lib/Target/Mips/AsmPrinter/MipsAsmPrinter.cpp

   1 //===-- MipsAsmPrinter.cpp - Mips 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 GAS-format MIPS assembly language.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #define DEBUG_TYPE "mips-asm-printer"
  16
  17 #include "Mips.h"
  18 #include "MipsSubtarget.h"
  19 #include "MipsInstrInfo.h"
  20 #include "MipsTargetMachine.h"
  21 #include "MipsMachineFunction.h"
  22 #include "llvm/Constants.h"
  23 #include "llvm/DerivedTypes.h"
  24 #include "llvm/Module.h"
  25 #include "llvm/Metadata.h"
  26 #include "llvm/CodeGen/AsmPrinter.h"
  27 #include "llvm/CodeGen/DwarfWriter.h"
  28 #include "llvm/CodeGen/MachineFunctionPass.h"
  29 #include "llvm/CodeGen/MachineConstantPool.h"
  30 #include "llvm/CodeGen/MachineFrameInfo.h"
  31 #include "llvm/CodeGen/MachineInstr.h"
  32 #include "llvm/Target/TargetAsmInfo.h"
  33 #include "llvm/Target/TargetData.h"
  34 #include "llvm/Target/TargetLoweringObjectFile.h"
  35 #include "llvm/Target/TargetMachine.h"
  36 #include "llvm/Target/TargetOptions.h"
  37 #include "llvm/Target/TargetRegistry.h"
  38 #include "llvm/Support/ErrorHandling.h"
  39 #include "llvm/Support/Mangler.h"
  40 #include "llvm/ADT/Statistic.h"
  41 #include "llvm/ADT/StringExtras.h"
  42 #include "llvm/Support/Debug.h"
  43 #include "llvm/Support/CommandLine.h"
  44 #include "llvm/Support/FormattedStream.h"
  45 #include "llvm/Support/MathExtras.h"
  46 #include <cctype>
  47
  48 using namespace llvm;
  49
  50 STATISTIC(EmittedInsts, "Number of machine instrs printed");
  51
  52 namespace {
  53   class VISIBILITY_HIDDEN MipsAsmPrinter : public AsmPrinter {
  54     const MipsSubtarget *Subtarget;
  55   public:
  56     explicit MipsAsmPrinter(formatted_raw_ostream &O, TargetMachine &TM,
  57                             const TargetAsmInfo *T, bool V)
  58       : AsmPrinter(O, TM, T, V) {
  59       Subtarget = &TM.getSubtarget<MipsSubtarget>();
  60     }
  61
  62     virtual const char *getPassName() const {
  63       return "Mips Assembly Printer";
  64     }
  65
  66     bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
  67                          unsigned AsmVariant, const char *ExtraCode);
  68     void printOperand(const MachineInstr *MI, int opNum);
  69     void printUnsignedImm(const MachineInstr *MI, int opNum);
  70     void printMemOperand(const MachineInstr *MI, int opNum,
  71                          const char *Modifier = 0);
  72     void printFCCOperand(const MachineInstr *MI, int opNum,
  73                          const char *Modifier = 0);
  74     void PrintGlobalVariable(const GlobalVariable *GVar);
  75     void printSavedRegsBitmask(MachineFunction &MF);
  76     void printHex32(unsigned int Value);
  77
  78     const char *emitCurrentABIString(void);
  79     void emitFunctionStart(MachineFunction &MF);
  80     void emitFunctionEnd(MachineFunction &MF);
  81     void emitFrameDirective(MachineFunction &MF);
  82
  83     bool printInstruction(const MachineInstr *MI);  // autogenerated.
  84     bool runOnMachineFunction(MachineFunction &F);
  85     bool doInitialization(Module &M);
  86   };
  87 } // end of anonymous namespace
  88
  89 #include "MipsGenAsmWriter.inc"
  90
  91 //===----------------------------------------------------------------------===//
  92 //
  93 //  Mips Asm Directives
  94 //
  95 //  -- Frame directive "frame Stackpointer, Stacksize, RARegister"
  96 //  Describe the stack frame.
