1 //===- LevelRaise.cpp - Code to change LLVM to higher level -----------------=//
3 // This file implements the 'raising' part of the LevelChange API. This is
4 // useful because, in general, it makes the LLVM code terser and easier to
5 // analyze. Note that it is good to run DCE after doing this transformation.
7 // Eliminate silly things in the source that do not effect the level, but do
10 // - getelementptr/load & getelementptr/store are folded into a direct
12 // - Convert this code (for both alloca and malloc):
13 // %reg110 = shl uint %n, ubyte 2 ;;<uint>
14 // %reg108 = alloca ubyte, uint %reg110 ;;<ubyte*>
15 // %cast76 = cast ubyte* %reg108 to uint* ;;<uint*>
16 // To: %cast76 = alloca uint, uint %n
17 // Convert explicit addressing to use getelementptr instruction where possible
20 // Convert explicit addressing on pointers to use getelementptr instruction.
21 // - If a pointer is used by arithmetic operation, insert an array casted
22 // version into the source program, only for the following pointer types:
23 // * Method argument pointers
24 // - Pointers returned by alloca or malloc
25 // - Pointers returned by function calls
26 // - If a pointer is indexed with a value scaled by a constant size equal
27 // to the element size of the array, the expression is replaced with a
28 // getelementptr instruction.
30 //===----------------------------------------------------------------------===//
32 #include "llvm/Transforms/LevelChange.h"
33 #include "llvm/Method.h"
34 #include "llvm/Support/STLExtras.h"
35 #include "llvm/iOther.h"
36 #include "llvm/iMemory.h"
37 #include "llvm/ConstPoolVals.h"
38 #include "llvm/Target/TargetData.h"
39 #include "llvm/Optimizations/ConstantHandling.h"
40 #include "llvm/Optimizations/DCE.h"
44 #include "llvm/Assembly/Writer.h"
46 //#define DEBUG_PEEPHOLE_INSTS 1
48 #ifdef DEBUG_PEEPHOLE_INSTS
49 #define PRINT_PEEPHOLE(ID, NUM, I) \
50 cerr << "Inst P/H " << ID << "[" << NUM << "] " << I;
52 #define PRINT_PEEPHOLE(ID, NUM, I)
55 #define PRINT_PEEPHOLE1(ID, I1) do { PRINT_PEEPHOLE(ID, 0, I1); } while (0)
56 #define PRINT_PEEPHOLE2(ID, I1, I2) \
57 do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); } while (0)
58 #define PRINT_PEEPHOLE3(ID, I1, I2, I3) \
59 do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \
60 PRINT_PEEPHOLE(ID, 2, I3); } while (0)
63 // TargetData Hack: Eventually we will have annotations given to us by the
64 // backend so that we know stuff about type size and alignments. For now
65 // though, just use this, because it happens to match the model that GCC uses.
67 const TargetData TD("LevelRaise: Should be GCC though!");
70 // losslessCastableTypes - Return true if the types are bitwise equivalent.
71 // This predicate returns true if it is possible to cast from one type to
72 // another without gaining or losing precision, or altering the bits in any way.
74 static bool losslessCastableTypes(const Type *T1, const Type *T2) {
75 if (!T1->isPrimitiveType() && !isa<PointerType>(T1)) return false;
76 if (!T2->isPrimitiveType() && !isa<PointerType>(T2)) return false;
78 if (T1->getPrimitiveID() == T2->getPrimitiveID())
79 return true; // Handles identity cast, and cast of differing pointer types
81 // Now we know that they are two differing primitive or pointer types
82 switch (T1->getPrimitiveID()) {
83 case Type::UByteTyID: return T2 == Type::SByteTy;
84 case Type::SByteTyID: return T2 == Type::UByteTy;
85 case Type::UShortTyID: return T2 == Type::ShortTy;
86 case Type::ShortTyID: return T2 == Type::UShortTy;
87 case Type::UIntTyID: return T2 == Type::IntTy;
88 case Type::IntTyID: return T2 == Type::UIntTy;
91 case Type::PointerTyID:
92 return T2 == Type::ULongTy || T2 == Type::LongTy ||
93 T2->getPrimitiveID() == Type::PointerTyID;
95 return false; // Other types have no identity values
100 // isReinterpretingCast - Return true if the cast instruction specified will
101 // cause the operand to be "reinterpreted". A value is reinterpreted if the
102 // cast instruction would cause the underlying bits to change.
