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1 : //===-- CodeGen/AsmPrinter/WinException.cpp - Dwarf Exception Impl ------===//
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 : // This file contains support for writing Win64 exception info into asm files.
11 : //
12 : //===----------------------------------------------------------------------===//
13 :
14 : #include "WinException.h"
15 : #include "llvm/ADT/Twine.h"
16 : #include "llvm/BinaryFormat/COFF.h"
17 : #include "llvm/BinaryFormat/Dwarf.h"
18 : #include "llvm/CodeGen/AsmPrinter.h"
19 : #include "llvm/CodeGen/MachineFrameInfo.h"
20 : #include "llvm/CodeGen/MachineFunction.h"
21 : #include "llvm/CodeGen/MachineModuleInfo.h"
22 : #include "llvm/CodeGen/TargetFrameLowering.h"
23 : #include "llvm/CodeGen/TargetLowering.h"
24 : #include "llvm/CodeGen/TargetSubtargetInfo.h"
25 : #include "llvm/CodeGen/WinEHFuncInfo.h"
26 : #include "llvm/IR/DataLayout.h"
27 : #include "llvm/IR/Mangler.h"
28 : #include "llvm/IR/Module.h"
29 : #include "llvm/MC/MCAsmInfo.h"
30 : #include "llvm/MC/MCContext.h"
31 : #include "llvm/MC/MCExpr.h"
32 : #include "llvm/MC/MCSection.h"
33 : #include "llvm/MC/MCStreamer.h"
34 : #include "llvm/MC/MCSymbol.h"
35 : #include "llvm/Support/ErrorHandling.h"
36 : #include "llvm/Support/FormattedStream.h"
37 : #include "llvm/Target/TargetLoweringObjectFile.h"
38 : #include "llvm/Target/TargetOptions.h"
39 : using namespace llvm;
40 :
41 604 : WinException::WinException(AsmPrinter *A) : EHStreamer(A) {
42 : // MSVC's EH tables are always composed of 32-bit words. All known 64-bit
43 : // platforms use an imagerel32 relocation to refer to symbols.
44 604 : useImageRel32 = (A->getDataLayout().getPointerSizeInBits() == 64);
45 604 : }
46 :
47 600 : WinException::~WinException() {}
48 :
49 : /// endModule - Emit all exception information that should come after the
50 : /// content.
51 600 : void WinException::endModule() {
52 600 : auto &OS = *Asm->OutStreamer;
53 600 : const Module *M = MMI->getModule();
54 4703 : for (const Function &F : *M)
55 4103 : if (F.hasFnAttribute("safeseh"))
56 31 : OS.EmitCOFFSafeSEH(Asm->getSymbol(&F));
57 600 : }
58 :
59 2494 : void WinException::beginFunction(const MachineFunction *MF) {
60 2494 : shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
61 :
62 : // If any landing pads survive, we need an EH table.
63 2494 : bool hasLandingPads = !MF->getLandingPads().empty();
64 2494 : bool hasEHFunclets = MF->hasEHFunclets();
65 :
66 2494 : const Function &F = MF->getFunction();
67 :
68 2494 : shouldEmitMoves = Asm->needsSEHMoves() && MF->hasWinCFI();
69 :
70 2494 : const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
71 2494 : unsigned PerEncoding = TLOF.getPersonalityEncoding();
72 :
73 : EHPersonality Per = EHPersonality::Unknown;
74 : const Function *PerFn = nullptr;
75 2494 : if (F.hasPersonalityFn()) {
76 124 : PerFn = dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
77 124 : Per = classifyEHPersonality(PerFn);
78 : }
79 :
80 : bool forceEmitPersonality = F.hasPersonalityFn() &&
81 2502 : !isNoOpWithoutInvoke(Per) &&
82 8 : F.needsUnwindTableEntry();
83 :
84 2494 : shouldEmitPersonality =
85 2486 : forceEmitPersonality || ((hasLandingPads || hasEHFunclets) &&
86 111 : PerEncoding != dwarf::DW_EH_PE_omit && PerFn);
87 :
88 2494 : unsigned LSDAEncoding = TLOF.getLSDAEncoding();
89 2494 : shouldEmitLSDA = shouldEmitPersonality &&
90 : LSDAEncoding != dwarf::DW_EH_PE_omit;
91 :
92 : // If we're not using CFI, we don't want the CFI or the personality, but we
93 : // might want EH tables if we had EH pads.
94 2494 : if (!Asm->MAI->usesWindowsCFI()) {
95 931 : if (Per == EHPersonality::MSVC_X86SEH && !hasEHFunclets) {
96 : // If this is 32-bit SEH and we don't have any funclets (really invokes),
97 : // make sure we emit the parent offset label. Some unreferenced filter
98 : // functions may still refer to it.
99 1 : const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
100 : StringRef FLinkageName =
101 1 : GlobalValue::dropLLVMManglingEscape(MF->getFunction().getName());
102 1 : emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
103 : }
104 931 : shouldEmitLSDA = hasEHFunclets;
105 931 : shouldEmitPersonality = false;
106 931 : return;
107 : }
108 :
109 3126 : beginFunclet(MF->front(), Asm->CurrentFnSym);
110 : }
111 :
112 : /// endFunction - Gather and emit post-function exception information.
113 : ///
114 2494 : void WinException::endFunction(const MachineFunction *MF) {
115 2494 : if (!shouldEmitPersonality && !shouldEmitMoves && !shouldEmitLSDA)
116 : return;
117 :
118 496 : const Function &F = MF->getFunction();
119 : EHPersonality Per = EHPersonality::Unknown;
120 496 : if (F.hasPersonalityFn())
121 222 : Per = classifyEHPersonality(F.getPersonalityFn()->stripPointerCasts());
122 :
123 : // Get rid of any dead landing pads if we're not using funclets. In funclet
124 : // schemes, the landing pad is not actually reachable. It only exists so
125 : // that we can emit the right table data.
126 : if (!isFuncletEHPersonality(Per)) {
127 : MachineFunction *NonConstMF = const_cast<MachineFunction*>(MF);
128 408 : NonConstMF->tidyLandingPads();
129 : }
130 :
131 496 : endFunclet();
132 :
133 : // endFunclet will emit the necessary .xdata tables for x64 SEH.
134 496 : if (Per == EHPersonality::MSVC_Win64SEH && MF->hasEHFunclets())
135 : return;
136 :
137 485 : if (shouldEmitPersonality || shouldEmitLSDA) {
138 194 : Asm->OutStreamer->PushSection();
139 :
140 : // Just switch sections to the right xdata section.
141 194 : MCSection *XData = Asm->OutStreamer->getAssociatedXDataSection(
142 : Asm->OutStreamer->getCurrentSectionOnly());
143 194 : Asm->OutStreamer->SwitchSection(XData);
144 :
145 : // Emit the tables appropriate to the personality function in use. If we
146 : // don't recognize the personality, assume it uses an Itanium-style LSDA.
147 97 : if (Per == EHPersonality::MSVC_Win64SEH)
148 0 : emitCSpecificHandlerTable(MF);
149 97 : else if (Per == EHPersonality::MSVC_X86SEH)
150 13 : emitExceptHandlerTable(MF);
151 84 : else if (Per == EHPersonality::MSVC_CXX)
152 56 : emitCXXFrameHandler3Table(MF);
153 28 : else if (Per == EHPersonality::CoreCLR)
154 7 : emitCLRExceptionTable(MF);
155 : else
156 21 : emitExceptionTable();
157 :
158 194 : Asm->OutStreamer->PopSection();
159 : }
160 : }
161 :
162 : /// Retrieve the MCSymbol for a GlobalValue or MachineBasicBlock.
163 0 : static MCSymbol *getMCSymbolForMBB(AsmPrinter *Asm,
164 : const MachineBasicBlock *MBB) {
165 0 : if (!MBB)
166 0 : return nullptr;
167 :
168 : assert(MBB->isEHFuncletEntry());
169 :
170 : // Give catches and cleanups a name based off of their parent function and
171 : // their funclet entry block's number.
