LLVM API Documentation

ExprTypeConvert.cpp

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00001 //===- ExprTypeConvert.cpp - Code to change an LLVM Expr Type -------------===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and is distributed under
00006 // the University of Illinois Open Source License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file implements the part of level raising that checks to see if it is
00011 // possible to coerce an entire expression tree into a different type.  If
00012 // convertible, other routines from this file will do the conversion.
00013 //
00014 //===----------------------------------------------------------------------===//
00015 
00016 #include "TransformInternals.h"
00017 #include "llvm/Constants.h"
00018 #include "llvm/Instructions.h"
00019 #include "llvm/ADT/STLExtras.h"
00020 #include "llvm/Support/Debug.h"
00021 #include <algorithm>
00022 #include <iostream>
00023 using namespace llvm;
00024 
00025 static bool OperandConvertibleToType(User *U, Value *V, const Type *Ty,
00026                                      ValueTypeCache &ConvertedTypes,
00027                                      const TargetData &TD);
00028 
00029 static void ConvertOperandToType(User *U, Value *OldVal, Value *NewVal,
00030                                  ValueMapCache &VMC, const TargetData &TD);
00031 
00032 
00033 // ExpressionConvertibleToType - Return true if it is possible
00034 bool llvm::ExpressionConvertibleToType(Value *V, const Type *Ty,
00035                                  ValueTypeCache &CTMap, const TargetData &TD) {
00036   // Expression type must be holdable in a register.
00037   if (!Ty->isFirstClassType())
00038     return false;
00039 
00040   ValueTypeCache::iterator CTMI = CTMap.find(V);
00041   if (CTMI != CTMap.end()) return CTMI->second == Ty;
00042 
00043   // If it's a constant... all constants can be converted to a different
00044   // type.
00045   //
00046   if (isa<Constant>(V) && !isa<GlobalValue>(V))
00047     return true;
00048 
00049   CTMap[V] = Ty;
00050   if (V->getType() == Ty) return true;  // Expression already correct type!
00051 
00052   Instruction *I = dyn_cast<Instruction>(V);
00053   if (I == 0) return false;              // Otherwise, we can't convert!
00054 
00055   switch (I->getOpcode()) {
00056   case Instruction::Cast:
00057     // We can convert the expr if the cast destination type is losslessly
00058     // convertible to the requested type.
00059     if (!Ty->isLosslesslyConvertibleTo(I->getType())) return false;
00060 
00061     // We also do not allow conversion of a cast that casts from a ptr to array
00062     // of X to a *X.  For example: cast [4 x %List *] * %val to %List * *
00063     //
00064     if (const PointerType *SPT =
00065         dyn_cast<PointerType>(I->getOperand(0)->getType()))
00066       if (const PointerType *DPT = dyn_cast<PointerType>(I->getType()))
00067         if (const ArrayType *AT = dyn_cast<ArrayType>(SPT->getElementType()))
00068           if (AT->getElementType() == DPT->getElementType())
00069             return false;
00070     break;
00071 
00072   case Instruction::Add:
00073   case Instruction::Sub:
00074     if (!Ty->isInteger() && !Ty->isFloatingPoint()) return false;
00075     if (!ExpressionConvertibleToType(I->getOperand(0), Ty, CTMap, TD) ||
00076         !ExpressionConvertibleToType(I->getOperand(1), Ty, CTMap, TD))
00077       return false;
00078     break;
00079   case Instruction::Shr:
00080     if (!Ty->isInteger()) return false;
00081     if (Ty->isSigned() != V->getType()->isSigned()) return false;
00082     // FALL THROUGH
00083   case Instruction::Shl:
00084     if (!Ty->isInteger()) return false;
00085     if (!ExpressionConvertibleToType(I->getOperand(0), Ty, CTMap, TD))
00086       return false;
00087     break;
00088 
00089   case Instruction::Load: {
00090     LoadInst *LI = cast<LoadInst>(I);
00091     if (!ExpressionConvertibleToType(LI->getPointerOperand(),
00092                                      PointerType::get(Ty), CTMap, TD))
00093       return false;
00094     break;
00095   }
00096   case Instruction::PHI: {
00097     PHINode *PN = cast<PHINode>(I);
00098     // Be conservative if we find a giant PHI node.
00099     if (PN->getNumIncomingValues() > 32) return false;
00100 
00101     for (unsigned i = 0; i < PN->getNumIncomingValues(); ++i)
00102       if (!ExpressionConvertibleToType(PN->getIncomingValue(i), Ty, CTMap, TD))
00103         return false;
00104     break;
00105   }
00106 
00107   case Instruction::GetElementPtr: {
00108     // GetElementPtr's are directly convertible to a pointer type if they have
00109     // a number of zeros at the end.  Because removing these values does not
00110     // change the logical offset of the GEP, it is okay and fair to remove them.
00111     // This can change this:
00112     //   %t1 = getelementptr %Hosp * %hosp, ubyte 4, ubyte 0  ; <%List **>
00113     //   %t2 = cast %List * * %t1 to %List *
00114     // into
00115     //   %t2 = getelementptr %Hosp * %hosp, ubyte 4           ; <%List *>
00116     //
00117     GetElementPtrInst *GEP = cast<GetElementPtrInst>(I);
00118     const PointerType *PTy = dyn_cast<PointerType>(Ty);
00119     if (!PTy) return false;  // GEP must always return a pointer...
00120     const Type *PVTy = PTy->getElementType();
00121 
00122     // Check to see if there are zero elements that we can remove from the
00123     // index array.  If there are, check to see if removing them causes us to
00124     // get to the right type...