104 static inline bool isReinterpretingCast(const CastInst *CI) {
105 return !losslessCastableTypes(CI->getOperand(0)->getType(), CI->getType());
109 // getPointedToStruct - If the argument is a pointer type, and the pointed to
110 // value is a struct type, return the struct type, else return null.
112 static const StructType *getPointedToStruct(const Type *Ty) {
113 const PointerType *PT = dyn_cast<PointerType>(Ty);
114 return PT ? dyn_cast<StructType>(PT->getValueType()) : 0;
118 // getStructOffsetType - Return a vector of offsets that are to be used to index
119 // into the specified struct type to get as close as possible to index as we
120 // can. Note that it is possible that we cannot get exactly to Offset, in which
121 // case we update offset to be the offset we actually obtained. The resultant
122 // leaf type is returned.
124 static const Type *getStructOffsetType(const Type *Ty, unsigned &Offset,
125 vector<ConstPoolVal*> &Offsets) {
126 if (!isa<StructType>(Ty)) {
127 Offset = 0; // Return the offset that we were able to acheive
128 return Ty; // Return the leaf type
131 assert(Offset < TD.getTypeSize(Ty) && "Offset not in struct!");
132 const StructType *STy = cast<StructType>(Ty);
133 const StructLayout *SL = TD.getStructLayout(STy);
135 // This loop terminates always on a 0 <= i < MemberOffsets.size()
137 for (i = 0; i < SL->MemberOffsets.size()-1; ++i)
138 if (Offset >= SL->MemberOffsets[i] && Offset < SL->MemberOffsets[i+1])
141 assert(Offset >= SL->MemberOffsets[i] &&
142 (i == SL->MemberOffsets.size()-1 || Offset < SL->MemberOffsets[i+1]));
144 // Make sure to save the current index...
145 Offsets.push_back(ConstPoolUInt::get(Type::UByteTy, i));
147 unsigned SubOffs = Offset - SL->MemberOffsets[i];
148 const Type *LeafTy = getStructOffsetType(STy->getElementTypes()[i], SubOffs,
150 Offset = SL->MemberOffsets[i] + SubOffs;
156 // ReplaceInstWithValue - Replace all uses of an instruction (specified by BI)
157 // with a value, then remove and delete the original instruction.
159 static void ReplaceInstWithValue(BasicBlock::InstListType &BIL,
160 BasicBlock::iterator &BI, Value *V) {
161 Instruction *I = *BI;
162 // Replaces all of the uses of the instruction with uses of the value
163 I->replaceAllUsesWith(V);
165 // Remove the unneccesary instruction now...
168 // Make sure to propogate a name if there is one already...
169 if (I->hasName() && !V->hasName())
170 V->setName(I->getName(), BIL.getParent()->getSymbolTable());
172 // Remove the dead instruction now...
177 // ReplaceInstWithInst - Replace the instruction specified by BI with the
178 // instruction specified by I. The original instruction is deleted and BI is
179 // updated to point to the new instruction.
181 static void ReplaceInstWithInst(BasicBlock::InstListType &BIL,
182 BasicBlock::iterator &BI, Instruction *I) {
183 assert(I->getParent() == 0 &&
184 "ReplaceInstWithInst: Instruction already inserted into basic block!");
186 // Insert the new instruction into the basic block...
187 BI = BIL.insert(BI, I)+1;
189 // Replace all uses of the old instruction, and delete it.
190 ReplaceInstWithValue(BIL, BI, I);
192 // Reexamine the instruction just inserted next time around the cleanup pass
198 // ExpressionConvertableToType - Return true if it is possible
199 static bool ExpressionConvertableToType(Value *V, const Type *Ty) {
200 Instruction *I = dyn_cast<Instruction>(V);
202 // It's not an instruction, check to see if it's a constant... all constants
203 // can be converted to an equivalent value (except pointers, they can't be
204 // const prop'd in general).
206 if (isa<ConstPoolVal>(V) &&
207 !isa<PointerType>(V->getType()) && !isa<PointerType>(Ty)) return true;
209 return false; // Otherwise, we can't convert!
