X86AsmPrinter.cpp revision 52c0253f04e9641436f0997b95a0c60266da3c26 
1//===-- X86AsmPrinter.cpp - Convert X86 LLVM IR to X86 assembly -----------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file the shared super class printer that converts from our internal
11// representation of machine-dependent LLVM code to Intel and AT&T format
12// assembly language.
13// This printer is the output mechanism used by `llc'.
14//
15//===----------------------------------------------------------------------===//
16
17#include "X86AsmPrinter.h"
18#include "X86ATTAsmPrinter.h"
19#include "X86COFF.h"
20#include "X86IntelAsmPrinter.h"
21#include "X86MachineFunctionInfo.h"
22#include "X86Subtarget.h"
23#include "llvm/ADT/StringExtras.h"
24#include "llvm/CallingConv.h"
25#include "llvm/Constants.h"
26#include "llvm/Module.h"
27#include "llvm/DerivedTypes.h"
28#include "llvm/Type.h"
29#include "llvm/Assembly/Writer.h"
30#include "llvm/Support/Mangler.h"
31#include "llvm/Target/TargetAsmInfo.h"
32#include "llvm/Target/TargetOptions.h"
33using namespace llvm;
34
35static X86MachineFunctionInfo calculateFunctionInfo(const Function *F,
36                                                    const TargetData *TD) {
37  X86MachineFunctionInfo Info;
38  uint64_t Size = 0;
39
40  switch (F->getCallingConv()) {
41  case CallingConv::X86_StdCall:
42    Info.setDecorationStyle(StdCall);
43    break;
44  case CallingConv::X86_FastCall:
45    Info.setDecorationStyle(FastCall);
46    break;
47  default:
48    return Info;
49  }
50
51  for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
52       AI != AE; ++AI)
53    // Size should be aligned to DWORD boundary
54    Size += ((TD->getTypeSize(AI->getType()) + 3)/4)*4;
55
56  // We're not supporting tooooo huge arguments :)
57  Info.setBytesToPopOnReturn((unsigned int)Size);
58  return Info;
59}
60
61
62/// decorateName - Query FunctionInfoMap and use this information for various
63/// name decoration.
64void X86SharedAsmPrinter::decorateName(std::string &Name,
65                                       const GlobalValue *GV) {
66  const Function *F = dyn_cast<Function>(GV);
67  if (!F) return;
68
69  // We don't want to decorate non-stdcall or non-fastcall functions right now
70  unsigned CC = F->getCallingConv();
71  if (CC != CallingConv::X86_StdCall && CC != CallingConv::X86_FastCall)
72    return;
73
74  // Decorate names only when we're targeting Cygwin/Mingw32 targets
75  if (!Subtarget->isTargetCygMing())
76    return;
77
78  FMFInfoMap::const_iterator info_item = FunctionInfoMap.find(F);
79
80  const X86MachineFunctionInfo *Info;
81  if (info_item == FunctionInfoMap.end()) {
82    // Calculate apropriate function info and populate map
83    FunctionInfoMap[F] = calculateFunctionInfo(F, TM.getTargetData());
84    Info = &FunctionInfoMap[F];
85  } else {
86    Info = &info_item->second;
87  }
88
89  const FunctionType *FT = F->getFunctionType();
90  switch (Info->getDecorationStyle()) {
91  case None:
92    break;
93  case StdCall:
94    // "Pure" variadic functions do not receive @0 suffix.
95    if (!FT->isVarArg() || (FT->getNumParams() == 0) ||
96        (FT->getNumParams() == 1 && FT->isStructReturn()))
97      Name += '@' + utostr_32(Info->getBytesToPopOnReturn());
98    break;
99  case FastCall:
100    // "Pure" variadic functions do not receive @0 suffix.
101    if (!FT->isVarArg() || (FT->getNumParams() == 0) ||
102        (FT->getNumParams() == 1 && FT->isStructReturn()))
103      Name += '@' + utostr_32(Info->getBytesToPopOnReturn());
104
105    if (Name[0] == '_') {
106      Name[0] = '@';
107    } else {
108      Name = '@' + Name;
109    }
110    break;
111  default:
112    assert(0 && "Unsupported DecorationStyle");
113  }
114}
115
116/// doInitialization
117bool X86SharedAsmPrinter::doInitialization(Module &M) {
118  if (TAI->doesSupportDebugInformation()) {
119    // Emit initial debug information.
