| //===- LevelRaise.cpp - Code to change LLVM to higher level -----------------=// |
| // |
| // This file implements the 'raising' part of the LevelChange API. This is |
| // useful because, in general, it makes the LLVM code terser and easier to |
| // analyze. Note that it is good to run DCE after doing this transformation. |
| // |
| // Eliminate silly things in the source that do not effect the level, but do |
| // clean up the code: |
| // * Casts of casts |
| // - getelementptr/load & getelementptr/store are folded into a direct |
| // load or store |
| // - Convert this code (for both alloca and malloc): |
| // %reg110 = shl uint %n, ubyte 2 ;;<uint> |
| // %reg108 = alloca ubyte, uint %reg110 ;;<ubyte*> |
| // %cast76 = cast ubyte* %reg108 to uint* ;;<uint*> |
| // To: %cast76 = alloca uint, uint %n |
| // Convert explicit addressing to use getelementptr instruction where possible |
| // - ... |
| // |
| // Convert explicit addressing on pointers to use getelementptr instruction. |
| // - If a pointer is used by arithmetic operation, insert an array casted |
| // version into the source program, only for the following pointer types: |
| // * Method argument pointers |
| // - Pointers returned by alloca or malloc |
| // - Pointers returned by function calls |
| // - If a pointer is indexed with a value scaled by a constant size equal |
| // to the element size of the array, the expression is replaced with a |
| // getelementptr instruction. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Transforms/LevelChange.h" |
| #include "TransformInternals.h" |
| #include "llvm/Method.h" |
| #include "llvm/Support/STLExtras.h" |
| #include "llvm/iOther.h" |
| #include "llvm/iMemory.h" |
| #include "llvm/ConstPoolVals.h" |
| #include "llvm/Optimizations/ConstantHandling.h" |
| #include "llvm/Optimizations/DCE.h" |
| #include "llvm/Analysis/Expressions.h" |
| #include <algorithm> |
| |
| #include "llvm/Assembly/Writer.h" |
| |
| //#define DEBUG_PEEPHOLE_INSTS 1 |
| |
| #ifdef DEBUG_PEEPHOLE_INSTS |
| #define PRINT_PEEPHOLE(ID, NUM, I) \ |
| cerr << "Inst P/H " << ID << "[" << NUM << "] " << I; |
| #else |
| #define PRINT_PEEPHOLE(ID, NUM, I) |
| #endif |
| |
| #define PRINT_PEEPHOLE1(ID, I1) do { PRINT_PEEPHOLE(ID, 0, I1); } while (0) |
| #define PRINT_PEEPHOLE2(ID, I1, I2) \ |
| do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); } while (0) |
| #define PRINT_PEEPHOLE3(ID, I1, I2, I3) \ |
| do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \ |
| PRINT_PEEPHOLE(ID, 2, I3); } while (0) |
| #define PRINT_PEEPHOLE4(ID, I1, I2, I3, I4) \ |
| do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \ |
| PRINT_PEEPHOLE(ID, 2, I3); PRINT_PEEPHOLE(ID, 3, I4); } while (0) |
| |
| |
| // isReinterpretingCast - Return true if the cast instruction specified will |
| // cause the operand to be "reinterpreted". A value is reinterpreted if the |
| // cast instruction would cause the underlying bits to change. |
| // |
| static inline bool isReinterpretingCast(const CastInst *CI) { |
| return !losslessCastableTypes(CI->getOperand(0)->getType(), CI->getType()); |
| } |
| |
| |
| |
| |
| // DoInsertArrayCast - If the argument value has a pointer type, and if the |
| // argument value is used as an array, insert a cast before the specified |
| // basic block iterator that casts the value to an array pointer. Return the |
| // new cast instruction (in the CastResult var), or null if no cast is inserted. |
| // |
| static bool DoInsertArrayCast(Method *CurMeth, Value *V, BasicBlock *BB, |
| BasicBlock::iterator &InsertBefore, |
| CastInst *&CastResult) { |
| const PointerType *ThePtrType = dyn_cast<PointerType>(V->getType()); |
| if (!ThePtrType) return false; |
| bool InsertCast = false; |
