Bug Summary

File:llvm/lib/CodeGen/AsmPrinter/WinException.cpp
Warning:line 1203, column 34
Use of zero-allocated memory

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name WinException.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/CodeGen/AsmPrinter -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/CodeGen/AsmPrinter -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/lib/CodeGen/AsmPrinter -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include -D NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/CodeGen/AsmPrinter -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-09-04-040900-46481-1 -x c++ /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
1//===-- CodeGen/AsmPrinter/WinException.cpp - Dwarf Exception Impl ------===//
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// This file contains support for writing Win64 exception info into asm files.
10//
11//===----------------------------------------------------------------------===//
12
13#include "WinException.h"
14#include "llvm/ADT/Twine.h"
15#include "llvm/BinaryFormat/COFF.h"
16#include "llvm/BinaryFormat/Dwarf.h"
17#include "llvm/CodeGen/AsmPrinter.h"
18#include "llvm/CodeGen/MachineFrameInfo.h"
19#include "llvm/CodeGen/MachineFunction.h"
20#include "llvm/CodeGen/MachineModuleInfo.h"
21#include "llvm/CodeGen/TargetFrameLowering.h"
22#include "llvm/CodeGen/TargetLowering.h"
23#include "llvm/CodeGen/TargetSubtargetInfo.h"
24#include "llvm/CodeGen/WinEHFuncInfo.h"
25#include "llvm/IR/DataLayout.h"
26#include "llvm/IR/Mangler.h"
27#include "llvm/IR/Module.h"
28#include "llvm/MC/MCAsmInfo.h"
29#include "llvm/MC/MCContext.h"
30#include "llvm/MC/MCExpr.h"
31#include "llvm/MC/MCSection.h"
32#include "llvm/MC/MCStreamer.h"
33#include "llvm/MC/MCSymbol.h"
34#include "llvm/Support/ErrorHandling.h"
35#include "llvm/Support/FormattedStream.h"
36#include "llvm/Target/TargetLoweringObjectFile.h"
37#include "llvm/Target/TargetMachine.h"
38#include "llvm/Target/TargetOptions.h"
39using namespace llvm;
40
41WinException::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 useImageRel32 = (A->getDataLayout().getPointerSizeInBits() == 64);
45 isAArch64 = Asm->TM.getTargetTriple().isAArch64();
46 isThumb = Asm->TM.getTargetTriple().isThumb();
47}
48
49WinException::~WinException() {}
50
51/// endModule - Emit all exception information that should come after the
52/// content.
53void WinException::endModule() {
54 auto &OS = *Asm->OutStreamer;
55 const Module *M = MMI->getModule();
56 for (const Function &F : *M)
57 if (F.hasFnAttribute("safeseh"))
58 OS.EmitCOFFSafeSEH(Asm->getSymbol(&F));
59
60 if (M->getModuleFlag("ehcontguard") && !EHContTargets.empty()) {
61 // Emit the symbol index of each ehcont target.
62 OS.SwitchSection(Asm->OutContext.getObjectFileInfo()->getGEHContSection());
63 for (const MCSymbol *S : EHContTargets) {
64 OS.EmitCOFFSymbolIndex(S);
65 }
66 }
67}
68
69void WinException::beginFunction(const MachineFunction *MF) {
70 shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
71
72 // If any landing pads survive, we need an EH table.
73 bool hasLandingPads = !MF->getLandingPads().empty();
74 bool hasEHFunclets = MF->hasEHFunclets();
75
76 const Function &F = MF->getFunction();
77
78 shouldEmitMoves = Asm->needsSEHMoves() && MF->hasWinCFI();
79
80 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
81 unsigned PerEncoding = TLOF.getPersonalityEncoding();
82
83 EHPersonality Per = EHPersonality::Unknown;
84 const Function *PerFn = nullptr;
85 if (F.hasPersonalityFn()) {
86 PerFn = dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
87 Per = classifyEHPersonality(PerFn);
88 }
89
90 bool forceEmitPersonality = F.hasPersonalityFn() &&
91 !isNoOpWithoutInvoke(Per) &&
92 F.needsUnwindTableEntry();
93
94 shouldEmitPersonality =
95 forceEmitPersonality || ((hasLandingPads || hasEHFunclets) &&
96 PerEncoding != dwarf::DW_EH_PE_omit && PerFn);
97
98 unsigned LSDAEncoding = TLOF.getLSDAEncoding();
99 shouldEmitLSDA = shouldEmitPersonality &&
100 LSDAEncoding != dwarf::DW_EH_PE_omit;
101
102 // If we're not using CFI, we don't want the CFI or the personality, but we
103 // might want EH tables if we had EH pads.
