| //===-- InstrForest.cpp - Build instruction forest for inst selection -----===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // The key goal is to group instructions into a single |
| // tree if one or more of them might be potentially combined into a single |
| // complex instruction in the target machine. |
| // Since this grouping is completely machine-independent, we do it as |
| // aggressive as possible to exploit any possible target instructions. |
| // In particular, we group two instructions O and I if: |
| // (1) Instruction O computes an operand used by instruction I, |
| // and (2) O and I are part of the same basic block, |
| // and (3) O has only a single use, viz., I. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Constant.h" |
| #include "llvm/Function.h" |
| #include "llvm/iTerminators.h" |
| #include "llvm/iMemory.h" |
| #include "llvm/Type.h" |
| #include "llvm/CodeGen/InstrForest.h" |
| #include "llvm/CodeGen/MachineCodeForInstruction.h" |
| #include "llvm/CodeGen/MachineInstr.h" |
| #include "Support/STLExtras.h" |
| #include "Config/alloca.h" |
| |
| //------------------------------------------------------------------------ |
| // class InstrTreeNode |
| //------------------------------------------------------------------------ |
| |
| void |
| InstrTreeNode::dump(int dumpChildren, int indent) const { |
| dumpNode(indent); |
| |
| if (dumpChildren) { |
| if (LeftChild) |
| LeftChild->dump(dumpChildren, indent+1); |
| if (RightChild) |
| RightChild->dump(dumpChildren, indent+1); |
| } |
| } |
| |
| |
| InstructionNode::InstructionNode(Instruction* I) |
| : InstrTreeNode(NTInstructionNode, I), codeIsFoldedIntoParent(false) |
| { |
| opLabel = I->getOpcode(); |
| |
| // Distinguish special cases of some instructions such as Ret and Br |
| // |
| if (opLabel == Instruction::Ret && cast<ReturnInst>(I)->getReturnValue()) { |
| opLabel = RetValueOp; // ret(value) operation |
| } |
| else if (opLabel ==Instruction::Br && !cast<BranchInst>(I)->isUnconditional()) |
| { |
| opLabel = BrCondOp; // br(cond) operation |
| } else if (opLabel >= Instruction::SetEQ && opLabel <= Instruction::SetGT) { |
| opLabel = SetCCOp; // common label for all SetCC ops |
| } else if (opLabel == Instruction::Alloca && I->getNumOperands() > 0) { |
| opLabel = AllocaN; // Alloca(ptr, N) operation |
| } else if (opLabel == Instruction::GetElementPtr && |
| cast<GetElementPtrInst>(I)->hasIndices()) { |
| opLabel = opLabel + 100; // getElem with index vector |
| } else if (opLabel == Instruction::Xor && |
| BinaryOperator::isNot(I)) { |
| opLabel = (I->getType() == Type::BoolTy)? NotOp // boolean Not operator |
| : BNotOp; // bitwise Not operator |
| } else if (opLabel == Instruction::And || opLabel == Instruction::Or || |
| opLabel == Instruction::Xor) { |
| // Distinguish bitwise operators from logical operators! |
| if (I->getType() != Type::BoolTy) |
| opLabel = opLabel + 100; // bitwise operator |
| } else if (opLabel == Instruction::Cast) { |
| const Type *ITy = I->getType(); |
| switch(ITy->getPrimitiveID()) |
| { |
| case Type::BoolTyID: opLabel = ToBoolTy; break; |
| case Type::UByteTyID: opLabel = ToUByteTy; break; |
| case Type::SByteTyID: opLabel = ToSByteTy; break; |
| case Type::UShortTyID: opLabel = ToUShortTy; break; |
| case Type::ShortTyID: opLabel = ToShortTy; break; |
| case Type::UIntTyID: opLabel = ToUIntTy; break; |
| case Type::IntTyID: opLabel = ToIntTy; break; |
| case Type::ULongTyID: opLabel = ToULongTy; break; |
| case Type::LongTyID: opLabel = ToLongTy; break; |
| case Type::FloatTyID: opLabel = ToFloatTy; break; |
| case Type::DoubleTyID: opLabel = ToDoubleTy; break; |
| case Type::ArrayTyID: opLabel = ToArrayTy; break; |
| case Type::PointerTyID: opLabel = ToPointerTy; break; |
| default: |
| // Just use `Cast' opcode otherwise. It's probably ignored. |
| break; |
| } |
| } |
| } |
| |
| |
| void |
| InstructionNode::dumpNode(int indent) const { |
