Ops.insert(Ops.begin(), ValueEntry(getRank(V2), V2));
- }
-
- return nullptr;
- }
-
- /// Build up a vector of value/power pairs factoring a product.
- ///
- /// Given a series of multiplication operands, build a vector of factors and
- /// the powers each is raised to when forming the final product. Sort them in
- /// the order of descending power.
- ///
- /// (x*x) -> [(x, 2)]
- /// ((x*x)*x) -> [(x, 3)]
- /// ((((x*y)*x)*y)*x) -> [(x, 3), (y, 2)]
- ///
- /// \returns Whether any factors have a power greater than one.
- static bool collectMultiplyFactors(SmallVectorImpl<ValueEntry> &Ops,
- SmallVectorImpl<Factor> &Factors) {
- // FIXME: Have Ops be (ValueEntry, Multiplicity) pairs, simplifying this.
- // Compute the sum of powers of simplifiable factors.
- unsigned FactorPowerSum = 0;
- for (unsigned Idx = 1, Size = Ops.size(); Idx < Size; ++Idx) {
- Value *Op = Ops[Idx-1].Op;
-
- // Count the number of occurrences of this value.
- unsigned Count = 1;
- for (; Idx < Size && Ops[Idx].Op == Op; ++Idx)
- ++Count;
- // Track for simplification all factors which occur 2 or more times.
- if (Count > 1)
- FactorPowerSum += Count;
- }
-
- // We can only simplify factors if the sum of the powers of our simplifiable
- // factors is 4 or higher. When that is the case, we will *always* have
- // a simplification. This is an important invariant to prevent cyclicly
- // trying to simplify already minimal formations.
- if (FactorPowerSum < 4)
- return false;
-
- // Now gather the simplifiable factors, removing them from Ops.
- FactorPowerSum = 0;
- for (unsigned Idx = 1; Idx < Ops.size(); ++Idx) {
- Value *Op = Ops[Idx-1].Op;
-
- // Count the number of occurrences of this value.
- unsigned Count = 1;
- for (; Idx < Ops.size() && Ops[Idx].Op == Op; ++Idx)
- ++Count;
- if (Count == 1)
- continue;
- // Move an even number of occurrences to Factors.
- Count &= ~1U;
- Idx -= Count;
- FactorPowerSum += Count;
- Factors.push_back(Factor(Op, Count));
- Ops.erase(Ops.begin()+Idx, Ops.begin()+Idx+Count);
- }
-
- // None of the adjustments above should have reduced the sum of factor powers
- // below our mininum of '4'.
- assert(FactorPowerSum >= 4);
-
- llvm::stable_sort(Factors, [](const Factor &LHS, const Factor &RHS) {
- return LHS.Power > RHS.Power;
- });
- return true;
- }
-
- /// Build a tree of multiplies, computing the product of Ops.
- static Value *buildMultiplyTree(IRBuilder<> &Builder,
- SmallVectorImpl<Value*> &Ops) {
- if (Ops.size() == 1)
- return Ops.back();
-
- Value *LHS = Ops.pop_back_val();
- do {
- 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;
- }
-
- /// Build a minimal multiplication DAG for (a^x)*(b^y)*(c^z)*...
- ///
- /// Given a vector of values raised to various powers, where no two values are
- /// equal and the powers are sorted in decreasing order, compute the minimal
- /// DAG of multiplies to compute the final product, and return that product
- /// value.
- Value *
- ReassociatePass::buildMinimalMultiplyDAG(IRBuilder<> &Builder,
- SmallVectorImpl<Factor> &Factors) {
- assert(Factors[0].Power);
- SmallVector<Value *, 4> OuterProduct;
- for (unsigned LastIdx = 0, Idx = 1, Size = Factors.size();
- Idx < Size && Factors[Idx].Power > 0; ++Idx) {
- if (Factors[Idx].Power != Factors[LastIdx].Power) {
- LastIdx = Idx;
- continue;
- }
-
- // We want to multiply across all the factors with the same power so that
- // we can raise them to that power as a single entity. Build a mini tree
- // for that.
- SmallVector<Value *, 4> InnerProduct;
- InnerProduct.push_back(Factors[LastIdx].Base);
- do {
- InnerProduct.push_back(Factors[Idx].Base);
- ++Idx;
- } while (Idx < Size && Factors[Idx].Power == Factors[LastIdx].Power);
-
- // Reset the base value of the first factor to the new expression tree.
- // We'll remove all the factors with the same power in a second pass.
- Value *M = Factors[LastIdx].Base = buildMultiplyTree(Builder, InnerProduct);
- if (Instruction *MI = dyn_cast<Instruction>(M))
- RedoInsts.insert(MI);
-
- LastIdx = Idx;
- }
- // Unique factors with equal powers -- we've folded them into the first one's
- // base.
- Factors.erase(std::unique(Factors.begin(), Factors.end(),
- [](const Factor &LHS, const Factor &RHS) {
- return LHS.Power == RHS.Power;
- }),
- Factors.end());
-
- // Iteratively collect the base of each factor with an add power into the
- // outer product, and halve each power in preparation for squaring the
- // expression.
