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AsmPrinter.cpp

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00001 //===-- AsmPrinter.cpp - Common AsmPrinter code ---------------------------===//
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 AsmPrinter class.
00011 //
00012 //===----------------------------------------------------------------------===//
00013 
00014 #include "llvm/CodeGen/AsmPrinter.h"
00015 #include "llvm/Constants.h"
00016 #include "llvm/Instruction.h"
00017 #include "llvm/Support/Mangler.h"
00018 #include "llvm/Target/TargetMachine.h"
00019 using namespace llvm;
00020 
00021 bool AsmPrinter::doInitialization(Module &M) {
00022   Mang = new Mangler(M, GlobalPrefix);
00023   return false;
00024 }
00025 
00026 bool AsmPrinter::doFinalization(Module &M) {
00027   delete Mang; Mang = 0;
00028   return false;
00029 }
00030 
00031 void AsmPrinter::setupMachineFunction(MachineFunction &MF) {
00032   // What's my mangled name?
00033   CurrentFnName = Mang->getValueName((Value*)MF.getFunction());
00034 }
00035 
00036 // emitAlignment - Emit an alignment directive to the specified power of two.
00037 void AsmPrinter::emitAlignment(unsigned NumBits) const {
00038   if (AlignmentIsInBytes) NumBits = 1 << NumBits;
00039   O << AlignDirective << NumBits << "\n";
00040 }
00041 
00042 /// emitZeros - Emit a block of zeros.
00043 ///
00044 void AsmPrinter::emitZeros(unsigned NumZeros) const {
00045   if (NumZeros) {
00046     if (ZeroDirective)
00047       O << ZeroDirective << NumZeros << "\n";
00048     else {
00049       for (; NumZeros; --NumZeros)
00050         O << Data8bitsDirective << "0\n";
00051     }
00052   }
00053 }
00054 
00055 // Print out the specified constant, without a storage class.  Only the
00056 // constants valid in constant expressions can occur here.
00057 void AsmPrinter::emitConstantValueOnly(const Constant *CV) {
00058   if (CV->isNullValue() || isa<UndefValue>(CV))
00059     O << "0";
00060   else if (const ConstantBool *CB = dyn_cast<ConstantBool>(CV)) {
00061     assert(CB == ConstantBool::True);
00062     O << "1";
00063   } else if (const ConstantSInt *CI = dyn_cast<ConstantSInt>(CV))
00064     if (((CI->getValue() << 32) >> 32) == CI->getValue())
00065       O << CI->getValue();
00066     else
00067       O << (unsigned long long)CI->getValue();
00068   else if (const ConstantUInt *CI = dyn_cast<ConstantUInt>(CV))
00069     O << CI->getValue();
00070   else if (isa<GlobalValue>((Value*)CV))
00071     // This is a constant address for a global variable or function.  Use the
00072     // name of the variable or function as the address value.
00073     O << Mang->getValueName(CV);
00074   else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV)) {
00075     const TargetData &TD = TM.getTargetData();
00076     switch(CE->getOpcode()) {
00077     case Instruction::GetElementPtr: {
00078       // generate a symbolic expression for the byte address
00079       const Constant *ptrVal = CE->getOperand(0);
00080       std::vector<Value*> idxVec(CE->op_begin()+1, CE->op_end());
00081       if (unsigned Offset = TD.getIndexedOffset(ptrVal->getType(), idxVec)) {
00082         O << "(";
00083         emitConstantValueOnly(ptrVal);
00084         O << ") + " << Offset;
00085       } else {
00086         emitConstantValueOnly(ptrVal);
00087       }
00088       break;
00089     }
00090     case Instruction::Cast: {
00091       // Support only non-converting or widening casts for now, that is, ones
00092       // that do not involve a change in value.  This assertion is really gross,
00093       // and may not even be a complete check.
