1 //===- SparcV9PreSelection.cpp - Specialize LLVM code for SparcV9 ---------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the PreSelection pass which specializes LLVM code for
11 // the SparcV9 instruction selector, while remaining in legal portable LLVM
12 // form and preserving type information and type safety. This is meant to enable
13 // dataflow optimizations on SparcV9-specific operations such as accesses to
14 // constants, globals, and array indexing.
16 //===----------------------------------------------------------------------===//
18 #include "SparcV9Internals.h"
19 #include "SparcV9BurgISel.h"
20 #include "llvm/Constants.h"
21 #include "llvm/DerivedTypes.h"
22 #include "llvm/Instructions.h"
23 #include "llvm/Module.h"
24 #include "llvm/Pass.h"
25 #include "llvm/Support/InstVisitor.h"
26 #include "llvm/Support/GetElementPtrTypeIterator.h"
27 #include "llvm/Target/TargetInstrInfo.h"
28 #include "llvm/Target/TargetMachine.h"
29 #include "llvm/Transforms/Scalar.h"
35 //===--------------------------------------------------------------------===//
36 // PreSelection Pass - Specialize LLVM code for the SparcV9 instr. selector.
38 class PreSelection : public FunctionPass, public InstVisitor<PreSelection> {
39 const TargetInstrInfo &instrInfo;
42 PreSelection(const TargetMachine &T)
43 : instrInfo(*T.getInstrInfo()) {}
45 // runOnFunction - apply this pass to each Function
46 bool runOnFunction(Function &F) {
50 const char *getPassName() const { return "SparcV9 Instr. Pre-selection"; }
52 // These methods do the actual work of specializing code
53 void visitInstruction(Instruction &I); // common work for every instr.
54 void visitGetElementPtrInst(GetElementPtrInst &I);
55 void visitCallInst(CallInst &I);
56 void visitPHINode(PHINode &PN);
58 void visitBasicBlock(BasicBlock &BB) {
59 if (isa<UnreachableInst>(BB.getTerminator())) {
60 BB.getInstList().pop_back();
61 const Type *RetTy = BB.getParent()->getReturnType();
62 Value *RetVal = RetTy == Type::VoidTy ? 0 : UndefValue::get(RetTy);
63 new ReturnInst(RetVal, &BB);
67 // Helper functions for visiting operands of every instruction
69 // visitOperands() works on every operand in [firstOp, lastOp-1].
70 // If lastOp==0, lastOp defaults to #operands or #incoming Phi values.
72 // visitOneOperand() does all the work for one operand.
74 void visitOperands(Instruction &I, int firstOp=0);
75 void visitOneOperand(Instruction &I, Value* Op, unsigned opNum,
76 Instruction& insertBefore);
80 // Register the pass...
81 RegisterPass<PreSelection> X("preselect",
82 "Specialize LLVM code for a target machine"
83 createPreselectionPass);
86 } // end anonymous namespace
89 //------------------------------------------------------------------------------
90 // Helper functions used by methods of class PreSelection
91 //------------------------------------------------------------------------------
94 // getGlobalAddr(): Put address of a global into a v. register.
95 static GetElementPtrInst* getGlobalAddr(Value* ptr, Instruction& insertBefore) {
97 return (isa<GlobalVariable>(ptr))
98 ? new GetElementPtrInst(ptr,
99 std::vector<Value*>(1, ConstantSInt::get(Type::LongTy, 0U)),
100 "addrOfGlobal:" + ptr->getName(), &insertBefore)
104 // Wrapper on Constant::classof to use in find_if
105 inline static bool nonConstant(const Use& U) {
106 return ! isa<Constant>(U);
109 static Instruction* DecomposeConstantExpr(ConstantExpr* CE,
110 Instruction& insertBefore)
112 Value *getArg1, *getArg2;
114 switch(CE->getOpcode())
116 case Instruction::Cast:
117 getArg1 = CE->getOperand(0);
118 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
119 getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
120 return new CastInst(getArg1, CE->getType(), "constantCast",&insertBefore);
122 case Instruction::GetElementPtr:
123 assert(find_if(CE->op_begin()+1, CE->op_end(),nonConstant) == CE->op_end()
124 && "All indices in ConstantExpr getelementptr must be constant!");
125 getArg1 = CE->getOperand(0);
126 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
127 getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
128 else if (GetElementPtrInst* gep = getGlobalAddr(getArg1, insertBefore))
130 return new GetElementPtrInst(getArg1,
131 std::vector<Value*>(CE->op_begin()+1, CE->op_end()),
132 "constantGEP:" + getArg1->getName(), &insertBefore);
134 case Instruction::Select: {
136 C = CE->getOperand (0);
137 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr> (C))
138 C = DecomposeConstantExpr (CEarg, insertBefore);
139 S1 = CE->getOperand (1);
140 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr> (S1))
141 S1 = DecomposeConstantExpr (CEarg, insertBefore);
142 S2 = CE->getOperand (2);
143 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr> (S2))
144 S2 = DecomposeConstantExpr (CEarg, insertBefore);
145 return new SelectInst (C, S1, S2, "constantSelect", &insertBefore);
148 default: // must be a binary operator
149 assert(CE->getOpcode() >= Instruction::BinaryOpsBegin &&
150 CE->getOpcode() < Instruction::BinaryOpsEnd &&
151 "Unhandled opcode in ConstantExpr");
152 getArg1 = CE->getOperand(0);
153 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
154 getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
155 getArg2 = CE->getOperand(1);
156 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg2))
157 getArg2 = DecomposeConstantExpr(CEarg, insertBefore);
158 return BinaryOperator::create((Instruction::BinaryOps) CE->getOpcode(),
160 "constantBinaryOp", &insertBefore);
164 static inline bool ConstantTypeMustBeLoaded(const Type* CVT) {
165 assert(CVT->isPrimitiveType() || isa<PointerType>(CVT));
166 return !(CVT->isIntegral() || isa<PointerType>(CVT));
169 //------------------------------------------------------------------------------
170 // Instruction visitor methods to perform instruction-specific operations
171 //------------------------------------------------------------------------------
173 PreSelection::visitOneOperand(Instruction &I, Value* Op, unsigned opNum,
174 Instruction& insertBefore)
176 assert(&insertBefore != NULL && "Must have instruction to insert before.");
178 if (GetElementPtrInst* gep = getGlobalAddr(Op, insertBefore)) {
179 I.setOperand(opNum, gep); // replace global operand
180 return; // nothing more to do for this op.
