1181834Sroberto//===- lib/MC/MCWin64EH.cpp - MCWin64EH implementation --------------------===//
2181834Sroberto//
3181834Sroberto//                     The LLVM Compiler Infrastructure
4181834Sroberto//
5181834Sroberto// This file is distributed under the University of Illinois Open Source
6181834Sroberto// License. See LICENSE.TXT for details.
7181834Sroberto//
8181834Sroberto//===----------------------------------------------------------------------===//
9181834Sroberto
10181834Sroberto#include "llvm/MC/MCWin64EH.h"
11181834Sroberto#include "llvm/ADT/Twine.h"
12181834Sroberto#include "llvm/MC/MCContext.h"
13181834Sroberto#include "llvm/MC/MCExpr.h"
14181834Sroberto#include "llvm/MC/MCObjectFileInfo.h"
15181834Sroberto#include "llvm/MC/MCSectionCOFF.h"
16181834Sroberto#include "llvm/MC/MCStreamer.h"
17181834Sroberto#include "llvm/MC/MCSymbol.h"
18181834Sroberto
19181834Srobertonamespace llvm {
20181834Sroberto
21181834Sroberto// NOTE: All relocations generated here are 4-byte image-relative.
22181834Sroberto
23181834Srobertostatic uint8_t CountOfUnwindCodes(std::vector<MCWin64EHInstruction> &instArray){
24181834Sroberto  uint8_t count = 0;
25181834Sroberto  for (std::vector<MCWin64EHInstruction>::const_iterator I = instArray.begin(),
26181834Sroberto       E = instArray.end(); I != E; ++I) {
27181834Sroberto    switch (I->getOperation()) {
28181834Sroberto    case Win64EH::UOP_PushNonVol:
29181834Sroberto    case Win64EH::UOP_AllocSmall:
30181834Sroberto    case Win64EH::UOP_SetFPReg:
31181834Sroberto    case Win64EH::UOP_PushMachFrame:
32181834Sroberto      count += 1;
33181834Sroberto      break;
34181834Sroberto    case Win64EH::UOP_SaveNonVol:
35181834Sroberto    case Win64EH::UOP_SaveXMM128:
36181834Sroberto      count += 2;
37181834Sroberto      break;
38181834Sroberto    case Win64EH::UOP_SaveNonVolBig:
39181834Sroberto    case Win64EH::UOP_SaveXMM128Big:
40181834Sroberto      count += 3;
41181834Sroberto      break;
42181834Sroberto    case Win64EH::UOP_AllocLarge:
43181834Sroberto      if (I->getSize() > 512*1024-8)
44181834Sroberto        count += 3;
45181834Sroberto      else
46181834Sroberto        count += 2;
47181834Sroberto      break;
48181834Sroberto    }
49181834Sroberto  }
50181834Sroberto  return count;
51181834Sroberto}
52181834Sroberto
53181834Srobertostatic void EmitAbsDifference(MCStreamer &streamer, MCSymbol *lhs,
54181834Sroberto                              MCSymbol *rhs) {
55181834Sroberto  MCContext &context = streamer.getContext();
56181834Sroberto  const MCExpr *diff = MCBinaryExpr::CreateSub(MCSymbolRefExpr::Create(
57181834Sroberto                                                                  lhs, context),
58181834Sroberto                                               MCSymbolRefExpr::Create(
59181834Sroberto                                                                  rhs, context),
60181834Sroberto                                               context);
61181834Sroberto  streamer.EmitAbsValue(diff, 1);
62181834Sroberto
63181834Sroberto}
64181834Sroberto
65181834Srobertostatic void EmitUnwindCode(MCStreamer &streamer, MCSymbol *begin,
66181834Sroberto                           MCWin64EHInstruction &inst) {
67181834Sroberto  uint8_t b2;
68181834Sroberto  uint16_t w;
69181834Sroberto  b2 = (inst.getOperation() & 0x0F);
70181834Sroberto  switch (inst.getOperation()) {
71181834Sroberto  case Win64EH::UOP_PushNonVol:
72181834Sroberto    EmitAbsDifference(streamer, inst.getLabel(), begin);
73181834Sroberto    b2 |= (inst.getRegister() & 0x0F) << 4;
74181834Sroberto    streamer.EmitIntValue(b2, 1);
75181834Sroberto    break;
76181834Sroberto  case Win64EH::UOP_AllocLarge:
77181834Sroberto    EmitAbsDifference(streamer, inst.getLabel(), begin);
78181834Sroberto    if (inst.getSize() > 512*1024-8) {
79181834Sroberto      b2 |= 0x10;
80181834Sroberto      streamer.EmitIntValue(b2, 1);
81181834Sroberto      w = inst.getSize() & 0xFFF8;
82181834Sroberto      streamer.EmitIntValue(w, 2);
83181834Sroberto      w = inst.getSize() >> 16;
84181834Sroberto    } else {
