1 //===- LevelRaise.cpp - Code to change LLVM to higher level ---------------===//
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 implements the 'raising' part of the LevelChange API. This is
11 // useful because, in general, it makes the LLVM code terser and easier to
14 //===----------------------------------------------------------------------===//
16 #include "llvm/Transforms/Scalar.h"
17 #include "llvm/Transforms/Utils/Local.h"
18 #include "TransformInternals.h"
19 #include "llvm/iOther.h"
20 #include "llvm/iMemory.h"
21 #include "llvm/Pass.h"
22 #include "llvm/ConstantHandling.h"
23 #include "llvm/Analysis/Expressions.h"
24 #include "llvm/Analysis/Verifier.h"
25 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
26 #include "Support/CommandLine.h"
27 #include "Support/Debug.h"
28 #include "Support/Statistic.h"
29 #include "Support/STLExtras.h"
34 // StartInst - This enables the -raise-start-inst=foo option to cause the level
35 // raising pass to start at instruction "foo", which is immensely useful for
38 static cl::opt<std::string>
39 StartInst("raise-start-inst", cl::Hidden, cl::value_desc("inst name"),
40 cl::desc("Start raise pass at the instruction with the specified name"));
43 NumLoadStorePeepholes("raise", "Number of load/store peepholes");
46 NumGEPInstFormed("raise", "Number of other getelementptr's formed");
49 NumExprTreesConv("raise", "Number of expression trees converted");
52 NumCastOfCast("raise", "Number of cast-of-self removed");
55 NumDCEorCP("raise", "Number of insts DCEd or constprop'd");
58 NumVarargCallChanges("raise", "Number of vararg call peepholes");
60 #define PRINT_PEEPHOLE(ID, NUM, I) \
61 DEBUG(std::cerr << "Inst P/H " << ID << "[" << NUM << "] " << I)
63 #define PRINT_PEEPHOLE1(ID, I1) do { PRINT_PEEPHOLE(ID, 0, I1); } while (0)
64 #define PRINT_PEEPHOLE2(ID, I1, I2) \
65 do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); } while (0)
66 #define PRINT_PEEPHOLE3(ID, I1, I2, I3) \
67 do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \
68 PRINT_PEEPHOLE(ID, 2, I3); } while (0)
69 #define PRINT_PEEPHOLE4(ID, I1, I2, I3, I4) \
70 do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \
71 PRINT_PEEPHOLE(ID, 2, I3); PRINT_PEEPHOLE(ID, 3, I4); } while (0)
74 struct RPR : public FunctionPass {
75 virtual bool runOnFunction(Function &F);
77 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
79 AU.addRequired<TargetData>();
83 bool DoRaisePass(Function &F);
84 bool PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI);
87 RegisterOpt<RPR> X("raise", "Raise Pointer References");
91 Pass *createRaisePointerReferencesPass() {
96 // isReinterpretingCast - Return true if the cast instruction specified will
97 // cause the operand to be "reinterpreted". A value is reinterpreted if the
98 // cast instruction would cause the underlying bits to change.
100 static inline bool isReinterpretingCast(const CastInst *CI) {
101 return!CI->getOperand(0)->getType()->isLosslesslyConvertibleTo(CI->getType());
105 // Peephole optimize the following instructions:
106 // %t1 = cast ? to x *
107 // %t2 = add x * %SP, %t1 ;; Constant must be 2nd operand
109 // Into: %t3 = getelementptr {<...>} * %SP, <element indices>
110 // %t2 = cast <eltype> * %t3 to {<...>}*
112 static bool HandleCastToPointer(BasicBlock::iterator BI,
113 const PointerType *DestPTy,
114 const TargetData &TD) {
115 CastInst &CI = cast<CastInst>(*BI);
116 if (CI.use_empty()) return false;
118 // Scan all of the uses, looking for any uses that are not add or sub
119 // instructions. If we have non-adds, do not make this transformation.
121 bool HasSubUse = false; // Keep track of any subtracts...
122 for (Value::use_iterator I = CI.use_begin(), E = CI.use_end();
124 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(*I)) {
125 if ((BO->getOpcode() != Instruction::Add &&
126 BO->getOpcode() != Instruction::Sub) ||
127 // Avoid add sbyte* %X, %X cases...
128 BO->getOperand(0) == BO->getOperand(1))
131 HasSubUse |= BO->getOpcode() == Instruction::Sub;
136 std::vector<Value*> Indices;
137 Value *Src = CI.getOperand(0);
138 const Type *Result = ConvertibleToGEP(DestPTy, Src, Indices, TD, &BI);
139 if (Result == 0) return false; // Not convertible...