172 0 : const MachineFunction *MF = MBB->getParent();
173 0 : const Function &F = MF->getFunction();
174 0 : StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName());
175 0 : MCContext &Ctx = MF->getContext();
176 0 : StringRef HandlerPrefix = MBB->isCleanupFuncletEntry() ? "dtor" : "catch";
177 0 : return Ctx.getOrCreateSymbol("?" + HandlerPrefix + "$" +
178 0 : Twine(MBB->getNumber()) + "@?0?" +
179 0 : FuncLinkageName + "@4HA");
180 : }
181 :
182 1680 : void WinException::beginFunclet(const MachineBasicBlock &MBB,
183 : MCSymbol *Sym) {
184 1680 : CurrentFuncletEntry = &MBB;
185 :
186 1680 : const Function &F = Asm->MF->getFunction();
187 : // If a symbol was not provided for the funclet, invent one.
188 1680 : if (!Sym) {
189 117 : Sym = getMCSymbolForMBB(Asm, &MBB);
190 :
191 : // Describe our funclet symbol as a function with internal linkage.
192 234 : Asm->OutStreamer->BeginCOFFSymbolDef(Sym);
193 234 : Asm->OutStreamer->EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
194 117 : Asm->OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
195 117 : << COFF::SCT_COMPLEX_TYPE_SHIFT);
196 234 : Asm->OutStreamer->EndCOFFSymbolDef();
197 :
198 : // We want our funclet's entry point to be aligned such that no nops will be
199 : // present after the label.
200 117 : Asm->EmitAlignment(std::max(Asm->MF->getAlignment(), MBB.getAlignment()),
201 : &F);
202 :
203 : // Now that we've emitted the alignment directive, point at our funclet.
204 234 : Asm->OutStreamer->EmitLabel(Sym);
205 : }
206 :
207 : // Mark 'Sym' as starting our funclet.
208 1680 : if (shouldEmitMoves || shouldEmitPersonality) {
209 547 : CurrentFuncletTextSection = Asm->OutStreamer->getCurrentSectionOnly();
210 547 : Asm->OutStreamer->EmitWinCFIStartProc(Sym);
211 : }
212 :
213 1680 : if (shouldEmitPersonality) {
214 159 : const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
215 : const Function *PerFn = nullptr;
216 :
217 : // Determine which personality routine we are using for this funclet.
218 159 : if (F.hasPersonalityFn())
219 159 : PerFn = dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
220 : const MCSymbol *PersHandlerSym =
221 159 : TLOF.getCFIPersonalitySymbol(PerFn, Asm->TM, MMI);
222 :
223 : // Do not emit a .seh_handler directives for cleanup funclets.
224 : // FIXME: This means cleanup funclets cannot handle exceptions. Given that
225 : // Clang doesn't produce EH constructs inside cleanup funclets and LLVM's
226 : // inliner doesn't allow inlining them, this isn't a major problem in
227 : // practice.
228 159 : if (!CurrentFuncletEntry->isCleanupFuncletEntry())
229 262 : Asm->OutStreamer->EmitWinEHHandler(PersHandlerSym, true, true);
230 : }
231 1680 : }
232 :
233 613 : void WinException::endFunclet() {
234 : // No funclet to process? Great, we have nothing to do.
235 613 : if (!CurrentFuncletEntry)
236 : return;
237 :
238 579 : const MachineFunction *MF = Asm->MF;
239 579 : if (shouldEmitMoves || shouldEmitPersonality) {
240 547 : const Function &F = MF->getFunction();
241 : EHPersonality Per = EHPersonality::Unknown;
242 547 : if (F.hasPersonalityFn())
243 324 : Per = classifyEHPersonality(F.getPersonalityFn()->stripPointerCasts());
244 :
245 : // Emit an UNWIND_INFO struct describing the prologue.
246 1094 : Asm->OutStreamer->EmitWinEHHandlerData();
247 :
248 547 : if (Per == EHPersonality::MSVC_CXX && shouldEmitPersonality &&
249 96 : !CurrentFuncletEntry->isCleanupFuncletEntry()) {
250 : // If this is a C++ catch funclet (or the parent function),
251 : // emit a reference to the LSDA for the parent function.
252 81 : StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName());
253 162 : MCSymbol *FuncInfoXData = Asm->OutContext.getOrCreateSymbol(
254 81 : Twine("$cppxdata$", FuncLinkageName));
255 162 : Asm->OutStreamer->EmitValue(create32bitRef(FuncInfoXData), 4);
256 466 : } else if (Per == EHPersonality::MSVC_Win64SEH && MF->hasEHFunclets() &&
257 16 : !CurrentFuncletEntry->isEHFuncletEntry()) {
258 : // If this is the parent function in Win64 SEH, emit the LSDA immediately
259 : // following .seh_handlerdata.
260 11 : emitCSpecificHandlerTable(MF);
261 : }
262 :
263 : // Switch back to the funclet start .text section now that we are done
264 : // writing to .xdata, and emit an .seh_endproc directive to mark the end of
265 : // the function.
266 1094 : Asm->OutStreamer->SwitchSection(CurrentFuncletTextSection);
267 1094 : Asm->OutStreamer->EmitWinCFIEndProc();
268 : }
269 :
270 : // Let's make sure we don't try to end the same funclet twice.
271 579 : CurrentFuncletEntry = nullptr;
272 : }
273 :
274 820 : const MCExpr *WinException::create32bitRef(const MCSymbol *Value) {
275 820 : if (!Value)
276 150 : return MCConstantExpr::create(0, Asm->OutContext);
277 670 : return MCSymbolRefExpr::create(Value, useImageRel32
278 : ? MCSymbolRefExpr::VK_COFF_IMGREL32
279 : : MCSymbolRefExpr::VK_None,
280 670 : Asm->OutContext);
281 : }
282 :
283 98 : const MCExpr *WinException::create32bitRef(const GlobalValue *GV) {
284 98 : if (!GV)
285 49 : return MCConstantExpr::create(0, Asm->OutContext);
286 49 : return create32bitRef(Asm->getSymbol(GV));
287 : }
288 :
289 130 : const MCExpr *WinException::getLabelPlusOne(const MCSymbol *Label) {
290 130 : return MCBinaryExpr::createAdd(create32bitRef(Label),
291 130 : MCConstantExpr::create(1, Asm->OutContext),
292 130 : Asm->OutContext);
293 : }
294 :
295 141 : const MCExpr *WinException::getOffset(const MCSymbol *OffsetOf,
296 : const MCSymbol *OffsetFrom) {
297 141 : return MCBinaryExpr::createSub(
298 141 : MCSymbolRefExpr::create(OffsetOf, Asm->OutContext),
299 141 : MCSymbolRefExpr::create(OffsetFrom, Asm->OutContext), Asm->OutContext);
300 : }
301 :
302 52 : const MCExpr *WinException::getOffsetPlusOne(const MCSymbol *OffsetOf,
303 : const MCSymbol *OffsetFrom) {
304 52 : return MCBinaryExpr::createAdd(getOffset(OffsetOf, OffsetFrom),
305 52 : MCConstantExpr::create(1, Asm->OutContext),
306 52 : Asm->OutContext);
307 : }
308 :
309 43 : int WinException::getFrameIndexOffset(int FrameIndex,
310 : const WinEHFuncInfo &FuncInfo) {
311 43 : const TargetFrameLowering &TFI = *Asm->MF->getSubtarget().getFrameLowering();
312 : unsigned UnusedReg;
313 43 : if (Asm->MAI->usesWindowsCFI()) {
314 : int Offset =
315 41 : TFI.getFrameIndexReferencePreferSP(*Asm->MF, FrameIndex, UnusedReg,
316 41 : /*IgnoreSPUpdates*/ true);
317 : assert(UnusedReg ==
318 : Asm->MF->getSubtarget()
319 : .getTargetLowering()
320 : ->getStackPointerRegisterToSaveRestore());
321 41 : return Offset;
322 : }
323 :
324 : // For 32-bit, offsets should be relative to the end of the EH registration
325 : // node. For 64-bit, it's relative to SP at the end of the prologue.