  97 //
  98 //  -- Mask directives "(f)mask  bitmask, offset"
  99 //  Tells the assembler which registers are saved and where.
 100 //  bitmask - contain a little endian bitset indicating which registers are
 101 //            saved on function prologue (e.g. with a 0x80000000 mask, the
 102 //            assembler knows the register 31 (RA) is saved at prologue.
 103 //  offset  - the position before stack pointer subtraction indicating where
 104 //            the first saved register on prologue is located. (e.g. with a
 105 //
 106 //  Consider the following function prologue:
 107 //
 108 //    .frame  $fp,48,$ra
 109 //    .mask   0xc0000000,-8
 110 //       addiu $sp, $sp, -48
 111 //       sw $ra, 40($sp)
 112 //       sw $fp, 36($sp)
 113 //
 114 //    With a 0xc0000000 mask, the assembler knows the register 31 (RA) and
 115 //    30 (FP) are saved at prologue. As the save order on prologue is from
 116 //    left to right, RA is saved first. A -8 offset means that after the
 117 //    stack pointer subtration, the first register in the mask (RA) will be
 118 //    saved at address 48-8=40.
 119 //
 120 //===----------------------------------------------------------------------===//
 121
 122 //===----------------------------------------------------------------------===//
 123 // Mask directives
 124 //===----------------------------------------------------------------------===//
 125
 126 // Create a bitmask with all callee saved registers for CPU or Floating Point
 127 // registers. For CPU registers consider RA, GP and FP for saving if necessary.
 128 void MipsAsmPrinter::
 129 printSavedRegsBitmask(MachineFunction &MF)
 130 {
 131   const TargetRegisterInfo &RI = *TM.getRegisterInfo();
 132   MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
 133
 134   // CPU and FPU Saved Registers Bitmasks
 135   unsigned int CPUBitmask = 0;
 136   unsigned int FPUBitmask = 0;
 137
 138   // Set the CPU and FPU Bitmasks
 139   MachineFrameInfo *MFI = MF.getFrameInfo();
 140   const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
 141   for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
 142     unsigned RegNum = MipsRegisterInfo::getRegisterNumbering(CSI[i].getReg());
 143     if (CSI[i].getRegClass() == Mips::CPURegsRegisterClass)
 144       CPUBitmask |= (1 << RegNum);
 145     else
 146       FPUBitmask |= (1 << RegNum);
 147   }
 148
 149   // Return Address and Frame registers must also be set in CPUBitmask.
 150   if (RI.hasFP(MF))
 151     CPUBitmask |= (1 << MipsRegisterInfo::
 152                 getRegisterNumbering(RI.getFrameRegister(MF)));
 153
 154   if (MF.getFrameInfo()->hasCalls())
 155     CPUBitmask |= (1 << MipsRegisterInfo::
 156                 getRegisterNumbering(RI.getRARegister()));
 157
 158   // Print CPUBitmask
 159   O << "\t.mask \t"; printHex32(CPUBitmask); O << ','
 160     << MipsFI->getCPUTopSavedRegOff() << '\n';
 161
 162   // Print FPUBitmask
 163   O << "\t.fmask\t"; printHex32(FPUBitmask); O << ","
 164     << MipsFI->getFPUTopSavedRegOff() << '\n';
 165 }
 166
 167 // Print a 32 bit hex number with all numbers.
