2 //---------------------------------------------------------------------------
7 // Convert SSA graph to instruction trees for instruction selection.
10 // The key goal is to group instructions into a single
11 // tree if one or more of them might be potentially combined into a single
12 // complex instruction in the target machine.
13 // Since this grouping is completely machine-independent, we do it as
14 // aggressive as possible to exploit any possible taret instructions.
15 // In particular, we group two instructions O and I if:
16 // (1) Instruction O computes an operand used by instruction I,
17 // and (2) O and I are part of the same basic block,
18 // and (3) O has only a single use, viz., I.
21 // 6/28/01 - Vikram Adve - Created
23 //---------------------------------------------------------------------------
25 //*************************** User Include Files ***************************/
27 #include "llvm/CodeGen/InstrForest.h"
28 #include "llvm/Method.h"
29 #include "llvm/iTerminators.h"
30 #include "llvm/iMemory.h"
31 #include "llvm/ConstPoolVals.h"
32 #include "llvm/BasicBlock.h"
33 #include "llvm/CodeGen/MachineInstr.h"
36 //------------------------------------------------------------------------
37 // class InstrTreeNode
38 //------------------------------------------------------------------------
41 InstrTreeNode::InstrTreeNode(InstrTreeNodeType nodeType,
43 : treeNodeType(nodeType),
46 basicNode.leftChild = NULL;
47 basicNode.rightChild = NULL;
48 basicNode.parent = NULL;
49 basicNode.opLabel = InvalidOp;
50 basicNode.treeNodePtr = this;
54 InstrTreeNode::dump(int dumpChildren,
57 this->dumpNode(indent);
62 leftChild()->dump(dumpChildren, indent+1);
64 rightChild()->dump(dumpChildren, indent+1);
69 InstructionNode::InstructionNode(Instruction* _instr)
70 : InstrTreeNode(NTInstructionNode, _instr)
72 OpLabel opLabel = _instr->getOpcode();
74 // Distinguish special cases of some instructions such as Ret and Br
76 if (opLabel == Instruction::Ret && ((ReturnInst*) _instr)->getReturnValue())
78 opLabel = RetValueOp; // ret(value) operation
80 else if (opLabel == Instruction::Br && ! ((BranchInst*) _instr)->isUnconditional())
82 opLabel = BrCondOp; // br(cond) operation
84 else if (opLabel >= Instruction::SetEQ && opLabel <= Instruction::SetGT)
86 opLabel = SetCCOp; // common label for all SetCC ops
88 else if (opLabel == Instruction::Alloca && _instr->getNumOperands() > 0)
90 opLabel = AllocaN; // Alloca(ptr, N) operation
92 else if ((opLabel == Instruction::Load ||
93 opLabel == Instruction::GetElementPtr)
94 && ((MemAccessInst*)_instr)->getFirstOffsetIdx() > 0)
96 opLabel = opLabel + 100; // load/getElem with index vector
98 else if (opLabel == Instruction::Cast)
100 const Type* instrValueType = _instr->getType();
101 switch(instrValueType->getPrimitiveID())
103 case Type::BoolTyID: opLabel = ToBoolTy; break;
104 case Type::UByteTyID: opLabel = ToUByteTy; break;
105 case Type::SByteTyID: opLabel = ToSByteTy; break;
106 case Type::UShortTyID: opLabel = ToUShortTy; break;
107 case Type::ShortTyID: opLabel = ToShortTy; break;
108 case Type::UIntTyID: opLabel = ToUIntTy; break;
109 case Type::IntTyID: opLabel = ToIntTy; break;
110 case Type::ULongTyID: opLabel = ToULongTy; break;
111 case Type::LongTyID: opLabel = ToLongTy; break;
112 case Type::FloatTyID: opLabel = ToFloatTy; break;
113 case Type::DoubleTyID: opLabel = ToDoubleTy; break;
115 if (instrValueType->isArrayType())
117 else if (instrValueType->isPointerType())
118 opLabel = ToPointerTy;
120 ; // Just use `Cast' opcode otherwise. It's probably ignored.
