X86AsmPrinter.cpp revision cdf38c4edb892c356cfaa3c09c57728bc8d6bfd0
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 "X86Subtarget.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; 28 29Statistic<> llvm::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 const X86Subtarget *Subtarget = &TM.getSubtarget<X86Subtarget>(); 45 46 forDarwin = false; 47 PrivateGlobalPrefix = ".L"; 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 JumpTableSection = "\t.const\n"; // FIXME: depends on PIC mode 58 LCOMMDirective = "\t.lcomm\t"; 59 COMMDirectiveTakesAlignment = false; 60 HasDotTypeDotSizeDirective = false; 61 forDarwin = true; 62 StaticCtorsSection = ".mod_init_func"; 63 StaticDtorsSection = ".mod_term_func"; 64 InlineAsmStart = InlineAsmEnd = ""; // Don't use #APP/#NO_APP 65 break; 66 case X86Subtarget::isCygwin: 67 GlobalPrefix = "_"; 68 COMMDirectiveTakesAlignment = false; 69 HasDotTypeDotSizeDirective = false; 70 break; 71 case X86Subtarget::isWindows: 72 GlobalPrefix = "_"; 73 HasDotTypeDotSizeDirective = false; 74 break; 75 default: break; 76 } 77 78 if (forDarwin) { 79 // Emit initial debug information. 80 DW.BeginModule(&M); 81 } 82 83 return AsmPrinter::doInitialization(M); 84} 85 86bool X86SharedAsmPrinter::doFinalization(Module &M) { 87 const TargetData &TD = TM.getTargetData(); 88 89 // Print out module-level global variables here. 90 for (Module::const_global_iterator I = M.global_begin(), E = M.global_end(); 91 I != E; ++I) { 92 if (!I->hasInitializer()) continue; // External global require no code 93 94 // Check to see if this is a special global used by LLVM, if so, emit it. 95 if (EmitSpecialLLVMGlobal(I)) 96 continue; 97 98 std::string name = Mang->getValueName(I); 99 Constant *C = I->getInitializer(); 100 unsigned Size = TD.getTypeSize(C->getType()); 101 unsigned Align = getPreferredAlignmentLog(I); 102 103 if (C->isNullValue() && /* FIXME: Verify correct */ 104 (I->hasInternalLinkage() || I->hasWeakLinkage() || 105 I->hasLinkOnceLinkage() || 106 (forDarwin && I->hasExternalLinkage() && !I->hasSection()))) { 107 if (Size == 0) Size = 1; // .comm Foo, 0 is undefined, avoid it. 108 if (I->hasExternalLinkage()) { 109 O << "\t.globl\t" << name << "\n"; 110 O << "\t.zerofill __DATA__, __common, " << name << ", " 111 << Size << ", " << Align; 112 } else { 113 SwitchSection(".data", I); 114 if (LCOMMDirective != NULL) { 115 if (I->hasInternalLinkage()) { 116 O << LCOMMDirective << name << "," << Size; 117 if (forDarwin) 118 O << "," << (AlignmentIsInBytes ? (1 << Align) : Align); 119 } else 120 O << COMMDirective << name << "," << Size; 121 } else { 122 if (I->hasInternalLinkage()) 123 O << "\t.local\t" << name << "\n"; 124 O << COMMDirective << name << "," << Size; 125 if (COMMDirectiveTakesAlignment) 126 O << "," << (AlignmentIsInBytes ? (1 << Align) : Align); 127 } 128 } 129 O << "\t\t" << CommentString << " " << I->getName() << "\n"; 130 } else { 131 switch (I->getLinkage()) { 132 case GlobalValue::LinkOnceLinkage: 133 case GlobalValue::WeakLinkage: 134 if (forDarwin) { 135 O << "\t.globl " << name << "\n" 136 << "\t.weak_definition " << name << "\n"; 137 SwitchSection(".section __DATA,__datacoal_nt,coalesced", I); 138 } else { 139 O << "\t.section\t.llvm.linkonce.d." << name << ",\"aw\",@progbits\n"; 140 O << "\t.weak " << name << "\n"; 141 } 142 break; 143 case GlobalValue::AppendingLinkage: 144 // FIXME: appending linkage variables should go into a section of 145 // their name or something. For now, just emit them as external. 