141 // Cannot handle subtracts if there is more than one index required...
142 if (HasSubUse && Indices.size() != 1) return false;
144 PRINT_PEEPHOLE2("cast-add-to-gep:in", Src, CI);
146 // If we have a getelementptr capability... transform all of the
147 // add instruction uses into getelementptr's.
148 while (!CI.use_empty()) {
149 BinaryOperator *I = cast<BinaryOperator>(*CI.use_begin());
150 assert((I->getOpcode() == Instruction::Add ||
151 I->getOpcode() == Instruction::Sub) &&
152 "Use is not a valid add instruction!");
154 // Get the value added to the cast result pointer...
155 Value *OtherPtr = I->getOperand((I->getOperand(0) == &CI) ? 1 : 0);
157 Instruction *GEP = new GetElementPtrInst(OtherPtr, Indices, I->getName());
158 PRINT_PEEPHOLE1("cast-add-to-gep:i", I);
160 // If the instruction is actually a subtract, we are guaranteed to only have
161 // one index (from code above), so we just need to negate the pointer index
163 if (I->getOpcode() == Instruction::Sub) {
164 Instruction *Neg = BinaryOperator::createNeg(GEP->getOperand(1),
165 GEP->getOperand(1)->getName()+".neg", I);
166 GEP->setOperand(1, Neg);
169 if (GEP->getType() == I->getType()) {
170 // Replace the old add instruction with the shiny new GEP inst
171 ReplaceInstWithInst(I, GEP);
173 // If the type produced by the gep instruction differs from the original
174 // add instruction type, insert a cast now.
177 // Insert the GEP instruction before the old add instruction...
178 I->getParent()->getInstList().insert(I, GEP);
180 PRINT_PEEPHOLE1("cast-add-to-gep:o", GEP);
181 GEP = new CastInst(GEP, I->getType());
183 // Replace the old add instruction with the shiny new GEP inst
184 ReplaceInstWithInst(I, GEP);
187 PRINT_PEEPHOLE1("cast-add-to-gep:o", GEP);
192 // Peephole optimize the following instructions:
193 // %t1 = cast ulong <const int> to {<...>} *
194 // %t2 = add {<...>} * %SP, %t1 ;; Constant must be 2nd operand
197 // %t1 = cast {<...>}* %SP to int*
198 // %t5 = cast ulong <const int> to int*
199 // %t2 = add int* %t1, %t5 ;; int is same size as field
201 // Into: %t3 = getelementptr {<...>} * %SP, <element indices>
202 // %t2 = cast <eltype> * %t3 to {<...>}*
204 static bool PeepholeOptimizeAddCast(BasicBlock *BB, BasicBlock::iterator &BI,
205 Value *AddOp1, CastInst *AddOp2,
206 const TargetData &TD) {
207 const CompositeType *CompTy;
208 Value *OffsetVal = AddOp2->getOperand(0);
209 Value *SrcPtr = 0; // Of type pointer to struct...
211 if ((CompTy = getPointedToComposite(AddOp1->getType()))) {
212 SrcPtr = AddOp1; // Handle the first case...
213 } else if (CastInst *AddOp1c = dyn_cast<CastInst>(AddOp1)) {
214 SrcPtr = AddOp1c->getOperand(0); // Handle the second case...
215 CompTy = getPointedToComposite(SrcPtr->getType());
218 // Only proceed if we have detected all of our conditions successfully...
219 if (!CompTy || !SrcPtr || !OffsetVal->getType()->isInteger())
222 std::vector<Value*> Indices;
223 if (!ConvertibleToGEP(SrcPtr->getType(), OffsetVal, Indices, TD, &BI))
224 return false; // Not convertible... perhaps next time
226 if (getPointedToComposite(AddOp1->getType())) { // case 1
227 PRINT_PEEPHOLE2("add-to-gep1:in", AddOp2, *BI);
229 PRINT_PEEPHOLE3("add-to-gep2:in", AddOp1, AddOp2, *BI);
232 GetElementPtrInst *GEP = new GetElementPtrInst(SrcPtr, Indices,
233 AddOp2->getName(), BI);
235 Instruction *NCI = new CastInst(GEP, AddOp1->getType());
236 ReplaceInstWithInst(BB->getInstList(), BI, NCI);
237 PRINT_PEEPHOLE2("add-to-gep:out", GEP, NCI);
241 bool RPR::PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI) {
243 const TargetData &TD = getAnalysis<TargetData>();
245 if (CastInst *CI = dyn_cast<CastInst>(I)) {
246 Value *Src = CI->getOperand(0);
247 Instruction *SrcI = dyn_cast<Instruction>(Src); // Nonnull if instr source
248 const Type *DestTy = CI->getType();
250 // Peephole optimize the following instruction:
251 // %V2 = cast <ty> %V to <ty>
255 if (DestTy == Src->getType()) { // Check for a cast to same type as src!!