85181834Sroberto      streamer.EmitIntValue(b2, 1);
86181834Sroberto      w = inst.getSize() >> 3;
87181834Sroberto    }
88181834Sroberto    streamer.EmitIntValue(w, 2);
89181834Sroberto    break;
90181834Sroberto  case Win64EH::UOP_AllocSmall:
91181834Sroberto    b2 |= (((inst.getSize()-8) >> 3) & 0x0F) << 4;
92181834Sroberto    EmitAbsDifference(streamer, inst.getLabel(), begin);
93181834Sroberto    streamer.EmitIntValue(b2, 1);
94181834Sroberto    break;
95181834Sroberto  case Win64EH::UOP_SetFPReg:
96181834Sroberto    EmitAbsDifference(streamer, inst.getLabel(), begin);
97181834Sroberto    streamer.EmitIntValue(b2, 1);
98181834Sroberto    break;
99181834Sroberto  case Win64EH::UOP_SaveNonVol:
100181834Sroberto  case Win64EH::UOP_SaveXMM128:
101181834Sroberto    b2 |= (inst.getRegister() & 0x0F) << 4;
102181834Sroberto    EmitAbsDifference(streamer, inst.getLabel(), begin);
103181834Sroberto    streamer.EmitIntValue(b2, 1);
104181834Sroberto    w = inst.getOffset() >> 3;
105181834Sroberto    if (inst.getOperation() == Win64EH::UOP_SaveXMM128)
106181834Sroberto      w >>= 1;
107181834Sroberto    streamer.EmitIntValue(w, 2);
108181834Sroberto    break;
109181834Sroberto  case Win64EH::UOP_SaveNonVolBig:
110181834Sroberto  case Win64EH::UOP_SaveXMM128Big:
111181834Sroberto    b2 |= (inst.getRegister() & 0x0F) << 4;
112181834Sroberto    EmitAbsDifference(streamer, inst.getLabel(), begin);
113181834Sroberto    streamer.EmitIntValue(b2, 1);
114181834Sroberto    if (inst.getOperation() == Win64EH::UOP_SaveXMM128Big)
115181834Sroberto      w = inst.getOffset() & 0xFFF0;
116181834Sroberto    else
117181834Sroberto      w = inst.getOffset() & 0xFFF8;
118181834Sroberto    streamer.EmitIntValue(w, 2);
119181834Sroberto    w = inst.getOffset() >> 16;
120181834Sroberto    streamer.EmitIntValue(w, 2);
121181834Sroberto    break;
122181834Sroberto  case Win64EH::UOP_PushMachFrame:
123181834Sroberto    if (inst.isPushCodeFrame())
124181834Sroberto      b2 |= 0x10;
125181834Sroberto    EmitAbsDifference(streamer, inst.getLabel(), begin);
126181834Sroberto    streamer.EmitIntValue(b2, 1);
127181834Sroberto    break;
128181834Sroberto  }
129181834Sroberto}
130181834Sroberto
131181834Srobertostatic void EmitSymbolRefWithOfs(MCStreamer &streamer,
132181834Sroberto                                 const MCSymbol *Base,
133181834Sroberto                                 const MCSymbol *Other) {
134181834Sroberto  MCContext &Context = streamer.getContext();
135181834Sroberto  const MCSymbolRefExpr *BaseRef = MCSymbolRefExpr::Create(Base, Context);
136181834Sroberto  const MCSymbolRefExpr *OtherRef = MCSymbolRefExpr::Create(Other, Context);
137181834Sroberto  const MCExpr *Ofs = MCBinaryExpr::CreateSub(OtherRef, BaseRef, Context);
138181834Sroberto  const MCSymbolRefExpr *BaseRefRel = MCSymbolRefExpr::Create(Base,
139181834Sroberto                                              MCSymbolRefExpr::VK_COFF_IMGREL32,
140181834Sroberto                                              Context);
141181834Sroberto  streamer.EmitValue(MCBinaryExpr::CreateAdd(BaseRefRel, Ofs, Context), 4);
142181834Sroberto}
143181834Sroberto
144181834Srobertostatic void EmitRuntimeFunction(MCStreamer &streamer,
145181834Sroberto                                const MCWin64EHUnwindInfo *info) {
146181834Sroberto  MCContext &context = streamer.getContext();
147181834Sroberto
148181834Sroberto  streamer.EmitValueToAlignment(4);
149181834Sroberto  EmitSymbolRefWithOfs(streamer, info->Function, info->Begin);
150181834Sroberto  EmitSymbolRefWithOfs(streamer, info->Function, info->End);
151181834Sroberto  streamer.EmitValue(MCSymbolRefExpr::Create(info->Symbol,
152181834Sroberto                                             MCSymbolRefExpr::VK_COFF_IMGREL32,
153181834Sroberto                                             context), 4);
154181834Sroberto}
155181834Sroberto
156181834Srobertostatic void EmitUnwindInfo(MCStreamer &streamer, MCWin64EHUnwindInfo *info) {
157181834Sroberto  // If this UNWIND_INFO already has a symbol, it's already been emitted.