| |
| for (Value::use_iterator I = V->use_begin(), E = V->use_end(); I != E; ++I) { |
| Instruction *Inst = cast<Instruction>(*I); |
| switch (Inst->getOpcode()) { |
| default: break; // Not an interesting use... |
| case Instruction::Add: // It's being used as an array index! |
| //case Instruction::Sub: |
| InsertCast = true; |
| break; |
| case Instruction::Cast: // There is already a cast instruction! |
| if (const PointerType *PT = dyn_cast<const PointerType>(Inst->getType())) |
| if (const ArrayType *AT = dyn_cast<const ArrayType>(PT->getValueType())) |
| if (AT->getElementType() == ThePtrType->getValueType()) { |
| // Cast already exists! Return the existing one! |
| CastResult = cast<CastInst>(Inst); |
| return false; // No changes made to program though... |
| } |
| break; |
| } |
| } |
| |
| if (!InsertCast) return false; // There is no reason to insert a cast! |
| |
| // Insert a cast! |
| const Type *ElTy = ThePtrType->getValueType(); |
| const PointerType *DestTy = PointerType::get(ArrayType::get(ElTy)); |
| |
| CastResult = new CastInst(V, DestTy); |
| BB->getInstList().insert(InsertBefore, CastResult); |
| //cerr << "Inserted cast: " << CastResult; |
| return true; // Made a change! |
| } |
| |
| |
| // DoInsertArrayCasts - Loop over all "incoming" values in the specified method, |
| // inserting a cast for pointer values that are used as arrays. For our |
| // purposes, an incoming value is considered to be either a value that is |
| // either a method parameter, a value created by alloca or malloc, or a value |
| // returned from a function call. All casts are kept attached to their original |
| // values through the PtrCasts map. |
| // |
| static bool DoInsertArrayCasts(Method *M, map<Value*, CastInst*> &PtrCasts) { |
| assert(!M->isExternal() && "Can't handle external methods!"); |
| |
| // Insert casts for all arguments to the function... |
| bool Changed = false; |
| BasicBlock *CurBB = M->front(); |
| BasicBlock::iterator It = CurBB->begin(); |
| for (Method::ArgumentListType::iterator AI = M->getArgumentList().begin(), |
| AE = M->getArgumentList().end(); AI != AE; ++AI) { |
| CastInst *TheCast = 0; |
| if (DoInsertArrayCast(M, *AI, CurBB, It, TheCast)) { |
| It = CurBB->begin(); // We might have just invalidated the iterator! |
| Changed = true; // Yes we made a change |
| ++It; // Insert next cast AFTER this one... |
| } |
| |
| if (TheCast) // Is there a cast associated with this value? |
| PtrCasts[*AI] = TheCast; // Yes, add it to the map... |
| } |
| |
| // TODO: insert casts for alloca, malloc, and function call results. Also, |
| // look for pointers that already have casts, to add to the map. |
| |
| return Changed; |
| } |
| |
| |
| |
| |
| // DoElminatePointerArithmetic - Loop over each incoming pointer variable, |
| // replacing indexing arithmetic with getelementptr calls. |
| // |
| static bool DoEliminatePointerArithmetic(const pair<Value*, CastInst*> &Val) { |
| Value *V = Val.first; // The original pointer |
| CastInst *CV = Val.second; // The array casted version of the pointer... |
| |
| for (Value::use_iterator I = V->use_begin(), E = V->use_end(); I != E; ++I) { |
| Instruction *Inst = cast<Instruction>(*I); |
| if (Inst->getOpcode() != Instruction::Add) |
| continue; // We only care about add instructions |
| |
| BinaryOperator *Add = cast<BinaryOperator>(Inst); |
| |
| // Make sure the array is the first operand of the add expression... |
| if (Add->getOperand(0) != V) |
| Add->swapOperands(); |
| |
| // Get the amount added to the pointer value... |
| Value *AddAmount = Add->getOperand(1); |
| |
| |
| } |
| return false; |
| } |
| |
| |
| // Peephole Malloc instructions: we take a look at the use chain of the |
