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 >= 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 >= DebugInstTrees)
89 cout << "\n\n*** Instruction trees for method "
90 << (method->hasName()? method->getName() : "")
95 if (DebugLevel > NoDebugInfo)
96 PrintMachineInstructions(method);
100 // Record instructions in the vector for each basic block
102 for (Method::iterator BI = method->begin(); BI != method->end(); ++BI)
104 MachineCodeForBasicBlock& bbMvec = (*BI)->getMachineInstrVec();
105 for (BasicBlock::iterator II = (*BI)->begin(); II != (*BI)->end(); ++II)
107 MachineCodeForVMInstr& mvec = (*II)->getMachineInstrVec();
108 for (unsigned i=0; i < mvec.size(); i++)
109 bbMvec.push_back(mvec[i]);
117 //---------------------------------------------------------------------------
118 // Function: FoldGetElemChain
121 // Fold a chain of GetElementPtr instructions into an equivalent
122 // (Pointer, IndexVector) pair. Returns the pointer Value, and
123 // stores the resulting IndexVector in argument chainIdxVec.
124 //---------------------------------------------------------------------------
127 FoldGetElemChain(const InstructionNode* getElemInstrNode,
128 vector<ConstPoolVal*>& chainIdxVec)
130 MemAccessInst* getElemInst = (MemAccessInst*)
131 getElemInstrNode->getInstruction();
133 // Initialize return values from the incoming instruction
134 Value* ptrVal = getElemInst->getPtrOperand();
135 chainIdxVec = getElemInst->getIndexVec(); // copies index vector values
137 // Now chase the chain of getElementInstr instructions, if any
138 InstrTreeNode* ptrChild = getElemInstrNode->leftChild();
139 while (ptrChild->getOpLabel() == Instruction::GetElementPtr ||
140 ptrChild->getOpLabel() == GetElemPtrIdx)
142 // Child is a GetElemPtr instruction
143 getElemInst = (MemAccessInst*)
144 ((InstructionNode*) ptrChild)->getInstruction();
145 const vector<ConstPoolVal*>& idxVec = getElemInst->getIndexVec();
147 // Get the pointer value out of ptrChild and *prepend* its index vector
148 ptrVal = getElemInst->getPtrOperand();
149 chainIdxVec.insert(chainIdxVec.begin(), idxVec.begin(), idxVec.end());
151 ptrChild = ptrChild->leftChild();
158 void PrintMachineInstructions(Method* method) {
159 cout << "\n" << method->getReturnType()
160 << " \"" << method->getName() << "\"" << endl;
162 for (Method::const_iterator bbIter = method->begin();
163 bbIter != method->end();
166 BasicBlock* bb = *bbIter;
168 << (bb->hasName()? bb->getName() : "Label")
169 << " (" << bb << ")" << ":"
172 for (BasicBlock::const_iterator instrIter = bb->begin();
173 instrIter != bb->end();
176 Instruction *instr = *instrIter;
177 const MachineCodeForVMInstr& minstrVec = instr->getMachineInstrVec();
178 for (unsigned i=0, N=minstrVec.size(); i < N; i++)
179 cout << "\t" << *minstrVec[i] << endl;
184 //*********************** Private Functions *****************************/
187 //---------------------------------------------------------------------------
188 // Function SelectInstructionsForTree
190 // Recursively walk the tree to select instructions.
191 // Do this top-down so that child instructions can exploit decisions
192 // made at the child instructions.
194 // E.g., if br(setle(reg,const)) decides the constant is 0 and uses
195 // a branch-on-integer-register instruction, then the setle node
196 // can use that information to avoid generating the SUBcc instruction.
198 // Note that this cannot be done bottom-up because setle must do this
199 // only if it is a child of the branch (otherwise, the result of setle
200 // may be used by multiple instructions).
201 //---------------------------------------------------------------------------
204 SelectInstructionsForTree(BasicTreeNode* treeRoot,
206 TargetMachine &Target)
208 // Use a static vector to avoid allocating a new one per VM instruction
209 static MachineInstr* minstrVec[MAX_INSTR_PER_VMINSTR];
211 // Get the rule that matches this node.
213 int ruleForNode = burm_rule(treeRoot->state, goalnt);
215 if (ruleForNode == 0)
217 cerr << "Could not match instruction tree for instr selection" << endl;
221 // Get this rule's non-terminals and the corresponding child nodes (if any)
223 short *nts = burm_nts[ruleForNode];
226 // First, select instructions for the current node and rule.
227 // (If this is a list node, not an instruction, then skip this step).
228 // This function is specific to the target architecture.
230 if (treeRoot->opLabel != VRegListOp)
232 InstructionNode* instrNode = (InstructionNode*) MainTreeNode(treeRoot);
233 assert(instrNode->getNodeType() == InstrTreeNode::NTInstructionNode);
235 unsigned N = GetInstructionsByRule(instrNode, ruleForNode, nts, Target,
237 assert(N <= MAX_INSTR_PER_VMINSTR);
238 for (unsigned i=0; i < N; i++)
240 assert(minstrVec[i] != NULL);
241 instrNode->getInstruction()->addMachineInstruction(minstrVec[i]);
245 // Then, recursively compile the child nodes, if any.
248 { // i.e., there is at least one kid
250 BasicTreeNode* kids[2];
251 int currentRule = ruleForNode;
252 burm_kids(treeRoot, currentRule, kids);
254 // First skip over any chain rules so that we don't visit
255 // the current node again.
257 while (ThisIsAChainRule(currentRule))
259 currentRule = burm_rule(treeRoot->state, nts[0]);
260 nts = burm_nts[currentRule];
261 burm_kids(treeRoot, currentRule, kids);
264 // Now we have the first non-chain rule so we have found
265 // the actual child nodes. Recursively compile them.
267 for (int i = 0; nts[i]; i++)
270 InstrTreeNode::InstrTreeNodeType
271 nodeType = MainTreeNode(kids[i])->getNodeType();
272 if (nodeType == InstrTreeNode::NTVRegListNode ||
273 nodeType == InstrTreeNode::NTInstructionNode)
275 if (SelectInstructionsForTree(kids[i], nts[i], Target))
276 return true; // failure
281 return false; // success