X86AsmPrinter.cpp revision 78ee7b78c3c47b71c4b7a1475438d6574216a64b 
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 "X86IntelAsmPrinter.h"
20#include "X86MachineFunctionInfo.h"
21#include "X86Subtarget.h"
22#include "llvm/ADT/StringExtras.h"
23#include "llvm/CallingConv.h"
24#include "llvm/Constants.h"
25#include "llvm/Module.h"
26#include "llvm/Type.h"
27#include "llvm/Assembly/Writer.h"
28#include "llvm/Support/Mangler.h"
29#include "llvm/Target/TargetAsmInfo.h"
30
31using namespace llvm;
32
33Statistic<> llvm::EmittedInsts("asm-printer",
34                               "Number of machine instrs printed");
35
36static X86FunctionInfo calculateFunctionInfo(const Function *F,
37                                             const TargetData *TD) {
38  X86FunctionInfo Info;
39  uint64_t Size = 0;
40
41  switch (F->getCallingConv()) {
42  case CallingConv::X86_StdCall:
43    Info.setDecorationStyle(StdCall);
44    break;
45  case CallingConv::X86_FastCall:
46    Info.setDecorationStyle(FastCall);
47    break;
48  default:
49    return Info;
50  }
51
52  for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
53       AI != AE; ++AI)
54    Size += TD->getTypeSize(AI->getType());
55
56  // Size should be aligned to DWORD boundary
57  Size = ((Size + 3)/4)*4;
58
59  // We're not supporting tooooo huge arguments :)
60  Info.setBytesToPopOnReturn((unsigned int)Size);
61  return Info;
62}
63
64
65/// decorateName - Query FunctionInfoMap and use this information for various
66/// name decoration.
67void X86SharedAsmPrinter::decorateName(std::string &Name,
68                                       const GlobalValue *GV) {
69  const Function *F = dyn_cast<Function>(GV);
70  if (!F) return;
71
72  // We don't want to decorate non-stdcall or non-fastcall functions right now
73  unsigned CC = F->getCallingConv();
74  if (CC != CallingConv::X86_StdCall && CC != CallingConv::X86_FastCall)
75    return;
76
77  FMFInfoMap::const_iterator info_item = FunctionInfoMap.find(F);
78
79  const X86FunctionInfo *Info;
80  if (info_item == FunctionInfoMap.end()) {
81    // Calculate apropriate function info and populate map
82    FunctionInfoMap[F] = calculateFunctionInfo(F, TM.getTargetData());
83    Info = &FunctionInfoMap[F];
84  } else {
85    Info = &info_item->second;
86  }
87
88  switch (Info->getDecorationStyle()) {
89  case None:
90    break;
91  case StdCall:
92    if (!F->isVarArg()) // Variadic functions do not receive @0 suffix.
93      Name += '@' + utostr_32(Info->getBytesToPopOnReturn());
94    break;
95  case FastCall:
96    if (!F->isVarArg()) // Variadic functions do not receive @0 suffix.
97      Name += '@' + utostr_32(Info->getBytesToPopOnReturn());
98
99    if (Name[0] == '_') {
100      Name[0] = '@';
101    } else {
102      Name = '@' + Name;
103    }
104    break;
105  default:
106    assert(0 && "Unsupported DecorationStyle");
107  }
108}
109
110/// doInitialization
111bool X86SharedAsmPrinter::doInitialization(Module &M) {
112  if (Subtarget->isTargetDarwin()) {
113    if (!Subtarget->is64Bit())
114      X86PICStyle = PICStyle::Stub;
115
116    // Emit initial debug information.
117    DW.BeginModule(&M);
118  } else if (Subtarget->isTargetELF() || Subtarget->isTargetCygwin()) {
119    // Emit initial debug information.
120    DW.BeginModule(&M);
121  }
122
123  return AsmPrinter::doInitialization(M);
124}
125
126bool X86SharedAsmPrinter::doFinalization(Module &M) {
127  // Note: this code is not shared by the Intel printer as it is too different
128  // from how MASM does things.  When making changes here don't forget to look
129  // at X86IntelAsmPrinter::doFinalization().
130  const TargetData *TD = TM.getTargetData();
131
132  // Print out module-level global variables here.
133  for (Module::const_global_iterator I = M.global_begin(), E = M.global_end();
134       I != E; ++I) {
135    if (!I->hasInitializer() && !I->hasExternalWeakLinkage())
136      continue;   // External global require no code
137
138    // Check to see if this is a special global used by LLVM, if so, emit it.
