2 //***************************************************************************
9 // 7/02/01 - Vikram Adve - Created
10 //**************************************************************************/
13 #include "llvm/CodeGen/InstrSelection.h"
14 #include "llvm/CodeGen/MachineInstr.h"
15 #include "llvm/Support/CommandLine.h"
16 #include "llvm/Type.h"
17 #include "llvm/iMemory.h"
18 #include "llvm/Instruction.h"
19 #include "llvm/BasicBlock.h"
20 #include "llvm/Method.h"
22 static bool SelectInstructionsForTree(InstrTreeNode* treeRoot, int goalnt,
23 TargetMachine &Target);
26 enum SelectDebugLevel_t {
28 Select_PrintMachineCode,
29 Select_DebugInstTrees,
30 Select_DebugBurgTrees,
33 // Enable Debug Options to be specified on the command line
34 cl::Enum<enum SelectDebugLevel_t> SelectDebugLevel("dselect", cl::NoFlags,
35 "enable instruction selection debugging information",
36 clEnumValN(Select_NoDebugInfo, "n", "disable debug output"),
37 clEnumValN(Select_PrintMachineCode, "y", "print generated machine code"),
38 clEnumValN(Select_DebugInstTrees, "i", "print instruction selection debug info"),
39 clEnumValN(Select_DebugBurgTrees, "b", "print burg trees"), 0);
43 //---------------------------------------------------------------------------
44 // Entry point for instruction selection using BURG.
45 // Returns true if instruction selection failed, false otherwise.
46 //---------------------------------------------------------------------------
49 SelectInstructionsForMethod(Method* method,
50 TargetMachine &Target)
55 // Build the instruction trees to be given as inputs to BURG.
57 InstrForest instrForest(method);
59 if (SelectDebugLevel >= Select_DebugInstTrees)
61 cout << "\n\n*** Instruction trees for method "
62 << (method->hasName()? method->getName() : "")
68 // Invoke BURG instruction selection for each tree
70 const hash_set<InstructionNode*> &treeRoots = instrForest.getRootSet();
71 for (hash_set<InstructionNode*>::const_iterator
72 treeRootIter = treeRoots.begin();
73 treeRootIter != treeRoots.end();
76 InstrTreeNode* basicNode = *treeRootIter;
78 // Invoke BURM to label each tree node with a state
79 (void) burm_label(basicNode);
81 if (SelectDebugLevel >= Select_DebugBurgTrees)
83 printcover(basicNode, 1, 0);
84 cerr << "\nCover cost == " << treecost(basicNode, 1, 0) << "\n\n";
85 printMatches(basicNode);
88 // Then recursively walk the tree to select instructions
89 if (SelectInstructionsForTree(basicNode, /*goalnt*/1, Target))
97 // Record instructions in the vector for each basic block
99 for (Method::iterator BI = method->begin(); BI != method->end(); ++BI)
101 MachineCodeForBasicBlock& bbMvec = (*BI)->getMachineInstrVec();
102 for (BasicBlock::iterator II = (*BI)->begin(); II != (*BI)->end(); ++II)
104 MachineCodeForVMInstr& mvec = (*II)->getMachineInstrVec();
105 for (unsigned i=0; i < mvec.size(); i++)
106 bbMvec.push_back(mvec[i]);
110 if (SelectDebugLevel >= Select_PrintMachineCode)
112 cout << endl << "*** Machine instructions after INSTRUCTION SELECTION" << endl;
113 PrintMachineInstructions(method);
120 //---------------------------------------------------------------------------
121 // Function: FoldGetElemChain
124 // Fold a chain of GetElementPtr instructions into an equivalent
125 // (Pointer, IndexVector) pair. Returns the pointer Value, and
126 // stores the resulting IndexVector in argument chainIdxVec.
