X86AsmPrinter.cpp revision f9c197e022521a83f8876890b4241fc23e63572c 
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    const X86Subtarget *Subtarget = &TM.getSubtarget<X86Subtarget>();
114    if (!Subtarget->is64Bit())
115      X86PICStyle = PICStyle::Stub;
116
117    // Emit initial debug information.
118    DW.BeginModule(&M);
119  }
120
121  return AsmPrinter::doInitialization(M);
122}
123
124bool X86SharedAsmPrinter::doFinalization(Module &M) {
125  // Note: this code is not shared by the Intel printer as it is too different
126  // from how MASM does things.  When making changes here don't forget to look
127  // at X86IntelAsmPrinter::doFinalization().
128  const TargetData *TD = TM.getTargetData();
129
130  // Print out module-level global variables here.
131  for (Module::const_global_iterator I = M.global_begin(), E = M.global_end();
132       I != E; ++I) {
133    if (!I->hasInitializer()) continue;   // External global require no code
134
135    // Check to see if this is a special global used by LLVM, if so, emit it.
136    if (EmitSpecialLLVMGlobal(I))
137      continue;
138
139    std::string name = Mang->getValueName(I);
140    Constant *C = I->getInitializer();
141    unsigned Size = TD->getTypeSize(C->getType());
142    unsigned Align = TD->getPreferredAlignmentLog(I);
143
144    if (C->isNullValue() && /* FIXME: Verify correct */
145        (I->hasInternalLinkage() || I->hasWeakLinkage() ||
146         I->hasLinkOnceLinkage() ||
147         (Subtarget->isTargetDarwin() &&
148          I->hasExternalLinkage() && !I->hasSection()))) {
149      if (Size == 0) Size = 1;   // .comm Foo, 0 is undefined, avoid it.
150      if (I->hasExternalLinkage()) {
151          O << "\t.globl\t" << name << "\n";
152          O << "\t.zerofill __DATA__, __common, " << name << ", "
153            << Size << ", " << Align;
154      } else {
155        SwitchToDataSection(TAI->getDataSection(), I);
156        if (TAI->getLCOMMDirective() != NULL) {
157          if (I->hasInternalLinkage()) {
158            O << TAI->getLCOMMDirective() << name << "," << Size;
159            if (Subtarget->isTargetDarwin())
160              O << "," << (TAI->getAlignmentIsInBytes() ? (1 << Align) : Align);
161          } else
162            O << TAI->getCOMMDirective()  << name << "," << Size;
163        } else {
164          if (!Subtarget->isTargetCygwin()) {
165            if (I->hasInternalLinkage())
166              O << "\t.local\t" << name << "\n";
167          }
168          O << TAI->getCOMMDirective()  << name << "," << Size;
169          if (TAI->getCOMMDirectiveTakesAlignment())
170            O << "," << (TAI->getAlignmentIsInBytes() ? (1 << Align) : Align);
171        }
172      }
173      O << "\t\t" << TAI->getCommentString() << " " << I->getName() << "\n";
174    } else {
175      switch (I->getLinkage()) {
176      case GlobalValue::LinkOnceLinkage:
177      case GlobalValue::WeakLinkage:
178        if (Subtarget->isTargetDarwin()) {
179          O << "\t.globl " << name << "\n"
180            << "\t.weak_definition " << name << "\n";
181          SwitchToDataSection(".section __DATA,__const_coal,coalesced", I);
182        } else if (Subtarget->isTargetCygwin()) {
183          std::string SectionName(".section\t.data$linkonce." +
184                                  name +
185                                  ",\"aw\"\n");
186          SwitchToDataSection(SectionName.c_str(), I);
187          O << "\t.globl " << name << "\n"
188            << "\t.linkonce same_size\n";
189        } else {
190          std::string SectionName("\t.section\t.llvm.linkonce.d." +
191                                  name +
192                                  ",\"aw\",@progbits\n");
193          SwitchToDataSection(SectionName.c_str(), I);
194          O << "\t.weak " << name << "\n";
195        }
196        break;
197      case GlobalValue::AppendingLinkage:
198        // FIXME: appending linkage variables should go into a section of
199        // their name or something.  For now, just emit them as external.
