X86AsmPrinter.cpp revision 62cbf2aab9fd5366281871974ef580fd072309cc 
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 "X86ATTAsmPrinter.h"
18#include "X86IntelAsmPrinter.h"
19#include "X86.h"
20#include "llvm/Module.h"
21#include "llvm/Type.h"
22#include "llvm/Assembly/Writer.h"
23#include "llvm/CodeGen/MachineConstantPool.h"
24#include "llvm/Support/Mangler.h"
25#include "llvm/Support/CommandLine.h"
26using namespace llvm;
27using namespace x86;
28
29Statistic<> llvm::x86::EmittedInsts("asm-printer",
30                                    "Number of machine instrs printed");
31
32enum AsmWriterFlavorTy { att, intel };
33cl::opt<AsmWriterFlavorTy>
34AsmWriterFlavor("x86-asm-syntax",
35                cl::desc("Choose style of code to emit from X86 backend:"),
36                cl::values(
37                           clEnumVal(att,   "  Emit AT&T-style assembly"),
38                           clEnumVal(intel, "  Emit Intel-style assembly"),
39                           clEnumValEnd),
40                cl::init(att));
41
42/// doInitialization
43bool X86SharedAsmPrinter::doInitialization(Module& M) {
44  bool leadingUnderscore = false;
45  forCygwin = false;
46  const std::string& TT = M.getTargetTriple();
47  if (TT.length() > 5) {
48    forCygwin = TT.find("cygwin") != std::string::npos ||
49                TT.find("mingw")  != std::string::npos;
50    forDarwin = TT.find("darwin") != std::string::npos;
51  } else if (TT.empty()) {
52#if defined(__CYGWIN__) || defined(__MINGW32__)
53    forCygwin = true;
54#elif defined(__APPLE__)
55    forDarwin = true;
56#elif defined(_WIN32)
57    leadingUnderscore = true;
58#else
59    leadingUnderscore = false;
60#endif
61  }
62
63  if (leadingUnderscore || forCygwin || forDarwin)
64    GlobalPrefix = "_";
65
66  if (forDarwin) {
67    AlignmentIsInBytes = false;
68    Data64bitsDirective = 0;       // we can't emit a 64-bit unit
69    ZeroDirective = "\t.space\t";  // ".space N" emits N zeros.
70    PrivateGlobalPrefix = "L";     // Marker for constant pool idxs
71  }
72
73  return AsmPrinter::doInitialization(M);
74}
75
76/// printConstantPool - Print to the current output stream assembly
77/// representations of the constants in the constant pool MCP. This is
78/// used to print out constants which have been "spilled to memory" by
79/// the code generator.
80///
81void X86SharedAsmPrinter::printConstantPool(MachineConstantPool *MCP) {
82  const std::vector<Constant*> &CP = MCP->getConstants();
83  const TargetData &TD = TM.getTargetData();
84
85  if (CP.empty()) return;
86
87  if (forDarwin) {
88    O << "\t.const\n";
89  } else {
90    O << "\t.section .rodata\n";
91  }
92
93  for (unsigned i = 0, e = CP.size(); i != e; ++i) {
94    // FIXME: force doubles to be naturally aligned.  We should handle this
95    // more correctly in the future.
96    if (CP[i]->getType() == Type::DoubleTy)
97      emitAlignment(3);
98    else
99      emitAlignment(TD.getTypeAlignmentShift(CP[i]->getType()));
100    O << PrivateGlobalPrefix << "CPI" << CurrentFnName << "_" << i
101      << ":\t\t\t\t\t" << CommentString << *CP[i] << "\n";
102    emitGlobalConstant(CP[i]);
103  }
104}
105
106bool X86SharedAsmPrinter::doFinalization(Module &M) {
107  const TargetData &TD = TM.getTargetData();
108  std::string CurSection;
109
110  // Print out module-level global variables here.
