MCWin64EH.cpp revision 9611873724b9f8d6cbbed7924c972e8d026cc263
1//===- lib/MC/MCWin64EH.cpp - MCWin64EH implementation --------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9 10#include "llvm/MC/MCWin64EH.h" 11#include "llvm/ADT/Twine.h" 12#include "llvm/MC/MCContext.h" 13#include "llvm/MC/MCExpr.h" 14#include "llvm/MC/MCObjectFileInfo.h" 15#include "llvm/MC/MCSectionCOFF.h" 16#include "llvm/MC/MCStreamer.h" 17#include "llvm/MC/MCSymbol.h" 18 19namespace llvm { 20 21// NOTE: All relocations generated here are 4-byte image-relative. 22 23static uint8_t CountOfUnwindCodes(std::vector<MCWin64EHInstruction> &instArray){ 24 uint8_t count = 0; 25 for (std::vector<MCWin64EHInstruction>::const_iterator I = instArray.begin(), 26 E = instArray.end(); I != E; ++I) { 27 switch (I->getOperation()) { 28 case Win64EH::UOP_PushNonVol: 29 case Win64EH::UOP_AllocSmall: 30 case Win64EH::UOP_SetFPReg: 31 case Win64EH::UOP_PushMachFrame: 32 count += 1; 33 break; 34 case Win64EH::UOP_SaveNonVol: 35 case Win64EH::UOP_SaveXMM128: 36 count += 2; 37 break; 38 case Win64EH::UOP_SaveNonVolBig: 39 case Win64EH::UOP_SaveXMM128Big: 40 count += 3; 41 break; 42 case Win64EH::UOP_AllocLarge: 43 if (I->getSize() > 512*1024-8) 44 count += 3; 45 else 46 count += 2; 47 break; 48 } 49 } 50 return count; 51} 52 53static void EmitAbsDifference(MCStreamer &streamer, MCSymbol *lhs, 54 MCSymbol *rhs) { 55 MCContext &context = streamer.getContext(); 56 const MCExpr *diff = MCBinaryExpr::CreateSub(MCSymbolRefExpr::Create( 57 lhs, context), 58 MCSymbolRefExpr::Create( 59 rhs, context), 60 context); 61 streamer.EmitAbsValue(diff, 1); 62 63} 64 65static void EmitUnwindCode(MCStreamer &streamer, MCSymbol *begin, 66 MCWin64EHInstruction &inst) { 67 uint8_t b2; 68 uint16_t w; 69 b2 = (inst.getOperation() & 0x0F); 70 switch (inst.getOperation()) { 71 case Win64EH::UOP_PushNonVol: 72 EmitAbsDifference(streamer, inst.getLabel(), begin); 73 b2 |= (inst.getRegister() & 0x0F) << 4; 74 streamer.EmitIntValue(b2, 1); 75 break; 76 case Win64EH::UOP_AllocLarge: 77 EmitAbsDifference(streamer, inst.getLabel(), begin); 78 if (inst.getSize() > 512*1024-8) { 79 b2 |= 0x10; 80 streamer.EmitIntValue(b2, 1); 81 w = inst.getSize() & 0xFFF8; 82 streamer.EmitIntValue(w, 2); 83 w = inst.getSize() >> 16; 84 } else { 85 streamer.EmitIntValue(b2, 1); 86 w = inst.getSize() >> 3; 87 } 88 streamer.EmitIntValue(w, 2); 89 break; 90 case Win64EH::UOP_AllocSmall: 91 b2 |= (((inst.getSize()-8) >> 3) & 0x0F) << 4; 92 EmitAbsDifference(streamer, inst.getLabel(), begin); 93 streamer.EmitIntValue(b2, 1); 94 break; 95 case Win64EH::UOP_SetFPReg: 96 EmitAbsDifference(streamer, inst.getLabel(), begin); 97 streamer.EmitIntValue(b2, 1); 98 break; 99 case Win64EH::UOP_SaveNonVol: 100 case Win64EH::UOP_SaveXMM128: 101 b2 |= (inst.getRegister() & 0x0F) << 4; 102 EmitAbsDifference(streamer, inst.getLabel(), begin); 103 streamer.EmitIntValue(b2, 1); 104 w = inst.getOffset() >> 3; 105 if (inst.getOperation() == Win64EH::UOP_SaveXMM128) 106 w >>= 1; 107 streamer.EmitIntValue(w, 2); 108 