125 basicNode.opLabel = opLabel;
130 InstructionNode::dumpNode(int indent) const
132 for (int i=0; i < indent; i++)
135 cout << getInstruction()->getOpcodeName();
137 const vector<MachineInstr*>& mvec = getInstruction()->getMachineInstrVec();
139 cout << "\tMachine Instructions: ";
140 for (unsigned int i=0; i < mvec.size(); i++)
143 if (i < mvec.size() - 1)
151 VRegListNode::VRegListNode()
152 : InstrTreeNode(NTVRegListNode, NULL)
154 basicNode.opLabel = VRegListOp;
158 VRegListNode::dumpNode(int indent) const
160 for (int i=0; i < indent; i++)
163 cout << "List" << endl;
167 VRegNode::VRegNode(Value* _val)
168 : InstrTreeNode(NTVRegNode, _val)
170 basicNode.opLabel = VRegNodeOp;
174 VRegNode::dumpNode(int indent) const
176 for (int i=0; i < indent; i++)
179 cout << "VReg " << getValue() << "\t(type "
180 << (int) getValue()->getValueType() << ")" << endl;
184 ConstantNode::ConstantNode(ConstPoolVal* constVal)
185 : InstrTreeNode(NTConstNode, constVal)
187 basicNode.opLabel = ConstantNodeOp;
191 ConstantNode::dumpNode(int indent) const
193 for (int i=0; i < indent; i++)
196 cout << "Constant " << getValue() << "\t(type "
197 << (int) getValue()->getValueType() << ")" << endl;
201 LabelNode::LabelNode(BasicBlock* _bblock)
202 : InstrTreeNode(NTLabelNode, _bblock)
204 basicNode.opLabel = LabelNodeOp;
208 LabelNode::dumpNode(int indent) const
210 for (int i=0; i < indent; i++)
213 cout << "Label " << getValue() << endl;
216 //------------------------------------------------------------------------
219 // A forest of instruction trees, usually for a single method.
220 //------------------------------------------------------------------------
223 InstrForest::buildTreesForMethod(Method *method)
225 for (Method::inst_iterator instrIter = method->inst_begin();
226 instrIter != method->inst_end();
229 Instruction *instr = *instrIter;
230 if (! instr->isPHINode())
231 (void) this->buildTreeForInstruction(instr);
237 InstrForest::dump() const
239 for (hash_set<InstructionNode*>::const_iterator
240 treeRootIter = treeRoots.begin();
241 treeRootIter != treeRoots.end();
244 (*treeRootIter)->dump(/*dumpChildren*/ 1, /*indent*/ 0);
249 InstrForest::noteTreeNodeForInstr(Instruction* instr,
250 InstructionNode* treeNode)
252 assert(treeNode->getNodeType() == InstrTreeNode::NTInstructionNode);
253 (*this)[instr] = treeNode;
254 treeRoots.insert(treeNode); // mark node as root of a new tree
259 InstrForest::setLeftChild(InstrTreeNode* parent, InstrTreeNode* child)
261 parent->basicNode.leftChild = & child->basicNode;
262 child->basicNode.parent = & parent->basicNode;
263 if (child->getNodeType() == InstrTreeNode::NTInstructionNode)
264 treeRoots.erase((InstructionNode*) child); // no longer a tree root
269 InstrForest::setRightChild(InstrTreeNode* parent, InstrTreeNode* child)
271 parent->basicNode.rightChild = & child->basicNode;
272 child->basicNode.parent = & parent->basicNode;
273 if (child->getNodeType() == InstrTreeNode::NTInstructionNode)
274 treeRoots.erase((InstructionNode*) child); // no longer a tree root
279 InstrForest::buildTreeForInstruction(Instruction* instr)
281 InstructionNode* treeNode = this->getTreeNodeForInstr(instr);
282 if (treeNode != NULL)
283 {// treeNode has already been constructed for this instruction
284 assert(treeNode->getInstruction() == instr);
288 // Otherwise, create a new tree node for this instruction.
290 treeNode = new InstructionNode(instr);
291 this->noteTreeNodeForInstr(instr, treeNode);
293 // If the instruction has more than 2 instruction operands,
294 // then we will not add any children. This assumes that instructions
295 // like 'call' that have more than 2 instruction operands do not
296 // ever get combined with the instructions that compute the operands.