 168 void MipsAsmPrinter::
 169 printHex32(unsigned int Value)
 170 {
 171   O << "0x";
 172   for (int i = 7; i >= 0; i--)
 173     O << utohexstr( (Value & (0xF << (i*4))) >> (i*4) );
 174 }
 175
 176 //===----------------------------------------------------------------------===//
 177 // Frame and Set directives
 178 //===----------------------------------------------------------------------===//
 179
 180 /// Frame Directive
 181 void MipsAsmPrinter::emitFrameDirective(MachineFunction &MF) {
 182   const TargetRegisterInfo &RI = *TM.getRegisterInfo();
 183
 184   unsigned stackReg  = RI.getFrameRegister(MF);
 185   unsigned returnReg = RI.getRARegister();
 186   unsigned stackSize = MF.getFrameInfo()->getStackSize();
 187
 188
 189   O << "\t.frame\t" << '$' << LowercaseString(RI.get(stackReg).AsmName)
 190                     << ',' << stackSize << ','
 191                     << '$' << LowercaseString(RI.get(returnReg).AsmName)
 192                     << '\n';
 193 }
 194
 195 /// Emit Set directives.
 196 const char *MipsAsmPrinter::emitCurrentABIString() {
 197   switch(Subtarget->getTargetABI()) {
 198     case MipsSubtarget::O32:  return "abi32";
 199     case MipsSubtarget::O64:  return "abiO64";
 200     case MipsSubtarget::N32:  return "abiN32";
 201     case MipsSubtarget::N64:  return "abi64";
 202     case MipsSubtarget::EABI: return "eabi32"; // TODO: handle eabi64
 203     default: break;
 204   }
 205
 206   llvm_unreachable("Unknown Mips ABI");
 207   return NULL;
 208 }
 209
 210 /// Emit the directives used by GAS on the start of functions
 211 void MipsAsmPrinter::emitFunctionStart(MachineFunction &MF) {
 212   // Print out the label for the function.
 213   const Function *F = MF.getFunction();
 214   SwitchToSection(getObjFileLowering().SectionForGlobal(F, Mang, TM));
 215
 216   // 2 bits aligned
 217   EmitAlignment(MF.getAlignment(), F);
 218
 219   O << "\t.globl\t"  << CurrentFnName << '\n';
 220   O << "\t.ent\t"    << CurrentFnName << '\n';
 221
 222   printVisibility(CurrentFnName, F->getVisibility());
 223
 224   if ((TAI->hasDotTypeDotSizeDirective()) && Subtarget->isLinux())
 225     O << "\t.type\t"   << CurrentFnName << ", @function\n";
 226
 227   O << CurrentFnName << ":\n";
 228
 229   emitFrameDirective(MF);
 230   printSavedRegsBitmask(MF);
 231
 232   O << '\n';
 233 }
 234
 235 /// Emit the directives used by GAS on the end of functions
 236 void MipsAsmPrinter::emitFunctionEnd(MachineFunction &MF) {
 237   // There are instruction for this macros, but they must
 238   // always be at the function end, and we can't emit and
 239   // break with BB logic.
 240   O << "\t.set\tmacro\n";
 241   O << "\t.set\treorder\n";
 242
 243   O << "\t.end\t" << CurrentFnName << '\n';
 244   if (TAI->hasDotTypeDotSizeDirective() && !Subtarget->isLinux())
 245     O << "\t.size\t" << CurrentFnName << ", .-" << CurrentFnName << '\n';
 246 }
 247
 248 /// runOnMachineFunction - This uses the printMachineInstruction()
 249 /// method to print assembly for each instruction.
 250 bool MipsAsmPrinter::runOnMachineFunction(MachineFunction &MF) {
 251   this->MF = &MF;
 252
 253   SetupMachineFunction(MF);
 254
 255   // Print out constants referenced by the function
 256   EmitConstantPool(MF.getConstantPool());
 257
 258   // Print out jump tables referenced by the function
 259   EmitJumpTableInfo(MF.getJumpTableInfo(), MF);
 260
 261   O << "\n\n";
 262
 263   // Emit the function start directives
 264   emitFunctionStart(MF);
 265
 266   // Print out code for the function.