200      case GlobalValue::DLLExportLinkage:
201        DLLExportedGVs.insert(Mang->makeNameProper(I->getName(),""));
202        // FALL THROUGH
203      case GlobalValue::ExternalLinkage:
204        // If external or appending, declare as a global symbol
205        O << "\t.globl " << name << "\n";
206        // FALL THROUGH
207      case GlobalValue::InternalLinkage:
208        SwitchToDataSection(TAI->getDataSection(), I);
209        break;
210      default:
211        assert(0 && "Unknown linkage type!");
212      }
213
214      EmitAlignment(Align, I);
215      O << name << ":\t\t\t\t" << TAI->getCommentString() << " " << I->getName()
216        << "\n";
217      if (TAI->hasDotTypeDotSizeDirective())
218        O << "\t.size " << name << ", " << Size << "\n";
219
220      EmitGlobalConstant(C);
221      O << '\n';
222    }
223  }
224
225  // Output linker support code for dllexported globals
226  if (DLLExportedGVs.begin() != DLLExportedGVs.end()) {
227    SwitchToDataSection(".section .drectve", 0);
228  }
229
230  for (std::set<std::string>::iterator i = DLLExportedGVs.begin(),
231         e = DLLExportedGVs.end();
232         i != e; ++i) {
233    O << "\t.ascii \" -export:" << *i << ",data\"\n";
234  }
235
236  if (DLLExportedFns.begin() != DLLExportedFns.end()) {
237    SwitchToDataSection(".section .drectve", 0);
238  }
239
240  for (std::set<std::string>::iterator i = DLLExportedFns.begin(),
241         e = DLLExportedFns.end();
242         i != e; ++i) {
243    O << "\t.ascii \" -export:" << *i << "\"\n";
244  }
245
246  if (Subtarget->isTargetDarwin()) {
247    SwitchToDataSection("", 0);
248
249    // Output stubs for dynamically-linked functions
250    unsigned j = 1;
251    for (std::set<std::string>::iterator i = FnStubs.begin(), e = FnStubs.end();
252         i != e; ++i, ++j) {
253      SwitchToDataSection(".section __IMPORT,__jump_table,symbol_stubs,"
254                          "self_modifying_code+pure_instructions,5", 0);
255      O << "L" << *i << "$stub:\n";
256      O << "\t.indirect_symbol " << *i << "\n";
257      O << "\thlt ; hlt ; hlt ; hlt ; hlt\n";
258    }
259
260    O << "\n";
261
262    // Output stubs for external and common global variables.
263    if (GVStubs.begin() != GVStubs.end())
264      SwitchToDataSection(
265                    ".section __IMPORT,__pointers,non_lazy_symbol_pointers", 0);
266    for (std::set<std::string>::iterator i = GVStubs.begin(), e = GVStubs.end();
267         i != e; ++i) {
268      O << "L" << *i << "$non_lazy_ptr:\n";
269      O << "\t.indirect_symbol " << *i << "\n";
270      O << "\t.long\t0\n";
271    }
272
273    // Emit initial debug information.
274    DW.EndModule();
275
276    // Funny Darwin hack: This flag tells the linker that no global symbols
277    // contain code that falls through to other global symbols (e.g. the obvious
278    // implementation of multiple entry points).  If this doesn't occur, the
279    // linker can safely perform dead code stripping.  Since LLVM never
280    // generates code that does this, it is always safe to set.
281    O << "\t.subsections_via_symbols\n";
282  }
283
284  AsmPrinter::doFinalization(M);
285  return false; // success
286}
287
288/// createX86CodePrinterPass - Returns a pass that prints the X86 assembly code
289/// for a MachineFunction to the given output stream, using the given target
290/// machine description.
291///
292FunctionPass *llvm::createX86CodePrinterPass(std::ostream &o,
293                                             X86TargetMachine &tm) {
294  const X86Subtarget *Subtarget = &tm.getSubtarget<X86Subtarget>();
295
296  if (Subtarget->isFlavorIntel()) {
297    return new X86IntelAsmPrinter(o, tm, tm.getTargetAsmInfo());
298  } else {
299    return new X86ATTAsmPrinter(o, tm, tm.getTargetAsmInfo());
300  }
301}
302