- for (unsigned Idx = 0, Size = Factors.size(); Idx != Size; ++Idx) {
- if (Factors[Idx].Power & 1)
- OuterProduct.push_back(Factors[Idx].Base);
- Factors[Idx].Power >>= 1;
- }
- if (Factors[0].Power) {
- Value *SquareRoot = buildMinimalMultiplyDAG(Builder, Factors);
- OuterProduct.push_back(SquareRoot);
- OuterProduct.push_back(SquareRoot);
- }
- if (OuterProduct.size() == 1)
- return OuterProduct.front();
-
- Value *V = buildMultiplyTree(Builder, OuterProduct);
- return V;
- }
-
- Value *ReassociatePass::OptimizeMul(BinaryOperator *I,
- SmallVectorImpl<ValueEntry> &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 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 nullptr; // All distinct factors, so nothing left for us to do.
-
- IRBuilder<> Builder(I);
- // The reassociate transformation for FP operations is performed only
- // if unsafe algebra is permitted by FastMathFlags. Propagate those flags
- // to the newly generated operations.
- if (auto FPI = dyn_cast<FPMathOperator>(I))
- Builder.setFastMathFlags(FPI->getFastMathFlags());
-
- Value *V = buildMinimalMultiplyDAG(Builder, Factors);
- if (Ops.empty())
- return V;
-
- ValueEntry NewEntry = ValueEntry(getRank(V), V);
- Ops.insert(llvm::lower_bound(Ops, NewEntry), NewEntry);
- return nullptr;
- }
-
- Value *ReassociatePass::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.
- 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.
- unsigned NumOps = Ops.size();
- switch (Opcode) {
- default: break;
- case Instruction::And:
- case Instruction::Or:
- 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 nullptr;
- }
-
- // Remove dead instructions and if any operands are trivially dead add them to
- // Insts so they will be removed as well.
- void ReassociatePass::RecursivelyEraseDeadInsts(Instruction *I,
- OrderedSet &Insts) {
- assert(isInstructionTriviallyDead(I) && "Trivially dead instructions only!");
- SmallVector<Value *, 4> Ops(I->op_begin(), I->op_end());
- ValueRankMap.erase(I);
- Insts.remove(I);
- RedoInsts.remove(I);
-+ llvm::salvageDebugInfoOrMarkUndef(*I);
- I->eraseFromParent();
- for (auto Op : Ops)
- if (Instruction *OpInst = dyn_cast<Instruction>(Op))
- if (OpInst->use_empty())
- Insts.insert(OpInst);
- }
-
- /// Zap the given instruction, adding interesting operands to the work list.
- void ReassociatePass::EraseInst(Instruction *I) {
- assert(isInstructionTriviallyDead(I) && "Trivially dead instructions only!");
- LLVM_DEBUG(dbgs() << "Erasing dead inst: "; I->dump());
-
- SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
- // Erase the dead instruction.
- ValueRankMap.erase(I);
- RedoInsts.remove(I);
-+ llvm::salvageDebugInfoOrMarkUndef(*I);
- I->eraseFromParent();
- // Optimize its operands.
- SmallPtrSet<Instruction *, 8> Visited; // Detect self-referential nodes.
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- if (Instruction *Op = dyn_cast<Instruction>(Ops[i])) {
- // 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->user_back()->getOpcode() == Opcode &&
- Visited.insert(Op).second)
- Op = Op->user_back();
-
- // The instruction we're going to push may be coming from a
- // dead block, and Reassociate skips the processing of unreachable
- // blocks because it's a waste of time and also because it can
- // lead to infinite loop due to LLVM's non-standard definition
- // of dominance.
- if (ValueRankMap.find(Op) != ValueRankMap.end())
- RedoInsts.insert(Op);
- }
-
- MadeChange = true;
- }
-
- /// Recursively analyze an expression to build a list of instructions that have
- /// negative floating-point constant operands. The caller can then transform
- /// the list to create positive constants for better reassociation and CSE.
- static void getNegatibleInsts(Value *V,
- SmallVectorImpl<Instruction *> &Candidates) {
- // Handle only one-use instructions. Combining negations does not justify
- // replicating instructions.
- Instruction *I;
- if (!match(V, m_OneUse(m_Instruction(I))))
- return;
-
- // Handle expressions of multiplications and divisions.
- // TODO: This could look through floating-point casts.
- const APFloat *C;
- switch (I->getOpcode()) {
- case Instruction::FMul:
- // Not expecting non-canonical code here. Bail out and wait.
- if (match(I->getOperand(0), m_Constant()))
- break;
-
- if (match(I->getOperand(1), m_APFloat(C)) && C->isNegative()) {
- Candidates.push_back(I);
- LLVM_DEBUG(dbgs() << "FMul with negative constant: " << *I << '\n');
- }
- getNegatibleInsts(I->getOperand(0), Candidates);
- getNegatibleInsts(I->getOperand(1), Candidates);
- break;
- case Instruction::FDiv:
- // Not expecting non-canonical code here. Bail out and wait.