 267   for (MachineFunction::const_iterator I = MF.begin(), E = MF.end();
 268        I != E; ++I) {
 269
 270     // Print a label for the basic block.
 271     if (I != MF.begin()) {
 272       printBasicBlockLabel(I, true, true);
 273       O << '\n';
 274     }
 275
 276     for (MachineBasicBlock::const_iterator II = I->begin(), E = I->end();
 277          II != E; ++II) {
 278       // Print the assembly for the instruction.
 279       printInstruction(II);
 280       ++EmittedInsts;
 281     }
 282
 283     // Each Basic Block is separated by a newline
 284     O << '\n';
 285   }
 286
 287   // Emit function end directives
 288   emitFunctionEnd(MF);
 289
 290   // We didn't modify anything.
 291   return false;
 292 }
 293
 294 // Print out an operand for an inline asm expression.
 295 bool MipsAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
 296                                      unsigned AsmVariant,const char *ExtraCode){
 297   // Does this asm operand have a single letter operand modifier?
 298   if (ExtraCode && ExtraCode[0])
 299     return true; // Unknown modifier.
 300
 301   printOperand(MI, OpNo);
 302   return false;
 303 }
 304
 305 void MipsAsmPrinter::printOperand(const MachineInstr *MI, int opNum) {
 306   const MachineOperand &MO = MI->getOperand(opNum);
 307   const TargetRegisterInfo  &RI = *TM.getRegisterInfo();
 308   bool closeP = false;
 309   bool isPIC = (TM.getRelocationModel() == Reloc::PIC_);
 310   bool isCodeLarge = (TM.getCodeModel() == CodeModel::Large);
 311
 312   // %hi and %lo used on mips gas to load global addresses on
 313   // static code. %got is used to load global addresses when
 314   // using PIC_. %call16 is used to load direct call targets
 315   // on PIC_ and small code size. %call_lo and %call_hi load
 316   // direct call targets on PIC_ and large code size.
 317   if (MI->getOpcode() == Mips::LUi && !MO.isReg() && !MO.isImm()) {
 318     if ((isPIC) && (isCodeLarge))
 319       O << "%call_hi(";
 320     else
 321       O << "%hi(";
 322     closeP = true;
 323   } else if ((MI->getOpcode() == Mips::ADDiu) && !MO.isReg() && !MO.isImm()) {
 324     const MachineOperand &firstMO = MI->getOperand(opNum-1);
 325     if (firstMO.getReg() == Mips::GP)
 326       O << "%gp_rel(";
 327     else
 328       O << "%lo(";
 329     closeP = true;
 330   } else if ((isPIC) && (MI->getOpcode() == Mips::LW) &&
 331              (!MO.isReg()) && (!MO.isImm())) {
 332     const MachineOperand &firstMO = MI->getOperand(opNum-1);
 333     const MachineOperand &lastMO  = MI->getOperand(opNum+1);
 334     if ((firstMO.isReg()) && (lastMO.isReg())) {
 335       if ((firstMO.getReg() == Mips::T9) && (lastMO.getReg() == Mips::GP)
 336           && (!isCodeLarge))
 337         O << "%call16(";
 338       else if ((firstMO.getReg() != Mips::T9) && (lastMO.getReg() == Mips::GP))
 339         O << "%got(";
 340       else if ((firstMO.getReg() == Mips::T9) && (lastMO.getReg() != Mips::GP)
 341                && (isCodeLarge))
 342         O << "%call_lo(";
 343       closeP = true;
 344     }
 345   }
 346
 347   switch (MO.getType())
 348   {
 349     case MachineOperand::MO_Register:
 350       if (TargetRegisterInfo::isPhysicalRegister(MO.getReg()))
 351         O << '$' << LowercaseString (RI.get(MO.getReg()).AsmName);
 352       else
 353         O << '$' << MO.getReg();
 354       break;
 355
 356     case MachineOperand::MO_Immediate:
 357       O << (short int)MO.getImm();
 358       break;
 359
 360     case MachineOperand::MO_MachineBasicBlock:
 361       printBasicBlockLabel(MO.getMBB());
 362       return;
 363
 364     case MachineOperand::MO_GlobalAddress:
 365       O << Mang->getMangledName(MO.getGlobal());
 366       break;
 367
 368     case MachineOperand::MO_ExternalSymbol:
 369       O << MO.getSymbolName();
 370       break;
 371
 372     case MachineOperand::MO_JumpTableIndex:
 373       O << TAI->getPrivateGlobalPrefix() << "JTI" << getFunctionNumber()
 374       << '_' << MO.getIndex();
 375       break;
 376
 377     case MachineOperand::MO_ConstantPoolIndex:
 378       O << TAI->getPrivateGlobalPrefix() << "CPI"
 379         << getFunctionNumber() << "_" << MO.getIndex();
 380       break;
 381
 382     default:
 383       llvm_unreachable("<unknown operand type>");
 384   }
 385
 386   if (closeP) O << ")";
 387 }
 388
 389 void MipsAsmPrinter::printUnsignedImm(const MachineInstr *MI, int opNum) {
 390   const MachineOperand &MO = MI->getOperand(opNum);
 391   if (MO.getType() == MachineOperand::MO_Immediate)
 392     O << (unsigned short int)MO.getImm();
 393   else
 394     printOperand(MI, opNum);
 395 }
 396
 397 void MipsAsmPrinter::
 398 printMemOperand(const MachineInstr *MI, int opNum, const char *Modifier) {
 399   // when using stack locations for not load/store instructions
 400   // print the same way as all normal 3 operand instructions.
 401   if (Modifier && !strcmp(Modifier, "stackloc")) {
 402     printOperand(MI, opNum+1);
 403     O << ", ";
 404     printOperand(MI, opNum);
 405     return;
 406   }
 407
 408   // Load/Store memory operands -- imm($reg)
 409   // If PIC target the target is loaded as the
 410   // pattern lw $25,%call16($28)
 411   printOperand(MI, opNum);
 412   O << "(";
 413   printOperand(MI, opNum+1);
 414   O << ")";
 415 }
 416
 417 void MipsAsmPrinter::
 418 printFCCOperand(const MachineInstr *MI, int opNum, const char *Modifier) {
 419   const MachineOperand& MO = MI->getOperand(opNum);
 420   O << Mips::MipsFCCToString((Mips::CondCode)MO.getImm());
 421 }
 422
 423 bool MipsAsmPrinter::doInitialization(Module &M) {
 424   // FIXME: Use SwitchToSection.
 425
 426   // Tell the assembler which ABI we are using
 427   O << "\t.section .mdebug." << emitCurrentABIString() << '\n';
 428
 429   // TODO: handle O64 ABI
 430   if (Subtarget->isABI_EABI())
 431     O << "\t.section .gcc_compiled_long" <<
 432       (Subtarget->isGP32bit() ? "32" : "64") << '\n';
 433
 434   // return to previous section
 435   O << "\t.previous" << '\n';
 436
 437   return AsmPrinter::doInitialization(M);
 438 }
 439
 440 void MipsAsmPrinter::PrintGlobalVariable(const GlobalVariable *GVar) {
 441   const TargetData *TD = TM.getTargetData();
 442
 443   if (!GVar->hasInitializer())
 444     return;   // External global require no code
 445
 446   // Check to see if this is a special global used by LLVM, if so, emit it.
 447   if (EmitSpecialLLVMGlobal(GVar))
 448     return;
 449
 450   O << "\n\n";
 451   std::string name = Mang->getMangledName(GVar);
 452   Constant *C = GVar->getInitializer();
 453   if (isa<MDNode>(C) || isa<MDString>(C))
 454     return;
 455   const Type *CTy = C->getType();
 456   unsigned Size = TD->getTypeAllocSize(CTy);
 457   const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
 458   bool printSizeAndType = true;
 459
 460   // A data structure or array is aligned in memory to the largest
 461   // alignment boundary required by any data type inside it (this matches
 462   // the Preferred Type Alignment). For integral types, the alignment is
 463   // the type size.