211 if (I->getType() == Ty) return false; // Expression already correct type!
213 switch (I->getOpcode()) {
214 case Instruction::Cast:
215 // We can convert the expr if the cast destination type is losslessly
216 // convertable to the requested type.
217 return losslessCastableTypes(Ty, I->getType());
219 case Instruction::Add:
220 case Instruction::Sub:
221 return ExpressionConvertableToType(I->getOperand(0), Ty) &&
222 ExpressionConvertableToType(I->getOperand(1), Ty);
223 case Instruction::Shl:
224 return ExpressionConvertableToType(I->getOperand(0), Ty);
225 case Instruction::Shr:
226 if (Ty->isSigned() != V->getType()->isSigned()) return false;
227 return ExpressionConvertableToType(I->getOperand(0), Ty);
229 case Instruction::Load: {
230 LoadInst *LI = cast<LoadInst>(I);
231 if (LI->hasIndices()) return false;
232 return ExpressionConvertableToType(LI->getPtrOperand(),
233 PointerType::get(Ty));
235 case Instruction::GetElementPtr: {
236 // GetElementPtr's are directly convertable to a pointer type if they have
237 // a number of zeros at the end. Because removing these values does not
238 // change the logical offset of the GEP, it is okay and fair to remove them.
239 // This can change this:
240 // %t1 = getelementptr %Hosp * %hosp, ubyte 4, ubyte 0 ; <%List **>
241 // %t2 = cast %List * * %t1 to %List *
243 // %t2 = getelementptr %Hosp * %hosp, ubyte 4 ; <%List *>
245 GetElementPtrInst *GEP = cast<GetElementPtrInst>(I);
246 const PointerType *PTy = dyn_cast<PointerType>(Ty);
247 if (!PTy) return false;
249 // Check to see if there are zero elements that we can remove from the
250 // index array. If there are, check to see if removing them causes us to
251 // get to the right type...
253 vector<ConstPoolVal*> Indices = GEP->getIndices();
254 const Type *BaseType = GEP->getPtrOperand()->getType();
256 while (Indices.size() &&
257 cast<ConstPoolUInt>(Indices.back())->getValue() == 0) {
259 const Type *ElTy = GetElementPtrInst::getIndexedType(BaseType, Indices,
261 if (ElTy == PTy->getValueType())
262 return true; // Found a match!!
264 break; // No match, maybe next time.
271 static Value *ConvertExpressionToType(Value *V, const Type *Ty) {
272 assert(ExpressionConvertableToType(V, Ty) && "Value is not convertable!");
273 Instruction *I = dyn_cast<Instruction>(V);
275 if (ConstPoolVal *CPV = cast<ConstPoolVal>(V)) {
276 // Constants are converted by constant folding the cast that is required.
277 // We assume here that all casts are implemented for constant prop.
278 Value *Result = opt::ConstantFoldCastInstruction(CPV, Ty);
279 if (!Result) cerr << "Couldn't fold " << CPV << " to " << Ty << endl;
280 assert(Result && "ConstantFoldCastInstruction Failed!!!");
285 BasicBlock *BB = I->getParent();
286 BasicBlock::InstListType &BIL = BB->getInstList();
287 string Name = I->getName(); if (!Name.empty()) I->setName("");
288 Instruction *Res; // Result of conversion
290 //cerr << endl << endl << "Type:\t" << Ty << "\nInst: " << I << "BB Before: " << BB << endl;
292 switch (I->getOpcode()) {
293 case Instruction::Cast:
294 Res = new CastInst(I->getOperand(0), Ty, Name);
297 case Instruction::Add:
298 case Instruction::Sub:
299 Res = BinaryOperator::create(cast<BinaryOperator>(I)->getOpcode(),
300 ConvertExpressionToType(I->getOperand(0), Ty),
301 ConvertExpressionToType(I->getOperand(1), Ty),
305 case Instruction::Shl:
306 case Instruction::Shr:
307 Res = new ShiftInst(cast<ShiftInst>(I)->getOpcode(),
308 ConvertExpressionToType(I->getOperand(0), Ty),
309 I->getOperand(1), Name);
312 case Instruction::Load: {
313 LoadInst *LI = cast<LoadInst>(I);
314 assert(!LI->hasIndices());
315 Res = new LoadInst(ConvertExpressionToType(LI->getPtrOperand(),
316 PointerType::get(Ty)), Name);
320 case Instruction::GetElementPtr: {
321 // GetElementPtr's are directly convertable to a pointer type if they have
322 // a number of zeros at the end. Because removing these values does not
323 // change the logical offset of the GEP, it is okay and fair to remove them.
