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68498cefe6
there are probably more to kill git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@261 91177308-0d34-0410-b5e6-96231b3b80d8
445 lines
13 KiB
C++
445 lines
13 KiB
C++
// $Id$
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//---------------------------------------------------------------------------
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// File:
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// InstrForest.cpp
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//
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// Purpose:
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// Convert SSA graph to instruction trees for instruction selection.
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//
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// Strategy:
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// The key goal is to group instructions into a single
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// tree if one or more of them might be potentially combined into a single
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// complex instruction in the target machine.
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// Since this grouping is completely machine-independent, we do it as
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// aggressive as possible to exploit any possible taret instructions.
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// In particular, we group two instructions O and I if:
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// (1) Instruction O computes an operand used by instruction I,
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// and (2) O and I are part of the same basic block,
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// and (3) O has only a single use, viz., I.
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//
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// History:
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// 6/28/01 - Vikram Adve - Created
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//
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//---------------------------------------------------------------------------
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//*************************** User Include Files ***************************/
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#include "llvm/CodeGen/InstrForest.h"
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#include "llvm/Method.h"
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#include "llvm/iTerminators.h"
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#include "llvm/iMemory.h"
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#include "llvm/ConstPoolVals.h"
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#include "llvm/BasicBlock.h"
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#include "llvm/CodeGen/MachineInstr.h"
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//------------------------------------------------------------------------
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// class InstrTreeNode
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//------------------------------------------------------------------------
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InstrTreeNode::InstrTreeNode(InstrTreeNodeType nodeType,
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Value* _val)
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: treeNodeType(nodeType),
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val(_val)
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{
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basicNode.leftChild = NULL;
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basicNode.rightChild = NULL;
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basicNode.parent = NULL;
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basicNode.opLabel = InvalidOp;
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basicNode.treeNodePtr = this;
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}
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InstrTreeNode::~InstrTreeNode()
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{}
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void
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InstrTreeNode::dump(int dumpChildren,
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int indent) const
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{
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this->dumpNode(indent);
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if (dumpChildren)
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{
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if (leftChild())
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leftChild()->dump(dumpChildren, indent+1);
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if (rightChild())
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rightChild()->dump(dumpChildren, indent+1);
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}
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}
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InstructionNode::InstructionNode(Instruction* _instr)
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: InstrTreeNode(NTInstructionNode, _instr)
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{
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OpLabel opLabel = _instr->getOpcode();
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// Distinguish special cases of some instructions such as Ret and Br
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//
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if (opLabel == Instruction::Ret && ((ReturnInst*) _instr)->getReturnValue())
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{
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opLabel = RetValueOp; // ret(value) operation
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}
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else if (opLabel == Instruction::Br && ! ((BranchInst*) _instr)->isUnconditional())
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{
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opLabel = BrCondOp; // br(cond) operation
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}
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else if (opLabel >= Instruction::SetEQ && opLabel <= Instruction::SetGT)
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{
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opLabel = SetCCOp; // common label for all SetCC ops
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}
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else if (opLabel == Instruction::Alloca && _instr->getNumOperands() > 0)
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{
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opLabel = AllocaN; // Alloca(ptr, N) operation
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}
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else if ((opLabel == Instruction::Load ||
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opLabel == Instruction::GetElementPtr)
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&& ((MemAccessInst*)_instr)->getFirstOffsetIdx() > 0)
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{
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opLabel = opLabel + 100; // load/getElem with index vector
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}
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else if (opLabel == Instruction::Cast)
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{
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const Type* instrValueType = _instr->getType();
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switch(instrValueType->getPrimitiveID())
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{
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case Type::BoolTyID: opLabel = ToBoolTy; break;
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case Type::UByteTyID: opLabel = ToUByteTy; break;
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case Type::SByteTyID: opLabel = ToSByteTy; break;
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case Type::UShortTyID: opLabel = ToUShortTy; break;
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case Type::ShortTyID: opLabel = ToShortTy; break;
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case Type::UIntTyID: opLabel = ToUIntTy; break;
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case Type::IntTyID: opLabel = ToIntTy; break;
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case Type::ULongTyID: opLabel = ToULongTy; break;
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case Type::LongTyID: opLabel = ToLongTy; break;
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case Type::FloatTyID: opLabel = ToFloatTy; break;
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case Type::DoubleTyID: opLabel = ToDoubleTy; break;
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default:
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if (instrValueType->isArrayType())
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opLabel = ToArrayTy;
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else if (instrValueType->isPointerType())
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opLabel = ToPointerTy;
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else
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; // Just use `Cast' opcode otherwise. It's probably ignored.