256 PRINT_PEEPHOLE1("cast-of-self-ty", CI);
257 CI->replaceAllUsesWith(Src);
258 if (!Src->hasName() && CI->hasName()) {
259 std::string Name = CI->getName();
261 Src->setName(Name, &BB->getParent()->getSymbolTable());
264 // DCE the instruction now, to avoid having the iterative version of DCE
265 // have to worry about it.
267 BI = BB->getInstList().erase(BI);
273 // Check to see if it's a cast of an instruction that does not depend on the
274 // specific type of the operands to do it's job.
275 if (!isReinterpretingCast(CI)) {
276 ValueTypeCache ConvertedTypes;
278 // Check to see if we can convert the source of the cast to match the
279 // destination type of the cast...
281 ConvertedTypes[CI] = CI->getType(); // Make sure the cast doesn't change
282 if (ExpressionConvertibleToType(Src, DestTy, ConvertedTypes, TD)) {
283 PRINT_PEEPHOLE3("CAST-SRC-EXPR-CONV:in ", Src, CI, BB->getParent());
285 DEBUG(std::cerr << "\nCONVERTING SRC EXPR TYPE:\n");
286 { // ValueMap must be destroyed before function verified!
287 ValueMapCache ValueMap;
288 Value *E = ConvertExpressionToType(Src, DestTy, ValueMap, TD);
290 if (Constant *CPV = dyn_cast<Constant>(E))
291 CI->replaceAllUsesWith(CPV);
293 PRINT_PEEPHOLE1("CAST-SRC-EXPR-CONV:out", E);
294 DEBUG(std::cerr << "DONE CONVERTING SRC EXPR TYPE: \n"
298 DEBUG(assert(verifyFunction(*BB->getParent()) == false &&
299 "Function broken!"));
300 BI = BB->begin(); // Rescan basic block. BI might be invalidated.
305 // Check to see if we can convert the users of the cast value to match the
306 // source type of the cast...
308 ConvertedTypes.clear();
309 // Make sure the source doesn't change type
310 ConvertedTypes[Src] = Src->getType();
311 if (ValueConvertibleToType(CI, Src->getType(), ConvertedTypes, TD)) {
312 PRINT_PEEPHOLE3("CAST-DEST-EXPR-CONV:in ", Src, CI, BB->getParent());
314 DEBUG(std::cerr << "\nCONVERTING EXPR TYPE:\n");
315 { // ValueMap must be destroyed before function verified!
316 ValueMapCache ValueMap;
317 ConvertValueToNewType(CI, Src, ValueMap, TD); // This will delete CI!
320 PRINT_PEEPHOLE1("CAST-DEST-EXPR-CONV:out", Src);
321 DEBUG(std::cerr << "DONE CONVERTING EXPR TYPE: \n\n" << BB->getParent());
323 DEBUG(assert(verifyFunction(*BB->getParent()) == false &&
324 "Function broken!"));
325 BI = BB->begin(); // Rescan basic block. BI might be invalidated.
331 // Otherwise find out it this cast is a cast to a pointer type, which is
332 // then added to some other pointer, then loaded or stored through. If
333 // so, convert the add into a getelementptr instruction...
335 if (const PointerType *DestPTy = dyn_cast<PointerType>(DestTy)) {
336 if (HandleCastToPointer(BI, DestPTy, TD)) {
337 BI = BB->begin(); // Rescan basic block. BI might be invalidated.
343 // Check to see if we are casting from a structure pointer to a pointer to
344 // the first element of the structure... to avoid munching other peepholes,
345 // we only let this happen if there are no add uses of the cast.
347 // Peephole optimize the following instructions:
348 // %t1 = cast {<...>} * %StructPtr to <ty> *
350 // Into: %t2 = getelementptr {<...>} * %StructPtr, <0, 0, 0, ...>
351 // %t1 = cast <eltype> * %t1 to <ty> *
353 if (const CompositeType *CTy = getPointedToComposite(Src->getType()))
354 if (const PointerType *DestPTy = dyn_cast<PointerType>(DestTy)) {
356 // Loop over uses of the cast, checking for add instructions. If an add
357 // exists, this is probably a part of a more complex GEP, so we don't
358 // want to mess around with the cast.