324 // This can change this:
325 // %t1 = getelementptr %Hosp * %hosp, ubyte 4, ubyte 0 ; <%List **>
326 // %t2 = cast %List * * %t1 to %List *
328 // %t2 = getelementptr %Hosp * %hosp, ubyte 4 ; <%List *>
330 GetElementPtrInst *GEP = cast<GetElementPtrInst>(I);
332 // Check to see if there are zero elements that we can remove from the
333 // index array. If there are, check to see if removing them causes us to
334 // get to the right type...
336 vector<ConstPoolVal*> Indices = GEP->getIndices();
337 const Type *BaseType = GEP->getPtrOperand()->getType();
338 const Type *PVTy = cast<PointerType>(Ty)->getValueType();
340 while (Indices.size() &&
341 cast<ConstPoolUInt>(Indices.back())->getValue() == 0) {
343 if (GetElementPtrInst::getIndexedType(BaseType, Indices, true) == PVTy) {
344 if (Indices.size() == 0) {
345 Res = new CastInst(GEP->getPtrOperand(), BaseType); // NOOP
347 Res = new GetElementPtrInst(GEP->getPtrOperand(), Indices, Name);
352 assert(Res && "Didn't find match!");
353 break; // No match, maybe next time.
357 assert(0 && "Expression convertable, but don't know how to convert?");
361 BasicBlock::iterator It = find(BIL.begin(), BIL.end(), I);
362 assert(It != BIL.end() && "Instruction not in own basic block??");
365 //cerr << "RInst: " << Res << "BB After: " << BB << endl << endl;
372 // DoInsertArrayCast - If the argument value has a pointer type, and if the
373 // argument value is used as an array, insert a cast before the specified
374 // basic block iterator that casts the value to an array pointer. Return the
375 // new cast instruction (in the CastResult var), or null if no cast is inserted.
377 static bool DoInsertArrayCast(Method *CurMeth, Value *V, BasicBlock *BB,
378 BasicBlock::iterator &InsertBefore,
379 CastInst *&CastResult) {
380 const PointerType *ThePtrType = dyn_cast<PointerType>(V->getType());
381 if (!ThePtrType) return false;
382 bool InsertCast = false;
384 for (Value::use_iterator I = V->use_begin(), E = V->use_end(); I != E; ++I) {
385 Instruction *Inst = cast<Instruction>(*I);
386 switch (Inst->getOpcode()) {
387 default: break; // Not an interesting use...
388 case Instruction::Add: // It's being used as an array index!
389 //case Instruction::Sub:
392 case Instruction::Cast: // There is already a cast instruction!
393 if (const PointerType *PT = dyn_cast<const PointerType>(Inst->getType()))
394 if (const ArrayType *AT = dyn_cast<const ArrayType>(PT->getValueType()))
395 if (AT->getElementType() == ThePtrType->getValueType()) {
396 // Cast already exists! Return the existing one!
397 CastResult = cast<CastInst>(Inst);
398 return false; // No changes made to program though...
404 if (!InsertCast) return false; // There is no reason to insert a cast!
407 const Type *ElTy = ThePtrType->getValueType();
408 const PointerType *DestTy = PointerType::get(ArrayType::get(ElTy));
410 CastResult = new CastInst(V, DestTy);
411 BB->getInstList().insert(InsertBefore, CastResult);
412 //cerr << "Inserted cast: " << CastResult;
413 return true; // Made a change!
417 // DoInsertArrayCasts - Loop over all "incoming" values in the specified method,
418 // inserting a cast for pointer values that are used as arrays. For our
419 // purposes, an incoming value is considered to be either a value that is
420 // either a method parameter, a value created by alloca or malloc, or a value
421 // returned from a function call. All casts are kept attached to their original
422 // values through the PtrCasts map.