326 : assert(FuncInfo.EHRegNodeEndOffset != INT_MAX);
327 2 : int Offset = TFI.getFrameIndexReference(*Asm->MF, FrameIndex, UnusedReg);
328 2 : Offset += FuncInfo.EHRegNodeEndOffset;
329 2 : return Offset;
330 : }
331 :
332 : namespace {
333 :
334 : /// Top-level state used to represent unwind to caller
335 : const int NullState = -1;
336 :
337 : struct InvokeStateChange {
338 : /// EH Label immediately after the last invoke in the previous state, or
339 : /// nullptr if the previous state was the null state.
340 : const MCSymbol *PreviousEndLabel;
341 :
342 : /// EH label immediately before the first invoke in the new state, or nullptr
343 : /// if the new state is the null state.
344 : const MCSymbol *NewStartLabel;
345 :
346 : /// State of the invoke following NewStartLabel, or NullState to indicate
347 : /// the presence of calls which may unwind to caller.
348 : int NewState;
349 : };
350 :
351 : /// Iterator that reports all the invoke state changes in a range of machine
352 : /// basic blocks. Changes to the null state are reported whenever a call that
353 : /// may unwind to caller is encountered. The MBB range is expected to be an
354 : /// entire function or funclet, and the start and end of the range are treated
355 : /// as being in the NullState even if there's not an unwind-to-caller call
356 : /// before the first invoke or after the last one (i.e., the first state change
357 : /// reported is the first change to something other than NullState, and a
358 : /// change back to NullState is always reported at the end of iteration).
359 : class InvokeStateChangeIterator {
360 : InvokeStateChangeIterator(const WinEHFuncInfo &EHInfo,
361 : MachineFunction::const_iterator MFI,
362 : MachineFunction::const_iterator MFE,
363 : MachineBasicBlock::const_iterator MBBI,
364 : int BaseState)
365 236 : : EHInfo(EHInfo), MFI(MFI), MFE(MFE), MBBI(MBBI), BaseState(BaseState) {
366 236 : LastStateChange.PreviousEndLabel = nullptr;
367 236 : LastStateChange.NewStartLabel = nullptr;
368 236 : LastStateChange.NewState = BaseState;
369 118 : scan();
370 : }
371 :
372 : public:
373 : static iterator_range<InvokeStateChangeIterator>
374 118 : range(const WinEHFuncInfo &EHInfo, MachineFunction::const_iterator Begin,
375 : MachineFunction::const_iterator End, int BaseState = NullState) {
376 : // Reject empty ranges to simplify bookkeeping by ensuring that we can get
377 : // the end of the last block.
378 : assert(Begin != End);
379 : auto BlockBegin = Begin->begin();
380 : auto BlockEnd = std::prev(End)->end();
381 : return make_range(
382 : InvokeStateChangeIterator(EHInfo, Begin, End, BlockBegin, BaseState),
383 236 : InvokeStateChangeIterator(EHInfo, End, End, BlockEnd, BaseState));
384 : }
385 :
386 : // Iterator methods.
387 : bool operator==(const InvokeStateChangeIterator &O) const {
388 : assert(BaseState == O.BaseState);
389 : // Must be visiting same block.
390 267 : if (MFI != O.MFI)
391 : return false;
392 : // Must be visiting same isntr.
393 176 : if (MBBI != O.MBBI)
394 : return false;
395 : // At end of block/instr iteration, we can still have two distinct states:
396 : // one to report the final EndLabel, and another indicating the end of the
397 : // state change iteration. Check for CurrentEndLabel equality to
398 : // distinguish these.
399 176 : return CurrentEndLabel == O.CurrentEndLabel;
400 : }
401 :
402 : bool operator!=(const InvokeStateChangeIterator &O) const {
403 : return !operator==(O);
404 : }
405 : InvokeStateChange &operator*() { return LastStateChange; }
406 : InvokeStateChange *operator->() { return &LastStateChange; }
407 35 : InvokeStateChangeIterator &operator++() { return scan(); }
408 :
409 : private:
410 : InvokeStateChangeIterator &scan();
411 :
412 : const WinEHFuncInfo &EHInfo;
413 : const MCSymbol *CurrentEndLabel = nullptr;
414 : MachineFunction::const_iterator MFI;
415 : MachineFunction::const_iterator MFE;
416 : MachineBasicBlock::const_iterator MBBI;
417 : InvokeStateChange LastStateChange;
418 : bool VisitingInvoke = false;
419 : int BaseState;
420 : };
421 :
422 : } // end anonymous namespace
423 :
424 385 : InvokeStateChangeIterator &InvokeStateChangeIterator::scan() {
425 : bool IsNewBlock = false;
426 651 : for (; MFI != MFE; ++MFI, IsNewBlock = true) {
427 357 : if (IsNewBlock)
428 148 : MBBI = MFI->begin();
429 2303 : for (auto MBBE = MFI->end(); MBBI != MBBE; ++MBBI) {
430 : const MachineInstr &MI = *MBBI;
431 2129 : if (!VisitingInvoke && LastStateChange.NewState != BaseState &&
432 2054 : MI.isCall() && !EHStreamer::callToNoUnwindFunction(&MI)) {
433 : // Indicate a change of state to the null state. We don't have
434 : // start/end EH labels handy but the caller won't expect them for
435 : // null state regions.
436 8 : LastStateChange.PreviousEndLabel = CurrentEndLabel;
437 8 : LastStateChange.NewStartLabel = nullptr;
438 8 : LastStateChange.NewState = BaseState;
439 8 : CurrentEndLabel = nullptr;
440 : // Don't re-visit this instr on the next scan
441 : ++MBBI;
442 91 : return *this;
443 : }
444 :
445 : // All other state changes are at EH labels before/after invokes.
446 2029 : if (!MI.isEHLabel())
447 1946 : continue;
448 184 : MCSymbol *Label = MI.getOperand(0).getMCSymbol();
449 184 : if (Label == CurrentEndLabel) {
450 92 : VisitingInvoke = false;
451 92 : continue;
452 : }
453 92 : auto InvokeMapIter = EHInfo.LabelToStateMap.find(Label);
454 : // Ignore EH labels that aren't the ones inserted before an invoke
455 184 : if (InvokeMapIter == EHInfo.LabelToStateMap.end())
456 : continue;
457 : auto &StateAndEnd = InvokeMapIter->second;
458 92 : int NewState = StateAndEnd.first;
459 : // Keep track of the fact that we're between EH start/end labels so
460 : // we know not to treat the inoke we'll see as unwinding to caller.
461 92 : VisitingInvoke = true;
462 92 : if (NewState == LastStateChange.NewState) {
463 : // The state isn't actually changing here. Record the new end and
464 : // keep going.
465 9 : CurrentEndLabel = StateAndEnd.second;
466 9 : continue;
467 : }
468 : // Found a state change to report
469 83 : LastStateChange.PreviousEndLabel = CurrentEndLabel;
470 83 : LastStateChange.NewStartLabel = Label;
471 83 : LastStateChange.NewState = NewState;
472 : // Start keeping track of the new current end
473 83 : CurrentEndLabel = StateAndEnd.second;
474 : // Don't re-visit this instr on the next scan
475 : ++MBBI;
476 83 : return *this;
477 : }
478 : }
479 : // Iteration hit the end of the block range.
480 294 : if (LastStateChange.NewState != BaseState) {
481 : // Report the end of the last new state
482 58 : LastStateChange.PreviousEndLabel = CurrentEndLabel;
483 58 : LastStateChange.NewStartLabel = nullptr;
484 58 : LastStateChange.NewState = BaseState;
485 : // Leave CurrentEndLabel non-null to distinguish this state from end.
486 : assert(CurrentEndLabel != nullptr);
487 58 : return *this;
488 : }
489 : // We've reported all state changes and hit the end state.
