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 "SparcV9InstrSelectionSupport.h"
20 #include "llvm/Constants.h"
21 #include "llvm/DerivedTypes.h"
22 #include "llvm/iMemory.h"
23 #include "llvm/iPHINode.h"
24 #include "llvm/iOther.h"
25 #include "llvm/Module.h"
26 #include "llvm/Pass.h"
27 #include "llvm/Support/InstVisitor.h"
28 #include "llvm/Support/GetElementPtrTypeIterator.h"
29 #include "llvm/Target/TargetInstrInfo.h"
30 #include "llvm/Target/TargetMachine.h"
31 #include "llvm/Transforms/Scalar.h"
37 //===--------------------------------------------------------------------===//
38 // PreSelection Pass - Specialize LLVM code for the SparcV9 instr. selector.
40 class PreSelection : public FunctionPass, public InstVisitor<PreSelection> {
41 const TargetInstrInfo &instrInfo;
44 PreSelection(const TargetMachine &T)
45 : instrInfo(*T.getInstrInfo()) {}
47 // runOnFunction - apply this pass to each Function
48 bool runOnFunction(Function &F) {
52 const char *getPassName() const { return "SparcV9 Instr. Pre-selection"; }
54 // These methods do the actual work of specializing code
55 void visitInstruction(Instruction &I); // common work for every instr.
56 void visitGetElementPtrInst(GetElementPtrInst &I);
57 void visitCallInst(CallInst &I);
58 void visitPHINode(PHINode &PN);
60 // Helper functions for visiting operands of every instruction
62 // visitOperands() works on every operand in [firstOp, lastOp-1].
63 // If lastOp==0, lastOp defaults to #operands or #incoming Phi values.
65 // visitOneOperand() does all the work for one operand.
67 void visitOperands(Instruction &I, int firstOp=0);
68 void visitOneOperand(Instruction &I, Value* Op, unsigned opNum,
69 Instruction& insertBefore);
73 // Register the pass...
74 RegisterPass<PreSelection> X("preselect",
75 "Specialize LLVM code for a target machine"
76 createPreselectionPass);
79 } // end anonymous namespace
82 //------------------------------------------------------------------------------
83 // Helper functions used by methods of class PreSelection
84 //------------------------------------------------------------------------------
87 // getGlobalAddr(): Put address of a global into a v. register.
88 static GetElementPtrInst* getGlobalAddr(Value* ptr, Instruction& insertBefore) {
90 return (isa<GlobalVariable>(ptr))
91 ? new GetElementPtrInst(ptr,
92 std::vector<Value*>(1, ConstantSInt::get(Type::LongTy, 0U)),
93 "addrOfGlobal:" + ptr->getName(), &insertBefore)
97 // Wrapper on Constant::classof to use in find_if
98 inline static bool nonConstant(const Use& U) {
99 return ! isa<Constant>(U);
102 static Instruction* DecomposeConstantExpr(ConstantExpr* CE,
103 Instruction& insertBefore)
105 Value *getArg1, *getArg2;
107 switch(CE->getOpcode())
109 case Instruction::Cast:
110 getArg1 = CE->getOperand(0);
111 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
112 getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
113 return new CastInst(getArg1, CE->getType(), "constantCast",&insertBefore);
115 case Instruction::GetElementPtr:
116 assert(find_if(CE->op_begin()+1, CE->op_end(),nonConstant) == CE->op_end()
117 && "All indices in ConstantExpr getelementptr must be constant!");
118 getArg1 = CE->getOperand(0);
119 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
120 getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
121 else if (GetElementPtrInst* gep = getGlobalAddr(getArg1, insertBefore))
123 return new GetElementPtrInst(getArg1,
124 std::vector<Value*>(CE->op_begin()+1, CE->op_end()),
125 "constantGEP:" + getArg1->getName(), &insertBefore);
127 case Instruction::Select: {
129 C = CE->getOperand (0);
130 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr> (C))
131 C = DecomposeConstantExpr (CEarg, insertBefore);
132 S1 = CE->getOperand (1);
133 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr> (S1))
134 S1 = DecomposeConstantExpr (CEarg, insertBefore);
135 S2 = CE->getOperand (2);
136 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr> (S2))
137 S2 = DecomposeConstantExpr (CEarg, insertBefore);
138 return new SelectInst (C, S1, S2, "constantSelect", &insertBefore);
141 default: // must be a binary operator
142 assert(CE->getOpcode() >= Instruction::BinaryOpsBegin &&
143 CE->getOpcode() < Instruction::BinaryOpsEnd &&
144 "Unhandled opcode in ConstantExpr");
145 getArg1 = CE->getOperand(0);
146 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
147 getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
148 getArg2 = CE->getOperand(1);
149 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg2))
150 getArg2 = DecomposeConstantExpr(CEarg, insertBefore);
151 return BinaryOperator::create((Instruction::BinaryOps) CE->getOpcode(),
153 "constantBinaryOp", &insertBefore);
158 //------------------------------------------------------------------------------
159 // Instruction visitor methods to perform instruction-specific operations
160 //------------------------------------------------------------------------------
162 PreSelection::visitOneOperand(Instruction &I, Value* Op, unsigned opNum,
163 Instruction& insertBefore)
165 assert(&insertBefore != NULL && "Must have instruction to insert before.");
167 if (GetElementPtrInst* gep = getGlobalAddr(Op, insertBefore)) {
168 I.setOperand(opNum, gep); // replace global operand
169 return; // nothing more to do for this op.