424 static bool DoInsertArrayCasts(Method *M, map<Value*, CastInst*> &PtrCasts) {
425 assert(!M->isExternal() && "Can't handle external methods!");
427 // Insert casts for all arguments to the function...
428 bool Changed = false;
429 BasicBlock *CurBB = M->front();
430 BasicBlock::iterator It = CurBB->begin();
431 for (Method::ArgumentListType::iterator AI = M->getArgumentList().begin(),
432 AE = M->getArgumentList().end(); AI != AE; ++AI) {
433 CastInst *TheCast = 0;
434 if (DoInsertArrayCast(M, *AI, CurBB, It, TheCast)) {
435 It = CurBB->begin(); // We might have just invalidated the iterator!
436 Changed = true; // Yes we made a change
437 ++It; // Insert next cast AFTER this one...
440 if (TheCast) // Is there a cast associated with this value?
441 PtrCasts[*AI] = TheCast; // Yes, add it to the map...
444 // TODO: insert casts for alloca, malloc, and function call results. Also,
445 // look for pointers that already have casts, to add to the map.
453 // DoElminatePointerArithmetic - Loop over each incoming pointer variable,
454 // replacing indexing arithmetic with getelementptr calls.
456 static bool DoEliminatePointerArithmetic(const pair<Value*, CastInst*> &Val) {
457 Value *V = Val.first; // The original pointer
458 CastInst *CV = Val.second; // The array casted version of the pointer...
460 for (Value::use_iterator I = V->use_begin(), E = V->use_end(); I != E; ++I) {
461 Instruction *Inst = cast<Instruction>(*I);
462 if (Inst->getOpcode() != Instruction::Add)
463 continue; // We only care about add instructions
465 BinaryOperator *Add = cast<BinaryOperator>(Inst);
467 // Make sure the array is the first operand of the add expression...
468 if (Add->getOperand(0) != V)
471 // Get the amount added to the pointer value...
472 Value *AddAmount = Add->getOperand(1);
480 // Peephole Malloc instructions: we take a look at the use chain of the
481 // malloc instruction, and try to find out if the following conditions hold:
482 // 1. The malloc is of the form: 'malloc [sbyte], uint <constant>'
483 // 2. The only users of the malloc are cast instructions
484 // 3. Of the cast instructions, there is only one destination pointer type
485 // [RTy] where the size of the pointed to object is equal to the number
486 // of bytes allocated.
488 // If these conditions hold, we convert the malloc to allocate an [RTy]
489 // element. This should be extended in the future to handle arrays. TODO
491 static bool PeepholeMallocInst(BasicBlock *BB, BasicBlock::iterator &BI) {
492 MallocInst *MI = cast<MallocInst>(*BI);
493 if (!MI->isArrayAllocation()) return false; // No array allocation?
495 ConstPoolUInt *Amt = dyn_cast<ConstPoolUInt>(MI->getArraySize());
496 if (Amt == 0 || MI->getAllocatedType() != ArrayType::get(Type::SByteTy))
499 // Get the number of bytes allocated...
500 unsigned Size = Amt->getValue();
501 const Type *ResultTy = 0;
503 // Loop over all of the uses of the malloc instruction, inspecting casts.
504 for (Value::use_iterator I = MI->use_begin(), E = MI->use_end();
506 if (!isa<CastInst>(*I)) {
507 //cerr << "\tnon" << *I;
508 return false; // A non cast user?
510 CastInst *CI = cast<CastInst>(*I);
511 //cerr << "\t" << CI;
513 // We only work on casts to pointer types for sure, be conservative
514 if (!isa<PointerType>(CI->getType())) {
515 cerr << "Found cast of malloc value to non pointer type:\n" << CI;
519 const Type *DestTy = cast<PointerType>(CI->getType())->getValueType();
520 if (TD.getTypeSize(DestTy) == Size && DestTy != ResultTy) {
521 // Does the size of the allocated type match the number of bytes
525 ResultTy = DestTy; // Keep note of this for future uses...
527 // It's overdefined! We don't know which type to convert to!
533 // If we get this far, we have either found, or not, a type that is cast to
534 // that is of the same size as the malloc instruction.
