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 "llvm/Constants.h"
20 #include "llvm/DerivedTypes.h"
21 #include "llvm/iMemory.h"
22 #include "llvm/iPHINode.h"
23 #include "llvm/iOther.h"
24 #include "llvm/Module.h"
25 #include "llvm/Pass.h"
26 #include "llvm/Support/InstVisitor.h"
27 #include "llvm/Support/GetElementPtrTypeIterator.h"
28 #include "llvm/Target/TargetInstrInfo.h"
29 #include "llvm/Target/TargetMachine.h"
30 #include "llvm/Transforms/Scalar.h"
36 //===--------------------------------------------------------------------===//
37 // PreSelection Pass - Specialize LLVM code for the SparcV9 instr. selector.
39 class PreSelection : public FunctionPass, public InstVisitor<PreSelection> {
40 const TargetInstrInfo &instrInfo;
43 PreSelection(const TargetMachine &T)
44 : instrInfo(*T.getInstrInfo()) {}
46 // runOnFunction - apply this pass to each Function
47 bool runOnFunction(Function &F) {
51 const char *getPassName() const { return "SparcV9 Instr. Pre-selection"; }
53 // These methods do the actual work of specializing code
54 void visitInstruction(Instruction &I); // common work for every instr.
55 void visitGetElementPtrInst(GetElementPtrInst &I);
56 void visitCallInst(CallInst &I);
57 void visitPHINode(PHINode &PN);
59 // Helper functions for visiting operands of every instruction
61 // visitOperands() works on every operand in [firstOp, lastOp-1].
62 // If lastOp==0, lastOp defaults to #operands or #incoming Phi values.
64 // visitOneOperand() does all the work for one operand.
66 void visitOperands(Instruction &I, int firstOp=0);
67 void visitOneOperand(Instruction &I, Value* Op, unsigned opNum,
68 Instruction& insertBefore);
72 // Register the pass...
73 RegisterPass<PreSelection> X("preselect",
74 "Specialize LLVM code for a target machine"
75 createPreselectionPass);
78 } // end anonymous namespace
81 //------------------------------------------------------------------------------
82 // Helper functions used by methods of class PreSelection
83 //------------------------------------------------------------------------------
86 // getGlobalAddr(): Put address of a global into a v. register.
87 static GetElementPtrInst* getGlobalAddr(Value* ptr, Instruction& insertBefore) {
89 return (isa<GlobalVariable>(ptr))
90 ? new GetElementPtrInst(ptr,
91 std::vector<Value*>(1, ConstantSInt::get(Type::LongTy, 0U)),
92 "addrOfGlobal:" + ptr->getName(), &insertBefore)
96 // Wrapper on Constant::classof to use in find_if
97 inline static bool nonConstant(const Use& U) {
98 return ! isa<Constant>(U);
101 static Instruction* DecomposeConstantExpr(ConstantExpr* CE,
102 Instruction& insertBefore)
104 Value *getArg1, *getArg2;
106 switch(CE->getOpcode())
108 case Instruction::Cast:
109 getArg1 = CE->getOperand(0);
110 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
111 getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
112 return new CastInst(getArg1, CE->getType(), "constantCast",&insertBefore);
114 case Instruction::GetElementPtr:
115 assert(find_if(CE->op_begin()+1, CE->op_end(),nonConstant) == CE->op_end()
116 && "All indices in ConstantExpr getelementptr must be constant!");
117 getArg1 = CE->getOperand(0);
118 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
119 getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
120 else if (GetElementPtrInst* gep = getGlobalAddr(getArg1, insertBefore))
122 return new GetElementPtrInst(getArg1,
123 std::vector<Value*>(CE->op_begin()+1, CE->op_end()),
124 "constantGEP:" + getArg1->getName(), &insertBefore);
126 case Instruction::Select: {
128 C = CE->getOperand (0);
129 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr> (C))
130 C = DecomposeConstantExpr (CEarg, insertBefore);
131 S1 = CE->getOperand (1);
132 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr> (S1))
133 S1 = DecomposeConstantExpr (CEarg, insertBefore);
134 S2 = CE->getOperand (2);
135 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr> (S2))
136 S2 = DecomposeConstantExpr (CEarg, insertBefore);
137 return new SelectInst (C, S1, S2, "constantSelect", &insertBefore);
140 default: // must be a binary operator
141 assert(CE->getOpcode() >= Instruction::BinaryOpsBegin &&
142 CE->getOpcode() < Instruction::BinaryOpsEnd &&
143 "Unhandled opcode in ConstantExpr");
144 getArg1 = CE->getOperand(0);
145 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
146 getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
147 getArg2 = CE->getOperand(1);
148 if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg2))
149 getArg2 = DecomposeConstantExpr(CEarg, insertBefore);
150 return BinaryOperator::create((Instruction::BinaryOps) CE->getOpcode(),
152 "constantBinaryOp", &insertBefore);
157 //------------------------------------------------------------------------------
158 // Instruction visitor methods to perform instruction-specific operations
159 //------------------------------------------------------------------------------
161 PreSelection::visitOneOperand(Instruction &I, Value* Op, unsigned opNum,
162 Instruction& insertBefore)
164 assert(&insertBefore != NULL && "Must have instruction to insert before.");
166 if (GetElementPtrInst* gep = getGlobalAddr(Op, insertBefore)) {
167 I.setOperand(opNum, gep); // replace global operand
168 return; // nothing more to do for this op.