490 236 : CurrentEndLabel = nullptr;
491 236 : return *this;
492 : }
493 :
494 : /// Emit the language-specific data that __C_specific_handler expects. This
495 : /// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
496 : /// up after faults with __try, __except, and __finally. The typeinfo values
497 : /// are not really RTTI data, but pointers to filter functions that return an
498 : /// integer (1, 0, or -1) indicating how to handle the exception. For __finally
499 : /// blocks and other cleanups, the landing pad label is zero, and the filter
500 : /// function is actually a cleanup handler with the same prototype. A catch-all
501 : /// entry is modeled with a null filter function field and a non-zero landing
502 : /// pad label.
503 : ///
504 : /// Possible filter function return values:
505 : /// EXCEPTION_EXECUTE_HANDLER (1):
506 : /// Jump to the landing pad label after cleanups.
507 : /// EXCEPTION_CONTINUE_SEARCH (0):
508 : /// Continue searching this table or continue unwinding.
509 : /// EXCEPTION_CONTINUE_EXECUTION (-1):
510 : /// Resume execution at the trapping PC.
511 : ///
512 : /// Inferred table structure:
513 : /// struct Table {
514 : /// int NumEntries;
515 : /// struct Entry {
516 : /// imagerel32 LabelStart;
517 : /// imagerel32 LabelEnd;
518 : /// imagerel32 FilterOrFinally; // One means catch-all.
519 : /// imagerel32 LabelLPad; // Zero means __finally.
520 : /// } Entries[NumEntries];
521 : /// };
522 11 : void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
523 11 : auto &OS = *Asm->OutStreamer;
524 11 : MCContext &Ctx = Asm->OutContext;
525 11 : const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
526 :
527 11 : bool VerboseAsm = OS.isVerboseAsm();
528 : auto AddComment = [&](const Twine &Comment) {
529 11 : if (VerboseAsm)
530 11 : OS.AddComment(Comment);
531 : };
532 :
533 : // Emit a label assignment with the SEH frame offset so we can use it for
534 : // llvm.x86.seh.recoverfp.
535 : StringRef FLinkageName =
536 11 : GlobalValue::dropLLVMManglingEscape(MF->getFunction().getName());
537 : MCSymbol *ParentFrameOffset =
538 11 : Ctx.getOrCreateParentFrameOffsetSymbol(FLinkageName);
539 : const MCExpr *MCOffset =
540 11 : MCConstantExpr::create(FuncInfo.SEHSetFrameOffset, Ctx);
541 22 : Asm->OutStreamer->EmitAssignment(ParentFrameOffset, MCOffset);
542 :
543 : // Use the assembler to compute the number of table entries through label
544 : // difference and division.
545 : MCSymbol *TableBegin =
546 11 : Ctx.createTempSymbol("lsda_begin", /*AlwaysAddSuffix=*/true);
547 : MCSymbol *TableEnd =
548 11 : Ctx.createTempSymbol("lsda_end", /*AlwaysAddSuffix=*/true);
549 11 : const MCExpr *LabelDiff = getOffset(TableEnd, TableBegin);
550 11 : const MCExpr *EntrySize = MCConstantExpr::create(16, Ctx);
551 : const MCExpr *EntryCount = MCBinaryExpr::createDiv(LabelDiff, EntrySize, Ctx);
552 11 : AddComment("Number of call sites");
553 11 : OS.EmitValue(EntryCount, 4);
554 :
555 11 : OS.EmitLabel(TableBegin);
556 :
557 : // Iterate over all the invoke try ranges. Unlike MSVC, LLVM currently only
558 : // models exceptions from invokes. LLVM also allows arbitrary reordering of
559 : // the code, so our tables end up looking a bit different. Rather than
560 : // trying to match MSVC's tables exactly, we emit a denormalized table. For
561 : // each range of invokes in the same state, we emit table entries for all
562 : // the actions that would be taken in that state. This means our tables are
563 : // slightly bigger, which is OK.
564 : const MCSymbol *LastStartLabel = nullptr;
565 : int LastEHState = -1;
566 : // Break out before we enter into a finally funclet.
567 : // FIXME: We need to emit separate EH tables for cleanups.
568 : MachineFunction::const_iterator End = MF->end();
569 : MachineFunction::const_iterator Stop = std::next(MF->begin());
570 44 : while (Stop != End && !Stop->isEHFuncletEntry())
571 : ++Stop;
572 : for (const auto &StateChange :
573 28 : InvokeStateChangeIterator::range(FuncInfo, MF->begin(), Stop)) {
574 : // Emit all the actions for the state we just transitioned out of
575 : // if it was not the null state
576 26 : if (LastEHState != -1)
577 15 : emitSEHActionsForRange(FuncInfo, LastStartLabel,
578 15 : StateChange.PreviousEndLabel, LastEHState);
579 26 : LastStartLabel = StateChange.NewStartLabel;
580 26 : LastEHState = StateChange.NewState;
581 : }
582 :
583 11 : OS.EmitLabel(TableEnd);
584 11 : }
585 :
586 15 : void WinException::emitSEHActionsForRange(const WinEHFuncInfo &FuncInfo,
587 : const MCSymbol *BeginLabel,
588 : const MCSymbol *EndLabel, int State) {
589 15 : auto &OS = *Asm->OutStreamer;
590 15 : MCContext &Ctx = Asm->OutContext;
591 :
592 15 : bool VerboseAsm = OS.isVerboseAsm();
593 : auto AddComment = [&](const Twine &Comment) {
594 84 : if (VerboseAsm)
595 84 : OS.AddComment(Comment);
596 : };
597 :
598 : assert(BeginLabel && EndLabel);
599 36 : while (State != -1) {
600 21 : const SEHUnwindMapEntry &UME = FuncInfo.SEHUnwindMap[State];
601 : const MCExpr *FilterOrFinally;
602 : const MCExpr *ExceptOrNull;
603 : auto *Handler = UME.Handler.get<MachineBasicBlock *>();
604 21 : if (UME.IsFinally) {
605 5 : FilterOrFinally = create32bitRef(getMCSymbolForMBB(Asm, Handler));
606 5 : ExceptOrNull = MCConstantExpr::create(0, Ctx);
607 : } else {
608 : // For an except, the filter can be 1 (catch-all) or a function
609 : // label.
610 16 : FilterOrFinally = UME.Filter ? create32bitRef(UME.Filter)
611 5 : : MCConstantExpr::create(1, Ctx);
612 16 : ExceptOrNull = create32bitRef(Handler->getSymbol());
613 : }
614 :
615 21 : AddComment("LabelStart");
616 21 : OS.EmitValue(getLabelPlusOne(BeginLabel), 4);
617 21 : AddComment("LabelEnd");
618 21 : OS.EmitValue(getLabelPlusOne(EndLabel), 4);
619 21 : AddComment(UME.IsFinally ? "FinallyFunclet" : UME.Filter ? "FilterFunction"
620 : : "CatchAll");
621 21 : OS.EmitValue(FilterOrFinally, 4);
622 21 : AddComment(UME.IsFinally ? "Null" : "ExceptionHandler");
623 21 : OS.EmitValue(ExceptOrNull, 4);
624 :
625 : assert(UME.ToState < State && "states should decrease");
626 21 : State = UME.ToState;
627 : }
628 15 : }
629 :
630 56 : void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
631 56 : const Function &F = MF->getFunction();
632 56 : auto &OS = *Asm->OutStreamer;
633 56 : const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
634 :
635 56 : StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName());
636 :
637 : SmallVector<std::pair<const MCExpr *, int>, 4> IPToStateTable;
638 : MCSymbol *FuncInfoXData = nullptr;
639 56 : if (shouldEmitPersonality) {
640 : // If we're 64-bit, emit a pointer to the C++ EH data, and build a map from
641 : // IPs to state numbers.
