X86AsmPrinter.cpp revision d1239b7c69e3c8f36d21c30d5df923cfeb96583e 
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 "X86Subtarget.h"
20#include "X86.h"
21#include "llvm/Constants.h"
22#include "llvm/Module.h"
23#include "llvm/Type.h"
24#include "llvm/Assembly/Writer.h"
25#include "llvm/Support/Mangler.h"
26#include "llvm/Support/CommandLine.h"
27using namespace llvm;
28using namespace x86;
29
30Statistic<> llvm::x86::EmittedInsts("asm-printer",
31                                    "Number of machine instrs printed");
32
33enum AsmWriterFlavorTy { att, intel };
34cl::opt<AsmWriterFlavorTy>
35AsmWriterFlavor("x86-asm-syntax",
36                cl::desc("Choose style of code to emit from X86 backend:"),
37                cl::values(
38                           clEnumVal(att,   "  Emit AT&T-style assembly"),
39                           clEnumVal(intel, "  Emit Intel-style assembly"),
40                           clEnumValEnd),
41                cl::init(att));
42
43/// doInitialization
44bool X86SharedAsmPrinter::doInitialization(Module &M) {
45  const X86Subtarget *Subtarget = &TM.getSubtarget<X86Subtarget>();
46
47  forDarwin = false;
48
49  switch (Subtarget->TargetType) {
50  case X86Subtarget::isDarwin:
51    AlignmentIsInBytes = false;
52    GlobalPrefix = "_";
53    Data64bitsDirective = 0;       // we can't emit a 64-bit unit
54    ZeroDirective = "\t.space\t";  // ".space N" emits N zeros.
55    PrivateGlobalPrefix = "L";     // Marker for constant pool idxs
56    ConstantPoolSection = "\t.const\n";
57    LCOMMDirective = "\t.lcomm\t";
58    COMMDirectiveTakesAlignment = false;
59    HasDotTypeDotSizeDirective = false;
60    forDarwin = true;
61    StaticCtorsSection = ".mod_init_func";
62    StaticDtorsSection = ".mod_term_func";
63    break;
64  case X86Subtarget::isCygwin:
65    GlobalPrefix = "_";
66    COMMDirectiveTakesAlignment = false;
67    HasDotTypeDotSizeDirective = false;
68    break;
69  case X86Subtarget::isWindows:
70    GlobalPrefix = "_";
71    HasDotTypeDotSizeDirective = false;
72    break;
73  default: break;
74  }
75
76  return AsmPrinter::doInitialization(M);
77}
78
79bool X86SharedAsmPrinter::doFinalization(Module &M) {
80  const TargetData &TD = TM.getTargetData();
81
82  // Print out module-level global variables here.
83  for (Module::const_global_iterator I = M.global_begin(),
84       E = M.global_end(); I != E; ++I) {
85    if (!I->hasInitializer()) continue;   // External global require no code
86
87    // Check to see if this is a special global used by LLVM, if so, emit it.
88    if (I->hasAppendingLinkage() && EmitSpecialLLVMGlobal(I))
89      continue;
90
91    O << "\n\n";
92    std::string name = Mang->getValueName(I);
93    Constant *C = I->getInitializer();
94    unsigned Size = TD.getTypeSize(C->getType());
95    unsigned Align = TD.getTypeAlignmentShift(C->getType());
96
97    switch (I->getLinkage()) {
98    default: assert(0 && "Unknown linkage type!");
99    case GlobalValue::LinkOnceLinkage:
100    case GlobalValue::WeakLinkage:   // FIXME: Verify correct for weak.
