Instruction selection via pattern matching on instruction trees using BURG.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/InstrSelection/InstrForest.cpp b/lib/CodeGen/InstrSelection/InstrForest.cpp
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+++ b/lib/CodeGen/InstrSelection/InstrForest.cpp
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+// $Id$
+//---------------------------------------------------------------------------
+// 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;
+}
+