00125     //
00126     std::vector<Value*> Indices(GEP->idx_begin(), GEP->idx_end());
00127     const Type *BaseType = GEP->getPointerOperand()->getType();
00128     const Type *ElTy = 0;
00129 
00130     while (!Indices.empty() &&
00131            Indices.back() == Constant::getNullValue(Indices.back()->getType())){
00132       Indices.pop_back();
00133       ElTy = GetElementPtrInst::getIndexedType(BaseType, Indices, true);
00134       if (ElTy == PVTy)
00135         break;  // Found a match!!
00136       ElTy = 0;
00137     }
00138 
00139     if (ElTy) break;   // Found a number of zeros we can strip off!
00140 
00141     // Otherwise, it could be that we have something like this:
00142     //     getelementptr [[sbyte] *] * %reg115, long %reg138    ; [sbyte]**
00143     // and want to convert it into something like this:
00144     //     getelemenptr [[int] *] * %reg115, long %reg138      ; [int]**
00145     //
00146     if (GEP->getNumOperands() == 2 &&
00147         PTy->getElementType()->isSized() &&
00148         TD.getTypeSize(PTy->getElementType()) ==
00149         TD.getTypeSize(GEP->getType()->getElementType())) {
00150       const PointerType *NewSrcTy = PointerType::get(PVTy);
00151       if (!ExpressionConvertibleToType(I->getOperand(0), NewSrcTy, CTMap, TD))
00152         return false;
00153       break;
00154     }
00155 
00156     return false;   // No match, maybe next time.
00157   }
00158 
00159   case Instruction::Call: {
00160     if (isa<Function>(I->getOperand(0)))
00161       return false;  // Don't even try to change direct calls.
00162 
00163     // If this is a function pointer, we can convert the return type if we can
00164     // convert the source function pointer.
00165     //
00166     const PointerType *PT = cast<PointerType>(I->getOperand(0)->getType());
00167     const FunctionType *FT = cast<FunctionType>(PT->getElementType());
00168     std::vector<const Type *> ArgTys(FT->param_begin(), FT->param_end());
00169     const FunctionType *NewTy =
00170       FunctionType::get(Ty, ArgTys, FT->isVarArg());
00171     if (!ExpressionConvertibleToType(I->getOperand(0),
00172                                      PointerType::get(NewTy), CTMap, TD))
00173       return false;
00174     break;
00175   }
00176   default:
00177     return false;
00178   }
00179 
00180   // Expressions are only convertible if all of the users of the expression can
00181   // have this value converted.  This makes use of the map to avoid infinite
00182   // recursion.
00183   //
00184   for (Value::use_iterator It = I->use_begin(), E = I->use_end(); It != E; ++It)
00185     if (!OperandConvertibleToType(*It, I, Ty, CTMap, TD))
00186       return false;
00187 
00188   return true;
00189 }
00190 
00191 
00192 Value *llvm::ConvertExpressionToType(Value *V, const Type *Ty,
00193                                      ValueMapCache &VMC, const TargetData &TD) {
00194   if (V->getType() == Ty) return V;  // Already where we need to be?
00195 
00196   ValueMapCache::ExprMapTy::iterator VMCI = VMC.ExprMap.find(V);
00197   if (VMCI != VMC.ExprMap.end()) {
00198     assert(VMCI->second->getType() == Ty);
00199 
00200     if (Instruction *I = dyn_cast<Instruction>(V))
00201       ValueHandle IHandle(VMC, I);  // Remove I if it is unused now!
00202 
00203     return VMCI->second;
00204   }
00205 
00206   DEBUG(std::cerr << "CETT: " << (void*)V << " " << *V);
00207 
00208   Instruction *I = dyn_cast<Instruction>(V);
00209   if (I == 0) {
00210     Constant *CPV = cast<Constant>(V);
00211     // Constants are converted by constant folding the cast that is required.
00212     // We assume here that all casts are implemented for constant prop.
00213     Value *Result = ConstantExpr::getCast(CPV, Ty);
00214     // Add the instruction to the expression map
00215     //VMC.ExprMap[V] = Result;
00216     return Result;
00217   }
00218 
00219 
00220   BasicBlock *BB = I->getParent();
00221   std::string Name = I->getName();  if (!Name.empty()) I->setName("");