| // malloc instruction, and try to find out if the following conditions hold: |
| // 1. The malloc is of the form: 'malloc [sbyte], uint <constant>' |
| // 2. The only users of the malloc are cast & add instructions |
| // 3. Of the cast instructions, there is only one destination pointer type |
| // [RTy] where the size of the pointed to object is equal to the number |
| // of bytes allocated. |
| // |
| // If these conditions hold, we convert the malloc to allocate an [RTy] |
| // element. This should be extended in the future to handle arrays. TODO |
| // |
| static bool PeepholeMallocInst(BasicBlock *BB, BasicBlock::iterator &BI) { |
| MallocInst *MI = cast<MallocInst>(*BI); |
| if (!MI->isArrayAllocation()) return false; // No array allocation? |
| |
| ConstPoolUInt *Amt = dyn_cast<ConstPoolUInt>(MI->getArraySize()); |
| if (Amt == 0 || MI->getAllocatedType() != ArrayType::get(Type::SByteTy)) |
| return false; |
| |
| // Get the number of bytes allocated... |
| unsigned Size = Amt->getValue(); |
| const Type *ResultTy = 0; |
| |
| // Loop over all of the uses of the malloc instruction, inspecting casts. |
| for (Value::use_iterator I = MI->use_begin(), E = MI->use_end(); |
| I != E; ++I) { |
| if (CastInst *CI = dyn_cast<CastInst>(*I)) { |
| //cerr << "\t" << CI; |
| |
| // We only work on casts to pointer types for sure, be conservative |
| if (!isa<PointerType>(CI->getType())) { |
| cerr << "Found cast of malloc value to non pointer type:\n" << CI; |
| return false; |
| } |
| |
| const Type *DestTy = cast<PointerType>(CI->getType())->getValueType(); |
| if (isa<ArrayType>(DestTy)) { |
| cerr << "Avoided malloc conversion because of type: " << DestTy |
| << " TODO.\n"; |
| return false; |
| } |
| if (TD.getTypeSize(DestTy) == Size && DestTy != ResultTy) { |
| // Does the size of the allocated type match the number of bytes |
| // allocated? |
| // |
| if (ResultTy == 0) { |
| ResultTy = DestTy; // Keep note of this for future uses... |
| } else { |
| // It's overdefined! We don't know which type to convert to! |
| return false; |
| } |
| } |
| } |
| } |
| |
| // If we get this far, we have either found, or not, a type that is cast to |
| // that is of the same size as the malloc instruction. |
| if (!ResultTy) return false; |
| |
| // Now we check to see if we can convert the return value of malloc to the |
| // specified pointer type. All this is moot if we can't. |
| // |
| ValueTypeCache ConvertedTypes; |
| if (RetValConvertableToType(MI, PointerType::get(ResultTy), ConvertedTypes)) { |
| // Yup, it's convertable, do the transformation now! |
| PRINT_PEEPHOLE1("mall-refine:in ", MI); |
| |
| // Create a new malloc instruction, and insert it into the method... |
| MallocInst *NewMI = new MallocInst(PointerType::get(ResultTy)); |
| NewMI->setName(MI->getName()); |
| MI->setName(""); |
| BI = BB->getInstList().insert(BI, NewMI)+1; |
| |
| // Create a new cast instruction to cast it to the old type... |
| CastInst *NewCI = new CastInst(NewMI, MI->getType()); |
| BB->getInstList().insert(BI, NewCI); |
| |
| // Move all users of the old malloc instruction over to use the new cast... |
| MI->replaceAllUsesWith(NewCI); |
| |
| ValueMapCache ValueMap; |
| ConvertUsersType(NewCI, NewMI, ValueMap); // This will delete MI! |
| |
| BI = BB->begin(); // Rescan basic block. BI might be invalidated. |
| PRINT_PEEPHOLE1("mall-refine:out", NewMI); |
| return true; |
| } |
| return false; |
| } |
| |
| |
| |
| // Peephole optimize the following instructions: |
| // %t1 = cast ulong <const int> to {<...>} * |
| // %t2 = add {<...>} * %SP, %t1 ;; Constant must be 2nd operand |
| // |
| // or |
| // %t1 = cast {<...>}* %SP to int* |
| // %t5 = cast ulong <const int> to int* |
| // %t2 = add int* %t1, %t5 ;; int is same size as field |