120    DW.BeginModule(&M);
121  }
122
123  bool Result = AsmPrinter::doInitialization(M);
124
125  // Darwin wants symbols to be quoted if they have complex names.
126  if (Subtarget->isTargetDarwin())
127    Mang->setUseQuotes(true);
128
129  return Result;
130}
131
132bool X86SharedAsmPrinter::doFinalization(Module &M) {
133  // Note: this code is not shared by the Intel printer as it is too different
134  // from how MASM does things.  When making changes here don't forget to look
135  // at X86IntelAsmPrinter::doFinalization().
136  const TargetData *TD = TM.getTargetData();
137
138  // Print out module-level global variables here.
139  for (Module::const_global_iterator I = M.global_begin(), E = M.global_end();
140       I != E; ++I) {
141    if (!I->hasInitializer())
142      continue;   // External global require no code
143
144    // Check to see if this is a special global used by LLVM, if so, emit it.
145    if (EmitSpecialLLVMGlobal(I)) {
146      if (Subtarget->isTargetDarwin() &&
147          TM.getRelocationModel() == Reloc::Static) {
148        if (I->getName() == "llvm.global_ctors")
149          O << ".reference .constructors_used\n";
150        else if (I->getName() == "llvm.global_dtors")
151          O << ".reference .destructors_used\n";
152      }
153      continue;
154    }
155
156    std::string name = Mang->getValueName(I);
157    Constant *C = I->getInitializer();
158    const Type *Type = C->getType();
159    unsigned Size = TD->getTypeSize(Type);
160    unsigned Align = TD->getPreferredAlignmentLog(I);
161
162    if (I->hasHiddenVisibility()) {
163      if (const char *Directive = TAI->getHiddenDirective())
164        O << Directive << name << "\n";
165    } else if (I->hasProtectedVisibility()) {
166      if (const char *Directive = TAI->getProtectedDirective())
167        O << Directive << name << "\n";
168    }
169
170    if (Subtarget->isTargetELF())
171      O << "\t.type\t" << name << ",@object\n";
172
173    if (C->isNullValue() && !I->hasSection()) {
174      if (I->hasExternalLinkage()) {
175        if (const char *Directive = TAI->getZeroFillDirective()) {
176          O << "\t.globl\t" << name << "\n";
177          O << Directive << "__DATA__, __common, " << name << ", "
178            << Size << ", " << Align << "\n";
179          continue;
180        }
181      }
182
183      if (!I->isThreadLocal() &&
184          (I->hasInternalLinkage() || I->hasWeakLinkage() ||
185           I->hasLinkOnceLinkage())) {
186        if (Size == 0) Size = 1;   // .comm Foo, 0 is undefined, avoid it.
187        if (!NoZerosInBSS && TAI->getBSSSection())
188          SwitchToDataSection(TAI->getBSSSection(), I);
189        else
190          SwitchToDataSection(TAI->getDataSection(), I);
191        if (TAI->getLCOMMDirective() != NULL) {
192          if (I->hasInternalLinkage()) {
193            O << TAI->getLCOMMDirective() << name << "," << Size;
194            if (Subtarget->isTargetDarwin())
195              O << "," << Align;
196          } else
197            O << TAI->getCOMMDirective()  << name << "," << Size;
198        } else {
199          if (!Subtarget->isTargetCygMing()) {
200            if (I->hasInternalLinkage())
201              O << "\t.local\t" << name << "\n";
202          }
203          O << TAI->getCOMMDirective()  << name << "," << Size;
204          if (TAI->getCOMMDirectiveTakesAlignment())
205            O << "," << (TAI->getAlignmentIsInBytes() ? (1 << Align) : Align);
206        }
207        O << "\t\t" << TAI->getCommentString() << " " << I->getName() << "\n";
208        continue;
209      }
210    }
211
212    switch (I->getLinkage()) {
213    case GlobalValue::LinkOnceLinkage:
214    case GlobalValue::WeakLinkage:
215      if (Subtarget->isTargetDarwin()) {
216        O << "\t.globl\t" << name << "\n"
217          << "\t.weak_definition " << name << "\n";
218        SwitchToDataSection(".section __DATA,__const_coal,coalesced", I);
219      } else if (Subtarget->isTargetCygMing()) {
220        std::string SectionName(".section\t.data$linkonce." +
221                                name +
222                                ",\"aw\"");
223        SwitchToDataSection(SectionName.c_str(), I);
224        O << "\t.globl\t" << name << "\n"
225          << "\t.linkonce same_size\n";
226      } else {
227        std::string SectionName("\t.section\t.llvm.linkonce.d." +
228                                name +
229                                ",\"aw\",@progbits");
230        SwitchToDataSection(SectionName.c_str(), I);
231        O << "\t.weak\t" << name << "\n";
232      }
233      break;
234    case GlobalValue::DLLExportLinkage:
235      DLLExportedGVs.insert(Mang->makeNameProper(I->getName(),""));
236      // FALL THROUGH
237    case GlobalValue::AppendingLinkage:
238      // FIXME: appending linkage variables should go into a section of
239      // their name or something.  For now, just emit them as external.
