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      1 //===-- XCoreAsmPrinter.cpp - XCore LLVM assembly writer ------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file contains a printer that converts from our internal representation
     11 // of machine-dependent LLVM code to the XAS-format XCore assembly language.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #define DEBUG_TYPE "asm-printer"
     16 #include "XCore.h"
     17 #include "InstPrinter/XCoreInstPrinter.h"
     18 #include "XCoreInstrInfo.h"
     19 #include "XCoreMCInstLower.h"
     20 #include "XCoreSubtarget.h"
     21 #include "XCoreTargetMachine.h"
     22 #include "llvm/ADT/SmallString.h"
     23 #include "llvm/ADT/StringExtras.h"
     24 #include "llvm/CodeGen/AsmPrinter.h"
     25 #include "llvm/CodeGen/MachineConstantPool.h"
     26 #include "llvm/CodeGen/MachineFunctionPass.h"
     27 #include "llvm/CodeGen/MachineInstr.h"
     28 #include "llvm/CodeGen/MachineJumpTableInfo.h"
     29 #include "llvm/CodeGen/MachineModuleInfo.h"
     30 #include "llvm/DebugInfo.h"
     31 #include "llvm/IR/Constants.h"
     32 #include "llvm/IR/DataLayout.h"
     33 #include "llvm/IR/DerivedTypes.h"
     34 #include "llvm/IR/Module.h"
     35 #include "llvm/MC/MCAsmInfo.h"
     36 #include "llvm/MC/MCInst.h"
     37 #include "llvm/MC/MCStreamer.h"
     38 #include "llvm/MC/MCSymbol.h"
     39 #include "llvm/Support/CommandLine.h"
     40 #include "llvm/Support/ErrorHandling.h"
     41 #include "llvm/Support/TargetRegistry.h"
     42 #include "llvm/Support/raw_ostream.h"
     43 #include "llvm/Target/Mangler.h"
     44 #include "llvm/Target/TargetLoweringObjectFile.h"
     45 #include <algorithm>
     46 #include <cctype>
     47 using namespace llvm;
     48 
     49 static cl::opt<unsigned> MaxThreads("xcore-max-threads", cl::Optional,
     50   cl::desc("Maximum number of threads (for emulation thread-local storage)"),
     51   cl::Hidden,
     52   cl::value_desc("number"),
     53   cl::init(8));
     54 
     55 namespace {
     56   class XCoreAsmPrinter : public AsmPrinter {
     57     const XCoreSubtarget &Subtarget;
     58     XCoreMCInstLower MCInstLowering;
     59     void PrintDebugValueComment(const MachineInstr *MI, raw_ostream &OS);
     60   public:
     61     explicit XCoreAsmPrinter(TargetMachine &TM, MCStreamer &Streamer)
     62       : AsmPrinter(TM, Streamer), Subtarget(TM.getSubtarget<XCoreSubtarget>()),
     63         MCInstLowering(*this) {}
     64 
     65     virtual const char *getPassName() const {
     66       return "XCore Assembly Printer";
     67     }
     68 
     69     void printInlineJT(const MachineInstr *MI, int opNum, raw_ostream &O,
     70                        const std::string &directive = ".jmptable");
     71     void printInlineJT32(const MachineInstr *MI, int opNum, raw_ostream &O) {
     72       printInlineJT(MI, opNum, O, ".jmptable32");
     73     }
     74     void printOperand(const MachineInstr *MI, int opNum, raw_ostream &O);
     75     bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
     76                          unsigned AsmVariant, const char *ExtraCode,
     77                          raw_ostream &O);
     78 
     79     void emitArrayBound(MCSymbol *Sym, const GlobalVariable *GV);
     80     virtual void EmitGlobalVariable(const GlobalVariable *GV);
     81 
     82     void EmitFunctionEntryLabel();
     83     void EmitInstruction(const MachineInstr *MI);
     84     void EmitFunctionBodyStart();
     85     void EmitFunctionBodyEnd();
     86     virtual MachineLocation getDebugValueLocation(const MachineInstr *MI) const;
     87   };
     88 } // end of anonymous namespace
     89 
     90 void XCoreAsmPrinter::emitArrayBound(MCSymbol *Sym, const GlobalVariable *GV) {
     91   assert(((GV->hasExternalLinkage() ||
     92     GV->hasWeakLinkage()) ||
     93     GV->hasLinkOnceLinkage()) && "Unexpected linkage");
     94   if (ArrayType *ATy = dyn_cast<ArrayType>(
     95     cast<PointerType>(GV->getType())->getElementType())) {
     96     OutStreamer.EmitSymbolAttribute(Sym, MCSA_Global);
     97     // FIXME: MCStreamerize.