158181834Sroberto  if (info->Symbol) return;
159181834Sroberto
160181834Sroberto  MCContext &context = streamer.getContext();
161181834Sroberto  streamer.EmitValueToAlignment(4);
162181834Sroberto  info->Symbol = context.CreateTempSymbol();
163181834Sroberto  streamer.EmitLabel(info->Symbol);
164181834Sroberto
165181834Sroberto  // Upper 3 bits are the version number (currently 1).
166181834Sroberto  uint8_t flags = 0x01;
167181834Sroberto  if (info->ChainedParent)
168181834Sroberto    flags |= Win64EH::UNW_ChainInfo << 3;
169181834Sroberto  else {
170181834Sroberto    if (info->HandlesUnwind)
171181834Sroberto      flags |= Win64EH::UNW_TerminateHandler << 3;
172181834Sroberto    if (info->HandlesExceptions)
173181834Sroberto      flags |= Win64EH::UNW_ExceptionHandler << 3;
174181834Sroberto  }
175181834Sroberto  streamer.EmitIntValue(flags, 1);
176181834Sroberto
177181834Sroberto  if (info->PrologEnd)
178181834Sroberto    EmitAbsDifference(streamer, info->PrologEnd, info->Begin);
179181834Sroberto  else
180181834Sroberto    streamer.EmitIntValue(0, 1);
181181834Sroberto
182181834Sroberto  uint8_t numCodes = CountOfUnwindCodes(info->Instructions);
183181834Sroberto  streamer.EmitIntValue(numCodes, 1);
184181834Sroberto
185181834Sroberto  uint8_t frame = 0;
186181834Sroberto  if (info->LastFrameInst >= 0) {
187181834Sroberto    MCWin64EHInstruction &frameInst = info->Instructions[info->LastFrameInst];
188181834Sroberto    assert(frameInst.getOperation() == Win64EH::UOP_SetFPReg);
189181834Sroberto    frame = (frameInst.getRegister() & 0x0F) |
190181834Sroberto            (frameInst.getOffset() & 0xF0);
191181834Sroberto  }
192181834Sroberto  streamer.EmitIntValue(frame, 1);
193181834Sroberto
194181834Sroberto  // Emit unwind instructions (in reverse order).
195181834Sroberto  uint8_t numInst = info->Instructions.size();
196181834Sroberto  for (uint8_t c = 0; c < numInst; ++c) {
197181834Sroberto    MCWin64EHInstruction inst = info->Instructions.back();
198181834Sroberto    info->Instructions.pop_back();
199181834Sroberto    EmitUnwindCode(streamer, info->Begin, inst);
200181834Sroberto  }
201181834Sroberto
202181834Sroberto  // For alignment purposes, the instruction array will always have an even
203181834Sroberto  // number of entries, with the final entry potentially unused (in which case
204181834Sroberto  // the array will be one longer than indicated by the count of unwind codes
205181834Sroberto  // field).
206181834Sroberto  if (numCodes & 1) {
207181834Sroberto    streamer.EmitIntValue(0, 2);
208181834Sroberto  }
209181834Sroberto
210181834Sroberto  if (flags & (Win64EH::UNW_ChainInfo << 3))
211181834Sroberto    EmitRuntimeFunction(streamer, info->ChainedParent);
212181834Sroberto  else if (flags &
213181834Sroberto           ((Win64EH::UNW_TerminateHandler|Win64EH::UNW_ExceptionHandler) << 3))
214181834Sroberto    streamer.EmitValue(MCSymbolRefExpr::Create(info->ExceptionHandler,
215181834Sroberto                                              MCSymbolRefExpr::VK_COFF_IMGREL32,
216181834Sroberto                                              context), 4);
217181834Sroberto  else if (numCodes == 0) {
218181834Sroberto    // The minimum size of an UNWIND_INFO struct is 8 bytes. If we're not
219181834Sroberto    // a chained unwind info, if there is no handler, and if there are fewer
220181834Sroberto    // than 2 slots used in the unwind code array, we have to pad to 8 bytes.