101      if (C->isNullValue()) {
102        O << COMMDirective << name << "," << Size;
103        if (COMMDirectiveTakesAlignment)
104          O << "," << (1 << Align);
105        O << "\t\t" << CommentString << " " << I->getName() << "\n";
106        continue;
107      }
108
109      // Nonnull linkonce -> weak
110      O << "\t.weak " << name << "\n";
111      O << "\t.section\t.llvm.linkonce.d." << name << ",\"aw\",@progbits\n";
112      SwitchSection("", I);
113      break;
114    case GlobalValue::InternalLinkage:
115      if (C->isNullValue()) {
116        if (LCOMMDirective) {
117          O << LCOMMDirective << name << "," << Size << "," << Align;
118          continue;
119        } else {
120          SwitchSection(".bss", I);
121          O << "\t.local " << name << "\n";
122          O << COMMDirective << name << "," << Size;
123          if (COMMDirectiveTakesAlignment)
124            O << "," << (1 << Align);
125          O << "\t\t# ";
126          WriteAsOperand(O, I, true, true, &M);
127          O << "\n";
128          continue;
129        }
130      }
131      SwitchSection(".data", I);
132      break;
133    case GlobalValue::AppendingLinkage:
134      // FIXME: appending linkage variables should go into a section of
135      // their name or something.  For now, just emit them as external.
136    case GlobalValue::ExternalLinkage:
137      SwitchSection(C->isNullValue() ? ".bss" : ".data", I);
138      // If external or appending, declare as a global symbol
139      O << "\t.globl " << name << "\n";
140      break;
141    }
142
143    EmitAlignment(Align);
144    if (HasDotTypeDotSizeDirective) {
145      O << "\t.type " << name << ",@object\n";
146      O << "\t.size " << name << "," << Size << "\n";
147    }
148    O << name << ":\t\t\t" << CommentString << ' ' << I->getName() << '\n';
149    EmitGlobalConstant(C);
150  }
151
152  if (forDarwin) {
153    SwitchSection("", 0);
154    // Output stubs for external global variables
155    if (GVStubs.begin() != GVStubs.end())
156      O << "\t.non_lazy_symbol_pointer\n";
157    for (std::set<std::string>::iterator i = GVStubs.begin(), e = GVStubs.end();
158         i != e; ++i) {
159      O << "L" << *i << "$non_lazy_ptr:\n";
160      O << "\t.indirect_symbol " << *i << "\n";
161      O << "\t.long\t0\n";
162    }
163
164    // Output stubs for dynamically-linked functions
165    unsigned j = 1;
166    for (std::set<std::string>::iterator i = FnStubs.begin(), e = FnStubs.end();
167         i != e; ++i, ++j) {
168      O << "\t.symbol_stub\n";
169      O << "L" << *i << "$stub:\n";
170      O << "\t.indirect_symbol " << *i << "\n";
171      O << "\tjmp\t*L" << j << "$lz\n";
172      O << "L" << *i << "$stub_binder:\n";
173      O << "\tpushl\t$L" << j << "$lz\n";
174      O << "\tjmp\tdyld_stub_binding_helper\n";
175      O << "\t.section __DATA, __la_sym_ptr3,lazy_symbol_pointers\n";
176      O << "L" << j << "$lz:\n";
177      O << "\t.indirect_symbol " << *i << "\n";
178      O << "\t.long\tL" << *i << "$stub_binder\n";
179    }
180
181    O << "\n";
182
183    // Output stubs for link-once variables
184    if (LinkOnceStubs.begin() != LinkOnceStubs.end())
185      O << ".data\n.align 2\n";
186    for (std::set<std::string>::iterator i = LinkOnceStubs.begin(),
187         e = LinkOnceStubs.end(); i != e; ++i) {
188      O << "L" << *i << "$non_lazy_ptr:\n"
189        << "\t.long\t" << *i << '\n';
190    }
191  }
192
193  AsmPrinter::doFinalization(M);
194  return false; // success
195}
196
197/// createX86CodePrinterPass - Returns a pass that prints the X86 assembly code
198/// for a MachineFunction to the given output stream, using the given target
199/// machine description.
200///
201FunctionPass *llvm::createX86CodePrinterPass(std::ostream &o,TargetMachine &tm){
202  switch (AsmWriterFlavor) {
203  default:
204    assert(0 && "Unknown asm flavor!");
205  case intel:
206    return new X86IntelAsmPrinter(o, tm);
207  case att:
208    return new X86ATTAsmPrinter(o, tm);
209  }
210}
211