- if (match(I->getOperand(0), m_Constant()) &&
- match(I->getOperand(1), m_Constant()))
- break;
-
- if ((match(I->getOperand(0), m_APFloat(C)) && C->isNegative()) ||
- (match(I->getOperand(1), m_APFloat(C)) && C->isNegative())) {
- Candidates.push_back(I);
- LLVM_DEBUG(dbgs() << "FDiv with negative constant: " << *I << '\n');
- }
- getNegatibleInsts(I->getOperand(0), Candidates);
- getNegatibleInsts(I->getOperand(1), Candidates);
- break;
- default:
- break;
- }
- }
-
- /// Given an fadd/fsub with an operand that is a one-use instruction
- /// (the fadd/fsub), try to change negative floating-point constants into
- /// positive constants to increase potential for reassociation and CSE.
- Instruction *ReassociatePass::canonicalizeNegFPConstantsForOp(Instruction *I,
- Instruction *Op,
- Value *OtherOp) {
- assert((I->getOpcode() == Instruction::FAdd ||
- I->getOpcode() == Instruction::FSub) && "Expected fadd/fsub");
-
- // Collect instructions with negative FP constants from the subtree that ends
- // in Op.
- SmallVector<Instruction *, 4> Candidates;
- getNegatibleInsts(Op, Candidates);
- if (Candidates.empty())
- return nullptr;
-
- // Don't canonicalize x + (-Constant * y) -> x - (Constant * y), if the
- // resulting subtract will be broken up later. This can get us into an
- // infinite loop during reassociation.
- bool IsFSub = I->getOpcode() == Instruction::FSub;
- bool NeedsSubtract = !IsFSub && Candidates.size() % 2 == 1;
- if (NeedsSubtract && ShouldBreakUpSubtract(I))
- return nullptr;
-
- for (Instruction *Negatible : Candidates) {
- const APFloat *C;
- if (match(Negatible->getOperand(0), m_APFloat(C))) {
- assert(!match(Negatible->getOperand(1), m_Constant()) &&
- "Expecting only 1 constant operand");
- assert(C->isNegative() && "Expected negative FP constant");
- Negatible->setOperand(0, ConstantFP::get(Negatible->getType(), abs(*C)));
- MadeChange = true;
- }
- if (match(Negatible->getOperand(1), m_APFloat(C))) {
- assert(!match(Negatible->getOperand(0), m_Constant()) &&
- "Expecting only 1 constant operand");
- assert(C->isNegative() && "Expected negative FP constant");
- Negatible->setOperand(1, ConstantFP::get(Negatible->getType(), abs(*C)));
- MadeChange = true;
- }
- }
- assert(MadeChange == true && "Negative constant candidate was not changed");
-
- // Negations cancelled out.
- if (Candidates.size() % 2 == 0)
- return I;
-
- // Negate the final operand in the expression by flipping the opcode of this
- // fadd/fsub.
- assert(Candidates.size() % 2 == 1 && "Expected odd number");
- IRBuilder<> Builder(I);
- Value *NewInst = IsFSub ? Builder.CreateFAddFMF(OtherOp, Op, I)
- : Builder.CreateFSubFMF(OtherOp, Op, I);
- I->replaceAllUsesWith(NewInst);
- RedoInsts.insert(I);
- return dyn_cast<Instruction>(NewInst);
- }
-
- /// Canonicalize expressions that contain a negative floating-point constant
- /// of the following form:
- /// OtherOp + (subtree) -> OtherOp {+/-} (canonical subtree)
- /// (subtree) + OtherOp -> OtherOp {+/-} (canonical subtree)
- /// OtherOp - (subtree) -> OtherOp {+/-} (canonical subtree)
- ///
- /// The fadd/fsub opcode may be switched to allow folding a negation into the
- /// input instruction.
- Instruction *ReassociatePass::canonicalizeNegFPConstants(Instruction *I) {
- LLVM_DEBUG(dbgs() << "Combine negations for: " << *I << '\n');
- Value *X;
- Instruction *Op;
- if (match(I, m_FAdd(m_Value(X), m_OneUse(m_Instruction(Op)))))
- if (Instruction *R = canonicalizeNegFPConstantsForOp(I, Op, X))
- I = R;
- if (match(I, m_FAdd(m_OneUse(m_Instruction(Op)), m_Value(X))))
- if (Instruction *R = canonicalizeNegFPConstantsForOp(I, Op, X))
- I = R;
- if (match(I, m_FSub(m_Value(X), m_OneUse(m_Instruction(Op)))))
- if (Instruction *R = canonicalizeNegFPConstantsForOp(I, Op, X))
- I = R;
- return I;
- }
-
- /// Inspect and optimize the given instruction. Note that erasing
- /// instructions is not allowed.
- void ReassociatePass::OptimizeInst(Instruction *I) {
- // Only consider operations that we understand.