535 if (!ResultTy) return false;
537 PRINT_PEEPHOLE1("mall-refine:in ", MI);
538 ReplaceInstWithInst(BB->getInstList(), BI,
539 MI = new MallocInst(PointerType::get(ResultTy)));
540 PRINT_PEEPHOLE1("mall-refine:out", MI);
545 // Peephole optimize the following instructions:
546 // %t1 = cast int (uint) * %reg111 to uint (...) *
547 // %t2 = call uint (...) * %cast111( uint %key )
549 // Into: %t3 = call int (uint) * %reg111( uint %key )
550 // %t2 = cast int %t3 to uint
552 static bool PeepholeCallInst(BasicBlock *BB, BasicBlock::iterator &BI) {
553 CallInst *CI = cast<CallInst>(*BI);
558 static bool PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI) {
559 Instruction *I = *BI;
561 if (CastInst *CI = dyn_cast<CastInst>(I)) {
562 Value *Src = CI->getOperand(0);
563 Instruction *SrcI = dyn_cast<Instruction>(Src); // Nonnull if instr source
564 const Type *DestTy = CI->getType();
566 // Peephole optimize the following instruction:
567 // %V2 = cast <ty> %V to <ty>
571 if (DestTy == Src->getType()) { // Check for a cast to same type as src!!
572 PRINT_PEEPHOLE1("cast-of-self-ty", CI);
573 CI->replaceAllUsesWith(Src);
574 if (!Src->hasName() && CI->hasName()) {
575 string Name = CI->getName();
576 CI->setName(""); Src->setName(Name,
577 BB->getParent()->getSymbolTable());
582 // Peephole optimize the following instructions:
583 // %tmp = cast <ty> %V to <ty2>
584 // %V = cast <ty2> %tmp to <ty3> ; Where ty & ty2 are same size
586 // Into: cast <ty> %V to <ty3>
589 if (CastInst *CSrc = dyn_cast<CastInst>(SrcI))
590 if (isReinterpretingCast(CI) + isReinterpretingCast(CSrc) < 2) {
591 // We can only do c-c elimination if, at most, one cast does a
592 // reinterpretation of the input data.
594 // If legal, make this cast refer the the original casts argument!
596 PRINT_PEEPHOLE2("cast-cast:in ", CI, CSrc);
597 CI->setOperand(0, CSrc->getOperand(0));
598 PRINT_PEEPHOLE1("cast-cast:out", CI);
602 // Check to see if it's a cast of an instruction that does not depend on the
603 // specific type of the operands to do it's job.
604 if (!isReinterpretingCast(CI) &&
605 ExpressionConvertableToType(Src, DestTy)) {
606 PRINT_PEEPHOLE2("EXPR-CONV:in ", CI, Src);
607 CI->setOperand(0, ConvertExpressionToType(Src, DestTy));
608 BI = BB->begin(); // Rescan basic block. BI might be invalidated.
609 PRINT_PEEPHOLE2("EXPR-CONV:out", CI, CI->getOperand(0));
613 // Check to see if we are casting from a structure pointer to a pointer to
614 // the first element of the structure... to avoid munching other peepholes,
615 // we only let this happen if there are no add uses of the cast.
617 // Peephole optimize the following instructions:
618 // %t1 = cast {<...>} * %StructPtr to <ty> *
620 // Into: %t2 = getelementptr {<...>} * %StructPtr, <0, 0, 0, ...>
621 // %t1 = cast <eltype> * %t1 to <ty> *
623 if (const StructType *STy = getPointedToStruct(Src->getType()))
624 if (const PointerType *DestPTy = dyn_cast<PointerType>(DestTy)) {
626 // Loop over uses of the cast, checking for add instructions. If an add
627 // exists, this is probably a part of a more complex GEP, so we don't
628 // want to mess around with the cast.
630 bool HasAddUse = false;
631 for (Value::use_iterator I = CI->use_begin(), E = CI->use_end();
633 if (isa<Instruction>(*I) &&
634 cast<Instruction>(*I)->getOpcode() == Instruction::Add) {
635 HasAddUse = true; break;
638 // If it doesn't have an add use, check to see if the dest type is
639 // losslessly convertable to one of the types in the start of the struct
643 const Type *DestPointedTy = DestPTy->getValueType();
645 const StructType *CurSTy = STy;
646 const Type *ElTy = 0;
649 // Check for a zero element struct type... if we have one, bail.