| // |
| // Into: %t3 = getelementptr {<...>} * %SP, <element indices> |
| // %t2 = cast <eltype> * %t3 to {<...>}* |
| // |
| static bool PeepholeOptimizeAddCast(BasicBlock *BB, BasicBlock::iterator &BI, |
| Value *AddOp1, CastInst *AddOp2) { |
| Value *OffsetVal = AddOp2->getOperand(0); |
| Value *SrcPtr; // Of type pointer to struct... |
| const StructType *StructTy; |
| |
| if ((StructTy = getPointedToStruct(AddOp1->getType()))) { |
| SrcPtr = AddOp1; // Handle the first case... |
| } else if (CastInst *AddOp1c = dyn_cast<CastInst>(AddOp1)) { |
| SrcPtr = AddOp1c->getOperand(0); // Handle the second case... |
| StructTy = getPointedToStruct(SrcPtr->getType()); |
| } |
| |
| // Only proceed if we have detected all of our conditions successfully... |
| if (!StructTy || !SrcPtr || !OffsetVal->getType()->isIntegral()) |
| return false; |
| |
| // See if the cast is of an integer expression that is either a constant, |
| // or a value scaled by some amount with a possible offset. |
| // |
| analysis::ExprType Expr = analysis::ClassifyExpression(OffsetVal); |
| unsigned Offset = 0, Scale = 1; |
| |
| // The expression must either be a constant, or a scaled index to be useful |
| if (!Expr.Offset && !Expr.Scale) |
| return false; |
| |
| // Get the offset value if it exists... |
| if (Expr.Offset) { |
| if (ConstPoolSInt *CPSI = dyn_cast<ConstPoolSInt>(Expr.Offset)) |
| Offset = (unsigned)CPSI->getValue(); |
| else { |
| ConstPoolUInt *CPUI = cast<ConstPoolUInt>(Expr.Offset); |
| Offset = (unsigned)CPUI->getValue(); |
| } |
| assert(Offset != 0 && "Expression analysis failure!"); |
| } |
| |
| // Get the scale value if it exists... |
| if (Expr.Scale) { |
| if (ConstPoolSInt *CPSI = dyn_cast<ConstPoolSInt>(Expr.Scale)) |
| Scale = (unsigned)CPSI->getValue(); |
| else { |
| ConstPoolUInt *CPUI = cast<ConstPoolUInt>(Expr.Scale); |
| Scale = (unsigned)CPUI->getValue(); |
| } |
| assert(Scale != 1 && "Expression analysis failure!"); |
| } |
| |
| // Check to make sure the offset is not negative or really large, outside the |
| // scope of this structure... |
| // |
| if (Offset >= TD.getTypeSize(StructTy)) |
| return false; |
| |
| const StructLayout *SL = TD.getStructLayout(StructTy); |
| vector<ConstPoolVal*> Offsets; |
| unsigned ActualOffset = Offset; |
| const Type *ElTy = getStructOffsetType(StructTy, ActualOffset, Offsets); |
| |
| if (getPointedToStruct(AddOp1->getType())) { // case 1 |
| PRINT_PEEPHOLE2("add-to-gep1:in", AddOp2, *BI); |
| } else { |
| PRINT_PEEPHOLE3("add-to-gep2:in", AddOp1, AddOp2, *BI); |
| } |
| |
| GetElementPtrInst *GEP = new GetElementPtrInst(SrcPtr, Offsets); |
| //AddOp2->getName()); |
| BI = BB->getInstList().insert(BI, GEP)+1; |
| |
| Instruction *AddrSrc = GEP; |
| |
| if (const ArrayType *AT = dyn_cast<ArrayType>(ElTy)) { |
| assert((Scale == 1 || Offset == ActualOffset) && |
| "Cannot handle scaled expression and unused offset in the same " |
| "instruction until after GEP array works!"); |
| |
| // Check to see if we have bottomed out INSIDE of an array reference.. |
| // |
| if (Offset != ActualOffset) { |
| // Insert a cast of the "rest" of the offset to the appropriate |
| // pointer type. |
| CastInst *OffInst = |
| new CastInst(ConstPoolUInt::get(Type::ULongTy, |
| Offset-ActualOffset), |
| GEP->getType()); |
| BI = BB->getInstList().insert(BI, OffInst)+1; |
| |
| // Now insert an ADD to actually adjust the pointer... |
| Instruction *AddInst = |
| BinaryOperator::create(Instruction::Add, GEP, OffInst); |
| BI = BB->getInstList().insert(BI, AddInst)+1; |
| |
| PRINT_PEEPHOLE2("add-to-gep:out1", OffInst, AddInst); |
| |
| AddrSrc = AddInst; |
| } else if (Scale != 1) { |
| // If the scale factor occurs, then this means that there is an index into |