- if (!isa<UnaryOperator>(I) && !isa<BinaryOperator>(I))
- return;
-
- 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->user_back(), Instruction::Mul) ||
- isReassociableOp(I->user_back(), Instruction::Add)))) {
- Instruction *NI = ConvertShiftToMul(I);
- RedoInsts.insert(I);
- MadeChange = true;
- I = NI;
- }
-
- // 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);
-
- // Canonicalize negative constants out of expressions.
- if (Instruction *Res = canonicalizeNegFPConstants(I))
- I = Res;
-
- // Don't optimize floating-point instructions unless they are 'fast'.
- if (I->getType()->isFPOrFPVectorTy() && !I->isFast())
- return;
-
- // Do not reassociate boolean (i1) expressions. We want to preserve the
- // original order of evaluation for short-circuited comparisons that
- // SimplifyCFG has folded to AND/OR expressions. If the expression
- // is not further optimized, it is likely to be transformed back to a
- // short-circuited form for code gen, and the source order may have been
- // optimized for the most likely conditions.
- if (I->getType()->isIntegerTy(1))
- return;
-
- // If this is a subtract instruction which is not already in negate form,
- // see if we can convert it to X+-Y.
- if (I->getOpcode() == Instruction::Sub) {
- if (ShouldBreakUpSubtract(I)) {
- Instruction *NI = BreakUpSubtract(I, RedoInsts);
- RedoInsts.insert(I);
- MadeChange = true;
- I = NI;
- } else if (match(I, m_Neg(m_Value()))) {
- // 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::Mul) &&
- (!I->hasOneUse() ||
- !isReassociableOp(I->user_back(), Instruction::Mul))) {
- Instruction *NI = LowerNegateToMultiply(I);
- // If the negate was simplified, revisit the users to see if we can
- // reassociate further.
- for (User *U : NI->users()) {
- if (BinaryOperator *Tmp = dyn_cast<BinaryOperator>(U))
- RedoInsts.insert(Tmp);
- }
- RedoInsts.insert(I);
- MadeChange = true;
- I = NI;
- }
- }
- } else if (I->getOpcode() == Instruction::FNeg ||
- I->getOpcode() == Instruction::FSub) {
- if (ShouldBreakUpSubtract(I)) {
- Instruction *NI = BreakUpSubtract(I, RedoInsts);
- RedoInsts.insert(I);
- MadeChange = true;
- I = NI;
- } else if (match(I, m_FNeg(m_Value()))) {
- // 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.
- Value *Op = isa<BinaryOperator>(I) ? I->getOperand(1) :
- I->getOperand(0);
- if (isReassociableOp(Op, Instruction::FMul) &&
- (!I->hasOneUse() ||
- !isReassociableOp(I->user_back(), Instruction::FMul))) {
- // If the negate was simplified, revisit the users to see if we can
- // reassociate further.
- Instruction *NI = LowerNegateToMultiply(I);
- for (User *U : NI->users()) {
- if (BinaryOperator *Tmp = dyn_cast<BinaryOperator>(U))
- RedoInsts.insert(Tmp);
- }
- RedoInsts.insert(I);
- MadeChange = true;
- I = NI;
- }
- }
- }
-
- // If this instruction is an associative binary operator, process it.
- if (!I->isAssociative()) return;
- BinaryOperator *BO = cast<BinaryOperator>(I);
-
- // 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->user_back()->getOpcode() == Opcode) {
- // During the initial run we will get to the root of the tree.
- // But if we get here while we are redoing instructions, there is no
- // guarantee that the root will be visited. So Redo later
- if (BO->user_back() != BO &&
- BO->getParent() == BO->user_back()->getParent())
- RedoInsts.insert(BO->user_back());
- 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->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 ReassociatePass::ReassociateExpression(BinaryOperator *I) {
- // First, walk the expression tree, linearizing the tree, collecting the
- // operand information.
- SmallVector<RepeatedValue, 8> Tree;
- MadeChange |= LinearizeExprTree(I, Tree);
- SmallVector<ValueEntry, 8> Ops;
- Ops.reserve(Tree.size());
- for (unsigned i = 0, e = Tree.size(); i != e; ++i) {
- RepeatedValue E = Tree[i];
- Ops.append(E.second.getZExtValue(),
- ValueEntry(getRank(E.first), E.first));
- }
-
- LLVM_DEBUG(dbgs() << "RAIn:\t"; PrintOps(I, Ops); dbgs() << '\n');
-
- // Now that we have linearized the tree to a list and have gathered all of
- // the operands and their ranks, sort the operands by their rank. Use a
- // stable_sort so that values with equal ranks will have their relative
- // positions maintained (and so the compiler is deterministic). Note that
- // this sorts so that the highest ranking values end up at the beginning of
- // the vector.
- llvm::stable_sort(Ops);
-
- // 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)
- // Self-referential expression in unreachable code.
- return;
- // This expression tree simplified to something that isn't a tree,
- // eliminate it.
