1
//===- lib/MC/MCWin64EH.cpp - MCWin64EH implementation --------------------===//
3
// The LLVM Compiler Infrastructure
5
// This file is distributed under the University of Illinois Open Source
6
// License. See LICENSE.TXT for details.
8
//===----------------------------------------------------------------------===//
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
#include "llvm/Support/Win64EH.h"
22
// NOTE: All relocations generated here are 4-byte image-relative.
24
static uint8_t CountOfUnwindCodes(std::vector<WinEH::Instruction> &Insns) {
26
for (const auto &I : Insns) {
27
switch (static_cast<Win64EH::UnwindOpcodes>(I.Operation)) {
28
case Win64EH::UOP_PushNonVol:
29
case Win64EH::UOP_AllocSmall:
30
case Win64EH::UOP_SetFPReg:
31
case Win64EH::UOP_PushMachFrame:
34
case Win64EH::UOP_SaveNonVol:
35
case Win64EH::UOP_SaveXMM128:
38
case Win64EH::UOP_SaveNonVolBig:
39
case Win64EH::UOP_SaveXMM128Big:
42
case Win64EH::UOP_AllocLarge:
43
Count += (I.Offset > 512 * 1024 - 8) ? 3 : 2;
50
static void EmitAbsDifference(MCStreamer &Streamer, const MCSymbol *LHS,
51
const MCSymbol *RHS) {
52
MCContext &Context = Streamer.getContext();
54
MCBinaryExpr::createSub(MCSymbolRefExpr::create(LHS, Context),
55
MCSymbolRefExpr::create(RHS, Context), Context);
56
Streamer.EmitValue(Diff, 1);
59
static void EmitUnwindCode(MCStreamer &streamer, const MCSymbol *begin,
60
WinEH::Instruction &inst) {
63
b2 = (inst.Operation & 0x0F);
64
switch (static_cast<Win64EH::UnwindOpcodes>(inst.Operation)) {
65
case Win64EH::UOP_PushNonVol:
66
EmitAbsDifference(streamer, inst.Label, begin);
67
b2 |= (inst.Register & 0x0F) << 4;
68
streamer.EmitIntValue(b2, 1);
70
case Win64EH::UOP_AllocLarge:
71
EmitAbsDifference(streamer, inst.Label, begin);
72
if (inst.Offset > 512 * 1024 - 8) {
74
streamer.EmitIntValue(b2, 1);
75
w = inst.Offset & 0xFFF8;
76
streamer.EmitIntValue(w, 2);
77
w = inst.Offset >> 16;
79
streamer.EmitIntValue(b2, 1);
82
streamer.EmitIntValue(w, 2);
84
case Win64EH::UOP_AllocSmall:
85
b2 |= (((inst.Offset - 8) >> 3) & 0x0F) << 4;
86
EmitAbsDifference(streamer, inst.Label, begin);
87
streamer.EmitIntValue(b2, 1);
89
case Win64EH::UOP_SetFPReg:
90
EmitAbsDifference(streamer, inst.Label, begin);
91
streamer.EmitIntValue(b2, 1);
93
case Win64EH::UOP_SaveNonVol:
94
case Win64EH::UOP_SaveXMM128:
95
b2 |= (inst.Register & 0x0F) << 4;
96
EmitAbsDifference(streamer, inst.Label, begin);
97
streamer.EmitIntValue(b2, 1);
99
if (inst.Operation == Win64EH::UOP_SaveXMM128)
101
streamer.EmitIntValue(w, 2);
103
case Win64EH::UOP_SaveNonVolBig:
104
case Win64EH::UOP_SaveXMM128Big:
105
b2 |= (inst.Register & 0x0F) << 4;
106
EmitAbsDifference(streamer, inst.Label, begin);
107
streamer.EmitIntValue(b2, 1);
108
if (inst.Operation == Win64EH::UOP_SaveXMM128Big)
109
w = inst.Offset & 0xFFF0;
111
w = inst.Offset & 0xFFF8;
112
streamer.EmitIntValue(w, 2);
113
w = inst.Offset >> 16;
114
streamer.EmitIntValue(w, 2);
116
case Win64EH::UOP_PushMachFrame:
117
if (inst.Offset == 1)
119
EmitAbsDifference(streamer, inst.Label, begin);
120
streamer.EmitIntValue(b2, 1);
125
static void EmitSymbolRefWithOfs(MCStreamer &streamer,
126
const MCSymbol *Base,
127
const MCSymbol *Other) {
128
MCContext &Context = streamer.getContext();
129
const MCSymbolRefExpr *BaseRef = MCSymbolRefExpr::create(Base, Context);
130
const MCSymbolRefExpr *OtherRef = MCSymbolRefExpr::create(Other, Context);
131
const MCExpr *Ofs = MCBinaryExpr::createSub(OtherRef, BaseRef, Context);
132
const MCSymbolRefExpr *BaseRefRel = MCSymbolRefExpr::create(Base,
133
MCSymbolRefExpr::VK_COFF_IMGREL32,
135
streamer.EmitValue(MCBinaryExpr::createAdd(BaseRefRel, Ofs, Context), 4);
138
static void EmitRuntimeFunction(MCStreamer &streamer,
139
const WinEH::FrameInfo *info) {
140
MCContext &context = streamer.getContext();
142
streamer.EmitValueToAlignment(4);
143
EmitSymbolRefWithOfs(streamer, info->Function, info->Begin);
144
EmitSymbolRefWithOfs(streamer, info->Function, info->End);
145
streamer.EmitValue(MCSymbolRefExpr::create(info->Symbol,
146
MCSymbolRefExpr::VK_COFF_IMGREL32,
150
static void EmitUnwindInfo(MCStreamer &streamer, WinEH::FrameInfo *info) {
151
// If this UNWIND_INFO already has a symbol, it's already been emitted.