172 Constant* CV = dyn_cast<Constant>(Op);
176 if (ConstantExpr* CE = dyn_cast<ConstantExpr>(CV)) {
177 // load-time constant: factor it out so we optimize as best we can
178 Instruction* computeConst = DecomposeConstantExpr(CE, insertBefore);
179 I.setOperand(opNum, computeConst); // replace expr operand with result
180 } else if (instrInfo.ConstantTypeMustBeLoaded(CV)) {
181 // load address of constant into a register, then load the constant
182 // this is now done during instruction selection
183 // the constant will live in the MachineConstantPool later on
184 } else if (ConstantMayNotFitInImmedField(CV, &I)) {
185 // put the constant into a virtual register using a cast
186 CastInst* castI = new CastInst(CV, CV->getType(), "copyConst",
188 I.setOperand(opNum, castI); // replace operand with copy in v.reg.
192 /// visitOperands - transform individual operands of all instructions:
193 /// -- Load "large" int constants into a virtual register. What is large
194 /// depends on the type of instruction and on the target architecture.
195 /// -- For any constants that cannot be put in an immediate field,
196 /// load address into virtual register first, and then load the constant.
198 /// firstOp and lastOp can be used to skip leading and trailing operands.
199 /// If lastOp is 0, it defaults to #operands or #incoming Phi values.
201 inline void PreSelection::visitOperands(Instruction &I, int firstOp) {
202 // For any instruction other than PHI, copies go just before the instr.
203 for (unsigned i = firstOp, e = I.getNumOperands(); i != e; ++i)
204 visitOneOperand(I, I.getOperand(i), i, I);
208 void PreSelection::visitPHINode(PHINode &PN) {
209 // For a PHI, operand copies must be before the terminator of the
210 // appropriate predecessor basic block. Remaining logic is simple
211 // so just handle PHIs and other instructions separately.
213 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
214 visitOneOperand(PN, PN.getIncomingValue(i),
215 PN.getOperandNumForIncomingValue(i),
216 *PN.getIncomingBlock(i)->getTerminator());
217 // do not call visitOperands!
220 // Common work for *all* instructions. This needs to be called explicitly
221 // by other visit<InstructionType> functions.
222 inline void PreSelection::visitInstruction(Instruction &I) {
223 visitOperands(I); // Perform operand transformations
226 // GetElementPtr instructions: check if pointer is a global
227 void PreSelection::visitGetElementPtrInst(GetElementPtrInst &I) {
228 Instruction* curI = &I;
230 // The Sparc backend doesn't handle array indexes that are not long types, so
231 // insert a cast from whatever it is to long, if the sequential type index is
232 // not a long already.
234 for (gep_type_iterator TI = gep_type_begin(I), E = gep_type_end(I); TI != E;
236 if (isa<SequentialType>(*TI) &&
237 I.getOperand(Idx)->getType() != Type::LongTy) {
238 Value *Op = I.getOperand(Idx);
239 if (Op->getType()->isUnsigned()) // Must sign extend!
240 Op = new CastInst(Op, Op->getType()->getSignedVersion(), "v9", &I);
241 if (Op->getType() != Type::LongTy)
242 Op = new CastInst(Op, Type::LongTy, "v9", &I);
243 I.setOperand(Idx, Op);
247 // Decompose multidimensional array references
248 if (I.getNumIndices() >= 2) {
249 // DecomposeArrayRef() replaces I and deletes it, if successful,
250 // so remember predecessor in order to find the replacement instruction.
251 // Also remember the basic block in case there is no predecessor.
252 Instruction* prevI = I.getPrev();
253 BasicBlock* bb = I.getParent();
254 if (DecomposeArrayRef(&I))
255 // first instr. replacing I
256 curI = cast<GetElementPtrInst>(prevI? prevI->getNext() : &bb->front());
259 // Perform other transformations common to all instructions
260 visitInstruction(*curI);
263 void PreSelection::visitCallInst(CallInst &I) {
264 // Tell visitOperands to ignore the function name if this is a direct call.
265 visitOperands(I, (/*firstOp=*/ I.getCalledFunction()? 1 : 0));
268 /// createPreSelectionPass - Public entry point for the PreSelection pass
270 FunctionPass* llvm::createPreSelectionPass(const TargetMachine &TM) {
271 return new PreSelection(TM);