- LLVM_DEBUG(dbgs() << "Reassoc to scalar: " << *V << '\n');
- I->replaceAllUsesWith(V);
- if (Instruction *VI = dyn_cast<Instruction>(V))
- if (I->getDebugLoc())
- VI->setDebugLoc(I->getDebugLoc());
- RedoInsts.insert(I);
- ++NumAnnihil;
- return;
- }
-
- // We want to sink immediates as deeply as possible except in the case where
- // 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->hasOneUse()) {
- if (I->getOpcode() == Instruction::Mul &&
- cast<Instruction>(I->user_back())->getOpcode() == Instruction::Add &&
- isa<ConstantInt>(Ops.back().Op) &&
- cast<ConstantInt>(Ops.back().Op)->isMinusOne()) {
- 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);
- }
- }
-
- LLVM_DEBUG(dbgs() << "RAOut:\t"; PrintOps(I, Ops); dbgs() << '\n');
-
- if (Ops.size() == 1) {
- if (Ops[0].Op == I)
- // Self-referential expression in unreachable code.
- return;
-
- // This expression tree simplified to something that isn't a tree,
- // eliminate it.
- I->replaceAllUsesWith(Ops[0].Op);
- if (Instruction *OI = dyn_cast<Instruction>(Ops[0].Op))
- OI->setDebugLoc(I->getDebugLoc());
- RedoInsts.insert(I);
- return;
- }
-
- if (Ops.size() > 2 && Ops.size() <= GlobalReassociateLimit) {
- // Find the pair with the highest count in the pairmap and move it to the
- // back of the list so that it can later be CSE'd.
- // example:
- // a*b*c*d*e
- // if c*e is the most "popular" pair, we can express this as
- // (((c*e)*d)*b)*a
- unsigned Max = 1;
- unsigned BestRank = 0;
- std::pair<unsigned, unsigned> BestPair;
- unsigned Idx = I->getOpcode() - Instruction::BinaryOpsBegin;
- for (unsigned i = 0; i < Ops.size() - 1; ++i)
- for (unsigned j = i + 1; j < Ops.size(); ++j) {
- unsigned Score = 0;
- Value *Op0 = Ops[i].Op;
- Value *Op1 = Ops[j].Op;
- if (std::less<Value *>()(Op1, Op0))
- std::swap(Op0, Op1);
- auto it = PairMap[Idx].find({Op0, Op1});
- if (it != PairMap[Idx].end()) {
- // Functions like BreakUpSubtract() can erase the Values we're using
- // as keys and create new Values after we built the PairMap. There's a
- // small chance that the new nodes can have the same address as
- // something already in the table. We shouldn't accumulate the stored
- // score in that case as it refers to the wrong Value.
- if (it->second.isValid())
- Score += it->second.Score;
- }
-
- unsigned MaxRank = std::max(Ops[i].Rank, Ops[j].Rank);
- if (Score > Max || (Score == Max && MaxRank < BestRank)) {
- BestPair = {i, j};
- Max = Score;
- BestRank = MaxRank;
- }
- }
- if (Max > 1) {
- auto Op0 = Ops[BestPair.first];
- auto Op1 = Ops[BestPair.second];
- Ops.erase(&Ops[BestPair.second]);
- Ops.erase(&Ops[BestPair.first]);
- Ops.push_back(Op0);
- Ops.push_back(Op1);
- }
- }
- // Now that we ordered and optimized the expressions, splat them back into
- // the expression tree, removing any unneeded nodes.
- RewriteExprTree(I, Ops);
- }
-
- void
- ReassociatePass::BuildPairMap(ReversePostOrderTraversal<Function *> &RPOT) {
- // Make a "pairmap" of how often each operand pair occurs.
- for (BasicBlock *BI : RPOT) {
- for (Instruction &I : *BI) {
- if (!I.isAssociative())
- continue;
-
- // Ignore nodes that aren't at the root of trees.
- if (I.hasOneUse() && I.user_back()->getOpcode() == I.getOpcode())
- continue;
-
- // Collect all operands in a single reassociable expression.
- // Since Reassociate has already been run once, we can assume things
- // are already canonical according to Reassociation's regime.
- SmallVector<Value *, 8> Worklist = { I.getOperand(0), I.getOperand(1) };
- SmallVector<Value *, 8> Ops;
- while (!Worklist.empty() && Ops.size() <= GlobalReassociateLimit) {
- Value *Op = Worklist.pop_back_val();
- Instruction *OpI = dyn_cast<Instruction>(Op);
- if (!OpI || OpI->getOpcode() != I.getOpcode() || !OpI->hasOneUse()) {
- Ops.push_back(Op);
- continue;
- }
- // Be paranoid about self-referencing expressions in unreachable code.
- if (OpI->getOperand(0) != OpI)
- Worklist.push_back(OpI->getOperand(0));
- if (OpI->getOperand(1) != OpI)
- Worklist.push_back(OpI->getOperand(1));
- }
- // Skip extremely long expressions.
- if (Ops.size() > GlobalReassociateLimit)
- continue;
-
- // Add all pairwise combinations of operands to the pair map.