171 Constant* CV = dyn_cast<Constant>(Op);
175 if (ConstantExpr* CE = dyn_cast<ConstantExpr>(CV)) {
176 // load-time constant: factor it out so we optimize as best we can
177 Instruction* computeConst = DecomposeConstantExpr(CE, insertBefore);
178 I.setOperand(opNum, computeConst); // replace expr operand with result
179 } else if (instrInfo.ConstantTypeMustBeLoaded(CV)) {
180 // load address of constant into a register, then load the constant
181 // this is now done during instruction selection
182 // the constant will live in the MachineConstantPool later on
183 } else if (instrInfo.ConstantMayNotFitInImmedField(CV, &I)) {
184 // put the constant into a virtual register using a cast
185 CastInst* castI = new CastInst(CV, CV->getType(), "copyConst",
187 I.setOperand(opNum, castI); // replace operand with copy in v.reg.
191 /// visitOperands - transform individual operands of all instructions:
192 /// -- Load "large" int constants into a virtual register. What is large
193 /// depends on the type of instruction and on the target architecture.
194 /// -- For any constants that cannot be put in an immediate field,
195 /// load address into virtual register first, and then load the constant.
197 /// firstOp and lastOp can be used to skip leading and trailing operands.
198 /// If lastOp is 0, it defaults to #operands or #incoming Phi values.
200 inline void PreSelection::visitOperands(Instruction &I, int firstOp) {
201 // For any instruction other than PHI, copies go just before the instr.
202 for (unsigned i = firstOp, e = I.getNumOperands(); i != e; ++i)
203 visitOneOperand(I, I.getOperand(i), i, I);
207 void PreSelection::visitPHINode(PHINode &PN) {
208 // For a PHI, operand copies must be before the terminator of the
209 // appropriate predecessor basic block. Remaining logic is simple
210 // so just handle PHIs and other instructions separately.
212 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
213 visitOneOperand(PN, PN.getIncomingValue(i),
214 PN.getOperandNumForIncomingValue(i),
215 *PN.getIncomingBlock(i)->getTerminator());
216 // do not call visitOperands!
219 // Common work for *all* instructions. This needs to be called explicitly
220 // by other visit<InstructionType> functions.
221 inline void PreSelection::visitInstruction(Instruction &I) {
222 visitOperands(I); // Perform operand transformations
225 // GetElementPtr instructions: check if pointer is a global
226 void PreSelection::visitGetElementPtrInst(GetElementPtrInst &I) {
227 Instruction* curI = &I;
229 // The Sparc backend doesn't handle array indexes that are not long types, so
230 // insert a cast from whatever it is to long, if the sequential type index is
231 // not a long already.
233 for (gep_type_iterator TI = gep_type_begin(I), E = gep_type_end(I); TI != E;
235 if (isa<SequentialType>(*TI) &&
236 I.getOperand(Idx)->getType() != Type::LongTy) {
237 Value *Op = I.getOperand(Idx);
238 if (Op->getType()->isUnsigned()) // Must sign extend!
239 Op = new CastInst(Op, Op->getType()->getSignedVersion(), "v9", &I);
240 if (Op->getType() != Type::LongTy)
241 Op = new CastInst(Op, Type::LongTy, "v9", &I);
242 I.setOperand(Idx, Op);
246 // Decompose multidimensional array references
247 if (I.getNumIndices() >= 2) {
248 // DecomposeArrayRef() replaces I and deletes it, if successful,
249 // so remember predecessor in order to find the replacement instruction.
250 // Also remember the basic block in case there is no predecessor.
251 Instruction* prevI = I.getPrev();
252 BasicBlock* bb = I.getParent();
253 if (DecomposeArrayRef(&I))
254 // first instr. replacing I
255 curI = cast<GetElementPtrInst>(prevI? prevI->getNext() : &bb->front());
258 // Perform other transformations common to all instructions
259 visitInstruction(*curI);
262 void PreSelection::visitCallInst(CallInst &I) {
263 // Tell visitOperands to ignore the function name if this is a direct call.
264 visitOperands(I, (/*firstOp=*/ I.getCalledFunction()? 1 : 0));
267 /// createPreSelectionPass - Public entry point for the PreSelection pass
269 FunctionPass* llvm::createPreSelectionPass(const TargetMachine &TM) {
270 return new PreSelection(TM);