183 Constant* CV = dyn_cast<Constant>(Op);
187 if (ConstantExpr* CE = dyn_cast<ConstantExpr>(CV)) {
188 // load-time constant: factor it out so we optimize as best we can
189 Instruction* computeConst = DecomposeConstantExpr(CE, insertBefore);
190 I.setOperand(opNum, computeConst); // replace expr operand with result
191 } else if (ConstantTypeMustBeLoaded(CV->getType())) {
192 // load address of constant into a register, then load the constant
193 // this is now done during instruction selection
194 // the constant will live in the MachineConstantPool later on
195 } else if (ConstantMayNotFitInImmedField(CV, &I)) {
196 // put the constant into a virtual register using a cast
197 CastInst* castI = new CastInst(CV, CV->getType(), "copyConst",
199 I.setOperand(opNum, castI); // replace operand with copy in v.reg.
203 /// visitOperands - transform individual operands of all instructions:
204 /// -- Load "large" int constants into a virtual register. What is large
205 /// depends on the type of instruction and on the target architecture.
206 /// -- For any constants that cannot be put in an immediate field,
207 /// load address into virtual register first, and then load the constant.
209 /// firstOp and lastOp can be used to skip leading and trailing operands.
210 /// If lastOp is 0, it defaults to #operands or #incoming Phi values.
212 inline void PreSelection::visitOperands(Instruction &I, int firstOp) {
213 // For any instruction other than PHI, copies go just before the instr.
214 for (unsigned i = firstOp, e = I.getNumOperands(); i != e; ++i)
215 visitOneOperand(I, I.getOperand(i), i, I);
219 void PreSelection::visitPHINode(PHINode &PN) {
220 // For a PHI, operand copies must be before the terminator of the
221 // appropriate predecessor basic block. Remaining logic is simple
222 // so just handle PHIs and other instructions separately.
224 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
225 visitOneOperand(PN, PN.getIncomingValue(i),
226 PN.getOperandNumForIncomingValue(i),
227 *PN.getIncomingBlock(i)->getTerminator());
228 // do not call visitOperands!
231 // Common work for *all* instructions. This needs to be called explicitly
232 // by other visit<InstructionType> functions.
233 inline void PreSelection::visitInstruction(Instruction &I) {
234 visitOperands(I); // Perform operand transformations
237 // GetElementPtr instructions: check if pointer is a global
238 void PreSelection::visitGetElementPtrInst(GetElementPtrInst &I) {
239 Instruction* curI = &I;
241 // The Sparc backend doesn't handle array indexes that are not long types, so
242 // insert a cast from whatever it is to long, if the sequential type index is
243 // not a long already.
245 for (gep_type_iterator TI = gep_type_begin(I), E = gep_type_end(I); TI != E;
247 if (isa<SequentialType>(*TI) &&
248 I.getOperand(Idx)->getType() != Type::LongTy) {
249 Value *Op = I.getOperand(Idx);
250 if (Op->getType()->isUnsigned()) // Must sign extend!
251 Op = new CastInst(Op, Op->getType()->getSignedVersion(), "v9", &I);
252 if (Op->getType() != Type::LongTy)
253 Op = new CastInst(Op, Type::LongTy, "v9", &I);
254 I.setOperand(Idx, Op);
258 // Decompose multidimensional array references
259 if (I.getNumIndices() >= 2) {
260 // DecomposeArrayRef() replaces I and deletes it, if successful,
261 // so remember predecessor in order to find the replacement instruction.
262 // Also remember the basic block in case there is no predecessor.
263 Instruction* prevI = I.getPrev();
264 BasicBlock* bb = I.getParent();
265 if (DecomposeArrayRef(&I))
266 // first instr. replacing I
267 curI = cast<GetElementPtrInst>(prevI? prevI->getNext() : &bb->front());
270 // Perform other transformations common to all instructions
271 visitInstruction(*curI);
274 void PreSelection::visitCallInst(CallInst &I) {
275 // Tell visitOperands to ignore the function name if this is a direct call.
276 visitOperands(I, (/*firstOp=*/ I.getCalledFunction()? 1 : 0));
279 /// createPreSelectionPass - Public entry point for the PreSelection pass
281 FunctionPass* llvm::createPreSelectionPass(const TargetMachine &TM) {
282 return new PreSelection(TM);