- unsigned BinaryIdx = I.getOpcode() - Instruction::BinaryOpsBegin;
- SmallSet<std::pair<Value *, Value*>, 32> Visited;
- for (unsigned i = 0; i < Ops.size() - 1; ++i) {
- for (unsigned j = i + 1; j < Ops.size(); ++j) {
- // Canonicalize operand orderings.
- Value *Op0 = Ops[i];
- Value *Op1 = Ops[j];
- if (std::less<Value *>()(Op1, Op0))
- std::swap(Op0, Op1);
- if (!Visited.insert({Op0, Op1}).second)
- continue;
- auto res = PairMap[BinaryIdx].insert({{Op0, Op1}, {Op0, Op1, 1}});
- if (!res.second) {
- // If either key value has been erased then we've got the same
- // address by coincidence. That can't happen here because nothing is
- // erasing values but it can happen by the time we're querying the
- // map.
- assert(res.first->second.isValid() && "WeakVH invalidated");
- ++res.first->second.Score;
- }
- }
- }
- }
- }
- }
-
- PreservedAnalyses ReassociatePass::run(Function &F, FunctionAnalysisManager &) {
- // Get the functions basic blocks in Reverse Post Order. This order is used by
- // BuildRankMap to pre calculate ranks correctly. It also excludes dead basic
- // blocks (it has been seen that the analysis in this pass could hang when
- // analysing dead basic blocks).
- ReversePostOrderTraversal<Function *> RPOT(&F);
-
- // Calculate the rank map for F.
- BuildRankMap(F, RPOT);
-
- // Build the pair map before running reassociate.
- // Technically this would be more accurate if we did it after one round
- // of reassociation, but in practice it doesn't seem to help much on
- // real-world code, so don't waste the compile time running reassociate
- // twice.
- // If a user wants, they could expicitly run reassociate twice in their
- // pass pipeline for further potential gains.
- // It might also be possible to update the pair map during runtime, but the
- // overhead of that may be large if there's many reassociable chains.
- BuildPairMap(RPOT);
-
- MadeChange = false;
-
- // Traverse the same blocks that were analysed by BuildRankMap.
- for (BasicBlock *BI : RPOT) {
- assert(RankMap.count(&*BI) && "BB should be ranked.");
- // Optimize every instruction in the basic block.
- for (BasicBlock::iterator II = BI->begin(), IE = BI->end(); II != IE;)
- if (isInstructionTriviallyDead(&*II)) {
- EraseInst(&*II++);
- } else {
- OptimizeInst(&*II);
- assert(II->getParent() == &*BI && "Moved to a
diff erent block!");
- ++II;
- }
-
- // Make a copy of all the instructions to be redone so we can remove dead
- // instructions.
- OrderedSet ToRedo(RedoInsts);
- // Iterate over all instructions to be reevaluated and remove trivially dead
- // instructions. If any operand of the trivially dead instruction becomes
- // dead mark it for deletion as well. Continue this process until all
- // trivially dead instructions have been removed.
- while (!ToRedo.empty()) {
- Instruction *I = ToRedo.pop_back_val();
- if (isInstructionTriviallyDead(I)) {
- RecursivelyEraseDeadInsts(I, ToRedo);
- MadeChange = true;
- }
- }
-
- // Now that we have removed dead instructions, we can reoptimize the
- // remaining instructions.
- while (!RedoInsts.empty()) {
- Instruction *I = RedoInsts.front();
- RedoInsts.erase(RedoInsts.begin());
- if (isInstructionTriviallyDead(I))
- EraseInst(I);
- else
- OptimizeInst(I);
- }
- }
-
- // We are done with the rank map and pair map.
- RankMap.clear();
- ValueRankMap.clear();
- for (auto &Entry : PairMap)
- Entry.clear();
-
- if (MadeChange) {
- PreservedAnalyses PA;
- PA.preserveSet<CFGAnalyses>();
- PA.preserve<GlobalsAA>();
- return PA;
- }
-
- return PreservedAnalyses::all();
- }
-
- namespace {
-
- class ReassociateLegacyPass : public FunctionPass {
- ReassociatePass Impl;
-
- public:
- static char ID; // Pass identification, replacement for typeid
-
- ReassociateLegacyPass() : FunctionPass(ID) {
- initializeReassociateLegacyPassPass(*PassRegistry::getPassRegistry());
- }
-
- bool runOnFunction(Function &F) override {
- if (skipFunction(F))
- return false;
-
- FunctionAnalysisManager DummyFAM;
- auto PA = Impl.run(F, DummyFAM);
- return !PA.areAllPreserved();
- }
-
- void getAnalysisUsage(AnalysisUsage &AU) const override {
- AU.setPreservesCFG();
- AU.addPreserved<GlobalsAAWrapperPass>();
- }
- };
-
- } // end anonymous namespace
-
- char ReassociateLegacyPass::ID = 0;
-
- INITIALIZE_PASS(ReassociateLegacyPass, "reassociate",
- "Reassociate expressions", false, false)
-
- // Public interface to the Reassociate pass
- FunctionPass *llvm::createReassociatePass() {
- return new ReassociateLegacyPass();
- }
diff --git a/llvm/test/Transforms/Reassociate/reassociate_salvages_debug_info.ll b/llvm/test/Transforms/Reassociate/reassociate_salvages_debug_info.ll
deleted file mode 100644
index 34e0b9a04bb3..000000000000
--- a/llvm/test/Transforms/Reassociate/reassociate_salvages_debug_info.ll
+++ /dev/null
@@ -1,50 +0,0 @@
-; RUN: opt < %s -reassociate -S | FileCheck %s
-
-; Check that reassociate pass now salvages debug info when dropping instructions.