111  for (Module::const_global_iterator I = M.global_begin(),
112         E = M.global_end(); I != E; ++I)
113    if (I->hasInitializer()) {   // External global require no code
114      O << "\n\n";
115      std::string name = Mang->getValueName(I);
116      Constant *C = I->getInitializer();
117      unsigned Size = TD.getTypeSize(C->getType());
118      unsigned Align = TD.getTypeAlignmentShift(C->getType());
119
120      if (C->isNullValue() &&
121          (I->hasLinkOnceLinkage() || I->hasInternalLinkage() ||
122           I->hasWeakLinkage() /* FIXME: Verify correct */)) {
123        switchSection(O, CurSection, ".data");
124        if (!forCygwin && !forDarwin && I->hasInternalLinkage())
125          O << "\t.local " << name << "\n";
126        if (forDarwin && I->hasInternalLinkage())
127          O << "\t.lcomm " << name << "," << Size << "," << Align;
128        else
129          O << "\t.comm " << name << "," << Size;
130        if (!forCygwin && !forDarwin)
131          O << "," << (1 << Align);
132        O << "\t\t# ";
133        WriteAsOperand(O, I, true, true, &M);
134        O << "\n";
135      } else {
136        switch (I->getLinkage()) {
137        default: assert(0 && "Unknown linkage type!");
138        case GlobalValue::LinkOnceLinkage:
139        case GlobalValue::WeakLinkage:   // FIXME: Verify correct for weak.
140          // Nonnull linkonce -> weak
141          O << "\t.weak " << name << "\n";
142          switchSection(O, CurSection, "");
143          O << "\t.section\t.llvm.linkonce.d." << name << ",\"aw\",@progbits\n";
144          break;
145        case GlobalValue::AppendingLinkage:
146          // FIXME: appending linkage variables should go into a section of
147          // their name or something.  For now, just emit them as external.
148        case GlobalValue::ExternalLinkage:
149          // If external or appending, declare as a global symbol
150          O << "\t.globl " << name << "\n";
151          // FALL THROUGH
152        case GlobalValue::InternalLinkage:
153          if (C->isNullValue())
154            switchSection(O, CurSection, ".bss");
155          else
156            switchSection(O, CurSection, ".data");
157          break;
158        }
159
160        emitAlignment(Align);
161        if (!forCygwin && !forDarwin) {
162          O << "\t.type " << name << ",@object\n";
163          O << "\t.size " << name << "," << Size << "\n";
164        }
165        O << name << ":\t\t\t\t# ";
166        WriteAsOperand(O, I, true, true, &M);
167        O << " = ";
168        WriteAsOperand(O, C, false, false, &M);
169        O << "\n";
170        emitGlobalConstant(C);
171      }
172    }
173
174  if (forDarwin) {
175    // Output stubs for external global variables
176    if (GVStubs.begin() != GVStubs.end())
177      O << "\t.non_lazy_symbol_pointer\n";
178    for (std::set<std::string>::iterator i = GVStubs.begin(), e = GVStubs.end();
179         i != e; ++i) {
180      O << "L" << *i << "$non_lazy_ptr:\n";
181      O << "\t.indirect_symbol " << *i << "\n";
182      O << "\t.long\t0\n";
183    }
184
185    // Output stubs for dynamically-linked functions
186    unsigned j = 1;
187    for (std::set<std::string>::iterator i = FnStubs.begin(), e = FnStubs.end();
188         i != e; ++i, ++j) {
189      O << "\t.symbol_stub\n";
190      O << "L" << *i << "$stub:\n";
191      O << "\t.indirect_symbol " << *i << "\n";
192      O << "\tjmp\t*L" << j << "$lz\n";
193      O << "L" << *i << "$stub_binder:\n";
194      O << "\tpushl\t$L" << j << "$lz\n";
195      O << "\tjmp\tdyld_stub_binding_helper\n";
196      O << "\t.section __DATA, __la_sym_ptr3,lazy_symbol_pointers\n";
197      O << "L" << j << "$lz:\n";
198      O << "\t.indirect_symbol " << *i << "\n";
199      O << "\t.long\tL" << *i << "$stub_binder\n";
200    }
201
202    O << "\n";
203
204    // Output stubs for link-once variables
205    if (LinkOnceStubs.begin() != LinkOnceStubs.end())
206      O << ".data\n.align 2\n";
207    for (std::set<std::string>::iterator i = LinkOnceStubs.begin(),
208         e = LinkOnceStubs.end(); i != e; ++i) {
209      O << "L" << *i << "$non_lazy_ptr:\n"
210        << "\t.long\t" << *i << '\n';
211    }
212  }
213
214  AsmPrinter::doFinalization(M);
215  return false; // success
216}
217
218/// createX86CodePrinterPass - Returns a pass that prints the X86 assembly code
219/// for a MachineFunction to the given output stream, using the given target
220/// machine description.
221///
222FunctionPass *llvm::createX86CodePrinterPass(std::ostream &o,TargetMachine &tm){
223  switch (AsmWriterFlavor) {
224  default:
225    assert(0 && "Unknown asm flavor!");
226  case intel:
227    return new X86IntelAsmPrinter(o, tm);
228  case att:
229    return new X86ATTAsmPrinter(o, tm);
230  }
231}
232