155
MCContext &context = streamer.getContext();
156
MCSymbol *Label = context.createTempSymbol();
158
streamer.EmitValueToAlignment(4);
159
streamer.EmitLabel(Label);
160
info->Symbol = Label;
162
// Upper 3 bits are the version number (currently 1).
163
uint8_t flags = 0x01;
164
if (info->ChainedParent)
165
flags |= Win64EH::UNW_ChainInfo << 3;
167
if (info->HandlesUnwind)
168
flags |= Win64EH::UNW_TerminateHandler << 3;
169
if (info->HandlesExceptions)
170
flags |= Win64EH::UNW_ExceptionHandler << 3;
172
streamer.EmitIntValue(flags, 1);
175
EmitAbsDifference(streamer, info->PrologEnd, info->Begin);
177
streamer.EmitIntValue(0, 1);
179
uint8_t numCodes = CountOfUnwindCodes(info->Instructions);
180
streamer.EmitIntValue(numCodes, 1);
183
if (info->LastFrameInst >= 0) {
184
WinEH::Instruction &frameInst = info->Instructions[info->LastFrameInst];
185
assert(frameInst.Operation == Win64EH::UOP_SetFPReg);
186
frame = (frameInst.Register & 0x0F) | (frameInst.Offset & 0xF0);
188
streamer.EmitIntValue(frame, 1);
190
// Emit unwind instructions (in reverse order).
191
uint8_t numInst = info->Instructions.size();
192
for (uint8_t c = 0; c < numInst; ++c) {
193
WinEH::Instruction inst = info->Instructions.back();
194
info->Instructions.pop_back();
195
EmitUnwindCode(streamer, info->Begin, inst);
198
// For alignment purposes, the instruction array will always have an even
199
// number of entries, with the final entry potentially unused (in which case
200
// the array will be one longer than indicated by the count of unwind codes
203
streamer.EmitIntValue(0, 2);
206
if (flags & (Win64EH::UNW_ChainInfo << 3))
207
EmitRuntimeFunction(streamer, info->ChainedParent);
209
((Win64EH::UNW_TerminateHandler|Win64EH::UNW_ExceptionHandler) << 3))
210
streamer.EmitValue(MCSymbolRefExpr::create(info->ExceptionHandler,
211
MCSymbolRefExpr::VK_COFF_IMGREL32,
213
else if (numCodes == 0) {
214
// The minimum size of an UNWIND_INFO struct is 8 bytes. If we're not
215
// a chained unwind info, if there is no handler, and if there are fewer
216
// than 2 slots used in the unwind code array, we have to pad to 8 bytes.
217
streamer.EmitIntValue(0, 4);
222
void UnwindEmitter::Emit(MCStreamer &Streamer) const {
223
MCContext &Context = Streamer.getContext();
225
// Emit the unwind info structs first.
226
for (const auto &CFI : Streamer.getWinFrameInfos()) {
227
MCSection *XData = getXDataSection(CFI->Function, Context);
228
Streamer.SwitchSection(XData);
229
EmitUnwindInfo(Streamer, CFI);
232
// Now emit RUNTIME_FUNCTION entries.
233
for (const auto &CFI : Streamer.getWinFrameInfos()) {
234
MCSection *PData = getPDataSection(CFI->Function, Context);
235
Streamer.SwitchSection(PData);
236
EmitRuntimeFunction(Streamer, CFI);
240
void UnwindEmitter::EmitUnwindInfo(MCStreamer &Streamer,
241
WinEH::FrameInfo *info) const {
242
// Switch sections (the static function above is meant to be called from
243
// here and from Emit().
244
MCContext &context = Streamer.getContext();
245
MCSection *xdataSect = getXDataSection(info->Function, context);
246
Streamer.SwitchSection(xdataSect);
248
llvm::EmitUnwindInfo(Streamer, info);
251
} // End of namespace llvm