-
-define hidden i32 @main(i32 %argc, i8** %argv) {
-entry:
- ; CHECK: call void @llvm.dbg.value(metadata i32 %argc, metadata [[VAR_B:![0-9]+]], metadata !DIExpression(DW_OP_plus_uconst, 1, DW_OP_stack_value))
- %add = add nsw i32 %argc, 1, !dbg !26
- call void @llvm.dbg.value(metadata i32 %add, metadata !22, metadata !DIExpression()), !dbg !25
- %add1 = add nsw i32 %argc, %add, !dbg !27
- ret i32 %add1, !dbg !28
-}
-
-declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
-declare void @llvm.dbg.value(metadata, metadata, metadata) #1
-
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!3, !4, !5, !6}
-!llvm.ident = !{!7}
-
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 10.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, debugInfoForProfiling: true, nameTableKind: None)
-!1 = !DIFile(filename: "test2.cpp", directory: "C:\")
-!2 = !{}
-!3 = !{i32 2, !"Dwarf Version", i32 4}
-!4 = !{i32 2, !"Debug Info Version", i32 3}
-!5 = !{i32 1, !"wchar_size", i32 2}
-!6 = !{i32 7, !"PIC Level", i32 2}
-!7 = !{!"clang version 10.0.0"}
-!8 = distinct !DISubprogram(name: "main", scope: !9, file: !9, line: 1, type: !10, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !18)
-!9 = !DIFile(filename: "./test2.cpp", directory: "C:\")
-!10 = !DISubroutineType(types: !11)
-!11 = !{!12, !13, !14}
-!12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
-!13 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !12)
-!14 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !15, size: 64)
-!15 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !16, size: 64)
-!16 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !17)
-!17 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
-!18 = !{!19, !20, !21, !22, !23, !24}
-!19 = !DILocalVariable(name: "argc", arg: 1, scope: !8, file: !9, line: 1, type: !13)
-!20 = !DILocalVariable(name: "argv", arg: 2, scope: !8, file: !9, line: 1, type: !14)
-!21 = !DILocalVariable(name: "a", scope: !8, file: !9, line: 2, type: !12)
-; CHECK: [[VAR_B]] = !DILocalVariable(name: "b"
-!22 = !DILocalVariable(name: "b", scope: !8, file: !9, line: 3, type: !12)
-!23 = !DILocalVariable(name: "to_return", scope: !8, file: !9, line: 4, type: !12)
-!24 = !DILocalVariable(name: "result", scope: !8, file: !9, line: 5, type: !12)
-!25 = !DILocation(line: 0, scope: !8)
-!26 = !DILocation(line: 3, scope: !8)
-!27 = !DILocation(line: 4, scope: !8)
-!28 = !DILocation(line: 6, scope: !8)
diff --git a/llvm/test/Transforms/Reassociate/undef_intrinsics_when_deleting_instructions.ll b/llvm/test/Transforms/Reassociate/undef_intrinsics_when_deleting_instructions.ll
deleted file mode 100644
index 98c51c5cf8bb..000000000000
--- a/llvm/test/Transforms/Reassociate/undef_intrinsics_when_deleting_instructions.ll
+++ /dev/null
@@ -1,95 +0,0 @@
-; RUN: opt < %s -reassociate -S | FileCheck %s
-
-; Check that reassociate pass now undefs debug intrinsics that reference a value
-; that gets dropped and cannot be salvaged.