650 if (CurSTy->getElementTypes().size() == 0) break;
652 // Grab the first element of the struct type, which must lie at
653 // offset zero in the struct.
655 ElTy = CurSTy->getElementTypes()[0];
657 // Did we find what we're looking for?
658 if (losslessCastableTypes(ElTy, DestPointedTy)) break;
660 // Nope, go a level deeper.
662 CurSTy = dyn_cast<StructType>(ElTy);
666 // Did we find what we were looking for? If so, do the transformation
668 PRINT_PEEPHOLE1("cast-for-first:in", CI);
670 // Build the index vector, full of all zeros
671 vector<ConstPoolVal *> Indices(Depth,
672 ConstPoolUInt::get(Type::UByteTy,0));
674 // Insert the new T cast instruction... stealing old T's name
675 GetElementPtrInst *GEP = new GetElementPtrInst(Src, Indices,
678 BI = BB->getInstList().insert(BI, GEP)+1;
680 // Make the old cast instruction reference the new GEP instead of
681 // the old src value.
683 CI->setOperand(0, GEP);
685 PRINT_PEEPHOLE2("cast-for-first:out", GEP, CI);
692 } else if (MallocInst *MI = dyn_cast<MallocInst>(I)) {
693 if (PeepholeMallocInst(BB, BI)) return true;
695 } else if (CallInst *CI = dyn_cast<CallInst>(I)) {
696 if (PeepholeCallInst(BB, BI)) return true;
698 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
699 Value *Val = SI->getOperand(0);
700 Value *Pointer = SI->getPtrOperand();
702 // Peephole optimize the following instructions:
703 // %t1 = getelementptr {<...>} * %StructPtr, <element indices>
704 // store <elementty> %v, <elementty> * %t1
706 // Into: store <elementty> %v, {<...>} * %StructPtr, <element indices>
708 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Pointer)) {
709 PRINT_PEEPHOLE2("gep-store:in", GEP, SI);
710 ReplaceInstWithInst(BB->getInstList(), BI,
711 SI = new StoreInst(Val, GEP->getPtrOperand(),
713 PRINT_PEEPHOLE1("gep-store:out", SI);
717 // Peephole optimize the following instructions:
718 // %t = cast <T1>* %P to <T2> * ;; If T1 is losslessly convertable to T2
719 // store <T2> %V, <T2>* %t
722 // %t = cast <T2> %V to <T1>
723 // store <T1> %t2, <T1>* %P
725 if (CastInst *CI = dyn_cast<CastInst>(Pointer))
726 if (Value *CastSrc = CI->getOperand(0)) // CSPT = CastSrcPointerType
727 if (PointerType *CSPT = dyn_cast<PointerType>(CastSrc->getType()))
728 if (losslessCastableTypes(Val->getType(), // convertable types!
729 CSPT->getValueType()) &&
730 !SI->hasIndices()) { // No subscripts yet!
731 PRINT_PEEPHOLE3("st-src-cast:in ", Pointer, Val, SI);
733 // Insert the new T cast instruction... stealing old T's name
734 CastInst *NCI = new CastInst(Val, CSPT->getValueType(),
737 BI = BB->getInstList().insert(BI, NCI)+1;
739 // Replace the old store with a new one!