240    case GlobalValue::ExternalLinkage:
241      // If external or appending, declare as a global symbol
242      O << "\t.globl\t" << name << "\n";
243      // FALL THROUGH
244    case GlobalValue::InternalLinkage: {
245      if (I->isConstant()) {
246        const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
247        if (TAI->getCStringSection() && CVA && CVA->isCString()) {
248          SwitchToDataSection(TAI->getCStringSection(), I);
249          break;
250        }
251      }
252      // FIXME: special handling for ".ctors" & ".dtors" sections
253      if (I->hasSection() &&
254          (I->getSection() == ".ctors" ||
255           I->getSection() == ".dtors")) {
256        std::string SectionName = ".section " + I->getSection();
257
258        if (Subtarget->isTargetCygMing()) {
259          SectionName += ",\"aw\"";
260        } else {
261          assert(!Subtarget->isTargetDarwin());
262          SectionName += ",\"aw\",@progbits";
263        }
264
265        SwitchToDataSection(SectionName.c_str());
266      } else {
267        if (C->isNullValue() && !NoZerosInBSS && TAI->getBSSSection())
268          SwitchToDataSection(I->isThreadLocal() ? TAI->getTLSBSSSection() :
269                              TAI->getBSSSection(), I);
270        else if (!I->isConstant())
271          SwitchToDataSection(I->isThreadLocal() ? TAI->getTLSDataSection() :
272                              TAI->getDataSection(), I);
273        else if (I->isThreadLocal())
274          SwitchToDataSection(TAI->getTLSDataSection());
275        else {
276          // Read-only data.
277          bool HasReloc = C->ContainsRelocations();
278          if (HasReloc &&
279              Subtarget->isTargetDarwin() &&
280              TM.getRelocationModel() != Reloc::Static)
281            SwitchToDataSection("\t.const_data\n");
282          else if (!HasReloc && Size == 4 &&
283                   TAI->getFourByteConstantSection())
284            SwitchToDataSection(TAI->getFourByteConstantSection(), I);
285          else if (!HasReloc && Size == 8 &&
286                   TAI->getEightByteConstantSection())
287            SwitchToDataSection(TAI->getEightByteConstantSection(), I);
288          else if (!HasReloc && Size == 16 &&
289                   TAI->getSixteenByteConstantSection())
290            SwitchToDataSection(TAI->getSixteenByteConstantSection(), I);
291          else if (TAI->getReadOnlySection())
292            SwitchToDataSection(TAI->getReadOnlySection(), I);
293          else
294            SwitchToDataSection(TAI->getDataSection(), I);
295        }
296      }
297
298      break;
299    }
300    default:
301      assert(0 && "Unknown linkage type!");
302    }
303
304    EmitAlignment(Align, I);
305    O << name << ":\t\t\t\t" << TAI->getCommentString() << " " << I->getName()
306      << "\n";
307    if (TAI->hasDotTypeDotSizeDirective())
308      O << "\t.size\t" << name << ", " << Size << "\n";
309    // If the initializer is a extern weak symbol, remember to emit the weak
310    // reference!