 464   unsigned Align;
 465   if (CTy->getTypeID() == Type::IntegerTyID ||
 466       CTy->getTypeID() == Type::VoidTyID) {
 467     assert(!(Size & (Size-1)) && "Alignment is not a power of two!");
 468     Align = Log2_32(Size);
 469   } else
 470     Align = TD->getPreferredTypeAlignmentShift(CTy);
 471
 472   printVisibility(name, GVar->getVisibility());
 473
 474   SwitchToSection(getObjFileLowering().SectionForGlobal(GVar, Mang, TM));
 475
 476   if (C->isNullValue() && !GVar->hasSection()) {
 477     if (!GVar->isThreadLocal() &&
 478         (GVar->hasLocalLinkage() || GVar->isWeakForLinker())) {
 479       if (Size == 0) Size = 1;   // .comm Foo, 0 is undefined, avoid it.
 480
 481       if (GVar->hasLocalLinkage())
 482         O << "\t.local\t" << name << '\n';
 483
 484       O << TAI->getCOMMDirective() << name << ',' << Size;
 485       if (TAI->getCOMMDirectiveTakesAlignment())
 486         O << ',' << (1 << Align);
 487
 488       O << '\n';
 489       return;
 490     }
 491   }
 492   switch (GVar->getLinkage()) {
 493    case GlobalValue::LinkOnceAnyLinkage:
 494    case GlobalValue::LinkOnceODRLinkage:
 495    case GlobalValue::CommonLinkage:
 496    case GlobalValue::WeakAnyLinkage:
 497    case GlobalValue::WeakODRLinkage:
 498     // FIXME: Verify correct for weak.
 499     // Nonnull linkonce -> weak
 500     O << "\t.weak " << name << '\n';
 501     break;
 502    case GlobalValue::AppendingLinkage:
 503     // FIXME: appending linkage variables should go into a section of their name
 504     // or something.  For now, just emit them as external.
 505    case GlobalValue::ExternalLinkage:
 506     // If external or appending, declare as a global symbol
 507     O << TAI->getGlobalDirective() << name << '\n';
 508     // Fall Through
 509    case GlobalValue::PrivateLinkage:
 510    case GlobalValue::LinkerPrivateLinkage:
 511    case GlobalValue::InternalLinkage:
 512     if (CVA && CVA->isCString())
 513       printSizeAndType = false;
 514     break;
 515    case GlobalValue::GhostLinkage:
 516     llvm_unreachable("Should not have any unmaterialized functions!");
 517    case GlobalValue::DLLImportLinkage:
 518     llvm_unreachable("DLLImport linkage is not supported by this target!");
 519    case GlobalValue::DLLExportLinkage:
 520     llvm_unreachable("DLLExport linkage is not supported by this target!");
 521    default:
 522     llvm_unreachable("Unknown linkage type!");
 523   }
 524
 525   EmitAlignment(Align, GVar);
 526
 527   if (TAI->hasDotTypeDotSizeDirective() && printSizeAndType) {
 528     O << "\t.type " << name << ",@object\n";
 529     O << "\t.size " << name << ',' << Size << '\n';
 530   }
 531
 532   O << name << ":\n";
 533   EmitGlobalConstant(C);
 534 }
 535
 536
 537 // Force static initialization.
 538 extern "C" void LLVMInitializeMipsAsmPrinter() {
 539   RegisterAsmPrinter<MipsAsmPrinter> X(TheMipsTarget);
 540   RegisterAsmPrinter<MipsAsmPrinter> Y(TheMipselTarget);
 541 }