00222   Instruction *Res;     // Result of conversion
00223 
00224   ValueHandle IHandle(VMC, I);  // Prevent I from being removed!
00225 
00226   Constant *Dummy = Constant::getNullValue(Ty);
00227 
00228   switch (I->getOpcode()) {
00229   case Instruction::Cast:
00230     assert(VMC.NewCasts.count(ValueHandle(VMC, I)) == 0);
00231     Res = new CastInst(I->getOperand(0), Ty, Name);
00232     VMC.NewCasts.insert(ValueHandle(VMC, Res));
00233     break;
00234 
00235   case Instruction::Add:
00236   case Instruction::Sub:
00237     Res = BinaryOperator::create(cast<BinaryOperator>(I)->getOpcode(),
00238                                  Dummy, Dummy, Name);
00239     VMC.ExprMap[I] = Res;   // Add node to expression eagerly
00240 
00241     Res->setOperand(0, ConvertExpressionToType(I->getOperand(0), Ty, VMC, TD));
00242     Res->setOperand(1, ConvertExpressionToType(I->getOperand(1), Ty, VMC, TD));
00243     break;
00244 
00245   case Instruction::Shl:
00246   case Instruction::Shr:
00247     Res = new ShiftInst(cast<ShiftInst>(I)->getOpcode(), Dummy,
00248                         I->getOperand(1), Name);
00249     VMC.ExprMap[I] = Res;
00250     Res->setOperand(0, ConvertExpressionToType(I->getOperand(0), Ty, VMC, TD));
00251     break;
00252 
00253   case Instruction::Load: {
00254     LoadInst *LI = cast<LoadInst>(I);
00255 
00256     Res = new LoadInst(Constant::getNullValue(PointerType::get(Ty)), Name);
00257     VMC.ExprMap[I] = Res;
00258     Res->setOperand(0, ConvertExpressionToType(LI->getPointerOperand(),
00259                                                PointerType::get(Ty), VMC, TD));
00260     assert(Res->getOperand(0)->getType() == PointerType::get(Ty));
00261     assert(Ty == Res->getType());
00262     assert(Res->getType()->isFirstClassType() && "Load of structure or array!");
00263     break;
00264   }
00265 
00266   case Instruction::PHI: {
00267     PHINode *OldPN = cast<PHINode>(I);
00268     PHINode *NewPN = new PHINode(Ty, Name);
00269 
00270     VMC.ExprMap[I] = NewPN;   // Add node to expression eagerly
00271     while (OldPN->getNumOperands()) {
00272       BasicBlock *BB = OldPN->getIncomingBlock(0);
00273       Value *OldVal = OldPN->getIncomingValue(0);
00274       ValueHandle OldValHandle(VMC, OldVal);
00275       OldPN->removeIncomingValue(BB, false);
00276       Value *V = ConvertExpressionToType(OldVal, Ty, VMC, TD);
00277       NewPN->addIncoming(V, BB);
00278     }
00279     Res = NewPN;
00280     break;
00281   }
00282 
00283   case Instruction::GetElementPtr: {
00284     // GetElementPtr's are directly convertible to a pointer type if they have
00285     // a number of zeros at the end.  Because removing these values does not
00286     // change the logical offset of the GEP, it is okay and fair to remove them.
00287     // This can change this:
00288     //   %t1 = getelementptr %Hosp * %hosp, ubyte 4, ubyte 0  ; <%List **>
00289     //   %t2 = cast %List * * %t1 to %List *
00290     // into
00291     //   %t2 = getelementptr %Hosp * %hosp, ubyte 4           ; <%List *>
00292     //
00293     GetElementPtrInst *GEP = cast<GetElementPtrInst>(I);
00294 
00295     // Check to see if there are zero elements that we can remove from the
00296     // index array.  If there are, check to see if removing them causes us to
00297     // get to the right type...
00298     //
00299     std::vector<Value*> Indices(GEP->idx_begin(), GEP->idx_end());
00300     const Type *BaseType = GEP->getPointerOperand()->getType();
00301     const Type *PVTy = cast<PointerType>(Ty)->getElementType();
00302     Res = 0;
00303     while (!Indices.empty() &&
00304            Indices.back() == Constant::getNullValue(Indices.back()->getType())){
00305       Indices.pop_back();
00306       if (GetElementPtrInst::getIndexedType(BaseType, Indices, true) == PVTy) {
00307         if (Indices.size() == 0)
00308           Res = new CastInst(GEP->getPointerOperand(), BaseType); // NOOP CAST
00309         else
00310           Res = new GetElementPtrInst(GEP->getPointerOperand(), Indices, Name);
00311         break;
00312       }
00313     }
00314 
00315     // Otherwise, it could be that we have something like this:
00316     //     getelementptr [[sbyte] *] * %reg115, uint %reg138    ; [sbyte]**
00317     // and want to convert it into something like this:
00318     //     getelemenptr [[int] *] * %reg115, uint %reg138      ; [int]**
00319     //
00320     if (Res == 0) {
00321       const PointerType *NewSrcTy = PointerType::get(PVTy);
00322       std::vector<Value*> Indices(GEP->idx_begin(), GEP->idx_end());
00323       Res = new GetElementPtrInst(Constant::getNullValue(NewSrcTy),
00324                                   Indices, Name);
00325       VMC.ExprMap[I] = Res;
00326       Res->setOperand(0, ConvertExpressionToType(I->getOperand(0),
00327                                                  NewSrcTy, VMC, TD));
00328     }
00329 
00330 
00331     assert(Res && "Didn't find match!");
00332     break;
00333   }
00334 
00335   case Instruction::Call: {
00336     assert(!isa<Function>(I->getOperand(0)));
00337 
00338     // If this is a function pointer, we can convert the return type if we can
00339     // convert the source function pointer.
00340     //
00341     const PointerType *PT = cast<PointerType>(I->getOperand(0)->getType());
00342     const FunctionType *FT = cast<FunctionType>(PT->getElementType());
00343     std::vector<const Type *> ArgTys(FT->param_begin(), FT->param_end());
00344     const FunctionType *NewTy =
00345       FunctionType::get(Ty, ArgTys, FT->isVarArg());
00346     const PointerType *NewPTy = PointerType::get(NewTy);
00347     if (Ty == Type::VoidTy)
00348       Name = "";  // Make sure not to name calls that now return void!
00349 
00350     Res = new CallInst(Constant::getNullValue(NewPTy),
00351                        std::vector<Value*>(I->op_begin()+1, I->op_end()),
00352                        Name);
00353     if (cast<CallInst>(I)->isTailCall())
00354       cast<CallInst>(Res)->setTailCall();
00355     cast<CallInst>(Res)->setCallingConv(cast<CallInst>(I)->getCallingConv());
00356     VMC.ExprMap[I] = Res;
00357     Res->setOperand(0, ConvertExpressionToType(I->getOperand(0),NewPTy,VMC,TD));
00358     break;
00359   }
00360   default:
00361     assert(0 && "Expression convertible, but don't know how to convert?");
00362     return 0;
00363   }
00364 
00365   assert(Res->getType() == Ty && "Didn't convert expr to correct type!");
00366 
00367   BB->getInstList().insert(I, Res);
00368 
00369   // Add the instruction to the expression map
00370   VMC.ExprMap[I] = Res;
00371 
00372 
00373   //// WTF is this code!  FIXME: remove this.