740 ReplaceInstWithInst(BB->getInstList(), BI,
741 SI = new StoreInst(NCI, CastSrc));
742 PRINT_PEEPHOLE3("st-src-cast:out", NCI, CastSrc, SI);
747 } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
748 Value *Pointer = LI->getPtrOperand();
750 // Peephole optimize the following instructions:
751 // %t1 = getelementptr {<...>} * %StructPtr, <element indices>
752 // %V = load <elementty> * %t1
754 // Into: load {<...>} * %StructPtr, <element indices>
756 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Pointer)) {
757 PRINT_PEEPHOLE2("gep-load:in", GEP, LI);
758 ReplaceInstWithInst(BB->getInstList(), BI,
759 LI = new LoadInst(GEP->getPtrOperand(),
761 PRINT_PEEPHOLE1("gep-load:out", LI);
764 } else if (I->getOpcode() == Instruction::Add &&
765 isa<CastInst>(I->getOperand(1))) {
767 // Peephole optimize the following instructions:
768 // %t1 = cast ulong <const int> to {<...>} *
769 // %t2 = add {<...>} * %SP, %t1 ;; Constant must be 2nd operand
772 // %t1 = cast {<...>}* %SP to int*
773 // %t5 = cast ulong <const int> to int*
774 // %t2 = add int* %t1, %t5 ;; int is same size as field
776 // Into: %t3 = getelementptr {<...>} * %SP, <element indices>
777 // %t2 = cast <eltype> * %t3 to {<...>}*
779 Value *AddOp1 = I->getOperand(0);
780 CastInst *AddOp2 = cast<CastInst>(I->getOperand(1));
781 ConstPoolUInt *OffsetV = dyn_cast<ConstPoolUInt>(AddOp2->getOperand(0));
782 unsigned Offset = OffsetV ? OffsetV->getValue() : 0;
783 Value *SrcPtr; // Of type pointer to struct...
784 const StructType *StructTy;
786 if ((StructTy = getPointedToStruct(AddOp1->getType()))) {
787 SrcPtr = AddOp1; // Handle the first case...
788 } else if (CastInst *AddOp1c = dyn_cast<CastInst>(AddOp1)) {
789 SrcPtr = AddOp1c->getOperand(0); // Handle the second case...
790 StructTy = getPointedToStruct(SrcPtr->getType());
793 // Only proceed if we have detected all of our conditions successfully...
794 if (Offset && StructTy && SrcPtr && Offset < TD.getTypeSize(StructTy)) {
795 const StructLayout *SL = TD.getStructLayout(StructTy);
796 vector<ConstPoolVal*> Offsets;
797 unsigned ActualOffset = Offset;
798 const Type *ElTy = getStructOffsetType(StructTy, ActualOffset, Offsets);
800 if (getPointedToStruct(AddOp1->getType())) { // case 1
801 PRINT_PEEPHOLE2("add-to-gep1:in", AddOp2, I);
803 PRINT_PEEPHOLE3("add-to-gep2:in", AddOp1, AddOp2, I);
806 GetElementPtrInst *GEP = new GetElementPtrInst(SrcPtr, Offsets);
807 BI = BB->getInstList().insert(BI, GEP)+1;
809 assert(Offset-ActualOffset == 0 &&
810 "GEP to middle of element not implemented yet!");
812 ReplaceInstWithInst(BB->getInstList(), BI,
813 I = new CastInst(GEP, I->getType()));
814 PRINT_PEEPHOLE2("add-to-gep:out", GEP, I);
825 static bool DoRaisePass(Method *M) {
826 bool Changed = false;
827 for (Method::iterator MI = M->begin(), ME = M->end(); MI != ME; ++MI) {
828 BasicBlock *BB = *MI;
829 BasicBlock::InstListType &BIL = BB->getInstList();
831 for (BasicBlock::iterator BI = BB->begin(); BI != BB->end();) {
832 if (opt::DeadCodeElimination::dceInstruction(BIL, BI) ||
833 PeepholeOptimize(BB, BI))
843 // RaisePointerReferences::doit - Raise a method representation to a higher
846 bool RaisePointerReferences::doit(Method *M) {
847 if (M->isExternal()) return false;
848 bool Changed = false;
850 #ifdef DEBUG_PEEPHOLE_INSTS
851 cerr << "\n\n\nStarting to work on Method '" << M->getName() << "'\n";
854 while (DoRaisePass(M)) Changed = true;
856 // PtrCasts - Keep a mapping between the pointer values (the key of the
857 // map), and the cast to array pointer (the value) in this map. This is
858 // used when converting pointer math into array addressing.
860 map<Value*, CastInst*> PtrCasts;
862 // Insert casts for all incoming pointer values. Keep track of those casts
863 // and the identified incoming values in the PtrCasts map.
865 Changed |= DoInsertArrayCasts(M, PtrCasts);
867 // Loop over each incoming pointer variable, replacing indexing arithmetic
868 // with getelementptr calls.
870 Changed |= reduce_apply_bool(PtrCasts.begin(), PtrCasts.end(),
871 ptr_fun(DoEliminatePointerArithmetic));