311    if (const GlobalValue *GV = dyn_cast<GlobalValue>(C))
312      if (GV->hasExternalWeakLinkage())
313        ExtWeakSymbols.insert(GV);
314
315    EmitGlobalConstant(C);
316  }
317
318  // Output linker support code for dllexported globals
319  if (!DLLExportedGVs.empty()) {
320    SwitchToDataSection(".section .drectve");
321  }
322
323  for (std::set<std::string>::iterator i = DLLExportedGVs.begin(),
324         e = DLLExportedGVs.end();
325         i != e; ++i) {
326    O << "\t.ascii \" -export:" << *i << ",data\"\n";
327  }
328
329  if (!DLLExportedFns.empty()) {
330    SwitchToDataSection(".section .drectve");
331  }
332
333  for (std::set<std::string>::iterator i = DLLExportedFns.begin(),
334         e = DLLExportedFns.end();
335         i != e; ++i) {
336    O << "\t.ascii \" -export:" << *i << "\"\n";
337  }
338
339  if (Subtarget->isTargetDarwin()) {
340    SwitchToDataSection("");
341
342    // Output stubs for dynamically-linked functions
343    unsigned j = 1;
344    for (std::set<std::string>::iterator i = FnStubs.begin(), e = FnStubs.end();
345         i != e; ++i, ++j) {
346      SwitchToDataSection(".section __IMPORT,__jump_table,symbol_stubs,"
347                          "self_modifying_code+pure_instructions,5", 0);
348      O << "L" << *i << "$stub:\n";
349      O << "\t.indirect_symbol " << *i << "\n";
350      O << "\thlt ; hlt ; hlt ; hlt ; hlt\n";
351    }
352
353    O << "\n";
354
355    if (ExceptionHandling && TAI->doesSupportExceptionHandling() && MMI) {
356      // Add the (possibly multiple) personalities to the set of global values.
357      const std::vector<Function *>& Personalities = MMI->getPersonalities();
358
359      for (std::vector<Function *>::const_iterator I = Personalities.begin(),
360             E = Personalities.end(); I != E; ++I)
361        if (*I) GVStubs.insert("_" + (*I)->getName());
362    }
363
364    // Output stubs for external and common global variables.
365    if (!GVStubs.empty())
366      SwitchToDataSection(
367                    ".section __IMPORT,__pointers,non_lazy_symbol_pointers");
368    for (std::set<std::string>::iterator i = GVStubs.begin(), e = GVStubs.end();
369         i != e; ++i) {
370      O << "L" << *i << "$non_lazy_ptr:\n";
371      O << "\t.indirect_symbol " << *i << "\n";
372      O << "\t.long\t0\n";
373    }
374
375    // Emit final debug information.
376    DW.EndModule();
377
378    // Funny Darwin hack: This flag tells the linker that no global symbols
379    // contain code that falls through to other global symbols (e.g. the obvious
380    // implementation of multiple entry points).  If this doesn't occur, the
381    // linker can safely perform dead code stripping.  Since LLVM never
382    // generates code that does this, it is always safe to set.
383    O << "\t.subsections_via_symbols\n";
384  } else if (Subtarget->isTargetCygMing()) {
385    // Emit type information for external functions
386    for (std::set<std::string>::iterator i = FnStubs.begin(), e = FnStubs.end();
387         i != e; ++i) {
388      O << "\t.def\t " << *i
389        << ";\t.scl\t" << COFF::C_EXT
390        << ";\t.type\t" << (COFF::DT_FCN << COFF::N_BTSHFT)
391        << ";\t.endef\n";
392    }
393
394    // Emit final debug information.
395    DW.EndModule();
396  } else if (Subtarget->isTargetELF()) {
397    // Emit final debug information.
398    DW.EndModule();
399  }
400
401  return AsmPrinter::doFinalization(M);
402}
403
404/// createX86CodePrinterPass - Returns a pass that prints the X86 assembly code
405/// for a MachineFunction to the given output stream, using the given target
406/// machine description.
407///
408FunctionPass *llvm::createX86CodePrinterPass(std::ostream &o,
409                                             X86TargetMachine &tm) {
410  const X86Subtarget *Subtarget = &tm.getSubtarget<X86Subtarget>();
411
412  if (Subtarget->isFlavorIntel()) {
413    return new X86IntelAsmPrinter(o, tm, tm.getTargetAsmInfo());
414  } else {
415    return new X86ATTAsmPrinter(o, tm, tm.getTargetAsmInfo());
416  }
417}
418