     98     OutStreamer.EmitRawText(StringRef(".globound"));
     99     OutStreamer.EmitRawText("\t.set\t" + Twine(Sym->getName()));
    100     OutStreamer.EmitRawText(".globound," + Twine(ATy->getNumElements()));
    101     if (GV->hasWeakLinkage() || GV->hasLinkOnceLinkage()) {
    102       // TODO Use COMDAT groups for LinkOnceLinkage
    103       OutStreamer.EmitRawText(MAI->getWeakDefDirective() +Twine(Sym->getName())+
    104                               ".globound");
    105     }
    106   }
    107 }
    108 
    109 void XCoreAsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
    110   // Check to see if this is a special global used by LLVM, if so, emit it.
    111   if (!GV->hasInitializer() ||
    112       EmitSpecialLLVMGlobal(GV))
    113     return;
    114 
    115   const DataLayout *TD = TM.getDataLayout();
    116   OutStreamer.SwitchSection(getObjFileLowering().SectionForGlobal(GV, Mang,TM));
    117 
    118 
    119   MCSymbol *GVSym = Mang->getSymbol(GV);
    120   const Constant *C = GV->getInitializer();
    121   unsigned Align = (unsigned)TD->getPreferredTypeAlignmentShift(C->getType());
    122 
    123   // Mark the start of the global
    124   OutStreamer.EmitRawText("\t.cc_top " + Twine(GVSym->getName()) + ".data," +
    125                           GVSym->getName());
    126 
    127   switch (GV->getLinkage()) {
    128   case GlobalValue::AppendingLinkage:
    129     report_fatal_error("AppendingLinkage is not supported by this target!");
    130   case GlobalValue::LinkOnceAnyLinkage:
    131   case GlobalValue::LinkOnceODRLinkage:
    132   case GlobalValue::WeakAnyLinkage:
    133   case GlobalValue::WeakODRLinkage:
    134   case GlobalValue::ExternalLinkage:
    135     emitArrayBound(GVSym, GV);
    136     OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Global);
    137 
    138     // TODO Use COMDAT groups for LinkOnceLinkage
    139     if (GV->hasWeakLinkage() || GV->hasLinkOnceLinkage())
    140       OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Weak);
    141     // FALL THROUGH
    142   case GlobalValue::InternalLinkage:
    143   case GlobalValue::PrivateLinkage:
    144     break;
    145   case GlobalValue::DLLImportLinkage:
    146     llvm_unreachable("DLLImport linkage is not supported by this target!");
    147   case GlobalValue::DLLExportLinkage:
    148     llvm_unreachable("DLLExport linkage is not supported by this target!");
    149   default:
    150     llvm_unreachable("Unknown linkage type!");
    151   }
    152 
    153   EmitAlignment(Align > 2 ? Align : 2, GV);
    154 
    155   unsigned Size = TD->getTypeAllocSize(C->getType());
    156   if (GV->isThreadLocal()) {
    157     Size *= MaxThreads;
    158   }
    159   if (MAI->hasDotTypeDotSizeDirective()) {
    160     OutStreamer.EmitSymbolAttribute(GVSym, MCSA_ELF_TypeObject);
    161     OutStreamer.EmitRawText("\t.size " + Twine(GVSym->getName()) + "," +
    162                             Twine(Size));
    163   }
    164   OutStreamer.EmitLabel(GVSym);
    165 
    166   EmitGlobalConstant(C);
    167   if (GV->isThreadLocal()) {
    168     for (unsigned i = 1; i < MaxThreads; ++i)
    169       EmitGlobalConstant(C);
    170   }
    171   // The ABI requires that unsigned scalar types smaller than 32 bits
    172   // are padded to 32 bits.