break; 109 case Win64EH::UOP_SaveNonVolBig: 110 case Win64EH::UOP_SaveXMM128Big: 111 b2 |= (inst.getRegister() & 0x0F) << 4; 112 EmitAbsDifference(streamer, inst.getLabel(), begin); 113 streamer.EmitIntValue(b2, 1); 114 if (inst.getOperation() == Win64EH::UOP_SaveXMM128Big) 115 w = inst.getOffset() & 0xFFF0; 116 else 117 w = inst.getOffset() & 0xFFF8; 118 streamer.EmitIntValue(w, 2); 119 w = inst.getOffset() >> 16; 120 streamer.EmitIntValue(w, 2); 121 break; 122 case Win64EH::UOP_PushMachFrame: 123 if (inst.isPushCodeFrame()) 124 b2 |= 0x10; 125 EmitAbsDifference(streamer, inst.getLabel(), begin); 126 streamer.EmitIntValue(b2, 1); 127 break; 128 } 129} 130 131static void EmitRuntimeFunction(MCStreamer &streamer, 132 const MCWin64EHUnwindInfo *info) { 133 MCContext &context = streamer.getContext(); 134 135 streamer.EmitValueToAlignment(4); 136 streamer.EmitValue(MCSymbolRefExpr::Create(info->Begin, context), 4); 137 streamer.EmitValue(MCSymbolRefExpr::Create(info->End, context), 4); 138 streamer.EmitValue(MCSymbolRefExpr::Create(info->Symbol, context), 4); 139} 140 141static void EmitUnwindInfo(MCStreamer &streamer, MCWin64EHUnwindInfo *info) { 142 // If this UNWIND_INFO already has a symbol, it's already been emitted. 143 if (info->Symbol) return; 144 145 MCContext &context = streamer.getContext(); 146 streamer.EmitValueToAlignment(4); 147 // Upper 3 bits are the version number (currently 1). 148 uint8_t flags = 0x01; 149 info->Symbol = context.CreateTempSymbol(); 150 streamer.EmitLabel(info->Symbol); 151 152 if (info->ChainedParent) 153 flags |= Win64EH::UNW_ChainInfo << 3; 154 else { 155 if (info->HandlesUnwind) 156 flags |= Win64EH::UNW_TerminateHandler << 3; 157 if (info->HandlesExceptions) 158 flags |= Win64EH::UNW_ExceptionHandler << 3; 159 } 160 streamer.EmitIntValue(flags, 1); 161 162 if (info->PrologEnd) 163 EmitAbsDifference(streamer, info->PrologEnd, info->Begin); 164 else 165 streamer.EmitIntValue(0, 1); 166 167 uint8_t numCodes = CountOfUnwindCodes(info->Instructions); 168 streamer.EmitIntValue(numCodes, 1); 169 170 uint8_t frame = 0; 171 if (info->LastFrameInst >= 0) { 172 MCWin64EHInstruction &frameInst = info->Instructions[info->LastFrameInst]; 173 assert(frameInst.getOperation() == Win64EH::UOP_SetFPReg); 174 frame = (frameInst.getRegister() & 0x0F) | 175 (frameInst.getOffset() & 0xF0); 176 } 177 streamer.EmitIntValue(frame, 1); 178 179 // Emit unwind instructions (in reverse order). 180 uint8_t numInst = info->Instructions.size(); 181 for (uint8_t c = 0; c < numInst; ++c) { 182 MCWin64EHInstruction inst = info->Instructions.back(); 183 info->Instructions.pop_back(); 184 EmitUnwindCode(streamer, info->Begin, inst); 185 } 186 187 if (flags & (Win64EH::UNW_ChainInfo << 3)) 188 EmitRuntimeFunction(streamer, info->ChainedParent); 189 else if (flags & 190 ((Win64EH::UNW_TerminateHandler|Win64EH::UNW_ExceptionHandler) << 3)) 191 streamer.EmitValue(MCSymbolRefExpr::Create(info->ExceptionHandler, context), 192 4); 193 else if (numCodes < 2) { 194 // The minimum size of an UNWIND_INFO struct is 8 bytes. If we're not 195 // a chained unwind info, if there is no handler, and if there are fewer 196 // than 2 slots used in the unwind code array, we have to pad to 8 bytes. 