00094       Constant *Op = CE->getOperand(0);
00095       const Type *OpTy = Op->getType(), *Ty = CE->getType();
00096 
00097       // Remember, kids, pointers can be losslessly converted back and forth
00098       // into 32-bit or wider integers, regardless of signedness. :-P
00099       assert(((isa<PointerType>(OpTy)
00100                && (Ty == Type::LongTy || Ty == Type::ULongTy
00101                    || Ty == Type::IntTy || Ty == Type::UIntTy))
00102               || (isa<PointerType>(Ty)
00103                   && (OpTy == Type::LongTy || OpTy == Type::ULongTy
00104                       || OpTy == Type::IntTy || OpTy == Type::UIntTy))
00105               || (((TD.getTypeSize(Ty) >= TD.getTypeSize(OpTy))
00106                    && OpTy->isLosslesslyConvertibleTo(Ty))))
00107              && "FIXME: Don't yet support this kind of constant cast expr");
00108       O << "(";
00109       emitConstantValueOnly(Op);
00110       O << ")";
00111       break;
00112     }
00113     case Instruction::Add:
00114       O << "(";
00115       emitConstantValueOnly(CE->getOperand(0));
00116       O << ") + (";
00117       emitConstantValueOnly(CE->getOperand(1));
00118       O << ")";
00119       break;
00120     default:
00121       assert(0 && "Unsupported operator!");
00122     }
00123   } else {
00124     assert(0 && "Unknown constant value!");
00125   }
00126 }
00127 
00128 /// toOctal - Convert the low order bits of X into an octal digit.
00129 ///
00130 static inline char toOctal(int X) {
00131   return (X&7)+'0';
00132 }
00133 
00134 /// getAsCString - Return the specified array as a C compatible string, only if
00135 /// the predicate isString is true.
00136 ///
00137 static void printAsCString(std::ostream &O, const ConstantArray *CVA) {
00138   assert(CVA->isString() && "Array is not string compatible!");
00139 
00140   O << "\"";
00141   for (unsigned i = 0; i != CVA->getNumOperands(); ++i) {
00142     unsigned char C = cast<ConstantInt>(CVA->getOperand(i))->getRawValue();
00143 
00144     if (C == '"') {
00145       O << "\\\"";
00146     } else if (C == '\\') {
00147       O << "\\\\";
00148     } else if (isprint(C)) {
00149       O << C;
00150     } else {
00151       switch(C) {
00152       case '\b': O << "\\b"; break;
00153       case '\f': O << "\\f"; break;
00154       case '\n': O << "\\n"; break;
00155       case '\r': O << "\\r"; break;
00156       case '\t': O << "\\t"; break;
00157       default:
00158         O << '\\';
00159         O << toOctal(C >> 6);
00160         O << toOctal(C >> 3);
00161         O << toOctal(C >> 0);
00162         break;
00163       }
00164     }
00165   }
00166   O << "\"";
00167 }
00168 
00169 /// emitGlobalConstant - Print a general LLVM constant to the .s file.
00170 ///
00171 void AsmPrinter::emitGlobalConstant(const Constant *CV) {  
00172   const TargetData &TD = TM.getTargetData();
00173 
00174   if (CV->isNullValue() || isa<UndefValue>(CV)) {
00175     emitZeros(TD.getTypeSize(CV->getType()));
00176     return;
00177   } else if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV)) {
00178     if (CVA->isString()) {
00179       O << AsciiDirective;
00180       printAsCString(O, CVA);
00181       O << "\n";
00182     } else { // Not a string.  Print the values in successive locations
00183       for (unsigned i = 0, e = CVA->getNumOperands(); i != e; ++i)
00184         emitGlobalConstant(CVA->getOperand(i));
00185     }
00186     return;
00187   } else if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV)) {
00188     // Print the fields in successive locations. Pad to align if needed!
00189     const StructLayout *cvsLayout = TD.getStructLayout(CVS->getType());
00190     unsigned sizeSoFar = 0;
00191     for (unsigned i = 0, e = CVS->getNumOperands(); i != e; ++i) {
00192       const Constant* field = CVS->getOperand(i);
00193 
00194       // Check if padding is needed and insert one or more 0s.