221181834Sroberto    streamer.EmitIntValue(0, 4);
222181834Sroberto  }
223181834Sroberto}
224181834Sroberto
225181834SrobertoStringRef MCWin64EHUnwindEmitter::GetSectionSuffix(const MCSymbol *func) {
226181834Sroberto  if (!func || !func->isInSection()) return "";
227181834Sroberto  const MCSection *section = &func->getSection();
228181834Sroberto  const MCSectionCOFF *COFFSection;
229181834Sroberto  if ((COFFSection = dyn_cast<MCSectionCOFF>(section))) {
230181834Sroberto    StringRef name = COFFSection->getSectionName();
231181834Sroberto    size_t dollar = name.find('$');
232181834Sroberto    size_t dot = name.find('.', 1);
233181834Sroberto    if (dollar == StringRef::npos && dot == StringRef::npos)
234181834Sroberto      return "";
235181834Sroberto    if (dot == StringRef::npos)
236181834Sroberto      return name.substr(dollar);
237181834Sroberto    if (dollar == StringRef::npos || dot < dollar)
238181834Sroberto      return name.substr(dot);
239181834Sroberto    return name.substr(dollar);
240181834Sroberto  }
241181834Sroberto  return "";
242181834Sroberto}
243181834Sroberto
244181834Srobertostatic const MCSection *getWin64EHTableSection(StringRef suffix,
245181834Sroberto                                               MCContext &context) {
246181834Sroberto  if (suffix == "")
247181834Sroberto    return context.getObjectFileInfo()->getXDataSection();
248181834Sroberto
249181834Sroberto  return context.getCOFFSection((".xdata"+suffix).str(),
250181834Sroberto                                COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
251181834Sroberto                                COFF::IMAGE_SCN_MEM_READ,
252181834Sroberto                                SectionKind::getDataRel());
253181834Sroberto}
254181834Sroberto
255181834Srobertostatic const MCSection *getWin64EHFuncTableSection(StringRef suffix,
256181834Sroberto                                                   MCContext &context) {
257181834Sroberto  if (suffix == "")
258181834Sroberto    return context.getObjectFileInfo()->getPDataSection();
259181834Sroberto  return context.getCOFFSection((".pdata"+suffix).str(),
260181834Sroberto                                COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
261181834Sroberto                                COFF::IMAGE_SCN_MEM_READ,
262181834Sroberto                                SectionKind::getDataRel());
263181834Sroberto}
264181834Sroberto
265181834Srobertovoid MCWin64EHUnwindEmitter::EmitUnwindInfo(MCStreamer &streamer,
266181834Sroberto                                            MCWin64EHUnwindInfo *info) {
267181834Sroberto  // Switch sections (the static function above is meant to be called from
268181834Sroberto  // here and from Emit().
269181834Sroberto  MCContext &context = streamer.getContext();
270181834Sroberto  const MCSection *xdataSect =
271181834Sroberto    getWin64EHTableSection(GetSectionSuffix(info->Function), context);
272181834Sroberto  streamer.SwitchSection(xdataSect);
273181834Sroberto
274181834Sroberto  llvm::EmitUnwindInfo(streamer, info);
275181834Sroberto}
276181834Sroberto
277181834Srobertovoid MCWin64EHUnwindEmitter::Emit(MCStreamer &streamer) {
278181834Sroberto  MCContext &context = streamer.getContext();
279181834Sroberto  // Emit the unwind info structs first.
280181834Sroberto  for (unsigned i = 0; i < streamer.getNumW64UnwindInfos(); ++i) {
281181834Sroberto    MCWin64EHUnwindInfo &info = streamer.getW64UnwindInfo(i);
282181834Sroberto    const MCSection *xdataSect =
283181834Sroberto      getWin64EHTableSection(GetSectionSuffix(info.Function), context);
284181834Sroberto    streamer.SwitchSection(xdataSect);
285181834Sroberto    llvm::EmitUnwindInfo(streamer, &info);
286181834Sroberto  }
287181834Sroberto  // Now emit RUNTIME_FUNCTION entries.
288181834Sroberto  for (unsigned i = 0; i < streamer.getNumW64UnwindInfos(); ++i) {
289181834Sroberto    MCWin64EHUnwindInfo &info = streamer.getW64UnwindInfo(i);
290181834Sroberto    const MCSection *pdataSect =
291181834Sroberto      getWin64EHFuncTableSection(GetSectionSuffix(info.Function), context);
292181834Sroberto    streamer.SwitchSection(pdataSect);
293181834Sroberto    EmitRuntimeFunction(streamer, &info);
294181834Sroberto  }
295181834Sroberto}
296181834Sroberto
297181834Sroberto} // End of namespace llvm
298181834Sroberto
299181834Sroberto