2 //***************************************************************************
9 // 7/02/01 - Vikram Adve - Created
10 //***************************************************************************
13 #include "llvm/CodeGen/InstrSelection.h"
14 #include "llvm/Method.h"
15 #include "llvm/BasicBlock.h"
16 #include "llvm/Type.h"
17 #include "llvm/iMemory.h"
18 #include "llvm/Instruction.h"
19 #include "llvm/CodeGen/MachineInstr.h"
20 #include "llvm/Support/CommandLine.h"
28 // Enable Debug Options to be specified on the command line
29 cl::Enum<enum DebugLev> DebugLevel("debug_select", cl::NoFlags, // cl::Hidden
30 "enable instruction selection debugging information",
31 clEnumVal(NoDebugInfo , "disable debug output"),
32 clEnumVal(DebugInstTrees, "print instruction trees"),
33 clEnumVal(DebugBurgTrees, "print burg trees"), 0);
35 //************************* Forward Declarations ***************************/
37 static bool SelectInstructionsForTree(BasicTreeNode* treeRoot, int goalnt,
38 TargetMachine &Target);
41 //******************* Externally Visible Functions *************************/
44 //---------------------------------------------------------------------------
45 // Entry point for instruction selection using BURG.
46 // Returns true if instruction selection failed, false otherwise.
47 //---------------------------------------------------------------------------
49 bool SelectInstructionsForMethod(Method* method, TargetMachine &Target) {
52 InstrForest instrForest;
53 instrForest.buildTreesForMethod(method);
55 const hash_set<InstructionNode*> &treeRoots = instrForest.getRootSet();
58 // Invoke BURG instruction selection for each tree
60 for (hash_set<InstructionNode*>::const_iterator
61 treeRootIter = treeRoots.begin();
62 treeRootIter != treeRoots.end();
65 BasicTreeNode* basicNode = (*treeRootIter)->getBasicNode();
67 // Invoke BURM to label each tree node with a state
68 (void) burm_label(basicNode);
70 if (DebugLevel.getValue() >= DebugBurgTrees)
72 printcover(basicNode, 1, 0);
73 cerr << "\nCover cost == " << treecost(basicNode, 1, 0) << "\n\n";
74 printMatches(basicNode);
77 // Then recursively walk the tree to select instructions
78 if (SelectInstructionsForTree(basicNode, /*goalnt*/1, Target))
87 if (DebugLevel.getValue() >= DebugInstTrees)
89 cout << "\n\n*** Instruction trees for method "
90 << (method->hasName()? method->getName() : "")
95 if (DebugLevel.getValue() > NoDebugInfo)
96 PrintMachineInstructions(method);
103 //---------------------------------------------------------------------------
104 // Function: FoldGetElemChain
107 // Fold a chain of GetElementPtr instructions into an equivalent
108 // (Pointer, IndexVector) pair. Returns the pointer Value, and
109 // stores the resulting IndexVector in argument chainIdxVec.