00374   unsigned NumUses = I->getNumUses();
00375   for (unsigned It = 0; It < NumUses; ) {
00376     unsigned OldSize = NumUses;
00377     Value::use_iterator UI = I->use_begin();
00378     std::advance(UI, It);
00379     ConvertOperandToType(*UI, I, Res, VMC, TD);
00380     NumUses = I->getNumUses();
00381     if (NumUses == OldSize) ++It;
00382   }
00383 
00384   DEBUG(std::cerr << "ExpIn: " << (void*)I << " " << *I
00385                   << "ExpOut: " << (void*)Res << " " << *Res);
00386 
00387   return Res;
00388 }
00389 
00390 
00391 
00392 // ValueConvertibleToType - Return true if it is possible
00393 bool llvm::ValueConvertibleToType(Value *V, const Type *Ty,
00394                                   ValueTypeCache &ConvertedTypes,
00395                                   const TargetData &TD) {
00396   ValueTypeCache::iterator I = ConvertedTypes.find(V);
00397   if (I != ConvertedTypes.end()) return I->second == Ty;
00398   ConvertedTypes[V] = Ty;
00399 
00400   // It is safe to convert the specified value to the specified type IFF all of
00401   // the uses of the value can be converted to accept the new typed value.
00402   //
00403   if (V->getType() != Ty) {
00404     for (Value::use_iterator I = V->use_begin(), E = V->use_end(); I != E; ++I)
00405       if (!OperandConvertibleToType(*I, V, Ty, ConvertedTypes, TD))
00406         return false;
00407   }
00408 
00409   return true;
00410 }
00411 
00412 
00413 
00414 
00415 
00416 // OperandConvertibleToType - Return true if it is possible to convert operand
00417 // V of User (instruction) U to the specified type.  This is true iff it is
00418 // possible to change the specified instruction to accept this.  CTMap is a map
00419 // of converted types, so that circular definitions will see the future type of
00420 // the expression, not the static current type.
00421 //
00422 static bool OperandConvertibleToType(User *U, Value *V, const Type *Ty,
00423                                      ValueTypeCache &CTMap,
00424                                      const TargetData &TD) {
00425   //  if (V->getType() == Ty) return true;   // Operand already the right type?
00426 
00427   // Expression type must be holdable in a register.
00428   if (!Ty->isFirstClassType())
00429     return false;
00430 
00431   Instruction *I = dyn_cast<Instruction>(U);
00432   if (I == 0) return false;              // We can't convert!
00433 
00434   switch (I->getOpcode()) {
00435   case Instruction::Cast:
00436     assert(I->getOperand(0) == V);
00437     // We can convert the expr if the cast destination type is losslessly
00438     // convertible to the requested type.
00439     // Also, do not change a cast that is a noop cast.  For all intents and
00440     // purposes it should be eliminated.
00441     if (!Ty->isLosslesslyConvertibleTo(I->getOperand(0)->getType()) ||
00442         I->getType() == I->getOperand(0)->getType())
00443       return false;
00444 
00445     // Do not allow a 'cast ushort %V to uint' to have it's first operand be
00446     // converted to a 'short' type.  Doing so changes the way sign promotion
00447     // happens, and breaks things.  Only allow the cast to take place if the
00448     // signedness doesn't change... or if the current cast is not a lossy
00449     // conversion.
00450     //
00451     if (!I->getType()->isLosslesslyConvertibleTo(I->getOperand(0)->getType()) &&
00452         I->getOperand(0)->getType()->isSigned() != Ty->isSigned())
00453       return false;
00454 
00455     // We also do not allow conversion of a cast that casts from a ptr to array
00456     // of X to a *X.  For example: cast [4 x %List *] * %val to %List * *
00457     //
00458     if (const PointerType *SPT =
00459         dyn_cast<PointerType>(I->getOperand(0)->getType()))
00460       if (const PointerType *DPT = dyn_cast<PointerType>(I->getType()))
00461         if (const ArrayType *AT = dyn_cast<ArrayType>(SPT->getElementType()))
00462           if (AT->getElementType() == DPT->getElementType())
00463             return false;
00464     return true;
00465 
00466   case Instruction::Add:
00467   case Instruction::Sub: {
00468     if (!Ty->isInteger() && !Ty->isFloatingPoint()) return false;
00469 
00470     Value *OtherOp = I->getOperand((V == I->getOperand(0)) ? 1 : 0);
00471     return ValueConvertibleToType(I, Ty, CTMap, TD) &&
00472            ExpressionConvertibleToType(OtherOp, Ty, CTMap, TD);
00473   }
00474   case Instruction::SetEQ:
00475   case Instruction::SetNE: {
00476     Value *OtherOp = I->getOperand((V == I->getOperand(0)) ? 1 : 0);
00477     return ExpressionConvertibleToType(OtherOp, Ty, CTMap, TD);
00478   }
00479   case Instruction::Shr:
00480     if (Ty->isSigned() != V->getType()->isSigned()) return false;
00481     // FALL THROUGH
00482   case Instruction::Shl:
00483     if (I->getOperand(1) == V) return false;  // Cannot change shift amount type
00484     if (!Ty->isInteger()) return false;
00485     return ValueConvertibleToType(I, Ty, CTMap, TD);
00486 
00487   case Instruction::Free:
00488     assert(I->getOperand(0) == V);
00489     return isa<PointerType>(Ty);    // Free can free any pointer type!
00490 
00491   case Instruction::Load:
00492     // Cannot convert the types of any subscripts...