00195       unsigned fieldSize = TD.getTypeSize(field->getType());
00196       unsigned padSize = ((i == e-1? cvsLayout->StructSize
00197                            : cvsLayout->MemberOffsets[i+1])
00198                           - cvsLayout->MemberOffsets[i]) - fieldSize;
00199       sizeSoFar += fieldSize + padSize;
00200 
00201       // Now print the actual field value
00202       emitGlobalConstant(field);
00203 
00204       // Insert the field padding unless it's zero bytes...
00205       emitZeros(padSize);
00206     }
00207     assert(sizeSoFar == cvsLayout->StructSize &&
00208            "Layout of constant struct may be incorrect!");
00209     return;
00210   } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV)) {
00211     // FP Constants are printed as integer constants to avoid losing
00212     // precision...
00213     double Val = CFP->getValue();
00214     if (CFP->getType() == Type::DoubleTy) {
00215       union DU {                            // Abide by C TBAA rules
00216         double FVal;
00217         uint64_t UVal;
00218       } U;
00219       U.FVal = Val;
00220 
00221       if (Data64bitsDirective)
00222         O << Data64bitsDirective << U.UVal << "\t" << CommentString
00223           << " double value: " << Val << "\n";
00224       else if (TD.isBigEndian()) {
00225         O << Data32bitsDirective << unsigned(U.UVal >> 32)
00226           << "\t" << CommentString << " double most significant word "
00227           << Val << "\n";
00228         O << Data32bitsDirective << unsigned(U.UVal)
00229           << "\t" << CommentString << " double least significant word "
00230           << Val << "\n";
00231       } else {
00232         O << Data32bitsDirective << unsigned(U.UVal)
00233           << "\t" << CommentString << " double least significant word " << Val
00234           << "\n";
00235         O << Data32bitsDirective << unsigned(U.UVal >> 32)
00236           << "\t" << CommentString << " double most significant word " << Val
00237           << "\n";
00238       }
00239       return;
00240     } else {
00241       union FU {                            // Abide by C TBAA rules
00242         float FVal;
00243         int32_t UVal;
00244       } U;
00245       U.FVal = Val;
00246       
00247       O << Data32bitsDirective << U.UVal << "\t" << CommentString
00248         << " float " << Val << "\n";
00249       return;
00250     }
00251   } else if (CV->getType() == Type::ULongTy || CV->getType() == Type::LongTy) {
00252     if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
00253       uint64_t Val = CI->getRawValue();
00254         
00255       if (Data64bitsDirective)
00256         O << Data64bitsDirective << Val << "\n";
00257       else if (TD.isBigEndian()) {
00258         O << Data32bitsDirective << unsigned(Val >> 32)
00259           << "\t" << CommentString << " Double-word most significant word "
00260           << Val << "\n";
00261         O << Data32bitsDirective << unsigned(Val)
00262           << "\t" << CommentString << " Double-word least significant word "
00263           << Val << "\n";
00264       } else {
00265         O << Data32bitsDirective << unsigned(Val)
00266           << "\t" << CommentString << " Double-word least significant word "
00267           << Val << "\n";
00268         O << Data32bitsDirective << unsigned(Val >> 32)
00269           << "\t" << CommentString << " Double-word most significant word "
00270           << Val << "\n";
00271       }
00272       return;
00273     }
00274   }
00275 
00276   const Type *type = CV->getType();
00277   switch (type->getTypeID()) {
00278   case Type::BoolTyID: 
00279   case Type::UByteTyID: case Type::SByteTyID:
00280     O << Data8bitsDirective;
00281     break;
00282   case Type::UShortTyID: case Type::ShortTyID:
00283     O << Data16bitsDirective;
00284     break;
00285   case Type::PointerTyID:
00286   case Type::UIntTyID: case Type::IntTyID:
00287     O << Data32bitsDirective;
00288     break;
00289   case Type::ULongTyID: case Type::LongTyID:    
00290     assert (0 && "Should have already output double-word constant.");
00291   case Type::FloatTyID: case Type::DoubleTyID:
00292     assert (0 && "Should have already output floating point constant.");
00293   default:
00294     assert (0 && "Can't handle printing this type of thing");
00295     break;
00296   }
00297   emitConstantValueOnly(CV);
00298   O << "\n";
00299 }