104 if (!Asm->MAI->usesWindowsCFI()) {
105 if (Per == EHPersonality::MSVC_X86SEH && !hasEHFunclets) {
106 // If this is 32-bit SEH and we don't have any funclets (really invokes),
107 // make sure we emit the parent offset label. Some unreferenced filter
108 // functions may still refer to it.
109 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
110 StringRef FLinkageName =
111 GlobalValue::dropLLVMManglingEscape(MF->getFunction().getName());
112 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
113 }
114 shouldEmitLSDA = hasEHFunclets;
115 shouldEmitPersonality = false;
116 return;
117 }
118
119 beginFunclet(MF->front(), Asm->CurrentFnSym);
120}
121
122void WinException::markFunctionEnd() {
123 if (isAArch64 && CurrentFuncletEntry &&
124 (shouldEmitMoves || shouldEmitPersonality))
125 Asm->OutStreamer->EmitWinCFIFuncletOrFuncEnd();
126}
127
128/// endFunction - Gather and emit post-function exception information.
129///
130void WinException::endFunction(const MachineFunction *MF) {
131 if (!shouldEmitPersonality && !shouldEmitMoves && !shouldEmitLSDA)
1
Assuming field 'shouldEmitPersonality' is true
→
132 return;
133
134 const Function &F = MF->getFunction();
135 EHPersonality Per = EHPersonality::Unknown;
136 if (F.hasPersonalityFn())
2
←
Assuming the condition is true
→
3
←
Taking true branch
→
137 Per = classifyEHPersonality(F.getPersonalityFn()->stripPointerCasts());
138
139 // Get rid of any dead landing pads if we're not using funclets. In funclet
140 // schemes, the landing pad is not actually reachable. It only exists so
141 // that we can emit the right table data.
142 if (!isFuncletEHPersonality(Per)) {
4
←
Taking false branch
→
143 MachineFunction *NonConstMF = const_cast<MachineFunction*>(MF);
144 NonConstMF->tidyLandingPads();
145 }
146
147 endFuncletImpl();
148
149 // endFunclet will emit the necessary .xdata tables for table-based SEH.
150 if (Per
4.1
'Per' is not equal to MSVC_TableSEH
 == EHPersonality::MSVC_TableSEH && MF->hasEHFunclets())
151 return;
152
153 if (shouldEmitPersonality
4.2
Field 'shouldEmitPersonality' is true
 || shouldEmitLSDA) {
154 Asm->OutStreamer->PushSection();
155
156 // Just switch sections to the right xdata section.
157 MCSection *XData = Asm->OutStreamer->getAssociatedXDataSection(
158 Asm->OutStreamer->getCurrentSectionOnly());
159 Asm->OutStreamer->SwitchSection(XData);
160
161 // Emit the tables appropriate to the personality function in use. If we
162 // don't recognize the personality, assume it uses an Itanium-style LSDA.
163 if (Per
4.3
'Per' is not equal to MSVC_TableSEH
 == EHPersonality::MSVC_TableSEH)
5
←
Taking false branch
→
164 emitCSpecificHandlerTable(MF);
165 else if (Per
5.1
'Per' is not equal to MSVC_X86SEH
 == EHPersonality::MSVC_X86SEH)
6
←
Taking false branch
→
166 emitExceptHandlerTable(MF);
167 else if (Per
6.1
'Per' is not equal to MSVC_CXX
 == EHPersonality::MSVC_CXX)
7
←
Taking false branch
→
168 emitCXXFrameHandler3Table(MF);
169 else if (Per
7.1
'Per' is equal to CoreCLR
 == EHPersonality::CoreCLR)
8
←
Taking true branch
→
170 emitCLRExceptionTable(MF);
9
←
Calling 'WinException::emitCLRExceptionTable'
→
171 else
172 emitExceptionTable();
173
174 Asm->OutStreamer->PopSection();
175 }
176
177 if (!MF->getCatchretTargets().empty()) {
178 // Copy the function's catchret targets to a module-level list.
179 EHContTargets.insert(EHContTargets.end(), MF->getCatchretTargets().begin(),
180 MF->getCatchretTargets().end());
181 }
182}
183
184/// Retrieve the MCSymbol for a GlobalValue or MachineBasicBlock.
185static MCSymbol *getMCSymbolForMBB(AsmPrinter *Asm,
186 const MachineBasicBlock *MBB) {
187 if (!MBB)
188 return nullptr;
189
190 assert(MBB->isEHFuncletEntry())(static_cast<void> (0));
191
192 // Give catches and cleanups a name based off of their parent function and
193 // their funclet entry block's number.