642 : FuncInfoXData =
643 70 : Asm->OutContext.getOrCreateSymbol(Twine("$cppxdata$", FuncLinkageName));
644 35 : computeIP2StateTable(MF, FuncInfo, IPToStateTable);
645 : } else {
646 21 : FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(FuncLinkageName);
647 : }
648 :
649 : int UnwindHelpOffset = 0;
650 56 : if (Asm->MAI->usesWindowsCFI())
651 : UnwindHelpOffset =
652 35 : getFrameIndexOffset(FuncInfo.UnwindHelpFrameIdx, FuncInfo);
653 :
654 : MCSymbol *UnwindMapXData = nullptr;
655 : MCSymbol *TryBlockMapXData = nullptr;
656 : MCSymbol *IPToStateXData = nullptr;
657 56 : if (!FuncInfo.CxxUnwindMap.empty())
658 112 : UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
659 56 : Twine("$stateUnwindMap$", FuncLinkageName));
660 56 : if (!FuncInfo.TryBlockMap.empty())
661 : TryBlockMapXData =
662 94 : Asm->OutContext.getOrCreateSymbol(Twine("$tryMap$", FuncLinkageName));
663 56 : if (!IPToStateTable.empty())
664 : IPToStateXData =
665 70 : Asm->OutContext.getOrCreateSymbol(Twine("$ip2state$", FuncLinkageName));
666 :
667 56 : bool VerboseAsm = OS.isVerboseAsm();
668 : auto AddComment = [&](const Twine &Comment) {
669 1777 : if (VerboseAsm)
670 1755 : OS.AddComment(Comment);
671 : };
672 :
673 : // FuncInfo {
674 : // uint32_t MagicNumber
675 : // int32_t MaxState;
676 : // UnwindMapEntry *UnwindMap;
677 : // uint32_t NumTryBlocks;
678 : // TryBlockMapEntry *TryBlockMap;
679 : // uint32_t IPMapEntries; // always 0 for x86
680 : // IPToStateMapEntry *IPToStateMap; // always 0 for x86
681 : // uint32_t UnwindHelp; // non-x86 only
682 : // ESTypeList *ESTypeList;
683 : // int32_t EHFlags;
684 : // }
685 : // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
686 : // EHFlags & 2 -> ???
687 : // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
688 56 : OS.EmitValueToAlignment(4);
689 56 : OS.EmitLabel(FuncInfoXData);
690 :
691 56 : AddComment("MagicNumber");
692 56 : OS.EmitIntValue(0x19930522, 4);
693 :
694 56 : AddComment("MaxState");
695 112 : OS.EmitIntValue(FuncInfo.CxxUnwindMap.size(), 4);
696 :
697 56 : AddComment("UnwindMap");
698 56 : OS.EmitValue(create32bitRef(UnwindMapXData), 4);
699 :
700 56 : AddComment("NumTryBlocks");
701 112 : OS.EmitIntValue(FuncInfo.TryBlockMap.size(), 4);
702 :
703 56 : AddComment("TryBlockMap");
704 56 : OS.EmitValue(create32bitRef(TryBlockMapXData), 4);
705 :
706 56 : AddComment("IPMapEntries");
707 112 : OS.EmitIntValue(IPToStateTable.size(), 4);
708 :
709 56 : AddComment("IPToStateXData");
710 56 : OS.EmitValue(create32bitRef(IPToStateXData), 4);
711 :
712 56 : if (Asm->MAI->usesWindowsCFI()) {
713 35 : AddComment("UnwindHelp");
714 35 : OS.EmitIntValue(UnwindHelpOffset, 4);
715 : }
716 :
717 56 : AddComment("ESTypeList");
718 56 : OS.EmitIntValue(0, 4);
719 :
720 56 : AddComment("EHFlags");
721 56 : OS.EmitIntValue(1, 4);
722 :
723 : // UnwindMapEntry {
724 : // int32_t ToState;
725 : // void (*Action)();
726 : // };
727 56 : if (UnwindMapXData) {
728 56 : OS.EmitLabel(UnwindMapXData);
729 199 : for (const CxxUnwindMapEntry &UME : FuncInfo.CxxUnwindMap) {
730 : MCSymbol *CleanupSym =
731 143 : getMCSymbolForMBB(Asm, UME.Cleanup.dyn_cast<MachineBasicBlock *>());
732 143 : AddComment("ToState");
733 143 : OS.EmitIntValue(UME.ToState, 4);
734 :
735 143 : AddComment("Action");
736 143 : OS.EmitValue(create32bitRef(CleanupSym), 4);
737 : }
738 : }
739 :
740 : // TryBlockMap {
741 : // int32_t TryLow;
742 : // int32_t TryHigh;
743 : // int32_t CatchHigh;
744 : // int32_t NumCatches;
745 : // HandlerType *HandlerArray;
746 : // };
747 56 : if (TryBlockMapXData) {
748 47 : OS.EmitLabel(TryBlockMapXData);
749 : SmallVector<MCSymbol *, 1> HandlerMaps;
750 107 : for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
751 : const WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
752 :
753 60 : MCSymbol *HandlerMapXData = nullptr;
754 60 : if (!TBME.HandlerArray.empty())
755 60 : HandlerMapXData =
756 120 : Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$")
757 60 : .concat(Twine(I))
758 60 : .concat("$")
759 120 : .concat(FuncLinkageName));
760 60 : HandlerMaps.push_back(HandlerMapXData);
761 :
762 : // TBMEs should form intervals.
763 : assert(0 <= TBME.TryLow && "bad trymap interval");
764 : assert(TBME.TryLow <= TBME.TryHigh && "bad trymap interval");
765 : assert(TBME.TryHigh < TBME.CatchHigh && "bad trymap interval");
766 : assert(TBME.CatchHigh < int(FuncInfo.CxxUnwindMap.size()) &&
767 : "bad trymap interval");
768 :
769 60 : AddComment("TryLow");
770 60 : OS.EmitIntValue(TBME.TryLow, 4);
771 :
772 60 : AddComment("TryHigh");
773 60 : OS.EmitIntValue(TBME.TryHigh, 4);
774 :
775 60 : AddComment("CatchHigh");
776 60 : OS.EmitIntValue(TBME.CatchHigh, 4);
777 :
778 60 : AddComment("NumCatches");
779 120 : OS.EmitIntValue(TBME.HandlerArray.size(), 4);
780 :
781 60 : AddComment("HandlerArray");
782 60 : OS.EmitValue(create32bitRef(HandlerMapXData), 4);
783 : }
784 :
785 : // All funclets use the same parent frame offset currently.
786 : unsigned ParentFrameOffset = 0;
787 47 : if (shouldEmitPersonality) {
788 31 : const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
789 31 : ParentFrameOffset = TFI->getWinEHParentFrameOffset(*MF);
790 : }
791 :
792 107 : for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
793 : const WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
794 60 : MCSymbol *HandlerMapXData = HandlerMaps[I];
795 60 : if (!HandlerMapXData)
796 : continue;
797 : // HandlerType {
798 : // int32_t Adjectives;
799 : // TypeDescriptor *Type;
800 : // int32_t CatchObjOffset;
801 : // void (*Handler)();
802 : // int32_t ParentFrameOffset; // x64 only
803 : // };
804 60 : OS.EmitLabel(HandlerMapXData);
805 127 : for (const WinEHHandlerType &HT : TBME.HandlerArray) {
806 : // Get the frame escape label with the offset of the catch object. If
807 : // the index is INT_MAX, then there is no catch object, and we should
808 : // emit an offset of zero, indicating that no copy will occur.