| // this element of the array. Check to make sure the scale factor is the |
| // same as the size of the datatype that we are dealing with. |
| // |
| assert(Scale == TD.getTypeSize(AT->getElementType()) && |
| "Scaling by something other than the array element size!!"); |
| |
| // TODO: In the future, we will not want to cast the index and scale to |
| // pointer types first. We will want to create a GEP directly here. |
| |
| // Now we must actually perform the scaling operation to get an |
| // appropriate value to add in... but the scale has to be done in the |
| // appropriate destination pointer type, so cast the index value now. |
| // |
| // Cast the base index pointer |
| CastInst *IdxValue = new CastInst(Expr.Var, GEP->getType()); |
| BI = BB->getInstList().insert(BI, IdxValue)+1; |
| |
| // Case the scale amount as well... |
| CastInst *ScaleAmt = |
| new CastInst(ConstPoolUInt::get(Type::ULongTy, Scale), GEP->getType()); |
| BI = BB->getInstList().insert(BI, ScaleAmt)+1; |
| |
| // Insert the multiply now. Make sure to make the constant the second arg |
| Instruction *ScaledVal = |
| BinaryOperator::create(Instruction::Mul, IdxValue, ScaleAmt); |
| BI = BB->getInstList().insert(BI, ScaledVal)+1; |
| |
| // Now insert an ADD to actually adjust the pointer... |
| Instruction *AddInst = |
| BinaryOperator::create(Instruction::Add, GEP, ScaledVal); |
| BI = BB->getInstList().insert(BI, AddInst)+1; |
| |
| PRINT_PEEPHOLE4("add-to-gep:out1", IdxValue, ScaleAmt, ScaledVal, |
| AddInst); |
| AddrSrc = AddInst; |
| } |
| |
| // Insert a cast of the pointer to array of X to be a pointer to the |
| // element of the array. |
| // |
| // Insert a cast of the "rest" of the offset to the appropriate |
| // pointer type. |
| CastInst *ACI = new CastInst(AddrSrc, AT->getElementType()); |
| BI = BB->getInstList().insert(BI, ACI)+1; |
| AddrSrc = ACI; |
| |
| } else { |
| assert(Offset == ActualOffset && "GEP to middle of non array!"); |
| assert(Scale == 1 && "Scale factor for expr that is not an array idx!"); |
| } |
| |
| Instruction *NCI = new CastInst(AddrSrc, AddOp1->getType()); |
| ReplaceInstWithInst(BB->getInstList(), BI, NCI); |
| PRINT_PEEPHOLE2("add-to-gep:out", GEP, NCI); |
| return true; |
| } |
| |
| // Peephole optimize the following instructions: |
| // %t1 = cast int (uint) * %reg111 to uint (...) * |
| // %t2 = call uint (...) * %cast111( uint %key ) |
| // |
| // Into: %t3 = call int (uint) * %reg111( uint %key ) |
| // %t2 = cast int %t3 to uint |
| // |
| static bool PeepholeCallInst(BasicBlock *BB, BasicBlock::iterator &BI) { |
| CallInst *CI = cast<CallInst>(*BI); |
| return false; |
| } |
| |
| |
| static bool PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI) { |
| Instruction *I = *BI; |
| |
| if (CastInst *CI = dyn_cast<CastInst>(I)) { |
| Value *Src = CI->getOperand(0); |
| Instruction *SrcI = dyn_cast<Instruction>(Src); // Nonnull if instr source |
| const Type *DestTy = CI->getType(); |
| |
| // Peephole optimize the following instruction: |
| // %V2 = cast <ty> %V to <ty> |
| // |
| // Into: <nothing> |
| // |
| if (DestTy == Src->getType()) { // Check for a cast to same type as src!! |
| PRINT_PEEPHOLE1("cast-of-self-ty", CI); |
| CI->replaceAllUsesWith(Src); |
| if (!Src->hasName() && CI->hasName()) { |
| string Name = CI->getName(); |
| CI->setName(""); |
| Src->setName(Name, BB->getParent()->getSymbolTable()); |
| } |
| return true; |
| } |
| |
| // Peephole optimize the following instructions: |
| // %tmp = cast <ty> %V to <ty2> |
| // %V = cast <ty2> %tmp to <ty3> ; Where ty & ty2 are same size |
| // |
| // Into: cast <ty> %V to <ty3> |
| // |
| if (SrcI) |
| if (CastInst *CSrc = dyn_cast<CastInst>(SrcI)) |