139    if (EmitSpecialLLVMGlobal(I))
140      continue;
141
142    std::string name = Mang->getValueName(I);
143    Constant *C = I->getInitializer();
144    unsigned Size = TD->getTypeSize(C->getType());
145    unsigned Align = TD->getPreferredAlignmentLog(I);
146
147    if (C->isNullValue() && /* FIXME: Verify correct */
148        !I->hasSection() &&
149        (I->hasInternalLinkage() || I->hasWeakLinkage() ||
150         I->hasLinkOnceLinkage() ||
151         (Subtarget->isTargetDarwin() &&
152          I->hasExternalLinkage()))) {
153      if (Size == 0) Size = 1;   // .comm Foo, 0 is undefined, avoid it.
154      if (I->hasExternalLinkage()) {
155          O << "\t.globl\t" << name << "\n";
156          O << "\t.zerofill __DATA__, __common, " << name << ", "
157            << Size << ", " << Align;
158      } else {
159        SwitchToDataSection(TAI->getDataSection(), I);
160        if (TAI->getLCOMMDirective() != NULL) {
161          if (I->hasInternalLinkage()) {
162            O << TAI->getLCOMMDirective() << name << "," << Size;
163            if (Subtarget->isTargetDarwin())
164              O << "," << (TAI->getAlignmentIsInBytes() ? (1 << Align) : Align);
165          } else
166            O << TAI->getCOMMDirective()  << name << "," << Size;
167        } else {
168          if (!Subtarget->isTargetCygwin()) {
169            if (I->hasInternalLinkage())
170              O << "\t.local\t" << name << "\n";
171          }
172          O << TAI->getCOMMDirective()  << name << "," << Size;
173          if (TAI->getCOMMDirectiveTakesAlignment())
174            O << "," << (TAI->getAlignmentIsInBytes() ? (1 << Align) : Align);
175        }
176      }
177      O << "\t\t" << TAI->getCommentString() << " " << I->getName() << "\n";
178    } else {
179      switch (I->getLinkage()) {
180      case GlobalValue::ExternalWeakLinkage:
181       if (Subtarget->isTargetDarwin()) {
182         assert(0 && "External weak linkage for Darwin not implemented yet");
183       } else if (Subtarget->isTargetCygwin()) {
184         // There is no external weak linkage on Mingw32 platform.
185         // Defaulting just to external
186         O << "\t.globl " << name << "\n";
187       } else {
188         O << "\t.weak " << name << "\n";
189         break;
190       }
191      case GlobalValue::LinkOnceLinkage:
192      case GlobalValue::WeakLinkage:
193        if (Subtarget->isTargetDarwin()) {
194          O << "\t.globl " << name << "\n"
195            << "\t.weak_definition " << name << "\n";
196          SwitchToDataSection(".section __DATA,__const_coal,coalesced", I);
197        } else if (Subtarget->isTargetCygwin()) {
198          std::string SectionName(".section\t.data$linkonce." +
199                                  name +
200                                  ",\"aw\"");
201          SwitchToDataSection(SectionName.c_str(), I);
202          O << "\t.globl " << name << "\n"
203            << "\t.linkonce same_size\n";
204        } else {
205          std::string SectionName("\t.section\t.llvm.linkonce.d." +
206                                  name +
207                                  ",\"aw\",@progbits");
208          SwitchToDataSection(SectionName.c_str(), I);
209          O << "\t.weak " << name << "\n";
210        }
211        break;
212      case GlobalValue::AppendingLinkage:
213        // FIXME: appending linkage variables should go into a section of
214        // their name or something.  For now, just emit them as external.
