diff options
Diffstat (limited to 'lib/CodeGen/InstrSelection/InstrForest.cpp')
| -rw-r--r-- | lib/CodeGen/InstrSelection/InstrForest.cpp | 461 |
1 files changed, 461 insertions, 0 deletions
diff --git a/lib/CodeGen/InstrSelection/InstrForest.cpp b/lib/CodeGen/InstrSelection/InstrForest.cpp new file mode 100644 index 0000000000..8ea293129c --- /dev/null +++ b/lib/CodeGen/InstrSelection/InstrForest.cpp @@ -0,0 +1,461 @@ +// $Id$ +//--------------------------------------------------------------------------- +// File: +// InstrForest.cpp +// +// Purpose: +// Convert SSA graph to instruction trees for instruction selection. +// +// Strategy: +// 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 taret 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. +// +// History: +// 6/28/01 - Vikram Adve - Created +// +//--------------------------------------------------------------------------- + + +//************************** System Include Files **************************/ + +#include <assert.h> +#include <iostream.h> +#include <bool.h> +#include <string> + +//*************************** User Include Files ***************************/ + +#include "llvm/Type.h" +#include "llvm/Module.h" +#include "llvm/Method.h" +#include "llvm/Instruction.h" +#include "llvm/iTerminators.h" +#include "llvm/iMemory.h" +#include "llvm/ConstPoolVals.h" +#include "llvm/BasicBlock.h" +#include "llvm/Bytecode/Reader.h" +#include "llvm/Bytecode/Writer.h" +#include "llvm/Tools/CommandLine.h" +#include "llvm/LLC/CompileContext.h" +#include "llvm/Codegen/MachineInstr.h" +#include "llvm/Codegen/InstrForest.h" + +//************************ Class Implementations **************************/ + + +//------------------------------------------------------------------------ +// class InstrTreeNode +//------------------------------------------------------------------------ + + +InstrTreeNode::InstrTreeNode(InstrTreeNodeType nodeType, + Value* _val) + : treeNodeType(nodeType), + val(_val) +{ + basicNode.leftChild = NULL; + basicNode.rightChild = NULL; + basicNode.parent = NULL; + basicNode.opLabel = InvalidOp; + basicNode.treeNodePtr = this; +} + +InstrTreeNode::~InstrTreeNode() +{} + + +void +InstrTreeNode::dump(int dumpChildren, + int indent) const +{ + this->dumpNode(indent); + + if (dumpChildren) + { + if (leftChild()) + leftChild()->dump(dumpChildren, indent+1); + if (rightChild()) + rightChild()->dump(dumpChildren, indent+1); + } +} + + +InstructionNode::InstructionNode(Instruction* _instr) + : InstrTreeNode(NTInstructionNode, _instr) +{ + OpLabel opLabel = _instr->getOpcode(); + + // Distinguish special cases of some instructions such as Ret and Br + // + if (opLabel == Instruction::Ret && ((ReturnInst*) _instr)->getReturnValue()) + { + opLabel = RetValueOp; // ret(value) operation + } + else if (opLabel == Instruction::Br && ! ((BranchInst*) _instr)->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 && _instr->getNumOperands() > 0) + { + opLabel = AllocaN; // Alloca(ptr, N) operation + } + else if ((opLabel == Instruction::Load || + opLabel == Instruction::GetElementPtr) + && ((MemAccessInst*)_instr)->getFirstOffsetIdx() > 0) + { + opLabel = opLabel + 100; // load/getElem with index vector + } + else if (opLabel == Instruction::Cast) + { + const Type* instrValueType = _instr->getType(); + switch(instrValueType->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; + default: + if (instrValueType->isArrayType()) + opLabel = ToArrayTy; + else if (instrValueType->isPointerType()) + opLabel = ToPointerTy; + else + ; // Just use `Cast' opcode otherwise. It's probably ignored. + break; + } + } + + basicNode.opLabel = opLabel; +} + +void +InstructionNode::reverseBinaryArgumentOrder() +{ + assert(getInstruction()->isBinaryOp()); + + // switch arguments for the instruction + ((BinaryOperator*) getInstruction())->swapOperands(); + + // switch arguments for this tree node itself + BasicTreeNode* leftCopy = basicNode.leftChild; + basicNode.leftChild = basicNode.rightChild; + basicNode.rightChild = leftCopy; +} + +void +InstructionNode::dumpNode(int indent) const +{ + for (int i=0; i < indent; i++) + cout << " "; + + cout << getInstruction()->getOpcodeName(); + + const vector<MachineInstr*>& mvec = getInstruction()->getMachineInstrVec(); + if (mvec.size() > 0) + cout << "\tMachine Instructions: "; + for (unsigned int i=0; i < mvec.size(); i++) + { + mvec[i]->dump(0); + if (i < mvec.size() - 1) + cout << "; "; + } + + cout << endl; +} + + +VRegListNode::VRegListNode() + : InstrTreeNode(NTVRegListNode, NULL) +{ + basicNode.opLabel = VRegListOp; +} + +void +VRegListNode::dumpNode(int indent) const +{ + for (int i=0; i < indent; i++) + cout << " "; + + cout << "List" << endl; +} + + +VRegNode::VRegNode(Value* _val) + : InstrTreeNode(NTVRegNode, _val) +{ + basicNode.opLabel = VRegNodeOp; +} + +void +VRegNode::dumpNode(int indent) const +{ + for (int i=0; i < indent; i++) + cout << " "; + + cout << "VReg " << getValue() << "\t(type " + << (int) getValue()->getValueType() << ")" << endl; +} + + +ConstantNode::ConstantNode(ConstPoolVal* constVal) + : InstrTreeNode(NTConstNode, constVal) +{ + basicNode.opLabel = ConstantNodeOp; +} + +void +ConstantNode::dumpNode(int indent) const +{ + for (int i=0; i < indent; i++) + cout << " "; + + cout << "Constant " << getValue() << "\t(type " + << (int) getValue()->getValueType() << ")" << endl; +} + + +LabelNode::LabelNode(BasicBlock* _bblock) + : InstrTreeNode(NTLabelNode, _bblock) +{ + basicNode.opLabel = LabelNodeOp; +} + +void +LabelNode::dumpNode(int indent) const +{ + for (int i=0; i < indent; i++) + cout << " "; + + cout << "Label " << getValue() << endl; +} + +//------------------------------------------------------------------------ +// class InstrForest +// +// A forest of instruction trees, usually for a single method. +//------------------------------------------------------------------------ + +void +InstrForest::buildTreesForMethod(Method *method) +{ + for (Method::inst_iterator instrIter = method->inst_begin(); + instrIter != method->inst_end(); + ++instrIter) + { + Instruction *instr = *instrIter; + if (! instr->isPHINode()) + (void) this->buildTreeForInstruction(instr); + } +} + + +void +InstrForest::dump() const +{ + for (hash_set<InstructionNode*, ptrHashFunc >::const_iterator + treeRootIter = treeRoots.begin(); + treeRootIter != treeRoots.end(); + ++treeRootIter) + { + (*treeRootIter)->dump(/*dumpChildren*/ 1, /*indent*/ 0); + } +} + +inline void +InstrForest::noteTreeNodeForInstr(Instruction* instr, + InstructionNode* treeNode) +{ + assert(treeNode->getNodeType() == InstrTreeNode::NTInstructionNode); + (*this)[instr] = treeNode; + treeRoots.insert(treeNode); // mark node as root of a new tree +} + + +inline void +InstrForest::setLeftChild(InstrTreeNode* parent, InstrTreeNode* child) +{ + parent->basicNode.leftChild = & child->basicNode; + child->basicNode.parent = & parent->basicNode; + if (child->getNodeType() == InstrTreeNode::NTInstructionNode) + treeRoots.erase((InstructionNode*) child); // no longer a tree root +} + + +inline void +InstrForest::setRightChild(InstrTreeNode* parent, InstrTreeNode* child) +{ + parent->basicNode.rightChild = & child->basicNode; + child->basicNode.parent = & parent->basicNode; + if (child->getNodeType() == InstrTreeNode::NTInstructionNode) + treeRoots.erase((InstructionNode*) child); // no