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break;
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}
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}
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basicNode.opLabel = opLabel;
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}
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void
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InstructionNode::reverseBinaryArgumentOrder()
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{
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assert(getInstruction()->isBinaryOp());
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// switch arguments for the instruction
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((BinaryOperator*) getInstruction())->swapOperands();
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// switch arguments for this tree node itself
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BasicTreeNode* leftCopy = basicNode.leftChild;
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basicNode.leftChild = basicNode.rightChild;
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basicNode.rightChild = leftCopy;
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}
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void
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InstructionNode::dumpNode(int indent) const
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{
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for (int i=0; i < indent; i++)
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cout << " ";
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cout << getInstruction()->getOpcodeName();
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const vector<MachineInstr*>& mvec = getInstruction()->getMachineInstrVec();
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if (mvec.size() > 0)
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cout << "\tMachine Instructions: ";
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for (unsigned int i=0; i < mvec.size(); i++)
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{
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mvec[i]->dump(0);
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if (i < mvec.size() - 1)
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cout << "; ";
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}
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cout << endl;
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}
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VRegListNode::VRegListNode()
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: InstrTreeNode(NTVRegListNode, NULL)
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{
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basicNode.opLabel = VRegListOp;
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}
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void
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VRegListNode::dumpNode(int indent) const
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{
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for (int i=0; i < indent; i++)
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cout << " ";
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cout << "List" << endl;
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}
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VRegNode::VRegNode(Value* _val)
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: InstrTreeNode(NTVRegNode, _val)
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{
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basicNode.opLabel = VRegNodeOp;
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}
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void
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VRegNode::dumpNode(int indent) const
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{
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for (int i=0; i < indent; i++)
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cout << " ";
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cout << "VReg " << getValue() << "\t(type "
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<< (int) getValue()->getValueType() << ")" << endl;
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}
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ConstantNode::ConstantNode(ConstPoolVal* constVal)
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: InstrTreeNode(NTConstNode, constVal)
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{
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basicNode.opLabel = ConstantNodeOp;
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}
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void
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ConstantNode::dumpNode(int indent) const
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{
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for (int i=0; i < indent; i++)
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cout << " ";
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cout << "Constant " << getValue() << "\t(type "
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<< (int) getValue()->getValueType() << ")" << endl;
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}
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LabelNode::LabelNode(BasicBlock* _bblock)
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: InstrTreeNode(NTLabelNode, _bblock)
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{
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basicNode.opLabel = LabelNodeOp;
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}
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void
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LabelNode::dumpNode(int indent) const
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{
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for (int i=0; i < indent; i++)
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cout << " ";
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cout << "Label " << getValue() << endl;
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}
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//------------------------------------------------------------------------
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// class InstrForest
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//
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// A forest of instruction trees, usually for a single method.
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//------------------------------------------------------------------------
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void
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InstrForest::buildTreesForMethod(Method *method)
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{
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for (Method::inst_iterator instrIter = method->inst_begin();
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instrIter != method->inst_end();
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++instrIter)
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{
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Instruction *instr = *instrIter;
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if (! instr->isPHINode())
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(void) this->buildTreeForInstruction(instr);
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}
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}
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void
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InstrForest::dump() const
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{
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for (hash_set<InstructionNode*, ptrHashFunc >::const_iterator
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treeRootIter = treeRoots.begin();
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treeRootIter != treeRoots.end();
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++treeRootIter)
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{
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(*treeRootIter)->dump(/*dumpChildren*/ 1, /*indent*/ 0);
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}
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}
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inline void
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InstrForest::noteTreeNodeForInstr(Instruction* instr,
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InstructionNode* treeNode)
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{
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assert(treeNode->getNodeType() == InstrTreeNode::NTInstructionNode);
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(*this)[instr] = treeNode;
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treeRoots.insert(treeNode); // mark node as root of a new tree
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}
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inline void
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InstrForest::setLeftChild(InstrTreeNode* parent, InstrTreeNode* child)
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{
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parent->basicNode.leftChild = & child->basicNode;
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child->basicNode.parent = & parent->basicNode;
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if (child->getNodeType() == InstrTreeNode::NTInstructionNode)
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treeRoots.erase((InstructionNode*) child); // no longer a tree root
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}
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inline void
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InstrForest::setRightChild(InstrTreeNode* parent, InstrTreeNode* child)
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{
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parent->basicNode.rightChild = & child->basicNode;
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child->basicNode.parent = & parent->basicNode;
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if (child->getNodeType() == InstrTreeNode::NTInstructionNode)
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treeRoots.erase((InstructionNode*) child); // no longer a tree root
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}
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InstructionNode*
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InstrForest::buildTreeForInstruction(Instruction* instr)
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{
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InstructionNode* treeNode = this->getTreeNodeForInstr(instr);
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if (treeNode != NULL)
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{// treeNode has already been constructed for this instruction
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assert(treeNode->getInstruction() == instr);
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return treeNode;
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}
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// Otherwise, create a new tree node for this instruction.
