1 //===-- ARMWinCOFFStreamer.cpp - ARM Target WinCOFF Streamer ----*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "ARMMCTargetDesc.h"
10 #include "llvm/MC/MCAsmBackend.h"
11 #include "llvm/MC/MCAssembler.h"
12 #include "llvm/MC/MCCodeEmitter.h"
13 #include "llvm/MC/MCContext.h"
14 #include "llvm/MC/MCObjectWriter.h"
15 #include "llvm/MC/MCWin64EH.h"
16 #include "llvm/MC/MCWinCOFFStreamer.h"
17
18 using namespace llvm;
19
20 namespace {
21 class ARMWinCOFFStreamer : public MCWinCOFFStreamer {
22 Win64EH::ARMUnwindEmitter EHStreamer;
23
24 public:
ARMWinCOFFStreamer(MCContext & C,std::unique_ptr<MCAsmBackend> AB,std::unique_ptr<MCCodeEmitter> CE,std::unique_ptr<MCObjectWriter> OW)25 ARMWinCOFFStreamer(MCContext &C, std::unique_ptr<MCAsmBackend> AB,
26 std::unique_ptr<MCCodeEmitter> CE,
27 std::unique_ptr<MCObjectWriter> OW)
28 : MCWinCOFFStreamer(C, std::move(AB), std::move(CE), std::move(OW)) {}
29
30 void emitWinEHHandlerData(SMLoc Loc) override;
31 void emitWindowsUnwindTables() override;
32 void emitWindowsUnwindTables(WinEH::FrameInfo *Frame) override;
33
34 void emitThumbFunc(MCSymbol *Symbol) override;
35 void finishImpl() override;
36 };
37
emitWinEHHandlerData(SMLoc Loc)38 void ARMWinCOFFStreamer::emitWinEHHandlerData(SMLoc Loc) {
39 MCStreamer::emitWinEHHandlerData(Loc);
40
41 // We have to emit the unwind info now, because this directive
42 // actually switches to the .xdata section!
43 EHStreamer.EmitUnwindInfo(*this, getCurrentWinFrameInfo(),
44 /* HandlerData = */ true);
45 }
46
emitWindowsUnwindTables(WinEH::FrameInfo * Frame)47 void ARMWinCOFFStreamer::emitWindowsUnwindTables(WinEH::FrameInfo *Frame) {
48 EHStreamer.EmitUnwindInfo(*this, Frame, /* HandlerData = */ false);
49 }
50
emitWindowsUnwindTables()51 void ARMWinCOFFStreamer::emitWindowsUnwindTables() {
52 if (!getNumWinFrameInfos())
53 return;
54 EHStreamer.Emit(*this);
55 }
56
emitThumbFunc(MCSymbol * Symbol)57 void ARMWinCOFFStreamer::emitThumbFunc(MCSymbol *Symbol) {
58 getAssembler().setIsThumbFunc(Symbol);
59 }
60
finishImpl()61 void ARMWinCOFFStreamer::finishImpl() {
62 emitFrames(nullptr);
63 emitWindowsUnwindTables();
64
65 MCWinCOFFStreamer::finishImpl();
66 }
67 }
68
69 MCStreamer *
createARMWinCOFFStreamer(MCContext & Context,std::unique_ptr<MCAsmBackend> && MAB,std::unique_ptr<MCObjectWriter> && OW,std::unique_ptr<MCCodeEmitter> && Emitter)70 llvm::createARMWinCOFFStreamer(MCContext &Context,
71 std::unique_ptr<MCAsmBackend> &&MAB,
72 std::unique_ptr<MCObjectWriter> &&OW,
73 std::unique_ptr<MCCodeEmitter> &&Emitter) {
74 return new ARMWinCOFFStreamer(Context, std::move(MAB), std::move(Emitter),
75 std::move(OW));
76 }
77
78 namespace {
79 class ARMTargetWinCOFFStreamer : public llvm::ARMTargetStreamer {
80 private:
81 // True if we are processing SEH directives in an epilogue.
82 bool InEpilogCFI = false;
83
84 // Symbol of the current epilog for which we are processing SEH directives.