00493     if (I->getOperand(0) != V) return false;
00494 
00495     if (const PointerType *PT = dyn_cast<PointerType>(Ty)) {
00496       LoadInst *LI = cast<LoadInst>(I);
00497 
00498       const Type *LoadedTy = PT->getElementType();
00499 
00500       // They could be loading the first element of a composite type...
00501       if (const CompositeType *CT = dyn_cast<CompositeType>(LoadedTy)) {
00502         unsigned Offset = 0;     // No offset, get first leaf.
00503         std::vector<Value*> Indices;  // Discarded...
00504         LoadedTy = getStructOffsetType(CT, Offset, Indices, TD, false);
00505         assert(Offset == 0 && "Offset changed from zero???");
00506       }
00507 
00508       if (!LoadedTy->isFirstClassType())
00509         return false;
00510 
00511       if (TD.getTypeSize(LoadedTy) != TD.getTypeSize(LI->getType()))
00512         return false;
00513 
00514       return ValueConvertibleToType(LI, LoadedTy, CTMap, TD);
00515     }
00516     return false;
00517 
00518   case Instruction::Store: {
00519     if (V == I->getOperand(0)) {
00520       ValueTypeCache::iterator CTMI = CTMap.find(I->getOperand(1));
00521       if (CTMI != CTMap.end()) {   // Operand #1 is in the table already?
00522         // If so, check to see if it's Ty*, or, more importantly, if it is a
00523         // pointer to a structure where the first element is a Ty... this code
00524         // is necessary because we might be trying to change the source and
00525         // destination type of the store (they might be related) and the dest
00526         // pointer type might be a pointer to structure.  Below we allow pointer
00527         // to structures where the 0th element is compatible with the value,
00528         // now we have to support the symmetrical part of this.
00529         //
00530         const Type *ElTy = cast<PointerType>(CTMI->second)->getElementType();
00531 
00532         // Already a pointer to what we want?  Trivially accept...
00533         if (ElTy == Ty) return true;
00534 
00535         // Tricky case now, if the destination is a pointer to structure,
00536         // obviously the source is not allowed to be a structure (cannot copy
00537         // a whole structure at a time), so the level raiser must be trying to
00538         // store into the first field.  Check for this and allow it now:
00539         //
00540         if (const StructType *SElTy = dyn_cast<StructType>(ElTy)) {
00541           unsigned Offset = 0;
00542           std::vector<Value*> Indices;
00543           ElTy = getStructOffsetType(ElTy, Offset, Indices, TD, false);
00544           assert(Offset == 0 && "Offset changed!");
00545           if (ElTy == 0)    // Element at offset zero in struct doesn't exist!
00546             return false;   // Can only happen for {}*
00547 
00548           if (ElTy == Ty)   // Looks like the 0th element of structure is
00549             return true;    // compatible!  Accept now!
00550 
00551           // Otherwise we know that we can't work, so just stop trying now.
00552           return false;
00553         }
00554       }
00555 
00556       // Can convert the store if we can convert the pointer operand to match
00557       // the new  value type...
00558       return ExpressionConvertibleToType(I->getOperand(1), PointerType::get(Ty),
00559                                          CTMap, TD);
00560     } else if (const PointerType *PT = dyn_cast<PointerType>(Ty)) {
00561       const Type *ElTy = PT->getElementType();
00562       assert(V == I->getOperand(1));
00563 
00564       if (isa<StructType>(ElTy)) {
00565         // We can change the destination pointer if we can store our first
00566         // argument into the first element of the structure...
00567         //
00568         unsigned Offset = 0;
00569         std::vector<Value*> Indices;
00570         ElTy = getStructOffsetType(ElTy, Offset, Indices, TD, false);
00571         assert(Offset == 0 && "Offset changed!");
00572         if (ElTy == 0)    // Element at offset zero in struct doesn't exist!
00573           return false;   // Can only happen for {}*
00574       }
00575 
00576       // Must move the same amount of data...
00577       if (!ElTy->isSized() ||
00578           TD.getTypeSize(ElTy) != TD.getTypeSize(I->getOperand(0)->getType()))
00579         return false;
00580 
00581       // Can convert store if the incoming value is convertible and if the
00582       // result will preserve semantics...
00583       const Type *Op0Ty = I->getOperand(0)->getType();
00584       if (!(Op0Ty->isIntegral() ^ ElTy->isIntegral()) &&
00585           !(Op0Ty->isFloatingPoint() ^ ElTy->isFloatingPoint()))
00586         return ExpressionConvertibleToType(I->getOperand(0), ElTy, CTMap, TD);
00587     }
00588     return false;
00589   }
00590 
00591   case Instruction::PHI: {
00592     PHINode *PN = cast<PHINode>(I);
00593     // Be conservative if we find a giant PHI node.
00594     if (PN->getNumIncomingValues() > 32) return false;
00595 
00596     for (unsigned i = 0; i < PN->getNumIncomingValues(); ++i)
00597       if (!ExpressionConvertibleToType(PN->getIncomingValue(i), Ty, CTMap, TD))
00598         return false;
00599     return ValueConvertibleToType(PN, Ty, CTMap, TD);
00600   }
00601 
00602   case Instruction::Call: {
00603     User::op_iterator OI = std::find(I->op_begin(), I->op_end(), V);
00604     assert (OI != I->op_end() && "Not using value!");
00605     unsigned OpNum = OI - I->op_begin();
00606 
00607     // Are we trying to change the function pointer value to a new type?
00608     if (OpNum == 0) {
00609       const PointerType *PTy = dyn_cast<PointerType>(Ty);
00610       if (PTy == 0) return false;  // Can't convert to a non-pointer type...