    173   if (Size < 4)
    174     OutStreamer.EmitZeros(4 - Size);
    175 
    176   // Mark the end of the global
    177   OutStreamer.EmitRawText("\t.cc_bottom " + Twine(GVSym->getName()) + ".data");
    178 }
    179 
    180 void XCoreAsmPrinter::EmitFunctionBodyStart() {
    181   MCInstLowering.Initialize(Mang, &MF->getContext());
    182 }
    183 
    184 /// EmitFunctionBodyEnd - Targets can override this to emit stuff after
    185 /// the last basic block in the function.
    186 void XCoreAsmPrinter::EmitFunctionBodyEnd() {
    187   // Emit function end directives
    188   OutStreamer.EmitRawText("\t.cc_bottom " + Twine(CurrentFnSym->getName()) +
    189                           ".function");
    190 }
    191 
    192 void XCoreAsmPrinter::EmitFunctionEntryLabel() {
    193   // Mark the start of the function
    194   OutStreamer.EmitRawText("\t.cc_top " + Twine(CurrentFnSym->getName()) +
    195                           ".function," + CurrentFnSym->getName());
    196   OutStreamer.EmitLabel(CurrentFnSym);
    197 }
    198 
    199 void XCoreAsmPrinter::
    200 printInlineJT(const MachineInstr *MI, int opNum, raw_ostream &O,
    201               const std::string &directive) {
    202   unsigned JTI = MI->getOperand(opNum).getIndex();
    203   const MachineFunction *MF = MI->getParent()->getParent();
    204   const MachineJumpTableInfo *MJTI = MF->getJumpTableInfo();
    205   const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
    206   const std::vector<MachineBasicBlock*> &JTBBs = JT[JTI].MBBs;
    207   O << "\t" << directive << " ";
    208   for (unsigned i = 0, e = JTBBs.size(); i != e; ++i) {
    209     MachineBasicBlock *MBB = JTBBs[i];
    210     if (i > 0)
    211       O << ",";
    212     O << *MBB->getSymbol();
    213   }
    214 }
    215 
    216 void XCoreAsmPrinter::printOperand(const MachineInstr *MI, int opNum,
    217                                    raw_ostream &O) {
    218   const MachineOperand &MO = MI->getOperand(opNum);
    219   switch (MO.getType()) {
    220   case MachineOperand::MO_Register:
    221     O << XCoreInstPrinter::getRegisterName(MO.getReg());
    222     break;
    223   case MachineOperand::MO_Immediate:
    224     O << MO.getImm();
    225     break;
    226   case MachineOperand::MO_MachineBasicBlock:
    227     O << *MO.getMBB()->getSymbol();
    228     break;
    229   case MachineOperand::MO_GlobalAddress:
    230     O << *Mang->getSymbol(MO.getGlobal());
    231     break;
    232   case MachineOperand::MO_ExternalSymbol:
    233     O << MO.getSymbolName();
    234     break;
    235   case MachineOperand::MO_ConstantPoolIndex:
    236     O << MAI->getPrivateGlobalPrefix() << "CPI" << getFunctionNumber()
    237       << '_' << MO.getIndex();
    238     break;
    239   case MachineOperand::MO_JumpTableIndex:
    240     O << MAI->getPrivateGlobalPrefix() << "JTI" << getFunctionNumber()
    241       << '_' << MO.getIndex();
    242     break;
    243   case MachineOperand::MO_BlockAddress:
    244     O << *GetBlockAddressSymbol(MO.getBlockAddress());
    245     break;
    246   default:
    247     llvm_unreachable("not implemented");
    248   }
    249 }
    250 
    251 /// PrintAsmOperand - Print out an operand for an inline asm expression.
    252 ///
    253 bool XCoreAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
    254                                       unsigned AsmVariant,const char *ExtraCode,
    255                                       raw_ostream &O) {
    256   // Does this asm operand have a single letter operand modifier?