longer a tree root +} + + +InstructionNode* +InstrForest::buildTreeForInstruction(Instruction* instr) +{ + InstructionNode* treeNode = this->getTreeNodeForInstr(instr); + if (treeNode != NULL) + {// 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); + this->noteTreeNodeForInstr(instr, treeNode); + + // If the instruction has more than 2 instruction operands, + // then we will not add any children. This assumes that instructions + // like 'call' that have more than 2 instruction operands do not + // ever get combined with the instructions that compute the operands. + // Note that we only count operands of type instruction and not other + // values such as branch labels for a branch or switch instruction. + // + // To do this efficiently, we'll walk all operands, build treeNodes + // for all instruction operands and save them in an array, and then + // insert children at the end if there are not more than 2. + // As a performance optimization, allocate a child array only + // if a fixed array is too small. + // + int numChildren = 0; + const unsigned int MAX_CHILD = 8; + static InstrTreeNode* fixedChildArray[MAX_CHILD]; + InstrTreeNode** childArray = + (instr->getNumOperands() > MAX_CHILD) + ? new (InstrTreeNode*)[instr->getNumOperands()] + : fixedChildArray; + + // + // Walk the operands of the instruction + // + for (Instruction::op_iterator opIter = instr->op_begin(); + opIter != instr->op_end(); + ++opIter) + { + Value* operand = *opIter; + + // 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 = + ((operand->getValueType() == Value::BasicBlockVal + || operand->getValueType() == Value::MethodVal) + && ! instr->isTerminator()); + + if (/* (*opIter) != NULL + &&*/ includeAddressOperand + || operand->getValueType() == Value::InstructionVal + || operand->getValueType() == Value::ConstantVal + || operand->getValueType() == Value::MethodArgumentVal) + {// 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 instruction is not a PHI + // + // (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 (operand->getValueType() == Value::InstructionVal + && operand->use_size() == 1 + && ((Instruction*)operand)->getParent() == instr->getParent() + && ! ((Instruction*)operand)->isPHINode()) + { + // Recursively create a treeNode for it. + opTreeNode =this->buildTreeForInstruction((Instruction*)operand); + } + else if (operand->getValueType() == Value::ConstantVal) + { + // Create a leaf node for a constant + opTreeNode = new ConstantNode((ConstPoolVal*) operand); + } + else + { + // Create a leaf node for the virtual register + opTreeNode = new VRegNode(operand); + } + + childArray[numChildren] = opTreeNode; + numChildren++; + } + } + + //-------------------------------------------------------------------- + // 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; // new VRegListNode(); + int n; + + if (numChildren > 2) + { + unsigned instrOpcode = treeNode->getInstruction()->getOpcode(); + assert(instrOpcode == Instruction::Call || + instrOpcode == Instruction::Load || + instrOpcode == Instruction::Store || + instrOpcode == Instruction::GetElementPtr); + } + + // Insert the first child as a direct child + if (numChildren >= 1) + this->setLeftChild(parent, childArray[0]); + + // 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(); + this->setRightChild(parent, listNode); + this->setLeftChild(listNode, childArray[numChildren - n]); + parent = listNode; + } + + // Now insert the last remaining child (if any). + if (numChildren >= 2) + { + assert(n == 1); + this->setRightChild(parent, childArray[numChildren - 1]); + } + + if (childArray != fixedChildArray) + { + delete[] childArray; + } + + return treeNode; +} + |