00611       const FunctionType *FTy = dyn_cast<FunctionType>(PTy->getElementType());
00612       if (FTy == 0) return false;  // Can't convert to a non ptr to function...
00613 
00614       // Do not allow converting to a call where all of the operands are ...'s
00615       if (FTy->getNumParams() == 0 && FTy->isVarArg())
00616         return false;              // Do not permit this conversion!
00617 
00618       // Perform sanity checks to make sure that new function type has the
00619       // correct number of arguments...
00620       //
00621       unsigned NumArgs = I->getNumOperands()-1;  // Don't include function ptr
00622 
00623       // Cannot convert to a type that requires more fixed arguments than
00624       // the call provides...
00625       //
00626       if (NumArgs < FTy->getNumParams()) return false;
00627 
00628       // Unless this is a vararg function type, we cannot provide more arguments
00629       // than are desired...
00630       //
00631       if (!FTy->isVarArg() && NumArgs > FTy->getNumParams())
00632         return false;
00633 
00634       // Okay, at this point, we know that the call and the function type match
00635       // number of arguments.  Now we see if we can convert the arguments
00636       // themselves.  Note that we do not require operands to be convertible,
00637       // we can insert casts if they are convertible but not compatible.  The
00638       // reason for this is that we prefer to have resolved functions but casted
00639       // arguments if possible.
00640       //
00641       for (unsigned i = 0, NA = FTy->getNumParams(); i < NA; ++i)
00642         if (!FTy->getParamType(i)->isLosslesslyConvertibleTo(I->getOperand(i+1)->getType()))
00643           return false;   // Operands must have compatible types!
00644 
00645       // Okay, at this point, we know that all of the arguments can be
00646       // converted.  We succeed if we can change the return type if
00647       // necessary...
00648       //
00649       return ValueConvertibleToType(I, FTy->getReturnType(), CTMap, TD);
00650     }
00651 
00652     const PointerType *MPtr = cast<PointerType>(I->getOperand(0)->getType());
00653     const FunctionType *FTy = cast<FunctionType>(MPtr->getElementType());
00654     if (!FTy->isVarArg()) return false;
00655 
00656     if ((OpNum-1) < FTy->getNumParams())
00657       return false;  // It's not in the varargs section...
00658 
00659     // If we get this far, we know the value is in the varargs section of the
00660     // function!  We can convert if we don't reinterpret the value...
00661     //
00662     return Ty->isLosslesslyConvertibleTo(V->getType());
00663   }
00664   }
00665   return false;
00666 }
00667 
00668 
00669 void llvm::ConvertValueToNewType(Value *V, Value *NewVal, ValueMapCache &VMC,
00670                                  const TargetData &TD) {
00671   ValueHandle VH(VMC, V);
00672 
00673   // FIXME: This is horrible!
00674   unsigned NumUses = V->getNumUses();
00675   for (unsigned It = 0; It < NumUses; ) {
00676     unsigned OldSize = NumUses;
00677     Value::use_iterator UI = V->use_begin();
00678     std::advance(UI, It);
00679     ConvertOperandToType(*UI, V, NewVal, VMC, TD);
00680     NumUses = V->getNumUses();
00681     if (NumUses == OldSize) ++It;
00682   }
00683 }
00684 
00685 
00686 
00687 static void ConvertOperandToType(User *U, Value *OldVal, Value *NewVal,
00688                                  ValueMapCache &VMC, const TargetData &TD) {
00689   if (isa<ValueHandle>(U)) return;  // Valuehandles don't let go of operands...
00690 
00691   if (VMC.OperandsMapped.count(U)) return;
00692   VMC.OperandsMapped.insert(U);
00693 
00694   ValueMapCache::ExprMapTy::iterator VMCI = VMC.ExprMap.find(U);
00695   if (VMCI != VMC.ExprMap.end())
00696     return;
00697 
00698 
00699   Instruction *I = cast<Instruction>(U);  // Only Instructions convertible
00700 
00701   BasicBlock *BB = I->getParent();
00702   assert(BB != 0 && "Instruction not embedded in basic block!");
00703   std::string Name = I->getName();
00704   I->setName("");
00705   Instruction *Res;     // Result of conversion
00706 
00707   //std::cerr << endl << endl << "Type:\t" << Ty << "\nInst: " << I
00708   //          << "BB Before: " << BB << endl;
00709 
00710   // Prevent I from being removed...
00711   ValueHandle IHandle(VMC, I);
00712 
00713   const Type *NewTy = NewVal->getType();
00714   Constant *Dummy = (NewTy != Type::VoidTy) ?
00715                   Constant::getNullValue(NewTy) : 0;
00716 
00717   switch (I->getOpcode()) {
00718   case Instruction::Cast:
00719     if (VMC.NewCasts.count(ValueHandle(VMC, I))) {
00720       // This cast has already had it's value converted, causing a new cast to
00721       // be created.  We don't want to create YET ANOTHER cast instruction
00722       // representing the original one, so just modify the operand of this cast
00723       // instruction, which we know is newly created.
00724       I->setOperand(0, NewVal);
00725       I->setName(Name);  // give I its name back
00726       return;
00727 
00728     } else {
00729       Res = new CastInst(NewVal, I->getType(), Name);
00730     }
00731     break;
00732 
00733   case Instruction::Add:
00734   case Instruction::Sub:
00735   case Instruction::SetEQ:
00736   case Instruction::SetNE: {
00737     Res = BinaryOperator::create(cast<BinaryOperator>(I)->getOpcode(),
00738                                  Dummy, Dummy, Name);
00739     VMC.ExprMap[I] = Res;   // Add node to expression eagerly
00740 
00741     unsigned OtherIdx = (OldVal == I->getOperand(0)) ? 1 : 0;
00742     Value *OtherOp    = I->getOperand(OtherIdx);
00743     Res->setOperand(!OtherIdx, NewVal);
00744     Value *NewOther   = ConvertExpressionToType(OtherOp, NewTy, VMC, TD);
00745     Res->setOperand(OtherIdx, NewOther);
00746     break;
00747   }
00748   case Instruction::Shl:
00749   case Instruction::Shr:
00750     assert(I->getOperand(0) == OldVal);
00751     Res = new ShiftInst(cast<ShiftInst>(I)->getOpcode(), NewVal,
00752                         I->getOperand(1), Name);
00753     break;
00754 
00755   case Instruction::Free:            // Free can free any pointer type!