809 : const MCExpr *FrameAllocOffsetRef = nullptr;
810 67 : if (HT.CatchObj.FrameIndex != INT_MAX) {
811 8 : int Offset = getFrameIndexOffset(HT.CatchObj.FrameIndex, FuncInfo);
812 : assert(Offset != 0 && "Illegal offset for catch object!");
813 8 : FrameAllocOffsetRef = MCConstantExpr::create(Offset, Asm->OutContext);
814 : } else {
815 59 : FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
816 : }
817 :
818 : MCSymbol *HandlerSym =
819 67 : getMCSymbolForMBB(Asm, HT.Handler.dyn_cast<MachineBasicBlock *>());
820 :
821 67 : AddComment("Adjectives");
822 67 : OS.EmitIntValue(HT.Adjectives, 4);
823 :
824 67 : AddComment("Type");
825 67 : OS.EmitValue(create32bitRef(HT.TypeDescriptor), 4);
826 :
827 67 : AddComment("CatchObjOffset");
828 67 : OS.EmitValue(FrameAllocOffsetRef, 4);
829 :
830 67 : AddComment("Handler");
831 67 : OS.EmitValue(create32bitRef(HandlerSym), 4);
832 :
833 67 : if (shouldEmitPersonality) {
834 46 : AddComment("ParentFrameOffset");
835 46 : OS.EmitIntValue(ParentFrameOffset, 4);
836 : }
837 : }
838 : }
839 : }
840 :
841 : // IPToStateMapEntry {
842 : // void *IP;
843 : // int32_t State;
844 : // };
845 56 : if (IPToStateXData) {
846 35 : OS.EmitLabel(IPToStateXData);
847 204 : for (auto &IPStatePair : IPToStateTable) {
848 169 : AddComment("IP");
849 169 : OS.EmitValue(IPStatePair.first, 4);
850 169 : AddComment("ToState");
851 169 : OS.EmitIntValue(IPStatePair.second, 4);
852 : }
853 : }
854 56 : }
855 :
856 35 : void WinException::computeIP2StateTable(
857 : const MachineFunction *MF, const WinEHFuncInfo &FuncInfo,
858 : SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable) {
859 :
860 : for (MachineFunction::const_iterator FuncletStart = MF->begin(),
861 : FuncletEnd = MF->begin(),
862 : End = MF->end();
863 131 : FuncletStart != End; FuncletStart = FuncletEnd) {
864 : // Find the end of the funclet
865 188 : while (++FuncletEnd != End) {
866 153 : if (FuncletEnd->isEHFuncletEntry()) {
867 : break;
868 : }
869 : }
870 :
871 : // Don't emit ip2state entries for cleanup funclets. Any interesting
872 : // exceptional actions in cleanups must be handled in a separate IR
873 : // function.
874 96 : if (FuncletStart->isCleanupFuncletEntry())
875 : continue;
876 :
877 : MCSymbol *StartLabel;
878 : int BaseState;
879 81 : if (FuncletStart == MF->begin()) {
880 : BaseState = NullState;
881 35 : StartLabel = Asm->getFunctionBegin();
882 : } else {
883 : auto *FuncletPad =
884 46 : cast<FuncletPadInst>(FuncletStart->getBasicBlock()->getFirstNonPHI());
885 : assert(FuncInfo.FuncletBaseStateMap.count(FuncletPad) != 0);
886 46 : BaseState = FuncInfo.FuncletBaseStateMap.find(FuncletPad)->second;
887 46 : StartLabel = getMCSymbolForMBB(Asm, &*FuncletStart);
888 : }
889 : assert(StartLabel && "need local function start label");
890 162 : IPToStateTable.push_back(
891 81 : std::make_pair(create32bitRef(StartLabel), BaseState));
892 :
893 : for (const auto &StateChange : InvokeStateChangeIterator::range(
894 199 : FuncInfo, FuncletStart, FuncletEnd, BaseState)) {
895 : // Compute the label to report as the start of this entry; use the EH
896 : // start label for the invoke if we have one, otherwise (this is a call
897 : // which may unwind to our caller and does not have an EH start label, so)
898 : // use the previous end label.
899 88 : const MCSymbol *ChangeLabel = StateChange.NewStartLabel;
900 88 : if (!ChangeLabel)
901 39 : ChangeLabel = StateChange.PreviousEndLabel;
902 : // Emit an entry indicating that PCs after 'Label' have this EH state.
903 88 : IPToStateTable.push_back(
904 88 : std::make_pair(getLabelPlusOne(ChangeLabel), StateChange.NewState));
905 : // FIXME: assert that NewState is between CatchLow and CatchHigh.
906 : }
907 : }
908 35 : }
909 :
910 14 : void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
911 : StringRef FLinkageName) {
912 : // Outlined helpers called by the EH runtime need to know the offset of the EH
913 : // registration in order to recover the parent frame pointer. Now that we know
914 : // we've code generated the parent, we can emit the label assignment that
915 : // those helpers use to get the offset of the registration node.
916 :
917 : // Compute the parent frame offset. The EHRegNodeFrameIndex will be invalid if
918 : // after optimization all the invokes were eliminated. We still need to emit
919 : // the parent frame offset label, but it should be garbage and should never be
920 : // used.
921 : int64_t Offset = 0;
922 14 : int FI = FuncInfo.EHRegNodeFrameIndex;
923 14 : if (FI != INT_MAX) {
924 13 : const TargetFrameLowering *TFI = Asm->MF->getSubtarget().getFrameLowering();
925 : unsigned UnusedReg;
926 13 : Offset = TFI->getFrameIndexReference(*Asm->MF, FI, UnusedReg);
927 : }
928 :
929 14 : MCContext &Ctx = Asm->OutContext;
930 : MCSymbol *ParentFrameOffset =
931 14 : Ctx.getOrCreateParentFrameOffsetSymbol(FLinkageName);
932 14 : Asm->OutStreamer->EmitAssignment(ParentFrameOffset,
933 14 : MCConstantExpr::create(Offset, Ctx));
934 14 : }
935 :
936 : /// Emit the language-specific data that _except_handler3 and 4 expect. This is
937 : /// functionally equivalent to the __C_specific_handler table, except it is
938 : /// indexed by state number instead of IP.
939 13 : void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
940 13 : MCStreamer &OS = *Asm->OutStreamer;
941 13 : const Function &F = MF->getFunction();
942 13 : StringRef FLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName());
943 :
944 13 : bool VerboseAsm = OS.isVerboseAsm();
945 : auto AddComment = [&](const Twine &Comment) {
946 68 : if (VerboseAsm)
947 65 : OS.AddComment(Comment);
948 : };
949 :
950 13 : const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
951 13 : emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
952 :
953 : // Emit the __ehtable label that we use for llvm.x86.seh.lsda.
954 13 : MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FLinkageName);
955 13 : OS.EmitValueToAlignment(4);
956 13 : OS.EmitLabel(LSDALabel);
957 :
958 : const Function *Per =
959 13 : dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
960 13 : StringRef PerName = Per->getName();
961 : int BaseState = -1;
962 : if (PerName == "_except_handler4") {
963 : // The LSDA for _except_handler4 starts with this struct, followed by the
964 : // scope table:
965 : //
966 : // struct EH4ScopeTable {
967 : // int32_t GSCookieOffset;
968 : // int32_t GSCookieXOROffset;
969 : // int32_t EHCookieOffset;
970 : // int32_t EHCookieXOROffset;
971 : // ScopeTableEntry ScopeRecord[];
972 : // };
973 : //
974 : // Offsets are %ebp relative.
975 : //
976 : // The GS cookie is present only if the function needs stack protection.
977 : // GSCookieOffset = -2 means that GS cookie is not used.
978 : //
979 : // The EH cookie is always present.
980 : //
981 : // Check is done the following way:
982 : // (ebp+CookieXOROffset) ^ [ebp+CookieOffset] == _security_cookie
983 :
984 : // Retrieve the Guard Stack slot.
985 : int GSCookieOffset = -2;
986 2 : const MachineFrameInfo &MFI = MF->getFrameInfo();
987 2 : if (MFI.hasStackProtectorIndex()) {
988 : unsigned UnusedReg;
989 0 : const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
990 0 : int SSPIdx = MFI.getStackProtectorIndex();
991 0 : GSCookieOffset = TFI->getFrameIndexReference(*MF, SSPIdx, UnusedReg);
992 : }
993 :
994 : // Retrieve the EH Guard slot.
995 : // TODO(etienneb): Get rid of this value and change it for and assertion.