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//
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treeNode = new InstructionNode(instr);
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this->noteTreeNodeForInstr(instr, treeNode);
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// If the instruction has more than 2 instruction operands,
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// then we will not add any children. This assumes that instructions
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// like 'call' that have more than 2 instruction operands do not
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// ever get combined with the instructions that compute the operands.
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// Note that we only count operands of type instruction and not other
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// values such as branch labels for a branch or switch instruction.
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//
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// To do this efficiently, we'll walk all operands, build treeNodes
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// for all instruction operands and save them in an array, and then
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// insert children at the end if there are not more than 2.
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// As a performance optimization, allocate a child array only
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// if a fixed array is too small.
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//
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int numChildren = 0;
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const unsigned int MAX_CHILD = 8;
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static InstrTreeNode* fixedChildArray[MAX_CHILD];
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InstrTreeNode** childArray =
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(instr->getNumOperands() > MAX_CHILD)
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? new (InstrTreeNode*)[instr->getNumOperands()]
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: fixedChildArray;
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//
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// Walk the operands of the instruction
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//
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for (Instruction::op_iterator opIter = instr->op_begin();
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opIter != instr->op_end();
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++opIter)
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{
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Value* operand = *opIter;
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// Check if the operand is a data value, not an branch label, type,
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// method or module. If the operand is an address type (i.e., label
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// or method) that is used in an non-branching operation, e.g., `add'.
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// that should be considered a data value.
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// Check latter condition here just to simplify the next IF.
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bool includeAddressOperand =
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((operand->getValueType() == Value::BasicBlockVal
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|| operand->getValueType() == Value::MethodVal)
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&& ! instr->isTerminator());
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if (/* (*opIter) != NULL
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&&*/ includeAddressOperand
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|| operand->getValueType() == Value::InstructionVal
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|| operand->getValueType() == Value::ConstantVal
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|| operand->getValueType() == Value::MethodArgumentVal)
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{// This operand is a data value
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// An instruction that computes the incoming value is added as a
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// child of the current instruction if:
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// the value has only a single use
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// AND both instructions are in the same basic block
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// AND the instruction is not a PHI
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//
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// (Note that if the value has only a single use (viz., `instr'),
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// the def of the value can be safely moved just before instr
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// and therefore it is safe to combine these two instructions.)
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//
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// In all other cases, the virtual register holding the value
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// is used directly, i.e., made a child of the instruction node.
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//
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InstrTreeNode* opTreeNode;
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if (operand->getValueType() == Value::InstructionVal
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&& operand->use_size() == 1
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&& ((Instruction*)operand)->getParent() == instr->getParent()
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&& ! ((Instruction*)operand)->isPHINode())
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{
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// Recursively create a treeNode for it.
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opTreeNode =this->buildTreeForInstruction((Instruction*)operand);
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}
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else if (operand->getValueType() == Value::ConstantVal)
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{
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// Create a leaf node for a constant
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opTreeNode = new ConstantNode((ConstPoolVal*) operand);
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}
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else
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{
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// Create a leaf node for the virtual register
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opTreeNode = new VRegNode(operand);
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}
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childArray[numChildren] = opTreeNode;
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numChildren++;
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}
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}
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//--------------------------------------------------------------------
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// Add any selected operands as children in the tree.
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// Certain instructions can have more than 2 in some instances (viz.,
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// a CALL or a memory access -- LOAD, STORE, and GetElemPtr -- to an
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// array or struct). Make the operands of every such instruction into
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// a right-leaning binary tree with the operand nodes at the leaves
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// and VRegList nodes as internal nodes.
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//--------------------------------------------------------------------
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InstrTreeNode* parent = treeNode; // new VRegListNode();
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int n;
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if (numChildren > 2)
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{
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unsigned instrOpcode = treeNode->getInstruction()->getOpcode();
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assert(instrOpcode == Instruction::Call ||
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instrOpcode == Instruction::Load ||
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instrOpcode == Instruction::Store ||
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instrOpcode == Instruction::GetElementPtr);
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}
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// Insert the first child as a direct child
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if (numChildren >= 1)
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this->setLeftChild(parent, childArray[0]);
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// Create a list node for children 2 .. N-1, if any
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for (n = numChildren-1; n >= 2; n--)
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{ // We have more than two children
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InstrTreeNode* listNode = new VRegListNode();
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this->setRightChild(parent, listNode);
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this->setLeftChild(listNode, childArray[numChildren - n]);
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parent = listNode;
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}
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// Now insert the last remaining child (if any).
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if (numChildren >= 2)
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{
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assert(n == 1);
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this->setRightChild(parent, childArray[numChildren - 1]);
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}
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if (childArray != fixedChildArray)
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{
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delete[] childArray;
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}
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return treeNode;
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}
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