| for (int i=0; i < indent; i++) |
| std::cerr << " "; |
| std::cerr << getInstruction()->getOpcodeName() |
| << " [label " << getOpLabel() << "]" << "\n"; |
| } |
| |
| void |
| VRegListNode::dumpNode(int indent) const { |
| for (int i=0; i < indent; i++) |
| std::cerr << " "; |
| |
| std::cerr << "List" << "\n"; |
| } |
| |
| |
| void |
| VRegNode::dumpNode(int indent) const { |
| for (int i=0; i < indent; i++) |
| std::cerr << " "; |
| |
| std::cerr << "VReg " << getValue() << "\t(type " |
| << (int) getValue()->getValueType() << ")" << "\n"; |
| } |
| |
| void |
| ConstantNode::dumpNode(int indent) const { |
| for (int i=0; i < indent; i++) |
| std::cerr << " "; |
| |
| std::cerr << "Constant " << getValue() << "\t(type " |
| << (int) getValue()->getValueType() << ")" << "\n"; |
| } |
| |
| void LabelNode::dumpNode(int indent) const { |
| for (int i=0; i < indent; i++) |
| std::cerr << " "; |
| |
| std::cerr << "Label " << getValue() << "\n"; |
| } |
| |
| //------------------------------------------------------------------------ |
| // class InstrForest |
| // |
| // A forest of instruction trees, usually for a single method. |
| //------------------------------------------------------------------------ |
| |
| InstrForest::InstrForest(Function *F) { |
| for (Function::iterator BB = F->begin(), FE = F->end(); BB != FE; ++BB) { |
| for(BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) |
| buildTreeForInstruction(I); |
| } |
| } |
| |
| InstrForest::~InstrForest() { |
| for_each(treeRoots.begin(), treeRoots.end(), deleter<InstructionNode>); |
| } |
| |
| void InstrForest::dump() const { |
| for (const_root_iterator I = roots_begin(); I != roots_end(); ++I) |
| (*I)->dump(/*dumpChildren*/ 1, /*indent*/ 0); |
| } |
| |
| inline void InstrForest::eraseRoot(InstructionNode* node) { |
| for (RootSet::reverse_iterator RI=treeRoots.rbegin(), RE=treeRoots.rend(); |
| RI != RE; ++RI) |
| if (*RI == node) |
| treeRoots.erase(RI.base()-1); |
| } |
| |
| inline void InstrForest::noteTreeNodeForInstr(Instruction *instr, |
| InstructionNode *treeNode) { |
| (*this)[instr] = treeNode; |
| treeRoots.push_back(treeNode); // mark node as root of a new tree |
| } |
| |
| |
| inline void InstrForest::setLeftChild(InstrTreeNode *parent, |
| InstrTreeNode *child) { |
| parent->LeftChild = child; |
| child->Parent = parent; |
| if (InstructionNode* instrNode = dyn_cast<InstructionNode>(child)) |
| eraseRoot(instrNode); // no longer a tree root |
| } |
| |
| inline void InstrForest::setRightChild(InstrTreeNode *parent, |
| InstrTreeNode *child) { |
| parent->RightChild = child; |
| child->Parent = parent; |
| if (InstructionNode* instrNode = dyn_cast<InstructionNode>(child)) |
| eraseRoot(instrNode); // no longer a tree root |
| } |
| |
| |
| InstructionNode* InstrForest::buildTreeForInstruction(Instruction *instr) { |
| InstructionNode *treeNode = getTreeNodeForInstr(instr); |
| if (treeNode) { |
| // treeNode has already been constructed for this instruction |
| assert(treeNode->getInstruction() == instr); |
| return treeNode; |
| } |
| |
| // Otherwise, create a new tree node for this instruction. |
| // |
| treeNode = new InstructionNode(instr); |
| noteTreeNodeForInstr(instr, treeNode); |
| |
| if (instr->getOpcode() == Instruction::Call) { |
| // Operands of call instruction |
| return treeNode; |
| } |
| |
| // If the instruction has more than 2 instruction operands, |
| // then we need to create artificial list nodes to hold them. |
| // (Note that we only count operands that get tree nodes, and not |
| // others such as branch labels for a branch or switch instruction.) |
| // |
| // To do this efficiently, we'll walk all operands, build treeNodes |
| // for all appropriate operands and save them in an array. We then |
| // insert children at the end, creating list nodes where needed. |
| // As a performance optimization, allocate a child array only |
| // if a fixed array is too small. |
| // |