00756     assert(I->getOperand(0) == OldVal);
00757     Res = new FreeInst(NewVal);
00758     break;
00759 
00760 
00761   case Instruction::Load: {
00762     assert(I->getOperand(0) == OldVal && isa<PointerType>(NewVal->getType()));
00763     const Type *LoadedTy =
00764       cast<PointerType>(NewVal->getType())->getElementType();
00765 
00766     Value *Src = NewVal;
00767 
00768     if (const CompositeType *CT = dyn_cast<CompositeType>(LoadedTy)) {
00769       std::vector<Value*> Indices;
00770       Indices.push_back(Constant::getNullValue(Type::UIntTy));
00771 
00772       unsigned Offset = 0;   // No offset, get first leaf.
00773       LoadedTy = getStructOffsetType(CT, Offset, Indices, TD, false);
00774       assert(LoadedTy->isFirstClassType());
00775 
00776       if (Indices.size() != 1) {     // Do not generate load X, 0
00777         // Insert the GEP instruction before this load.
00778         Src = new GetElementPtrInst(Src, Indices, Name+".idx", I);
00779       }
00780     }
00781 
00782     Res = new LoadInst(Src, Name);
00783     assert(Res->getType()->isFirstClassType() && "Load of structure or array!");
00784     break;
00785   }
00786 
00787   case Instruction::Store: {
00788     if (I->getOperand(0) == OldVal) {  // Replace the source value
00789       // Check to see if operand #1 has already been converted...
00790       ValueMapCache::ExprMapTy::iterator VMCI =
00791         VMC.ExprMap.find(I->getOperand(1));
00792       if (VMCI != VMC.ExprMap.end()) {
00793         // Comments describing this stuff are in the OperandConvertibleToType
00794         // switch statement for Store...
00795         //
00796         const Type *ElTy =
00797           cast<PointerType>(VMCI->second->getType())->getElementType();
00798 
00799         Value *SrcPtr = VMCI->second;
00800 
00801         if (ElTy != NewTy) {
00802           // We check that this is a struct in the initial scan...
00803           const StructType *SElTy = cast<StructType>(ElTy);
00804 
00805           std::vector<Value*> Indices;
00806           Indices.push_back(Constant::getNullValue(Type::UIntTy));
00807 
00808           unsigned Offset = 0;
00809           const Type *Ty = getStructOffsetType(ElTy, Offset, Indices, TD,false);
00810           assert(Offset == 0 && "Offset changed!");
00811           assert(NewTy == Ty && "Did not convert to correct type!");
00812 
00813           // Insert the GEP instruction before this store.
00814           SrcPtr = new GetElementPtrInst(SrcPtr, Indices,
00815                                          SrcPtr->getName()+".idx", I);
00816         }
00817         Res = new StoreInst(NewVal, SrcPtr);
00818 
00819         VMC.ExprMap[I] = Res;
00820       } else {
00821         // Otherwise, we haven't converted Operand #1 over yet...
00822         const PointerType *NewPT = PointerType::get(NewTy);
00823         Res = new StoreInst(NewVal, Constant::getNullValue(NewPT));
00824         VMC.ExprMap[I] = Res;
00825         Res->setOperand(1, ConvertExpressionToType(I->getOperand(1),
00826                                                    NewPT, VMC, TD));
00827       }
00828     } else {                           // Replace the source pointer
00829       const Type *ValTy = cast<PointerType>(NewTy)->getElementType();
00830 
00831       Value *SrcPtr = NewVal;
00832 
00833       if (isa<StructType>(ValTy)) {
00834         std::vector<Value*> Indices;
00835         Indices.push_back(Constant::getNullValue(Type::UIntTy));
00836 
00837         unsigned Offset = 0;
00838         ValTy = getStructOffsetType(ValTy, Offset, Indices, TD, false);
00839 
00840         assert(Offset == 0 && ValTy);
00841 
00842         // Insert the GEP instruction before this store.
00843         SrcPtr = new GetElementPtrInst(SrcPtr, Indices,
00844                                        SrcPtr->getName()+".idx", I);
00845       }
00846 
00847       Res = new StoreInst(Constant::getNullValue(ValTy), SrcPtr);
00848       VMC.ExprMap[I] = Res;
00849       Res->setOperand(0, ConvertExpressionToType(I->getOperand(0),
00850                                                  ValTy, VMC, TD));
00851     }
00852     break;
00853   }
00854 
00855   case Instruction::PHI: {
00856     PHINode *OldPN = cast<PHINode>(I);
00857     PHINode *NewPN = new PHINode(NewTy, Name);
00858     VMC.ExprMap[I] = NewPN;
00859 
00860     while (OldPN->getNumOperands()) {
00861       BasicBlock *BB = OldPN->getIncomingBlock(0);
00862       Value *OldVal = OldPN->getIncomingValue(0);
00863       ValueHandle OldValHandle(VMC, OldVal);
00864       OldPN->removeIncomingValue(BB, false);
00865       Value *V = ConvertExpressionToType(OldVal, NewTy, VMC, TD);
00866       NewPN->addIncoming(V, BB);
00867     }
00868     Res = NewPN;
00869     break;
00870   }
00871 
00872   case Instruction::Call: {
00873     Value *Meth = I->getOperand(0);
00874     std::vector<Value*> Params(I->op_begin()+1, I->op_end());
00875 
00876     if (Meth == OldVal) {   // Changing the function pointer?
