MCWin64EH.cpp revision 7b06b7357aa5a7cbdd769edbf6edb10fa055ea09
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/MC/MCStreamer.h" 12#include "llvm/MC/MCContext.h" 13#include "llvm/MC/MCSymbol.h" 14#include "llvm/MC/MCSectionCOFF.h" 15#include "llvm/MC/MCExpr.h" 16#include "llvm/Target/TargetAsmInfo.h" 17 18namespace llvm { 19 20// NOTE: All relocations generated here are 4-byte image-relative. 21 22static uint8_t CountOfUnwindCodes(std::vector<MCWin64EHInstruction> &instArray){ 23 uint8_t count = 0; 24 for (std::vector<MCWin64EHInstruction>::const_iterator I = instArray.begin(), 25 E = instArray.end(); I != E; ++I) { 26 switch (I->getOperation()) { 27 case Win64EH::UOP_PushNonVol: 28 case Win64EH::UOP_AllocSmall: 29 case Win64EH::UOP_SetFPReg: 30 case Win64EH::UOP_PushMachFrame: 31 count += 1; 32 break; 33 case Win64EH::UOP_SaveNonVol: 34 case Win64EH::UOP_SaveXMM128: 35 count += 2; 36 break; 37 case Win64EH::UOP_SaveNonVolBig: 38 case Win64EH::UOP_SaveXMM128Big: 39 count += 3; 40 break; 41 case Win64EH::UOP_AllocLarge: 42 if (I->getSize() > 512*1024-8) 43 count += 3; 44 else 45 count += 2; 46 break; 47 } 48 } 49 return count; 50} 51 52static void EmitAbsDifference(MCStreamer &streamer, MCSymbol *lhs, 53 MCSymbol *rhs) { 54 MCContext &context = streamer.getContext(); 55 const MCExpr *diff = MCBinaryExpr::CreateSub(MCSymbolRefExpr::Create( 56 lhs, context), 57 MCSymbolRefExpr::Create( 58 rhs, context), 59 context); 60 streamer.EmitAbsValue(diff, 1); 61 62} 63 64static void EmitUnwindCode(MCStreamer &streamer, MCSymbol *begin, 65 MCWin64EHInstruction &inst) { 66 uint8_t b1, b2; 67 uint16_t w; 68 b2 = (inst.getOperation() & 0x0F); 69 switch (inst.getOperation()) { 70 case Win64EH::UOP_PushNonVol: 71 EmitAbsDifference(streamer, inst.getLabel(), begin); 72 b2 |= (inst.getRegister() & 0x0F) << 4; 73 streamer.EmitIntValue(b2, 1); 74 break; 75 case Win64EH::UOP_AllocLarge: 76 EmitAbsDifference(streamer, inst.getLabel(), begin); 77 if (inst.getSize() > 512*1024-8) { 78 b2 |= 0x10; 79 streamer.EmitIntValue(b2, 1); 80 w = inst.getSize() & 0xFFF8; 81 streamer.EmitIntValue(w, 2); 82 w = inst.getSize() >> 16; 83 } else { 84 streamer.EmitIntValue(b2, 1); 85 w = inst.getSize() >> 3; 86 } 87 streamer.EmitIntValue(w, 2); 88 break; 89 case Win64EH::UOP_AllocSmall: 90 b2 |= (((inst.getSize()-8) >> 3) & 0x0F) << 4; 91 EmitAbsDifference(streamer, inst.getLabel(), begin); 92 streamer.EmitIntValue(b2, 1); 93 break; 94 case Win64EH::UOP_SetFPReg: 95 b1 = inst.getOffset() & 0xF0; 96 streamer.EmitIntValue(b1, 1); 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 223void MCWin64EHUnwindEmitter::EmitUnwindInfo(MCStreamer &streamer, 224 MCWin64EHUnwindInfo *info) { 225 // Switch sections (the static function above is meant to be called from 226 // here and from Emit(). 227 MCContext &context = streamer.getContext(); 228 const TargetAsmInfo &asmInfo = context.getTargetAsmInfo(); 229 const MCSection *xdataSect = 230 asmInfo.getWin64EHTableSection(GetSectionSuffix(info->Function)); 231 streamer.SwitchSection(xdataSect); 232 233 llvm::EmitUnwindInfo(streamer, info); 234} 235 236void MCWin64EHUnwindEmitter::Emit(MCStreamer &streamer) { 237 MCContext &context = streamer.getContext(); 238 // Emit the unwind info structs first. 239 const TargetAsmInfo &asmInfo = context.getTargetAsmInfo(); 240 for (unsigned i = 0; i < streamer.getNumW64UnwindInfos(); ++i) { 241 MCWin64EHUnwindInfo &info = streamer.getW64UnwindInfo(i); 242 const MCSection *xdataSect = 243 asmInfo.getWin64EHTableSection(GetSectionSuffix(info.Function)); 244 streamer.SwitchSection(xdataSect); 245 llvm::EmitUnwindInfo(streamer, &info); 246 } 247 // Now emit RUNTIME_FUNCTION entries. 248 for (unsigned i = 0; i < streamer.getNumW64UnwindInfos(); ++i) { 249 MCWin64EHUnwindInfo &info = streamer.getW64UnwindInfo(i); 250 const MCSection *pdataSect = 251 asmInfo.getWin64EHFuncTableSection(GetSectionSuffix(info.Function)); 252 streamer.SwitchSection(pdataSect); 253 EmitRuntimeFunction(streamer, &info); 254 } 255} 256 257} // End of namespace llvm 258 259