197 if (numCodes == 1) 198 streamer.EmitIntValue(0, 2); 199 else 200 streamer.EmitIntValue(0, 4); 201 } 202} 203 204StringRef MCWin64EHUnwindEmitter::GetSectionSuffix(const MCSymbol *func) { 205 if (!func || !func->isInSection()) return ""; 206 const MCSection *section = &func->getSection(); 207 const MCSectionCOFF *COFFSection; 208 if ((COFFSection = dyn_cast<MCSectionCOFF>(section))) { 209 StringRef name = COFFSection->getSectionName(); 210 size_t dollar = name.find('$'); 211 size_t dot = name.find('.', 1); 212 if (dollar == StringRef::npos && dot == StringRef::npos) 213 return ""; 214 if (dot == StringRef::npos) 215 return name.substr(dollar); 216 if (dollar == StringRef::npos || dot < dollar) 217 return name.substr(dot); 218 return name.substr(dollar); 219 } 220 return ""; 221} 222 223static const MCSection *getWin64EHTableSection(StringRef suffix, 224 MCContext &context) { 225 if (suffix == "") 226 return context.getObjectFileInfo()->getXDataSection(); 227 228 return context.getCOFFSection((".xdata"+suffix).str(), 229 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 230 COFF::IMAGE_SCN_MEM_READ, 231 SectionKind::getDataRel()); 232} 233 234static const MCSection *getWin64EHFuncTableSection(StringRef suffix, 235 MCContext &context) { 236 if (suffix == "") 237 return context.getObjectFileInfo()->getPDataSection(); 238 return context.getCOFFSection((".pdata"+suffix).str(), 239 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 240 COFF::IMAGE_SCN_MEM_READ, 241 SectionKind::getDataRel()); 242} 243 244void MCWin64EHUnwindEmitter::EmitUnwindInfo(MCStreamer &streamer, 245 MCWin64EHUnwindInfo *info) { 246 // Switch sections (the static function above is meant to be called from 247 // here and from Emit(). 248 MCContext &context = streamer.getContext(); 249 const MCSection *xdataSect = 250 getWin64EHTableSection(GetSectionSuffix(info->Function), context); 251 streamer.SwitchSection(xdataSect); 252 253 llvm::EmitUnwindInfo(streamer, info); 254} 255 256void MCWin64EHUnwindEmitter::Emit(MCStreamer &streamer) { 257 MCContext &context = streamer.getContext(); 258 // Emit the unwind info structs first. 259 for (unsigned i = 0; i < streamer.getNumW64UnwindInfos(); ++i) { 260 MCWin64EHUnwindInfo &info = streamer.getW64UnwindInfo(i); 261 const MCSection *xdataSect = 262 getWin64EHTableSection(GetSectionSuffix(info.Function), context); 263 streamer.SwitchSection(xdataSect); 264 llvm::EmitUnwindInfo(streamer, &info); 265 } 266 // Now emit RUNTIME_FUNCTION entries. 267 for (unsigned i = 0; i < streamer.getNumW64UnwindInfos(); ++i) { 268 MCWin64EHUnwindInfo &info = streamer.getW64UnwindInfo(i); 269 const MCSection *pdataSect = 270 getWin64EHFuncTableSection(GetSectionSuffix(info.Function), context); 271 streamer.SwitchSection(pdataSect); 272 EmitRuntimeFunction(streamer, &info); 273 } 274} 275 276} // End of namespace llvm 277 278