996 : int EHCookieOffset = 9999;
997 2 : if (FuncInfo.EHGuardFrameIndex != INT_MAX) {
998 : unsigned UnusedReg;
999 2 : const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
1000 2 : int EHGuardIdx = FuncInfo.EHGuardFrameIndex;
1001 2 : EHCookieOffset = TFI->getFrameIndexReference(*MF, EHGuardIdx, UnusedReg);
1002 : }
1003 :
1004 2 : AddComment("GSCookieOffset");
1005 2 : OS.EmitIntValue(GSCookieOffset, 4);
1006 2 : AddComment("GSCookieXOROffset");
1007 2 : OS.EmitIntValue(0, 4);
1008 2 : AddComment("EHCookieOffset");
1009 2 : OS.EmitIntValue(EHCookieOffset, 4);
1010 2 : AddComment("EHCookieXOROffset");
1011 2 : OS.EmitIntValue(0, 4);
1012 : BaseState = -2;
1013 : }
1014 :
1015 : assert(!FuncInfo.SEHUnwindMap.empty());
1016 33 : for (const SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) {
1017 : auto *Handler = UME.Handler.get<MachineBasicBlock *>();
1018 : const MCSymbol *ExceptOrFinally =
1019 20 : UME.IsFinally ? getMCSymbolForMBB(Asm, Handler) : Handler->getSymbol();
1020 : // -1 is usually the base state for "unwind to caller", but for
1021 : // _except_handler4 it's -2. Do that replacement here if necessary.
1022 20 : int ToState = UME.ToState == -1 ? BaseState : UME.ToState;
1023 20 : AddComment("ToState");
1024 20 : OS.EmitIntValue(ToState, 4);
1025 20 : AddComment(UME.IsFinally ? "Null" : "FilterFunction");
1026 20 : OS.EmitValue(create32bitRef(UME.Filter), 4);
1027 20 : AddComment(UME.IsFinally ? "FinallyFunclet" : "ExceptionHandler");
1028 20 : OS.EmitValue(create32bitRef(ExceptOrFinally), 4);
1029 : }
1030 13 : }
1031 :
1032 : static int getTryRank(const WinEHFuncInfo &FuncInfo, int State) {
1033 : int Rank = 0;
1034 126 : while (State != -1) {
1035 56 : ++Rank;
1036 112 : State = FuncInfo.ClrEHUnwindMap[State].TryParentState;
1037 : }
1038 : return Rank;
1039 : }
1040 :
1041 35 : static int getTryAncestor(const WinEHFuncInfo &FuncInfo, int Left, int Right) {
1042 : int LeftRank = getTryRank(FuncInfo, Left);
1043 : int RightRank = getTryRank(FuncInfo, Right);
1044 :
1045 60 : while (LeftRank < RightRank) {
1046 25 : Right = FuncInfo.ClrEHUnwindMap[Right].TryParentState;
1047 25 : --RightRank;
1048 : }
1049 :
1050 60 : while (RightRank < LeftRank) {
1051 25 : Left = FuncInfo.ClrEHUnwindMap[Left].TryParentState;
1052 25 : --LeftRank;
1053 : }
1054 :
1055 36 : while (Left != Right) {
1056 1 : Left = FuncInfo.ClrEHUnwindMap[Left].TryParentState;
1057 2 : Right = FuncInfo.ClrEHUnwindMap[Right].TryParentState;
1058 : }
1059 :
1060 35 : return Left;
1061 : }
1062 :
1063 7 : void WinException::emitCLRExceptionTable(const MachineFunction *MF) {
1064 : // CLR EH "states" are really just IDs that identify handlers/funclets;
1065 : // states, handlers, and funclets all have 1:1 mappings between them, and a
1066 : // handler/funclet's "state" is its index in the ClrEHUnwindMap.
1067 7 : MCStreamer &OS = *Asm->OutStreamer;
1068 7 : const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
1069 7 : MCSymbol *FuncBeginSym = Asm->getFunctionBegin();
1070 7 : MCSymbol *FuncEndSym = Asm->getFunctionEnd();
1071 :
1072 : // A ClrClause describes a protected region.
1073 : struct ClrClause {
1074 : const MCSymbol *StartLabel; // Start of protected region
1075 : const MCSymbol *EndLabel; // End of protected region
1076 : int State; // Index of handler protecting the protected region
1077 : int EnclosingState; // Index of funclet enclosing the protected region
1078 : };
1079 7 : SmallVector<ClrClause, 8> Clauses;
1080 :
1081 : // Build a map from handler MBBs to their corresponding states (i.e. their
1082 : // indices in the ClrEHUnwindMap).
1083 7 : int NumStates = FuncInfo.ClrEHUnwindMap.size();
1084 : assert(NumStates > 0 && "Don't need exception table!");
1085 : DenseMap<const MachineBasicBlock *, int> HandlerStates;
1086 26 : for (int State = 0; State < NumStates; ++State) {
1087 : MachineBasicBlock *HandlerBlock =
1088 19 : FuncInfo.ClrEHUnwindMap[State].Handler.get<MachineBasicBlock *>();
1089 19 : HandlerStates[HandlerBlock] = State;
1090 : // Use this loop through all handlers to verify our assumption (used in
1091 : // the MinEnclosingState computation) that enclosing funclets have lower
1092 : // state numbers than their enclosed funclets.
1093 : assert(FuncInfo.ClrEHUnwindMap[State].HandlerParentState < State &&
1094 : "ill-formed state numbering");
1095 : }
1096 : // Map the main function to the NullState.
1097 7 : HandlerStates[&MF->front()] = NullState;
1098 :
1099 : // Write out a sentinel indicating the end of the standard (Windows) xdata
1100 : // and the start of the additional (CLR) info.
1101 7 : OS.EmitIntValue(0xffffffff, 4);
1102 : // Write out the number of funclets
1103 7 : OS.EmitIntValue(NumStates, 4);
1104 :
1105 : // Walk the machine blocks/instrs, computing and emitting a few things:
1106 : // 1. Emit a list of the offsets to each handler entry, in lexical order.
1107 : // 2. Compute a map (EndSymbolMap) from each funclet to the symbol at its end.
1108 : // 3. Compute the list of ClrClauses, in the required order (inner before
1109 : // outer, earlier before later; the order by which a forward scan with
1110 : // early termination will find the innermost enclosing clause covering
1111 : // a given address).
1112 : // 4. A map (MinClauseMap) from each handler index to the index of the
1113 : // outermost funclet/function which contains a try clause targeting the
1114 : // key handler. This will be used to determine IsDuplicate-ness when
1115 : // emitting ClrClauses. The NullState value is used to indicate that the
1116 : // top-level function contains a try clause targeting the key handler.
1117 : // HandlerStack is a stack of (PendingStartLabel, PendingState) pairs for
1118 : // try regions we entered before entering the PendingState try but which
1119 : // we haven't yet exited.
1120 : SmallVector<std::pair<const MCSymbol *, int>, 4> HandlerStack;
1121 : // EndSymbolMap and MinClauseMap are maps described above.
1122 7 : std::unique_ptr<MCSymbol *[]> EndSymbolMap(new MCSymbol *[NumStates]);
1123 7 : SmallVector<int, 4> MinClauseMap((size_t)NumStates, NumStates);
1124 :
1125 : // Visit the root function and each funclet.
1126 26 : for (MachineFunction::const_iterator FuncletStart = MF->begin(),
1127 : FuncletEnd = MF->begin(),
1128 : End = MF->end();
1129 33 : FuncletStart != End; FuncletStart = FuncletEnd) {
1130 26 : int FuncletState = HandlerStates[&*FuncletStart];
1131 : // Find the end of the funclet
1132 : MCSymbol *EndSymbol = FuncEndSym;
1133 49 : while (++FuncletEnd != End) {
1134 42 : if (FuncletEnd->isEHFuncletEntry()) {
1135 19 : EndSymbol = getMCSymbolForMBB(Asm, &*FuncletEnd);
1136 19 : break;
1137 : }
1138 : }
1139 : // Emit the function/funclet end and, if this is a funclet (and not the
1140 : // root function), record it in the EndSymbolMap.