110 //---------------------------------------------------------------------------
113 FoldGetElemChain(const InstructionNode* getElemInstrNode,
114 vector<ConstPoolVal*>& chainIdxVec)
116 MemAccessInst* getElemInst = (MemAccessInst*)
117 getElemInstrNode->getInstruction();
119 // Initialize return values from the incoming instruction
120 Value* ptrVal = getElemInst->getPtrOperand();
121 chainIdxVec = getElemInst->getIndexVec(); // copies index vector values
123 // Now chase the chain of getElementInstr instructions, if any
124 InstrTreeNode* ptrChild = getElemInstrNode->leftChild();
125 while (ptrChild->getOpLabel() == Instruction::GetElementPtr ||
126 ptrChild->getOpLabel() == GetElemPtrIdx)
128 // Child is a GetElemPtr instruction
129 getElemInst = (MemAccessInst*)
130 ((InstructionNode*) ptrChild)->getInstruction();
131 const vector<ConstPoolVal*>& idxVec = getElemInst->getIndexVec();
133 // Get the pointer value out of ptrChild and *prepend* its index vector
134 ptrVal = getElemInst->getPtrOperand();
135 chainIdxVec.insert(chainIdxVec.begin(), idxVec.begin(), idxVec.end());
137 ptrChild = ptrChild->leftChild();
144 void PrintMachineInstructions(Method* method) {
145 cout << "\n" << method->getReturnType()
146 << " \"" << method->getName() << "\"" << endl;
148 for (Method::const_iterator bbIter = method->begin();
149 bbIter != method->end();
152 BasicBlock* bb = *bbIter;
154 << (bb->hasName()? bb->getName() : "Label")
155 << " (" << bb << ")" << ":"
158 for (BasicBlock::const_iterator instrIter = bb->begin();
159 instrIter != bb->end();
162 Instruction *instr = *instrIter;
163 const MachineCodeForVMInstr& minstrVec = instr->getMachineInstrVec();
164 for (unsigned i=0, N=minstrVec.size(); i < N; i++)
165 cout << "\t" << *minstrVec[i] << endl;
170 //*********************** Private Functions *****************************/
173 //---------------------------------------------------------------------------
174 // Function SelectInstructionsForTree
176 // Recursively walk the tree to select instructions.
177 // Do this top-down so that child instructions can exploit decisions
178 // made at the child instructions.
180 // E.g., if br(setle(reg,const)) decides the constant is 0 and uses
181 // a branch-on-integer-register instruction, then the setle node
182 // can use that information to avoid generating the SUBcc instruction.
184 // Note that this cannot be done bottom-up because setle must do this
185 // only if it is a child of the branch (otherwise, the result of setle
186 // may be used by multiple instructions).
187 //---------------------------------------------------------------------------
190 SelectInstructionsForTree(BasicTreeNode* treeRoot,
192 TargetMachine &Target)
194 // Use a static vector to avoid allocating a new one per VM instruction
195 static MachineInstr* minstrVec[MAX_INSTR_PER_VMINSTR];
197 // Get the rule that matches this node.
199 int ruleForNode = burm_rule(treeRoot->state, goalnt);
201 if (ruleForNode == 0)
203 cerr << "Could not match instruction tree for instr selection" << endl;
207 // Get this rule's non-terminals and the corresponding child nodes (if any)
209 short *nts = burm_nts[ruleForNode];
212 // First, select instructions for the current node and rule.
213 // (If this is a list node, not an instruction, then skip this step).
214 // This function is specific to the target architecture.
216 if (treeRoot->opLabel != VRegListOp)
218 InstructionNode* instrNode = (InstructionNode*) MainTreeNode(treeRoot);
219 assert(instrNode->getNodeType() == InstrTreeNode::NTInstructionNode);
221 unsigned N = GetInstructionsByRule(instrNode, ruleForNode, nts, Target,
223 assert(N <= MAX_INSTR_PER_VMINSTR);
224 for (unsigned i=0; i < N; i++)
226 assert(minstrVec[i] != NULL);
227 instrNode->getInstruction()->addMachineInstruction(minstrVec[i]);
231 // Then, recursively compile the child nodes, if any.
234 { // i.e., there is at least one kid
236 BasicTreeNode* kids[2];
237 int currentRule = ruleForNode;
238 burm_kids(treeRoot, currentRule, kids);
240 // First skip over any chain rules so that we don't visit
241 // the current node again.
243 while (ThisIsAChainRule(currentRule))
245 currentRule = burm_rule(treeRoot->state, nts[0]);
246 nts = burm_nts[currentRule];
247 burm_kids(treeRoot, currentRule, kids);
250 // Now we have the first non-chain rule so we have found
251 // the actual child nodes. Recursively compile them.
253 for (int i = 0; nts[i]; i++)
256 InstrTreeNode::InstrTreeNodeType
257 nodeType = MainTreeNode(kids[i])->getNodeType();
258 if (nodeType == InstrTreeNode::NTVRegListNode ||
259 nodeType == InstrTreeNode::NTInstructionNode)
261 if (SelectInstructionsForTree(kids[i], nts[i], Target))
262 return true; // failure
267 return false; // success