194 const MachineFunction *MF = MBB->getParent();
195 const Function &F = MF->getFunction();
196 StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName());
197 MCContext &Ctx = MF->getContext();
198 StringRef HandlerPrefix = MBB->isCleanupFuncletEntry() ? "dtor" : "catch";
199 return Ctx.getOrCreateSymbol("?" + HandlerPrefix + "$" +
200 Twine(MBB->getNumber()) + "@?0?" +
201 FuncLinkageName + "@4HA");
202}
203
204void WinException::beginFunclet(const MachineBasicBlock &MBB,
205 MCSymbol *Sym) {
206 CurrentFuncletEntry = &MBB;
207
208 const Function &F = Asm->MF->getFunction();
209 // If a symbol was not provided for the funclet, invent one.
210 if (!Sym) {
211 Sym = getMCSymbolForMBB(Asm, &MBB);
212
213 // Describe our funclet symbol as a function with internal linkage.
214 Asm->OutStreamer->BeginCOFFSymbolDef(Sym);
215 Asm->OutStreamer->EmitCOFFSymbolStorageClass(COFF::IMAGE_SYM_CLASS_STATIC);
216 Asm->OutStreamer->EmitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
217 << COFF::SCT_COMPLEX_TYPE_SHIFT);
218 Asm->OutStreamer->EndCOFFSymbolDef();
219
220 // We want our funclet's entry point to be aligned such that no nops will be
221 // present after the label.
222 Asm->emitAlignment(std::max(Asm->MF->getAlignment(), MBB.getAlignment()),
223 &F);
224
225 // Now that we've emitted the alignment directive, point at our funclet.
226 Asm->OutStreamer->emitLabel(Sym);
227 }
228
229 // Mark 'Sym' as starting our funclet.
230 if (shouldEmitMoves || shouldEmitPersonality) {
231 CurrentFuncletTextSection = Asm->OutStreamer->getCurrentSectionOnly();
232 Asm->OutStreamer->EmitWinCFIStartProc(Sym);
233 }
234
235 if (shouldEmitPersonality) {
236 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
237 const Function *PerFn = nullptr;
238
239 // Determine which personality routine we are using for this funclet.
240 if (F.hasPersonalityFn())
241 PerFn = dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
242 const MCSymbol *PersHandlerSym =
243 TLOF.getCFIPersonalitySymbol(PerFn, Asm->TM, MMI);
244
245 // Do not emit a .seh_handler directives for cleanup funclets.
246 // FIXME: This means cleanup funclets cannot handle exceptions. Given that
247 // Clang doesn't produce EH constructs inside cleanup funclets and LLVM's
248 // inliner doesn't allow inlining them, this isn't a major problem in
249 // practice.
250 if (!CurrentFuncletEntry->isCleanupFuncletEntry())
251 Asm->OutStreamer->EmitWinEHHandler(PersHandlerSym, true, true);
252 }
253}
254
255void WinException::endFunclet() {
256 if (isAArch64 && CurrentFuncletEntry &&
257 (shouldEmitMoves || shouldEmitPersonality)) {
258 Asm->OutStreamer->SwitchSection(CurrentFuncletTextSection);
259 Asm->OutStreamer->EmitWinCFIFuncletOrFuncEnd();
260 }
261 endFuncletImpl();
262}
263
264void WinException::endFuncletImpl() {
265 // No funclet to process? Great, we have nothing to do.
266 if (!CurrentFuncletEntry)
267 return;
268
269 const MachineFunction *MF = Asm->MF;
270 if (shouldEmitMoves || shouldEmitPersonality) {
271 const Function &F = MF->getFunction();
272 EHPersonality Per = EHPersonality::Unknown;
273 if (F.hasPersonalityFn())
274 Per = classifyEHPersonality(F.getPersonalityFn()->stripPointerCasts());
275
276 if (Per == EHPersonality::MSVC_CXX && shouldEmitPersonality &&
277 !CurrentFuncletEntry->isCleanupFuncletEntry()) {
278 // Emit an UNWIND_INFO struct describing the prologue.
279 Asm->OutStreamer->EmitWinEHHandlerData();
280
281 // If this is a C++ catch funclet (or the parent function),
282 // emit a reference to the LSDA for the parent function.
283 StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName());
284 MCSymbol *FuncInfoXData = Asm->OutContext.getOrCreateSymbol(
285 Twine("$cppxdata$", FuncLinkageName));
286 Asm->OutStreamer->emitValue(create32bitRef(FuncInfoXData), 4);
287 } else if (Per == EHPersonality::MSVC_TableSEH && MF->hasEHFunclets() &&
288 !CurrentFuncletEntry->isEHFuncletEntry()) {
289 // Emit an UNWIND_INFO struct describing the prologue.
290 Asm->OutStreamer->EmitWinEHHandlerData();
291
292 // If this is the parent function in Win64 SEH, emit the LSDA immediately
293 // following .seh_handlerdata.
294 emitCSpecificHandlerTable(MF);
295 } else if (shouldEmitPersonality || shouldEmitLSDA) {
296 // Emit an UNWIND_INFO struct describing the prologue.