-
-define hidden i32 @main() local_unnamed_addr {
-entry:
- %foo = alloca i32, align 4, !dbg !20
- %foo.0.foo.0..sroa_cast = bitcast i32* %foo to i8*, !dbg !20
- call void @llvm.lifetime.start.p0i8(i64 4, i8* nonnull %foo.0.foo.0..sroa_cast), !dbg !20
- store volatile i32 4, i32* %foo, align 4, !dbg !20, !tbaa !21
- %foo.0.foo.0. = load volatile i32, i32* %foo, align 4, !dbg !25, !tbaa !21
- %foo.0.foo.0.15 = load volatile i32, i32* %foo, align 4, !dbg !27, !tbaa !21
- %foo.0.foo.0.16 = load volatile i32, i32* %foo, align 4, !dbg !28, !tbaa !21
- ; CHECK-NOT: %add = add nsw i32 %foo.0.foo.0., %foo.0.foo.0.15
- %add = add nsw i32 %foo.0.foo.0., %foo.0.foo.0.15, !dbg !29
- ; CHECK: call void @llvm.dbg.value(metadata i32 undef, metadata [[VAR_A:![0-9]+]], metadata !DIExpression())
- call void @llvm.dbg.value(metadata i32 %add, metadata !19, metadata !DIExpression()), !dbg !26
- %foo.0.foo.0.17 = load volatile i32, i32* %foo, align 4, !dbg !30, !tbaa !21
- %cmp = icmp eq i32 %foo.0.foo.0.17, 4, !dbg !30
- br i1 %cmp, label %if.then, label %if.end, !dbg !32
-
- ; CHECK-LABEL: if.then:
-if.then:
- ; CHECK-NOT: %add1 = add nsw i32 %add, %foo.0.foo.0.16
- %add1 = add nsw i32 %add, %foo.0.foo.0.16, !dbg !33
- ; CHECK: call void @llvm.dbg.value(metadata i32 undef, metadata [[VAR_A]], metadata !DIExpression())
- call void @llvm.dbg.value(metadata i32 %add1, metadata !19, metadata !DIExpression()), !dbg !26
- ; CHECK: call void @llvm.dbg.value(metadata i32 undef, metadata [[VAR_CHEESE:![0-9]+]], metadata !DIExpression())
- call void @llvm.dbg.value(metadata i32 %add, metadata !18, metadata !DIExpression()), !dbg !26
- %sub = add nsw i32 %add, -12, !dbg !34
- %sub3 = sub nsw i32 %add1, %sub, !dbg !34
- %mul = mul nsw i32 %sub3, 20, !dbg !36
- %div = sdiv i32 %mul, 3, !dbg !37
- br label %if.end, !dbg !38
-
-if.end:
- %a.0 = phi i32 [ %div, %if.then ], [ 0, %entry ], !dbg !39
- call void @llvm.lifetime.end.p0i8(i64 4, i8* nonnull %foo.0.foo.0..sroa_cast), !dbg !40
- ret i32 %a.0, !dbg !41
-}
-
-declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture) #1
-declare void @llvm.dbg.declare(metadata, metadata, metadata) #2
-declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture) #1
-declare void @llvm.dbg.value(metadata, metadata, metadata) #2
-
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!3, !4, !5, !6}
-!llvm.ident = !{!7}
-
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, debugInfoForProfiling: true, nameTableKind: None)
-!1 = !DIFile(filename: "test.cpp", directory: "F:\")
-!2 = !{}
-!3 = !{i32 2, !"Dwarf Version", i32 4}
-!4 = !{i32 2, !"Debug Info Version", i32 3}
-!5 = !{i32 1, !"wchar_size", i32 2}
-!6 = !{i32 7, !"PIC Level", i32 2}
-!7 = !{!"clang version 10.0.0"}
-!8 = distinct !DISubprogram(name: "main", scope: !9, file: !9, line: 1, type: !10, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !13)
-!9 = !DIFile(filename: "./test.cpp", directory: "F:\")
-!10 = !DISubroutineType(types: !11)
-!11 = !{!12}
-!12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
-!13 = !{!14, !16, !17, !18, !19}
-!14 = !DILocalVariable(name: "foo", scope: !8, file: !9, line: 2, type: !15)
-!15 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !12)
-!16 = !DILocalVariable(name: "read1", scope: !8, file: !9, line: 3, type: !12)
-!17 = !DILocalVariable(name: "read2", scope: !8, file: !9, line: 4, type: !12)
-; CHECK: [[VAR_CHEESE]] = !DILocalVariable(name: "cheese"
-!18 = !DILocalVariable(name: "cheese", scope: !8, file: !9, line: 6, type: !12)
-; CHECK: [[VAR_A]] = !DILocalVariable(name: "a"
-!19 = !DILocalVariable(name: "a", scope: !8, file: !9, line: 7, type: !12)
-!20 = !DILocation(line: 2, scope: !8)
-!21 = !{!22, !22, i64 0}
-!22 = !{!"int", !23, i64 0}
-!23 = !{!"omnipotent char", !24, i64 0}
-!24 = !{!"Simple C++ TBAA"}
-!25 = !DILocation(line: 3, scope: !8)
-!26 = !DILocation(line: 0, scope: !8)
-!27 = !DILocation(line: 4, scope: !8)
-!28 = !DILocation(line: 6, scope: !8)
-!29 = !DILocation(line: 7, scope: !8)
-!30 = !DILocation(line: 10, scope: !31)
-!31 = distinct !DILexicalBlock(scope: !8, file: !9, line: 10)
-!32 = !DILocation(line: 10, scope: !8)
-!33 = !DILocation(line: 8, scope: !8)
-!34 = !DILocation(line: 12, scope: !35)
-!35 = distinct !DILexicalBlock(scope: !31, file: !9, line: 10)
-!36 = !DILocation(line: 13, scope: !35)
-!37 = !DILocation(line: 14, scope: !35)
-!38 = !DILocation(line: 15, scope: !35)
-!39 = !DILocation(line: 0, scope: !31)
-!40 = !DILocation(line: 20, scope: !8)
-!41 = !DILocation(line: 19, scope: !8)
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