297 // Note that we only count operands of type instruction and not other
298 // values such as branch labels for a branch or switch instruction.
300 // To do this efficiently, we'll walk all operands, build treeNodes
301 // for all instruction operands and save them in an array, and then
302 // insert children at the end if there are not more than 2.
303 // As a performance optimization, allocate a child array only
304 // if a fixed array is too small.
307 const unsigned int MAX_CHILD = 8;
308 static InstrTreeNode* fixedChildArray[MAX_CHILD];
309 InstrTreeNode** childArray =
310 (instr->getNumOperands() > MAX_CHILD)
311 ? new (InstrTreeNode*)[instr->getNumOperands()]
315 // Walk the operands of the instruction
317 for (Instruction::op_iterator opIter = instr->op_begin();
318 opIter != instr->op_end();
321 Value* operand = *opIter;
323 // Check if the operand is a data value, not an branch label, type,
324 // method or module. If the operand is an address type (i.e., label
325 // or method) that is used in an non-branching operation, e.g., `add'.
326 // that should be considered a data value.
328 // Check latter condition here just to simplify the next IF.
329 bool includeAddressOperand =
330 ((operand->getValueType() == Value::BasicBlockVal
331 || operand->getValueType() == Value::MethodVal)
332 && ! instr->isTerminator());
334 if (/* (*opIter) != NULL
335 &&*/ includeAddressOperand
336 || operand->getValueType() == Value::InstructionVal
337 || operand->getValueType() == Value::ConstantVal
338 || operand->getValueType() == Value::MethodArgumentVal)
339 {// This operand is a data value
341 // An instruction that computes the incoming value is added as a
342 // child of the current instruction if:
343 // the value has only a single use
344 // AND both instructions are in the same basic block
345 // AND the instruction is not a PHI
347 // (Note that if the value has only a single use (viz., `instr'),
348 // the def of the value can be safely moved just before instr
349 // and therefore it is safe to combine these two instructions.)
351 // In all other cases, the virtual register holding the value
352 // is used directly, i.e., made a child of the instruction node.
354 InstrTreeNode* opTreeNode;
355 if (operand->getValueType() == Value::InstructionVal
356 && operand->use_size() == 1
357 && ((Instruction*)operand)->getParent() == instr->getParent()
358 && ! ((Instruction*)operand)->isPHINode())
360 // Recursively create a treeNode for it.
361 opTreeNode =this->buildTreeForInstruction((Instruction*)operand);
363 else if (operand->getValueType() == Value::ConstantVal)
365 // Create a leaf node for a constant
366 opTreeNode = new ConstantNode((ConstPoolVal*) operand);
370 // Create a leaf node for the virtual register
371 opTreeNode = new VRegNode(operand);
374 childArray[numChildren] = opTreeNode;
379 //--------------------------------------------------------------------
380 // Add any selected operands as children in the tree.
381 // Certain instructions can have more than 2 in some instances (viz.,
382 // a CALL or a memory access -- LOAD, STORE, and GetElemPtr -- to an
383 // array or struct). Make the operands of every such instruction into
384 // a right-leaning binary tree with the operand nodes at the leaves
385 // and VRegList nodes as internal nodes.
386 //--------------------------------------------------------------------
388 InstrTreeNode* parent = treeNode; // new VRegListNode();
393 unsigned instrOpcode = treeNode->getInstruction()->getOpcode();
394 assert(instrOpcode == Instruction::Call ||
395 instrOpcode == Instruction::Load ||
396 instrOpcode == Instruction::Store ||
397 instrOpcode == Instruction::GetElementPtr);
400 // Insert the first child as a direct child
401 if (numChildren >= 1)
402 this->setLeftChild(parent, childArray[0]);
404 // Create a list node for children 2 .. N-1, if any
405 for (n = numChildren-1; n >= 2; n--)
406 { // We have more than two children
407 InstrTreeNode* listNode = new VRegListNode();
408 this->setRightChild(parent, listNode);
409 this->setLeftChild(listNode, childArray[numChildren - n]);
413 // Now insert the last remaining child (if any).
414 if (numChildren >= 2)
417 this->setRightChild(parent, childArray[numChildren - 1]);
420 if (childArray != fixedChildArray)