| int numChildren = 0; |
| InstrTreeNode** childArray = new InstrTreeNode*[instr->getNumOperands()]; |
| |
| // |
| // Walk the operands of the instruction |
| // |
| for (Instruction::op_iterator O = instr->op_begin(); O!=instr->op_end(); ++O) |
| { |
| Value* operand = *O; |
| |
| // Check if the operand is a data value, not an branch label, type, |
| // method or module. If the operand is an address type (i.e., label |
| // or method) that is used in an non-branching operation, e.g., `add'. |
| // that should be considered a data value. |
| |
| // Check latter condition here just to simplify the next IF. |
| bool includeAddressOperand = |
| (isa<BasicBlock>(operand) || isa<Function>(operand)) |
| && !instr->isTerminator(); |
| |
| if (includeAddressOperand || isa<Instruction>(operand) || |
| isa<Constant>(operand) || isa<Argument>(operand) || |
| isa<GlobalVariable>(operand)) |
| { |
| // This operand is a data value |
| |
| // An instruction that computes the incoming value is added as a |
| // child of the current instruction if: |
| // the value has only a single use |
| // AND both instructions are in the same basic block. |
| // AND the current instruction is not a PHI (because the incoming |
| // value is conceptually in a predecessor block, |
| // even though it may be in the same static block) |
| // |
| // (Note that if the value has only a single use (viz., `instr'), |
| // the def of the value can be safely moved just before instr |
| // and therefore it is safe to combine these two instructions.) |
| // |
| // In all other cases, the virtual register holding the value |
| // is used directly, i.e., made a child of the instruction node. |
| // |
| InstrTreeNode* opTreeNode; |
| if (isa<Instruction>(operand) && operand->hasOneUse() && |
| cast<Instruction>(operand)->getParent() == instr->getParent() && |
| instr->getOpcode() != Instruction::PHI && |
| instr->getOpcode() != Instruction::Call) |
| { |
| // Recursively create a treeNode for it. |
| opTreeNode = buildTreeForInstruction((Instruction*)operand); |
| } else if (Constant *CPV = dyn_cast<Constant>(operand)) { |
| // Create a leaf node for a constant |
| opTreeNode = new ConstantNode(CPV); |
| } else { |
| // Create a leaf node for the virtual register |
| opTreeNode = new VRegNode(operand); |
| } |
| |
| childArray[numChildren++] = opTreeNode; |
| } |
| } |
| |
| //-------------------------------------------------------------------- |
| // Add any selected operands as children in the tree. |
| // Certain instructions can have more than 2 in some instances (viz., |
| // a CALL or a memory access -- LOAD, STORE, and GetElemPtr -- to an |
| // array or struct). Make the operands of every such instruction into |
| // a right-leaning binary tree with the operand nodes at the leaves |
| // and VRegList nodes as internal nodes. |
| //-------------------------------------------------------------------- |
| |
| InstrTreeNode *parent = treeNode; |
| |
| if (numChildren > 2) { |
| unsigned instrOpcode = treeNode->getInstruction()->getOpcode(); |
| assert(instrOpcode == Instruction::PHI || |
| instrOpcode == Instruction::Call || |
| instrOpcode == Instruction::Load || |
| instrOpcode == Instruction::Store || |
| instrOpcode == Instruction::GetElementPtr); |
| } |
| |
| // Insert the first child as a direct child |
| if (numChildren >= 1) |
| setLeftChild(parent, childArray[0]); |
| |
| int n; |
| |
| // Create a list node for children 2 .. N-1, if any |
| for (n = numChildren-1; n >= 2; n--) { |
| // We have more than two children |
| InstrTreeNode *listNode = new VRegListNode(); |
| setRightChild(parent, listNode); |
| setLeftChild(listNode, childArray[numChildren - n]); |
| parent = listNode; |
| } |
| |
| // Now insert the last remaining child (if any). |
| if (numChildren >= 2) { |
| assert(n == 1); |
| setRightChild(parent, childArray[numChildren - 1]); |
| } |
| |
| delete [] childArray; |
| return treeNode; |
| } |