85 MCSymbol *CurrentEpilog = nullptr;
86
87 public:
ARMTargetWinCOFFStreamer(llvm::MCStreamer & S)88 ARMTargetWinCOFFStreamer(llvm::MCStreamer &S) : ARMTargetStreamer(S) {}
89
90 // The unwind codes on ARM Windows are documented at
91 // https://docs.microsoft.com/en-us/cpp/build/arm-exception-handling
92 void emitARMWinCFIAllocStack(unsigned Size, bool Wide) override;
93 void emitARMWinCFISaveRegMask(unsigned Mask, bool Wide) override;
94 void emitARMWinCFISaveSP(unsigned Reg) override;
95 void emitARMWinCFISaveFRegs(unsigned First, unsigned Last) override;
96 void emitARMWinCFISaveLR(unsigned Offset) override;
97 void emitARMWinCFIPrologEnd(bool Fragment) override;
98 void emitARMWinCFINop(bool Wide) override;
99 void emitARMWinCFIEpilogStart(unsigned Condition) override;
100 void emitARMWinCFIEpilogEnd() override;
101 void emitARMWinCFICustom(unsigned Opcode) override;
102
103 private:
104 void emitARMWinUnwindCode(unsigned UnwindCode, int Reg, int Offset);
105 };
106
107 // Helper function to common out unwind code setup for those codes that can
108 // belong to both prolog and epilog.
emitARMWinUnwindCode(unsigned UnwindCode,int Reg,int Offset)109 void ARMTargetWinCOFFStreamer::emitARMWinUnwindCode(unsigned UnwindCode,
110 int Reg, int Offset) {
111 auto &S = getStreamer();
112 WinEH::FrameInfo *CurFrame = S.EnsureValidWinFrameInfo(SMLoc());
113 if (!CurFrame)
114 return;
115 MCSymbol *Label = S.emitCFILabel();
116 auto Inst = WinEH::Instruction(UnwindCode, Label, Reg, Offset);
117 if (InEpilogCFI)
118 CurFrame->EpilogMap[CurrentEpilog].Instructions.push_back(Inst);
119 else
120 CurFrame->Instructions.push_back(Inst);
121 }
122
emitARMWinCFIAllocStack(unsigned Size,bool Wide)123 void ARMTargetWinCOFFStreamer::emitARMWinCFIAllocStack(unsigned Size,
124 bool Wide) {
125 unsigned Op = Win64EH::UOP_AllocSmall;
126 if (!Wide) {
127 if (Size / 4 > 0xffff)
128 Op = Win64EH::UOP_AllocHuge;
129 else if (Size / 4 > 0x7f)
130 Op = Win64EH::UOP_AllocLarge;
131 } else {
132 Op = Win64EH::UOP_WideAllocMedium;
133 if (Size / 4 > 0xffff)
134 Op = Win64EH::UOP_WideAllocHuge;
135 else if (Size / 4 > 0x3ff)
136 Op = Win64EH::UOP_WideAllocLarge;
137 }
138 emitARMWinUnwindCode(Op, -1, Size);
139 }
140
emitARMWinCFISaveRegMask(unsigned Mask,bool Wide)141 void ARMTargetWinCOFFStreamer::emitARMWinCFISaveRegMask(unsigned Mask,
142 bool Wide) {
143 assert(Mask != 0);
144 int Lr = (Mask & 0x4000) ? 1 : 0;
145 Mask &= ~0x4000;
146 if (Wide)
147 assert((Mask & ~0x1fff) == 0);
148 else
149 assert((Mask & ~0x00ff) == 0);
150 if (Mask && ((Mask + (1 << 4)) & Mask) == 0) {
151 if (Wide && (Mask & 0x1000) == 0 && (Mask & 0xff) == 0xf0) {
152 // One continuous range from r4 to r8-r11
153 for (int I = 11; I >= 8; I--) {
154 if (Mask & (1 << I)) {
155 emitARMWinUnwindCode(Win64EH::UOP_WideSaveRegsR4R11LR, I, Lr);
156 return;
157 }
158 }
159 // If it actually was from r4 to r4-r7, continue below.