127 //---------------------------------------------------------------------------
130 FoldGetElemChain(const InstructionNode* getElemInstrNode,
131 vector<ConstPoolVal*>& chainIdxVec)
133 MemAccessInst* getElemInst = (MemAccessInst*)
134 getElemInstrNode->getInstruction();
136 // Initialize return values from the incoming instruction
137 Value* ptrVal = getElemInst->getPtrOperand();
138 chainIdxVec = getElemInst->getIndexVec(); // copies index vector values
140 // Now chase the chain of getElementInstr instructions, if any
141 InstrTreeNode* ptrChild = getElemInstrNode->leftChild();
142 while (ptrChild->getOpLabel() == Instruction::GetElementPtr ||
143 ptrChild->getOpLabel() == GetElemPtrIdx)
145 // Child is a GetElemPtr instruction
146 getElemInst = (MemAccessInst*)
147 ((InstructionNode*) ptrChild)->getInstruction();
148 const vector<ConstPoolVal*>& idxVec = getElemInst->getIndexVec();
150 // Get the pointer value out of ptrChild and *prepend* its index vector
151 ptrVal = getElemInst->getPtrOperand();
152 chainIdxVec.insert(chainIdxVec.begin(), idxVec.begin(), idxVec.end());
154 ptrChild = ptrChild->leftChild();
161 //*********************** Private Functions *****************************/
164 //---------------------------------------------------------------------------
165 // Function SelectInstructionsForTree
167 // Recursively walk the tree to select instructions.
168 // Do this top-down so that child instructions can exploit decisions
169 // made at the child instructions.
171 // E.g., if br(setle(reg,const)) decides the constant is 0 and uses
172 // a branch-on-integer-register instruction, then the setle node
173 // can use that information to avoid generating the SUBcc instruction.
175 // Note that this cannot be done bottom-up because setle must do this
176 // only if it is a child of the branch (otherwise, the result of setle
177 // may be used by multiple instructions).
178 //---------------------------------------------------------------------------
181 SelectInstructionsForTree(InstrTreeNode* treeRoot, int goalnt,
182 TargetMachine &Target)
184 // Use a static vector to avoid allocating a new one per VM instruction
185 static MachineInstr* minstrVec[MAX_INSTR_PER_VMINSTR];
187 // Get the rule that matches this node.
189 int ruleForNode = burm_rule(treeRoot->state, goalnt);
191 if (ruleForNode == 0)
193 cerr << "Could not match instruction tree for instr selection" << endl;
197 // Get this rule's non-terminals and the corresponding child nodes (if any)
199 short *nts = burm_nts[ruleForNode];
202 // First, select instructions for the current node and rule.
203 // (If this is a list node, not an instruction, then skip this step).
204 // This function is specific to the target architecture.
206 if (treeRoot->opLabel != VRegListOp)
208 InstructionNode* instrNode = (InstructionNode*)treeRoot;
209 assert(instrNode->getNodeType() == InstrTreeNode::NTInstructionNode);
211 unsigned N = GetInstructionsByRule(instrNode, ruleForNode, nts, Target,
213 assert(N <= MAX_INSTR_PER_VMINSTR);
214 for (unsigned i=0; i < N; i++)
216 assert(minstrVec[i] != NULL);
217 instrNode->getInstruction()->addMachineInstruction(minstrVec[i]);
221 // Then, recursively compile the child nodes, if any.
224 { // i.e., there is at least one kid
226 InstrTreeNode* kids[2];
227 int currentRule = ruleForNode;
228 burm_kids(treeRoot, currentRule, kids);
230 // First skip over any chain rules so that we don't visit
231 // the current node again.
233 while (ThisIsAChainRule(currentRule))
235 currentRule = burm_rule(treeRoot->state, nts[0]);
236 nts = burm_nts[currentRule];
237 burm_kids(treeRoot, currentRule, kids);
240 // Now we have the first non-chain rule so we have found
241 // the actual child nodes. Recursively compile them.
243 for (int i = 0; nts[i]; i++)
246 InstrTreeNode::InstrTreeNodeType nodeType = kids[i]->getNodeType();
247 if (nodeType == InstrTreeNode::NTVRegListNode ||
248 nodeType == InstrTreeNode::NTInstructionNode)
250 if (SelectInstructionsForTree(kids[i], nts[i], Target))
251 return true; // failure
256 return false; // success