360 bool HasAddUse = false;
361 for (Value::use_iterator I = CI->use_begin(), E = CI->use_end();
363 if (isa<Instruction>(*I) &&
364 cast<Instruction>(*I)->getOpcode() == Instruction::Add) {
365 HasAddUse = true; break;
368 // If it doesn't have an add use, check to see if the dest type is
369 // losslessly convertible to one of the types in the start of the struct
373 const Type *DestPointedTy = DestPTy->getElementType();
375 const CompositeType *CurCTy = CTy;
376 const Type *ElTy = 0;
378 // Build the index vector, full of all zeros
379 std::vector<Value*> Indices;
380 Indices.push_back(ConstantSInt::get(Type::LongTy, 0));
381 while (CurCTy && !isa<PointerType>(CurCTy)) {
382 if (const StructType *CurSTy = dyn_cast<StructType>(CurCTy)) {
383 // Check for a zero element struct type... if we have one, bail.
384 if (CurSTy->getElementTypes().size() == 0) break;
386 // Grab the first element of the struct type, which must lie at
387 // offset zero in the struct.
389 ElTy = CurSTy->getElementTypes()[0];
391 ElTy = cast<ArrayType>(CurCTy)->getElementType();
394 // Insert a zero to index through this type...
395 Indices.push_back(Constant::getNullValue(CurCTy->getIndexType()));
397 // Did we find what we're looking for?
398 if (ElTy->isLosslesslyConvertibleTo(DestPointedTy)) break;
400 // Nope, go a level deeper.
402 CurCTy = dyn_cast<CompositeType>(ElTy);
406 // Did we find what we were looking for? If so, do the transformation
408 PRINT_PEEPHOLE1("cast-for-first:in", CI);
410 std::string Name = CI->getName(); CI->setName("");
412 // Insert the new T cast instruction... stealing old T's name
413 GetElementPtrInst *GEP = new GetElementPtrInst(Src, Indices,
416 // Make the old cast instruction reference the new GEP instead of
417 // the old src value.
419 CI->setOperand(0, GEP);
421 PRINT_PEEPHOLE2("cast-for-first:out", GEP, CI);
428 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
429 Value *Val = SI->getOperand(0);
430 Value *Pointer = SI->getPointerOperand();
432 // Peephole optimize the following instructions:
433 // %t = cast <T1>* %P to <T2> * ;; If T1 is losslessly convertible to T2
434 // store <T2> %V, <T2>* %t
437 // %t = cast <T2> %V to <T1>
438 // store <T1> %t2, <T1>* %P
440 // Note: This is not taken care of by expr conversion because there might
441 // not be a cast available for the store to convert the incoming value of.
442 // This code is basically here to make sure that pointers don't have casts
445 if (CastInst *CI = dyn_cast<CastInst>(Pointer))
446 if (Value *CastSrc = CI->getOperand(0)) // CSPT = CastSrcPointerType
447 if (const PointerType *CSPT = dyn_cast<PointerType>(CastSrc->getType()))
448 // convertible types?
449 if (Val->getType()->isLosslesslyConvertibleTo(CSPT->getElementType())) {
450 PRINT_PEEPHOLE3("st-src-cast:in ", Pointer, Val, SI);
452 // Insert the new T cast instruction... stealing old T's name
453 std::string Name(CI->getName()); CI->setName("");
454 CastInst *NCI = new CastInst(Val, CSPT->getElementType(),
457 // Replace the old store with a new one!
458 ReplaceInstWithInst(BB->getInstList(), BI,
459 SI = new StoreInst(NCI, CastSrc));
460 PRINT_PEEPHOLE3("st-src-cast:out", NCI, CastSrc, SI);
461 ++NumLoadStorePeepholes;
465 } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
466 Value *Pointer = LI->getOperand(0);
467 const Type *PtrElType =
468 cast<PointerType>(Pointer->getType())->getElementType();
470 // Peephole optimize the following instructions:
471 // %Val = cast <T1>* to <T2>* ;; If T1 is losslessly convertible to T2
472 // %t = load <T2>* %P
475 // %t = load <T1>* %P
476 // %Val = cast <T1> to <T2>
478 // Note: This is not taken care of by expr conversion because there might
479 // not be a cast available for the store to convert the incoming value of.
480 // This code is basically here to make sure that pointers don't have casts
483 if (CastInst *CI = dyn_cast<CastInst>(Pointer))
484 if (Value *CastSrc = CI->getOperand(0)) // CSPT = CastSrcPointerType
485 if (const PointerType *CSPT = dyn_cast<PointerType>(CastSrc->getType()))
486 // convertible types?