215      case GlobalValue::DLLExportLinkage:
216        DLLExportedGVs.insert(Mang->makeNameProper(I->getName(),""));
217        // FALL THROUGH
218      case GlobalValue::ExternalLinkage:
219        // If external or appending, declare as a global symbol
220        O << "\t.globl " << name << "\n";
221        // FALL THROUGH
222      case GlobalValue::InternalLinkage: {
223        if (I->isConstant()) {
224          const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
225          if (TAI->getCStringSection() && CVA && CVA->isCString()) {
226            SwitchToDataSection(TAI->getCStringSection(), I);
227            break;
228          }
229        }
230        // FIXME: special handling for ".ctors" & ".dtors" sections
231        if (I->hasSection() &&
232            (I->getSection() == ".ctors" ||
233             I->getSection() == ".dtors")) {
234          std::string SectionName = ".section " + I->getSection();
235
236          if (Subtarget->isTargetCygwin()) {
237            SectionName += ",\"aw\"";
238          } else {
239            assert(!Subtarget->isTargetDarwin());
240            SectionName += ",\"aw\",@progbits";
241          }
242
243          SwitchToDataSection(SectionName.c_str());
244        } else {
245          SwitchToDataSection(TAI->getDataSection(), I);
246        }
247
248        break;
249      }
250      default:
251        assert(0 && "Unknown linkage type!");
252      }
253
254      EmitAlignment(Align, I);
255      O << name << ":\t\t\t\t" << TAI->getCommentString() << " " << I->getName()
256        << "\n";
257      if (TAI->hasDotTypeDotSizeDirective())
258        O << "\t.size " << name << ", " << Size << "\n";
259
260      EmitGlobalConstant(C);
261      O << '\n';
262    }
263  }
264
265  // Output linker support code for dllexported globals
266  if (DLLExportedGVs.begin() != DLLExportedGVs.end()) {
267    SwitchToDataSection(".section .drectve");
268  }
269
270  for (std::set<std::string>::iterator i = DLLExportedGVs.begin(),
271         e = DLLExportedGVs.end();
272         i != e; ++i) {
273    O << "\t.ascii \" -export:" << *i << ",data\"\n";
274  }
275
276  if (DLLExportedFns.begin() != DLLExportedFns.end()) {
277    SwitchToDataSection(".section .drectve");
278  }
279
280  for (std::set<std::string>::iterator i = DLLExportedFns.begin(),
281         e = DLLExportedFns.end();
282         i != e; ++i) {
283    O << "\t.ascii \" -export:" << *i << "\"\n";
284  }
285
286  if (Subtarget->isTargetDarwin()) {
287    if (ExtWeakSymbols.begin() != ExtWeakSymbols.end())
288      assert(0 && "External weak linkage for Darwin not implemented yet");
289  } else if (Subtarget->isTargetCygwin()) {
290    // There is no external weak linkage on Mingw32 platform.
291    // Defaulting to external
292  } else {
293    if (ExtWeakSymbols.begin() != ExtWeakSymbols.end())
294      SwitchToDataSection("");
295
296    for (std::set<std::string>::iterator i = ExtWeakSymbols.begin(),
297         e = ExtWeakSymbols.end();
298         i != e; ++i) {
299      O << "\t.weak " << *i << "\n";
300    }
301  }
302
303  if (Subtarget->isTargetDarwin()) {
304    SwitchToDataSection("");
305
306    // Output stubs for dynamically-linked functions
307    unsigned j = 1;
308    for (std::set<std::string>::iterator i = FnStubs.begin(), e = FnStubs.end();
309         i != e; ++i, ++j) {
310      SwitchToDataSection(".section __IMPORT,__jump_table,symbol_stubs,"
311                          "self_modifying_code+pure_instructions,5", 0);
312      O << "L" << *i << "$stub:\n";
313      O << "\t.indirect_symbol " << *i << "\n";
314      O << "\thlt ; hlt ; hlt ; hlt ; hlt\n";
315    }
316
317    O << "\n";
318
319    // Output stubs for external and common global variables.
320    if (GVStubs.begin() != GVStubs.end())
321      SwitchToDataSection(
322                    ".section __IMPORT,__pointers,non_lazy_symbol_pointers");
323    for (std::set<std::string>::iterator i = GVStubs.begin(), e = GVStubs.end();
324         i != e; ++i) {
325      O << "L" << *i << "$non_lazy_ptr:\n";
326      O << "\t.indirect_symbol " << *i << "\n";
327      O << "\t.long\t0\n";
328    }
329
330    // Emit final debug information.
331    DW.EndModule();
332
333    // Funny Darwin hack: This flag tells the linker that no global symbols
334    // contain code that falls through to other global symbols (e.g. the obvious
335    // implementation of multiple entry points).  If this doesn't occur, the
336    // linker can safely perform dead code stripping.  Since LLVM never
337    // generates code that does this, it is always safe to set.
338    O << "\t.subsections_via_symbols\n";
339  } else if (Subtarget->isTargetELF() || Subtarget->isTargetCygwin()) {
340    // Emit final debug information.
341    DW.EndModule();
342  }
343
344  AsmPrinter::doFinalization(M);
345  return false; // success
346}
347
348/// createX86CodePrinterPass - Returns a pass that prints the X86 assembly code
349/// for a MachineFunction to the given output stream, using the given target
350/// machine description.
351///
352FunctionPass *llvm::createX86CodePrinterPass(std::ostream &o,
353                                             X86TargetMachine &tm) {
354  const X86Subtarget *Subtarget = &tm.getSubtarget<X86Subtarget>();
355
356  if (Subtarget->isFlavorIntel()) {
357    return new X86IntelAsmPrinter(o, tm, tm.getTargetAsmInfo());
358  } else {
359    return new X86ATTAsmPrinter(o, tm, tm.getTargetAsmInfo());
360  }
361}
362