| if (isReinterpretingCast(CI) + isReinterpretingCast(CSrc) < 2) { |
| // We can only do c-c elimination if, at most, one cast does a |
| // reinterpretation of the input data. |
| // |
| // If legal, make this cast refer the the original casts argument! |
| // |
| PRINT_PEEPHOLE2("cast-cast:in ", CI, CSrc); |
| CI->setOperand(0, CSrc->getOperand(0)); |
| PRINT_PEEPHOLE1("cast-cast:out", CI); |
| return true; |
| } |
| |
| // Check to see if it's a cast of an instruction that does not depend on the |
| // specific type of the operands to do it's job. |
| if (!isReinterpretingCast(CI)) { |
| ValueTypeCache ConvertedTypes; |
| if (RetValConvertableToType(CI, Src->getType(), ConvertedTypes)) { |
| PRINT_PEEPHOLE2("CAST-DEST-EXPR-CONV:in ", CI, Src); |
| |
| #ifdef DEBUG_PEEPHOLE_INSTS |
| cerr << "\nCONVERTING EXPR TYPE:\n"; |
| #endif |
| ValueMapCache ValueMap; |
| ConvertUsersType(CI, Src, ValueMap); // This will delete CI! |
| |
| BI = BB->begin(); // Rescan basic block. BI might be invalidated. |
| PRINT_PEEPHOLE1("CAST-DEST-EXPR-CONV:out", Src); |
| #ifdef DEBUG_PEEPHOLE_INSTS |
| cerr << "DONE CONVERTING EXPR TYPE: \n\n";// << BB->getParent(); |
| #endif |
| return true; |
| } else { |
| ConvertedTypes.clear(); |
| if (ExpressionConvertableToType(Src, DestTy, ConvertedTypes)) { |
| PRINT_PEEPHOLE2("CAST-SRC-EXPR-CONV:in ", CI, Src); |
| |
| #ifdef DEBUG_PEEPHOLE_INSTS |
| cerr << "\nCONVERTING SRC EXPR TYPE:\n"; |
| #endif |
| ValueMapCache ValueMap; |
| Value *E = ConvertExpressionToType(Src, DestTy, ValueMap); |
| if (ConstPoolVal *CPV = dyn_cast<ConstPoolVal>(E)) |
| CI->replaceAllUsesWith(CPV); |
| |
| BI = BB->begin(); // Rescan basic block. BI might be invalidated. |
| PRINT_PEEPHOLE1("CAST-SRC-EXPR-CONV:out", E); |
| #ifdef DEBUG_PEEPHOLE_INSTS |
| cerr << "DONE CONVERTING SRC EXPR TYPE: \n\n";// << BB->getParent(); |
| #endif |
| return true; |
| } |
| } |
| |
| } |
| |
| // Check to see if we are casting from a structure pointer to a pointer to |
| // the first element of the structure... to avoid munching other peepholes, |
| // we only let this happen if there are no add uses of the cast. |
| // |
| // Peephole optimize the following instructions: |
| // %t1 = cast {<...>} * %StructPtr to <ty> * |
| // |
| // Into: %t2 = getelementptr {<...>} * %StructPtr, <0, 0, 0, ...> |
| // %t1 = cast <eltype> * %t1 to <ty> * |
| // |
| #if 1 |
| if (const StructType *STy = getPointedToStruct(Src->getType())) |
| if (const PointerType *DestPTy = dyn_cast<PointerType>(DestTy)) { |
| |
| // Loop over uses of the cast, checking for add instructions. If an add |
| // exists, this is probably a part of a more complex GEP, so we don't |
| // want to mess around with the cast. |
| // |
| bool HasAddUse = false; |
| for (Value::use_iterator I = CI->use_begin(), E = CI->use_end(); |
| I != E; ++I) |
| if (isa<Instruction>(*I) && |
| cast<Instruction>(*I)->getOpcode() == Instruction::Add) { |
| HasAddUse = true; break; |
| } |
| |
| // If it doesn't have an add use, check to see if the dest type is |
| // losslessly convertable to one of the types in the start of the struct |
| // type. |
| // |
| if (!HasAddUse) { |
| const Type *DestPointedTy = DestPTy->getValueType(); |
| unsigned Depth = 1; |
| const StructType *CurSTy = STy; |
| const Type *ElTy = 0; |
| while (CurSTy) { |
| |
| // Check for a zero element struct type... if we have one, bail. |
| if (CurSTy->getElementTypes().size() == 0) break; |
| |
| // Grab the first element of the struct type, which must lie at |
| // offset zero in the struct. |
| // |
| ElTy = CurSTy->getElementTypes()[0]; |
| |
| // Did we find what we're looking for? |
| if (losslessCastableTypes(ElTy, DestPointedTy)) break; |
| |
| // Nope, go a level deeper. |