146 case GlobalValue::ExternalLinkage: 147 // If external or appending, declare as a global symbol 148 O << "\t.globl " << name << "\n"; 149 // FALL THROUGH 150 case GlobalValue::InternalLinkage: 151 SwitchSection(".data", I); 152 break; 153 default: 154 assert(0 && "Unknown linkage type!"); 155 } 156 157 EmitAlignment(Align, I); 158 O << name << ":\t\t\t\t" << CommentString << " " << I->getName() 159 << "\n"; 160 if (HasDotTypeDotSizeDirective) 161 O << "\t.size " << name << ", " << Size << "\n"; 162 163 EmitGlobalConstant(C); 164 O << '\n'; 165 } 166 } 167 168 if (forDarwin) { 169 SwitchSection("", 0); 170 171 // Output stubs for dynamically-linked functions 172 unsigned j = 1; 173 for (std::set<std::string>::iterator i = FnStubs.begin(), e = FnStubs.end(); 174 i != e; ++i, ++j) { 175 SwitchSection(".section __IMPORT,__jump_table,symbol_stubs," 176 "self_modifying_code+pure_instructions,5", 0); 177 O << "L" << *i << "$stub:\n"; 178 O << "\t.indirect_symbol " << *i << "\n"; 179 O << "\thlt ; hlt ; hlt ; hlt ; hlt\n"; 180 } 181 182 O << "\n"; 183 184 // Output stubs for external and common global variables. 185 if (GVStubs.begin() != GVStubs.end()) 186 SwitchSection(".section __IMPORT,__pointers,non_lazy_symbol_pointers", 0); 187 for (std::set<std::string>::iterator i = GVStubs.begin(), e = GVStubs.end(); 188 i != e; ++i) { 189 O << "L" << *i << "$non_lazy_ptr:\n"; 190 O << "\t.indirect_symbol " << *i << "\n"; 191 O << "\t.long\t0\n"; 192 } 193 194 // Emit initial debug information. 195 DW.EndModule(); 196 197 // Funny Darwin hack: This flag tells the linker that no global symbols 198 // contain code that falls through to other global symbols (e.g. the obvious 199 // implementation of multiple entry points). If this doesn't occur, the 200 // linker can safely perform dead code stripping. Since LLVM never 201 // generates code that does this, it is always safe to set. 202 O << "\t.subsections_via_symbols\n"; 203 } 204 205 AsmPrinter::doFinalization(M); 206 return false; // success 207} 208 209void X86SharedAsmPrinter::printBasicBlockLabel(const MachineBasicBlock *MBB, 210 bool printColon, 211 bool printComment) const { 212 O << PrivateGlobalPrefix << "BB" 213 << Mang->getValueName(MBB->getParent()->getFunction()) << "_" 214 << MBB->getNumber(); 215 if (printColon) 216 O << ':'; 217 if (printComment) 218 O << '\t' << CommentString << MBB->getBasicBlock()->getName(); 219} 220 221/// createX86CodePrinterPass - Returns a pass that prints the X86 assembly code 222/// for a MachineFunction to the given output stream, using the given target 223/// machine description. 224/// 225FunctionPass *llvm::createX86CodePrinterPass(std::ostream &o, 226 X86TargetMachine &tm){ 227 switch (AsmWriterFlavor) { 228 default: 229 assert(0 && "Unknown asm flavor!"); 230 case intel: 231 return new X86IntelAsmPrinter(o, tm); 232 case att: 233 return new X86ATTAsmPrinter(o, tm); 234 } 235} 236