1141 26 : OS.EmitValue(getOffset(EndSymbol, FuncBeginSym), 4);
1142 26 : if (FuncletState != NullState) {
1143 : // Record the end of the handler.
1144 38 : EndSymbolMap[FuncletState] = EndSymbol;
1145 : }
1146 :
1147 : // Walk the state changes in this function/funclet and compute its clauses.
1148 : // Funclets always start in the null state.
1149 26 : const MCSymbol *CurrentStartLabel = nullptr;
1150 26 : int CurrentState = NullState;
1151 : assert(HandlerStack.empty());
1152 : for (const auto &StateChange :
1153 67 : InvokeStateChangeIterator::range(FuncInfo, FuncletStart, FuncletEnd)) {
1154 : // Close any try regions we're not still under
1155 : int StillPendingState =
1156 35 : getTryAncestor(FuncInfo, CurrentState, StateChange.NewState);
1157 61 : while (CurrentState != StillPendingState) {
1158 : assert(CurrentState != NullState &&
1159 : "Failed to find still-pending state!");
1160 : // Close the pending clause
1161 26 : Clauses.push_back({CurrentStartLabel, StateChange.PreviousEndLabel,
1162 : CurrentState, FuncletState});
1163 : // Now the next-outer try region is current
1164 52 : CurrentState = FuncInfo.ClrEHUnwindMap[CurrentState].TryParentState;
1165 : // Pop the new start label from the handler stack if we've exited all
1166 : // inner try regions of the corresponding try region.
1167 26 : if (HandlerStack.back().second == CurrentState)
1168 19 : CurrentStartLabel = HandlerStack.pop_back_val().first;
1169 : }
1170 :
1171 35 : if (StateChange.NewState != CurrentState) {
1172 : // For each clause we're starting, update the MinClauseMap so we can
1173 : // know which is the topmost funclet containing a clause targeting
1174 : // it.
1175 26 : for (int EnteredState = StateChange.NewState;
1176 45 : EnteredState != CurrentState;
1177 26 : EnteredState =
1178 : FuncInfo.ClrEHUnwindMap[EnteredState].TryParentState) {
1179 26 : int &MinEnclosingState = MinClauseMap[EnteredState];
1180 26 : if (FuncletState < MinEnclosingState)
1181 22 : MinEnclosingState = FuncletState;
1182 : }
1183 : // Save the previous current start/label on the stack and update to
1184 : // the newly-current start/state.
1185 19 : HandlerStack.emplace_back(CurrentStartLabel, CurrentState);
1186 19 : CurrentStartLabel = StateChange.NewStartLabel;
1187 19 : CurrentState = StateChange.NewState;
1188 : }
1189 : }
1190 : assert(HandlerStack.empty());
1191 : }
1192 :
1193 : // Now emit the clause info, starting with the number of clauses.
1194 14 : OS.EmitIntValue(Clauses.size(), 4);
1195 33 : for (ClrClause &Clause : Clauses) {
1196 : // Emit a CORINFO_EH_CLAUSE :
1197 : /*
1198 : struct CORINFO_EH_CLAUSE
1199 : {
1200 : CORINFO_EH_CLAUSE_FLAGS Flags; // actually a CorExceptionFlag
1201 : DWORD TryOffset;
1202 : DWORD TryLength; // actually TryEndOffset
1203 : DWORD HandlerOffset;
1204 : DWORD HandlerLength; // actually HandlerEndOffset
1205 : union
1206 : {
1207 : DWORD ClassToken; // use for catch clauses
1208 : DWORD FilterOffset; // use for filter clauses
1209 : };
1210 : };
1211 :
1212 : enum CORINFO_EH_CLAUSE_FLAGS
1213 : {
1214 : CORINFO_EH_CLAUSE_NONE = 0,
1215 : CORINFO_EH_CLAUSE_FILTER = 0x0001, // This clause is for a filter
1216 : CORINFO_EH_CLAUSE_FINALLY = 0x0002, // This clause is a finally clause
1217 : CORINFO_EH_CLAUSE_FAULT = 0x0004, // This clause is a fault clause
1218 : };
1219 : typedef enum CorExceptionFlag
1220 : {
1221 : COR_ILEXCEPTION_CLAUSE_NONE,
1222 : COR_ILEXCEPTION_CLAUSE_FILTER = 0x0001, // This is a filter clause
1223 : COR_ILEXCEPTION_CLAUSE_FINALLY = 0x0002, // This is a finally clause
1224 : COR_ILEXCEPTION_CLAUSE_FAULT = 0x0004, // This is a fault clause
1225 : COR_ILEXCEPTION_CLAUSE_DUPLICATED = 0x0008, // duplicated clause. This
1226 : // clause was duplicated
1227 : // to a funclet which was
1228 : // pulled out of line
1229 : } CorExceptionFlag;
1230 : */
1231 : // Add 1 to the start/end of the EH clause; the IP associated with a
1232 : // call when the runtime does its scan is the IP of the next instruction
1233 : // (the one to which control will return after the call), so we need
1234 : // to add 1 to the end of the clause to cover that offset. We also add
1235 : // 1 to the start of the clause to make sure that the ranges reported
1236 : // for all clauses are disjoint. Note that we'll need some additional
1237 : // logic when machine traps are supported, since in that case the IP
1238 : // that the runtime uses is the offset of the faulting instruction
1239 : // itself; if such an instruction immediately follows a call but the
1240 : // two belong to different clauses, we'll need to insert a nop between
1241 : // them so the runtime can distinguish the point to which the call will
1242 : // return from the point at which the fault occurs.
1243 :
1244 : const MCExpr *ClauseBegin =
1245 26 : getOffsetPlusOne(Clause.StartLabel, FuncBeginSym);
1246 26 : const MCExpr *ClauseEnd = getOffsetPlusOne(Clause.EndLabel, FuncBeginSym);
1247 :
1248 26 : const ClrEHUnwindMapEntry &Entry = FuncInfo.ClrEHUnwindMap[Clause.State];
1249 : MachineBasicBlock *HandlerBlock = Entry.Handler.get<MachineBasicBlock *>();
1250 26 : MCSymbol *BeginSym = getMCSymbolForMBB(Asm, HandlerBlock);
1251 26 : const MCExpr *HandlerBegin = getOffset(BeginSym, FuncBeginSym);
1252 26 : MCSymbol *EndSym = EndSymbolMap[Clause.State];
1253 26 : const MCExpr *HandlerEnd = getOffset(EndSym, FuncBeginSym);
1254 :
1255 : uint32_t Flags = 0;
1256 26 : switch (Entry.HandlerType) {
1257 : case ClrHandlerType::Catch:
1258 : // Leaving bits 0-2 clear indicates catch.
1259 : break;
1260 : case ClrHandlerType::Filter:
1261 : Flags |= 1;
1262 : break;
1263 : case ClrHandlerType::Finally:
1264 : Flags |= 2;
1265 : break;
1266 : case ClrHandlerType::Fault:
1267 : Flags |= 4;
1268 : break;
1269 : }
1270 52 : if (Clause.EnclosingState != MinClauseMap[Clause.State]) {
1271 : // This is a "duplicate" clause; the handler needs to be entered from a
1272 : // frame above the one holding the invoke.
1273 : assert(Clause.EnclosingState > MinClauseMap[Clause.State]);
1274 7 : Flags |= 8;
1275 : }
1276 26 : OS.EmitIntValue(Flags, 4);
1277 :
1278 : // Write the clause start/end
1279 26 : OS.EmitValue(ClauseBegin, 4);
1280 26 : OS.EmitValue(ClauseEnd, 4);
1281 :
1282 : // Write out the handler start/end
1283 26 : OS.EmitValue(HandlerBegin, 4);
1284 26 : OS.EmitValue(HandlerEnd, 4);
1285 :
1286 : // Write out the type token or filter offset
1287 : assert(Entry.HandlerType != ClrHandlerType::Filter && "NYI: filters");
1288 26 : OS.EmitIntValue(Entry.TypeToken, 4);
1289 : }
1290 7 : }
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