487 if (PtrElType->isLosslesslyConvertibleTo(CSPT->getElementType())) {
488 PRINT_PEEPHOLE2("load-src-cast:in ", Pointer, LI);
490 // Create the new load instruction... loading the pre-casted value
491 LoadInst *NewLI = new LoadInst(CastSrc, LI->getName(), BI);
493 // Insert the new T cast instruction... stealing old T's name
494 CastInst *NCI = new CastInst(NewLI, LI->getType(), CI->getName());
496 // Replace the old store with a new one!
497 ReplaceInstWithInst(BB->getInstList(), BI, NCI);
498 PRINT_PEEPHOLE3("load-src-cast:out", NCI, CastSrc, NewLI);
499 ++NumLoadStorePeepholes;
503 } else if (I->getOpcode() == Instruction::Add &&
504 isa<CastInst>(I->getOperand(1))) {
506 if (PeepholeOptimizeAddCast(BB, BI, I->getOperand(0),
507 cast<CastInst>(I->getOperand(1)), TD)) {
511 } else if (CallInst *CI = dyn_cast<CallInst>(I)) {
512 // If we have a call with all varargs arguments, convert the call to use the
513 // actual argument types present...
515 const PointerType *PTy = cast<PointerType>(CI->getCalledValue()->getType());
516 const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
518 // Is the call to a vararg variable with no real parameters?
519 if (FTy->isVarArg() && FTy->getNumParams() == 0 &&
520 !CI->getCalledFunction()) {
521 // If so, insert a new cast instruction, casting it to a function type
522 // that matches the current arguments...
524 std::vector<const Type *> Params; // Parameter types...
525 for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i)
526 Params.push_back(CI->getOperand(i)->getType());
528 FunctionType *NewFT = FunctionType::get(FTy->getReturnType(),
530 PointerType *NewPFunTy = PointerType::get(NewFT);
532 // Create a new cast, inserting it right before the function call...
534 Constant *ConstantCallSrc = 0;
535 if (Constant *CS = dyn_cast<Constant>(CI->getCalledValue()))
536 ConstantCallSrc = CS;
537 else if (GlobalValue *GV = dyn_cast<GlobalValue>(CI->getCalledValue()))
538 ConstantCallSrc = ConstantPointerRef::get(GV);
541 NewCast = ConstantExpr::getCast(ConstantCallSrc, NewPFunTy);
543 NewCast = new CastInst(CI->getCalledValue(), NewPFunTy,
544 CI->getCalledValue()->getName()+"_c",CI);
546 // Create a new call instruction...
547 CallInst *NewCall = new CallInst(NewCast,
548 std::vector<Value*>(CI->op_begin()+1, CI->op_end()));
550 ReplaceInstWithInst(CI, NewCall);
552 ++NumVarargCallChanges;
564 bool RPR::DoRaisePass(Function &F) {
565 bool Changed = false;
566 for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB)
567 for (BasicBlock::iterator BI = BB->begin(); BI != BB->end();) {
568 DEBUG(std::cerr << "Processing: " << *BI);
569 if (dceInstruction(BI) || doConstantPropagation(BI)) {
572 DEBUG(std::cerr << "***\t\t^^-- Dead code eliminated!\n");
573 } else if (PeepholeOptimize(BB, BI)) {
584 // runOnFunction - Raise a function representation to a higher level.
585 bool RPR::runOnFunction(Function &F) {
586 DEBUG(std::cerr << "\n\n\nStarting to work on Function '" << F.getName()
589 // Insert casts for all incoming pointer pointer values that are treated as
592 bool Changed = false, LocalChange;
594 // If the StartInst option was specified, then Peephole optimize that
595 // instruction first if it occurs in this function.
597 if (!StartInst.empty()) {
598 for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB)
599 for (BasicBlock::iterator BI = BB->begin(); BI != BB->end(); ++BI)
600 if (BI->getName() == StartInst) {
601 bool SavedDebug = DebugFlag; // Save the DEBUG() controlling flag.
602 DebugFlag = true; // Turn on DEBUG's
603 Changed |= PeepholeOptimize(BB, BI);
604 DebugFlag = SavedDebug; // Restore DebugFlag to previous state
609 DEBUG(std::cerr << "Looping: \n" << F);
611 // Iterate over the function, refining it, until it converges on a stable
614 while (DoRaisePass(F)) LocalChange = true;
615 Changed |= LocalChange;
617 } while (LocalChange);
622 } // End llvm namespace