| ++Depth; |
| CurSTy = dyn_cast<StructType>(ElTy); |
| ElTy = 0; |
| } |
| |
| // Did we find what we were looking for? If so, do the transformation |
| if (ElTy) { |
| PRINT_PEEPHOLE1("cast-for-first:in", CI); |
| |
| // Build the index vector, full of all zeros |
| vector<ConstPoolVal *> Indices(Depth, |
| ConstPoolUInt::get(Type::UByteTy,0)); |
| |
| // Insert the new T cast instruction... stealing old T's name |
| GetElementPtrInst *GEP = new GetElementPtrInst(Src, Indices, |
| CI->getName()); |
| CI->setName(""); |
| BI = BB->getInstList().insert(BI, GEP)+1; |
| |
| // Make the old cast instruction reference the new GEP instead of |
| // the old src value. |
| // |
| CI->setOperand(0, GEP); |
| |
| PRINT_PEEPHOLE2("cast-for-first:out", GEP, CI); |
| return true; |
| } |
| } |
| } |
| #endif |
| |
| #if 1 |
| } else if (MallocInst *MI = dyn_cast<MallocInst>(I)) { |
| if (PeepholeMallocInst(BB, BI)) return true; |
| |
| } else if (CallInst *CI = dyn_cast<CallInst>(I)) { |
| if (PeepholeCallInst(BB, BI)) return true; |
| |
| } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) { |
| Value *Val = SI->getOperand(0); |
| Value *Pointer = SI->getPointerOperand(); |
| |
| // Peephole optimize the following instructions: |
| // %t1 = getelementptr {<...>} * %StructPtr, <element indices> |
| // store <elementty> %v, <elementty> * %t1 |
| // |
| // Into: store <elementty> %v, {<...>} * %StructPtr, <element indices> |
| // |
| if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Pointer)) { |
| // Append any indices that the store instruction has onto the end of the |
| // ones that the GEP is carrying... |
| // |
| vector<ConstPoolVal*> Indices(GEP->getIndices()); |
| Indices.insert(Indices.end(), SI->getIndices().begin(), |
| SI->getIndices().end()); |
| |
| PRINT_PEEPHOLE2("gep-store:in", GEP, SI); |
| ReplaceInstWithInst(BB->getInstList(), BI, |
| SI = new StoreInst(Val, GEP->getPointerOperand(), |
| Indices)); |
| PRINT_PEEPHOLE1("gep-store:out", SI); |
| return true; |
| } |
| |
| // Peephole optimize the following instructions: |
| // %t = cast <T1>* %P to <T2> * ;; If T1 is losslessly convertable to T2 |
| // store <T2> %V, <T2>* %t |
| // |
| // Into: |
| // %t = cast <T2> %V to <T1> |
| // store <T1> %t2, <T1>* %P |
| // |
| if (CastInst *CI = dyn_cast<CastInst>(Pointer)) |
| if (Value *CastSrc = CI->getOperand(0)) // CSPT = CastSrcPointerType |
| if (PointerType *CSPT = dyn_cast<PointerType>(CastSrc->getType())) |
| if (losslessCastableTypes(Val->getType(), // convertable types! |
| CSPT->getValueType()) && |
| !SI->hasIndices()) { // No subscripts yet! |
| PRINT_PEEPHOLE3("st-src-cast:in ", Pointer, Val, SI); |
| |
| // Insert the new T cast instruction... stealing old T's name |
| CastInst *NCI = new CastInst(Val, CSPT->getValueType(), |
| CI->getName()); |
| CI->setName(""); |
| BI = BB->getInstList().insert(BI, NCI)+1; |
| |
| // Replace the old store with a new one! |
| ReplaceInstWithInst(BB->getInstList(), BI, |
| SI = new StoreInst(NCI, CastSrc)); |
| PRINT_PEEPHOLE3("st-src-cast:out", NCI, CastSrc, SI); |
| return true; |
| } |
| |
| |
| } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) { |
| Value *Pointer = LI->getPointerOperand(); |
| |
| // Peephole optimize the following instructions: |
| // %t1 = getelementptr {<...>} * %StructPtr, <element indices> |
| // %V = load <elementty> * %t1 |
| // |
| // Into: load {<...>} * %StructPtr, <element indices> |
| // |
| if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Pointer)) { |
| // Append any indices that the load instruction has onto the end of the |
| // ones that the GEP is carrying... |
| // |
| vector<ConstPoolVal*> Indices(GEP->getIndices()); |
| Indices.insert(Indices.end(), LI->getIndices().begin(), |