    257   if (ExtraCode && ExtraCode[0])
    258     if (ExtraCode[1] != 0) return true; // Unknown modifier.
    259 
    260     switch (ExtraCode[0]) {
    261     default:
    262       // See if this is a generic print operand
    263       return AsmPrinter::PrintAsmOperand(MI, OpNo, AsmVariant, ExtraCode, O);
    264     }
    265 
    266   printOperand(MI, OpNo, O);
    267   return false;
    268 }
    269 
    270 void XCoreAsmPrinter::PrintDebugValueComment(const MachineInstr *MI,
    271                                              raw_ostream &OS) {
    272   unsigned NOps = MI->getNumOperands();
    273   assert(NOps == 4);
    274   OS << '\t' << MAI->getCommentString() << "DEBUG_VALUE: ";
    275   // cast away const; DIetc do not take const operands for some reason.
    276   DIVariable V(const_cast<MDNode *>(MI->getOperand(NOps-1).getMetadata()));
    277   OS << V.getName();
    278   OS << " <- ";
    279   // Frame address.  Currently handles register +- offset only.
    280   assert(MI->getOperand(0).isReg() && MI->getOperand(1).isImm());
    281   OS << '['; printOperand(MI, 0, OS); OS << '+'; printOperand(MI, 1, OS);
    282   OS << ']';
    283   OS << "+";
    284   printOperand(MI, NOps-2, OS);
    285 }
    286 
    287 MachineLocation XCoreAsmPrinter::
    288 getDebugValueLocation(const MachineInstr *MI) const {
    289   // Handles frame addresses emitted in XCoreInstrInfo::emitFrameIndexDebugValue.
    290   assert(MI->getNumOperands() == 4 && "Invalid no. of machine operands!");
    291   assert(MI->getOperand(0).isReg() && MI->getOperand(1).isImm() &&
    292          "Unexpected MachineOperand types");
    293   return MachineLocation(MI->getOperand(0).getReg(),
    294                          MI->getOperand(1).getImm());
    295 }
    296 
    297 void XCoreAsmPrinter::EmitInstruction(const MachineInstr *MI) {
    298   SmallString<128> Str;
    299   raw_svector_ostream O(Str);
    300 
    301   switch (MI->getOpcode()) {
    302   case XCore::DBG_VALUE: {
    303     if (isVerbose() && OutStreamer.hasRawTextSupport()) {
    304       SmallString<128> TmpStr;
    305       raw_svector_ostream OS(TmpStr);
    306       PrintDebugValueComment(MI, OS);
    307       OutStreamer.EmitRawText(StringRef(OS.str()));
    308     }
    309     return;
    310   }
    311   case XCore::ADD_2rus:
    312     if (MI->getOperand(2).getImm() == 0) {
    313       O << "\tmov "
    314         << XCoreInstPrinter::getRegisterName(MI->getOperand(0).getReg()) << ", "
    315         << XCoreInstPrinter::getRegisterName(MI->getOperand(1).getReg());
    316       OutStreamer.EmitRawText(O.str());
    317       return;
    318     }
    319     break;
    320   case XCore::BR_JT:
    321   case XCore::BR_JT32:
    322     O << "\tbru "
    323       << XCoreInstPrinter::getRegisterName(MI->getOperand(1).getReg()) << '\n';
    324     if (MI->getOpcode() == XCore::BR_JT)
    325       printInlineJT(MI, 0, O);
    326     else
    327       printInlineJT32(MI, 0, O);
    328     O << '\n';
    329     OutStreamer.EmitRawText(O.str());
    330     return;
    331   }
    332 
    333   MCInst TmpInst;
    334   MCInstLowering.Lower(MI, TmpInst);
    335 
    336   OutStreamer.EmitInstruction(TmpInst);
    337 }
    338 
    339 // Force static initialization.
    340 extern "C" void LLVMInitializeXCoreAsmPrinter() {
    341   RegisterAsmPrinter<XCoreAsmPrinter> X(TheXCoreTarget);
    342 }
    343