00877       const PointerType *NewPTy = cast<PointerType>(NewVal->getType());
00878       const FunctionType *NewTy = cast<FunctionType>(NewPTy->getElementType());
00879 
00880       if (NewTy->getReturnType() == Type::VoidTy)
00881         Name = "";  // Make sure not to name a void call!
00882 
00883       // Get an iterator to the call instruction so that we can insert casts for
00884       // operands if need be.  Note that we do not require operands to be
00885       // convertible, we can insert casts if they are convertible but not
00886       // compatible.  The reason for this is that we prefer to have resolved
00887       // functions but casted arguments if possible.
00888       //
00889       BasicBlock::iterator It = I;
00890 
00891       // Convert over all of the call operands to their new types... but only
00892       // convert over the part that is not in the vararg section of the call.
00893       //
00894       for (unsigned i = 0; i != NewTy->getNumParams(); ++i)
00895         if (Params[i]->getType() != NewTy->getParamType(i)) {
00896           // Create a cast to convert it to the right type, we know that this
00897           // is a lossless cast...
00898           //
00899           Params[i] = new CastInst(Params[i], NewTy->getParamType(i),
00900                                    "callarg.cast." +
00901                                    Params[i]->getName(), It);
00902         }
00903       Meth = NewVal;  // Update call destination to new value
00904 
00905     } else {                   // Changing an argument, must be in vararg area
00906       std::vector<Value*>::iterator OI =
00907         std::find(Params.begin(), Params.end(), OldVal);
00908       assert (OI != Params.end() && "Not using value!");
00909 
00910       *OI = NewVal;
00911     }
00912 
00913     Res = new CallInst(Meth, Params, Name);
00914     if (cast<CallInst>(I)->isTailCall())
00915       cast<CallInst>(Res)->setTailCall();
00916     cast<CallInst>(Res)->setCallingConv(cast<CallInst>(I)->getCallingConv());
00917     break;
00918   }
00919   default:
00920     assert(0 && "Expression convertible, but don't know how to convert?");
00921     return;
00922   }
00923 
00924   // If the instruction was newly created, insert it into the instruction
00925   // stream.
00926   //
00927   BasicBlock::iterator It = I;
00928   assert(It != BB->end() && "Instruction not in own basic block??");
00929   BB->getInstList().insert(It, Res);   // Keep It pointing to old instruction
00930 
00931   DEBUG(std::cerr << "COT CREATED: "  << (void*)Res << " " << *Res
00932                   << "In: " << (void*)I << " " << *I << "Out: " << (void*)Res
00933                   << " " << *Res);
00934 
00935   // Add the instruction to the expression map
00936   VMC.ExprMap[I] = Res;
00937 
00938   if (I->getType() != Res->getType())
00939     ConvertValueToNewType(I, Res, VMC, TD);
00940   else {
00941     for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
00942          UI != E; )
00943       if (isa<ValueHandle>(*UI)) {
00944         ++UI;
00945       } else {
00946         Use &U = UI.getUse();
00947         ++UI;  // Do not invalidate UI.
00948         U.set(Res);
00949       }
00950   }
00951 }
00952 
00953 
00954 ValueHandle::ValueHandle(ValueMapCache &VMC, Value *V)
00955   : Instruction(Type::VoidTy, UserOp1, &Op, 1, ""), Op(V, this), Cache(VMC) {
00956   //DEBUG(std::cerr << "VH AQUIRING: " << (void*)V << " " << V);
00957 }
00958 
00959 ValueHandle::ValueHandle(const ValueHandle &VH)
00960   : Instruction(Type::VoidTy, UserOp1, &Op, 1, ""),
00961     Op(VH.Op, this), Cache(VH.Cache) {
00962   //DEBUG(std::cerr << "VH AQUIRING: " << (void*)V << " " << V);
00963 }
00964 
00965 static void RecursiveDelete(ValueMapCache &Cache, Instruction *I) {
00966   if (!I || !I->use_empty()) return;
00967 
00968   assert(I->getParent() && "Inst not in basic block!");
00969 
00970   //DEBUG(std::cerr << "VH DELETING: " << (void*)I << " " << I);
00971 
00972   for (User::op_iterator OI = I->op_begin(), OE = I->op_end();
00973        OI != OE; ++OI)
00974     if (Instruction *U = dyn_cast<Instruction>(OI)) {
00975       *OI = 0;
00976       RecursiveDelete(Cache, U);
00977     }
00978 
00979   I->getParent()->getInstList().remove(I);
00980 
00981   Cache.OperandsMapped.erase(I);
00982   Cache.ExprMap.erase(I);
00983   delete I;
00984 }
00985 
00986 ValueHandle::~ValueHandle() {
00987   if (Op->hasOneUse()) {
00988     Value *V = Op;
00989     Op.set(0);   // Drop use!
00990 
00991     // Now we just need to remove the old instruction so we don't get infinite
00992     // loops.  Note that we cannot use DCE because DCE won't remove a store
00993     // instruction, for example.
00994     //
00995     RecursiveDelete(Cache, dyn_cast<Instruction>(V));
00996   } else {
00997     //DEBUG(std::cerr << "VH RELEASING: " << (void*)Operands[0].get() << " "
00998     //                << Operands[0]->getNumUses() << " " << Operands[0]);
00999   }
01000 }
01001