| LI->getIndices().end()); |
| |
| PRINT_PEEPHOLE2("gep-load:in", GEP, LI); |
| ReplaceInstWithInst(BB->getInstList(), BI, |
| LI = new LoadInst(GEP->getPointerOperand(), |
| Indices)); |
| PRINT_PEEPHOLE1("gep-load:out", LI); |
| return true; |
| } |
| |
| |
| // Peephole optimize the following instructions: |
| // %t1 = cast <ty> * %t0 to <ty2> * |
| // %V = load <ty2> * %t1 |
| // |
| // Into: %t1 = load <ty> * %t0 |
| // %V = cast <ty> %t1 to <ty2> |
| // |
| // The idea behind this transformation is that if the expression type |
| // conversion engine could not convert the cast into some other nice form, |
| // that there is something fundementally wrong with the current shape of |
| // the program. Move the cast through the load and try again. This will |
| // leave the original cast instruction, to presumably become dead. |
| // |
| if (CastInst *CI = dyn_cast<CastInst>(Pointer)) { |
| Value *SrcVal = CI->getOperand(0); |
| const PointerType *SrcTy = dyn_cast<PointerType>(SrcVal->getType()); |
| const Type *ElTy = SrcTy ? SrcTy->getValueType() : 0; |
| |
| // Make sure that nothing will be lost in the new cast... |
| if (SrcTy && losslessCastableTypes(ElTy, LI->getType())) { |
| PRINT_PEEPHOLE2("CL-LoadCast:in ", CI, LI); |
| |
| string CName = CI->getName(); CI->setName(""); |
| LoadInst *NLI = new LoadInst(SrcVal, LI->getName()); |
| LI->setName(""); // Take over the old load's name |
| |
| // Insert the load before the old load |
| BI = BB->getInstList().insert(BI, NLI)+1; |
| |
| // Replace the old load with a new cast... |
| ReplaceInstWithInst(BB->getInstList(), BI, |
| CI = new CastInst(NLI, LI->getType(), CName)); |
| PRINT_PEEPHOLE2("CL-LoadCast:out", NLI, CI); |
| |
| return true; |
| } |
| } |
| } else if (I->getOpcode() == Instruction::Add && |
| isa<CastInst>(I->getOperand(1))) { |
| |
| if (PeepholeOptimizeAddCast(BB, BI, I->getOperand(0), |
| cast<CastInst>(I->getOperand(1)))) |
| return true; |
| |
| #endif |
| } |
| |
| return false; |
| } |
| |
| |
| |
| |
| static bool DoRaisePass(Method *M) { |
| bool Changed = false; |
| for (Method::iterator MI = M->begin(), ME = M->end(); MI != ME; ++MI) { |
| BasicBlock *BB = *MI; |
| BasicBlock::InstListType &BIL = BB->getInstList(); |
| |
| for (BasicBlock::iterator BI = BB->begin(); BI != BB->end();) { |
| if (opt::DeadCodeElimination::dceInstruction(BIL, BI)) { |
| Changed = true; |
| #ifdef DEBUG_PEEPHOLE_INSTS |
| cerr << "DeadCode Elinated!\n"; |
| #endif |
| } else if (PeepholeOptimize(BB, BI)) |
| Changed = true; |
| else |
| ++BI; |
| } |
| } |
| return Changed; |
| } |
| |
| |
| // RaisePointerReferences::doit - Raise a method representation to a higher |
| // level. |
| // |
| bool RaisePointerReferences::doit(Method *M) { |
| if (M->isExternal()) return false; |
| bool Changed = false; |
| |
| #ifdef DEBUG_PEEPHOLE_INSTS |
| cerr << "\n\n\nStarting to work on Method '" << M->getName() << "'\n"; |
| #endif |
| |
| while (DoRaisePass(M)) Changed = true; |
| |
| #if 0 |
| // PtrCasts - Keep a mapping between the pointer values (the key of the |
| // map), and the cast to array pointer (the value) in this map. This is |
| // used when converting pointer math into array addressing. |
| // |
| map<Value*, CastInst*> PtrCasts; |
| |
| // Insert casts for all incoming pointer values. Keep track of those casts |
| // and the identified incoming values in the PtrCasts map. |
| // |
| Changed |= DoInsertArrayCasts(M, PtrCasts); |
| |
| // Loop over each incoming pointer variable, replacing indexing arithmetic |
| // with getelementptr calls. |
| // |
| Changed |= reduce_apply_bool(PtrCasts.begin(), PtrCasts.end(), |
| ptr_fun(DoEliminatePointerArithmetic)); |
| #endif |
| |
| return Changed; |
| } |