160 } else if (!Wide) {
161 // One continuous range from r4 to r4-r7
162 for (int I = 7; I >= 4; I--) {
163 if (Mask & (1 << I)) {
164 emitARMWinUnwindCode(Win64EH::UOP_SaveRegsR4R7LR, I, Lr);
165 return;
166 }
167 }
168 llvm_unreachable("logic error");
169 }
170 }
171 Mask |= Lr << 14;
172 if (Wide)
173 emitARMWinUnwindCode(Win64EH::UOP_WideSaveRegMask, Mask, 0);
174 else
175 emitARMWinUnwindCode(Win64EH::UOP_SaveRegMask, Mask, 0);
176 }
177
emitARMWinCFISaveSP(unsigned Reg)178 void ARMTargetWinCOFFStreamer::emitARMWinCFISaveSP(unsigned Reg) {
179 emitARMWinUnwindCode(Win64EH::UOP_SaveSP, Reg, 0);
180 }
181
emitARMWinCFISaveFRegs(unsigned First,unsigned Last)182 void ARMTargetWinCOFFStreamer::emitARMWinCFISaveFRegs(unsigned First,
183 unsigned Last) {
184 assert(First <= Last);
185 assert(First >= 16 || Last < 16);
186 assert(First <= 31 && Last <= 31);
187 if (First == 8)
188 emitARMWinUnwindCode(Win64EH::UOP_SaveFRegD8D15, Last, 0);
189 else if (First <= 15)
190 emitARMWinUnwindCode(Win64EH::UOP_SaveFRegD0D15, First, Last);
191 else
192 emitARMWinUnwindCode(Win64EH::UOP_SaveFRegD16D31, First, Last);
193 }
194
emitARMWinCFISaveLR(unsigned Offset)195 void ARMTargetWinCOFFStreamer::emitARMWinCFISaveLR(unsigned Offset) {
196 emitARMWinUnwindCode(Win64EH::UOP_SaveLR, 0, Offset);
197 }
198
emitARMWinCFINop(bool Wide)199 void ARMTargetWinCOFFStreamer::emitARMWinCFINop(bool Wide) {
200 if (Wide)
201 emitARMWinUnwindCode(Win64EH::UOP_WideNop, -1, 0);
202 else
203 emitARMWinUnwindCode(Win64EH::UOP_Nop, -1, 0);
204 }
205
emitARMWinCFIPrologEnd(bool Fragment)206 void ARMTargetWinCOFFStreamer::emitARMWinCFIPrologEnd(bool Fragment) {
207 auto &S = getStreamer();
208 WinEH::FrameInfo *CurFrame = S.EnsureValidWinFrameInfo(SMLoc());
209 if (!CurFrame)
210 return;
211
212 MCSymbol *Label = S.emitCFILabel();
213 CurFrame->PrologEnd = Label;
214 WinEH::Instruction Inst =
215 WinEH::Instruction(Win64EH::UOP_End, /*Label=*/nullptr, -1, 0);
216 auto it = CurFrame->Instructions.begin();
217 CurFrame->Instructions.insert(it, Inst);
218 CurFrame->Fragment = Fragment;
219 }
220
emitARMWinCFIEpilogStart(unsigned Condition)221 void ARMTargetWinCOFFStreamer::emitARMWinCFIEpilogStart(unsigned Condition) {
222 auto &S = getStreamer();
223 WinEH::FrameInfo *CurFrame = S.EnsureValidWinFrameInfo(SMLoc());
224 if (!CurFrame)
225 return;
226
227 InEpilogCFI = true;
228 CurrentEpilog = S.emitCFILabel();
229 CurFrame->EpilogMap[CurrentEpilog].Condition = Condition;
230 }
231
emitARMWinCFIEpilogEnd()232 void ARMTargetWinCOFFStreamer::emitARMWinCFIEpilogEnd() {
233 auto &S = getStreamer();
234 WinEH::FrameInfo *CurFrame = S.EnsureValidWinFrameInfo(SMLoc());
235 if (!CurFrame)
236 return;
237
238 if (!CurrentEpilog) {
239 S.getContext().reportError(SMLoc(), "Stray .seh_endepilogue in " +
240 CurFrame->Function->getName());
241 return;
242 }
243
244 std::vector<WinEH::Instruction> &Epilog =
245 CurFrame->EpilogMap[CurrentEpilog].Instructions;
246
247 unsigned UnwindCode = Win64EH::UOP_End;
248 if (!Epilog.empty()) {
249 WinEH::Instruction EndInstr = Epilog.back();
250 if (EndInstr.Operation == Win64EH::UOP_Nop) {
251 UnwindCode = Win64EH::UOP_EndNop;
252 Epilog.pop_back();
253 } else if (EndInstr.Operation == Win64EH::UOP_WideNop) {
254 UnwindCode = Win64EH::UOP_WideEndNop;
255 Epilog.pop_back();
256 }
257 }
258
259 InEpilogCFI = false;
260 WinEH::Instruction Inst = WinEH::Instruction(UnwindCode, nullptr, -1, 0);
261 CurFrame->EpilogMap[CurrentEpilog].Instructions.push_back(Inst);
262 MCSymbol *Label = S.emitCFILabel();
263 CurFrame->EpilogMap[CurrentEpilog].End = Label;
264 CurrentEpilog = nullptr;
265 }
266
emitARMWinCFICustom(unsigned Opcode)267 void ARMTargetWinCOFFStreamer::emitARMWinCFICustom(unsigned Opcode) {
268 emitARMWinUnwindCode(Win64EH::UOP_Custom, 0, Opcode);
269 }
270
271 } // end anonymous namespace
272
createARMObjectTargetWinCOFFStreamer(MCStreamer & S)273 MCTargetStreamer *llvm::createARMObjectTargetWinCOFFStreamer(MCStreamer &S) {
274 return new ARMTargetWinCOFFStreamer(S);
275 }
276