297 Asm->OutStreamer->EmitWinEHHandlerData();
298 // In these cases, no further info is written to the .xdata section
299 // right here, but is written by e.g. emitExceptionTable in endFunction()
300 // above.
301 } else {
302 // No need to emit the EH handler data right here if nothing needs
303 // writing to the .xdata section; it will be emitted for all
304 // functions that need it in the end anyway.
305 }
306
307 // Switch back to the funclet start .text section now that we are done
308 // writing to .xdata, and emit an .seh_endproc directive to mark the end of
309 // the function.
310 Asm->OutStreamer->SwitchSection(CurrentFuncletTextSection);
311 Asm->OutStreamer->EmitWinCFIEndProc();
312 }
313
314 // Let's make sure we don't try to end the same funclet twice.
315 CurrentFuncletEntry = nullptr;
316}
317
318const MCExpr *WinException::create32bitRef(const MCSymbol *Value) {
319 if (!Value)
320 return MCConstantExpr::create(0, Asm->OutContext);
321 return MCSymbolRefExpr::create(Value, useImageRel32
322 ? MCSymbolRefExpr::VK_COFF_IMGREL32
323 : MCSymbolRefExpr::VK_None,
324 Asm->OutContext);
325}
326
327const MCExpr *WinException::create32bitRef(const GlobalValue *GV) {
328 if (!GV)
329 return MCConstantExpr::create(0, Asm->OutContext);
330 return create32bitRef(Asm->getSymbol(GV));
331}
332
333const MCExpr *WinException::getLabel(const MCSymbol *Label) {
334 return MCSymbolRefExpr::create(Label, MCSymbolRefExpr::VK_COFF_IMGREL32,
335 Asm->OutContext);
336}
337
338const MCExpr *WinException::getLabelPlusOne(const MCSymbol *Label) {
339 return MCBinaryExpr::createAdd(getLabel(Label),
340 MCConstantExpr::create(1, Asm->OutContext),
341 Asm->OutContext);
342}
343
344const MCExpr *WinException::getOffset(const MCSymbol *OffsetOf,
345 const MCSymbol *OffsetFrom) {
346 return MCBinaryExpr::createSub(
347 MCSymbolRefExpr::create(OffsetOf, Asm->OutContext),
348 MCSymbolRefExpr::create(OffsetFrom, Asm->OutContext), Asm->OutContext);
349}
350
351const MCExpr *WinException::getOffsetPlusOne(const MCSymbol *OffsetOf,
352 const MCSymbol *OffsetFrom) {
353 return MCBinaryExpr::createAdd(getOffset(OffsetOf, OffsetFrom),
354 MCConstantExpr::create(1, Asm->OutContext),
355 Asm->OutContext);
356}
357
358int WinException::getFrameIndexOffset(int FrameIndex,
359 const WinEHFuncInfo &FuncInfo) {
360 const TargetFrameLowering &TFI = *Asm->MF->getSubtarget().getFrameLowering();
361 Register UnusedReg;
362 if (Asm->MAI->usesWindowsCFI()) {
363 StackOffset Offset =
364 TFI.getFrameIndexReferencePreferSP(*Asm->MF, FrameIndex, UnusedReg,
365 /*IgnoreSPUpdates*/ true);
366 assert(UnusedReg ==(static_cast<void> (0))
367 Asm->MF->getSubtarget()(static_cast<void> (0))
368 .getTargetLowering()(static_cast<void> (0))
369 ->getStackPointerRegisterToSaveRestore())(static_cast<void> (0));
370 return Offset.getFixed();
371 }
372
373 // For 32-bit, offsets should be relative to the end of the EH registration
374 // node. For 64-bit, it's relative to SP at the end of the prologue.
375 assert(FuncInfo.EHRegNodeEndOffset != INT_MAX)(static_cast<void> (0));
376 StackOffset Offset = TFI.getFrameIndexReference(*Asm->MF, FrameIndex, UnusedReg);
377 Offset += StackOffset::getFixed(FuncInfo.EHRegNodeEndOffset);
378 assert(!Offset.getScalable() &&(static_cast<void> (0))
379 "Frame offsets with a scalable component are not supported")(static_cast<void> (0));
380 return Offset.getFixed();
381}
382
383namespace {
384
385/// Top-level state used to represent unwind to caller
386const int NullState = -1;
387
388struct InvokeStateChange {
389 /// EH Label immediately after the last invoke in the previous state, or
390 /// nullptr if the previous state was the null state.
391 const MCSymbol *PreviousEndLabel;
392
393 /// EH label immediately before the first invoke in the new state, or nullptr
394 /// if the new state is the null state.
395 const MCSymbol *NewStartLabel;
396
397 /// State of the invoke following NewStartLabel, or NullState to indicate
398 /// the presence of calls which may unwind to caller.
399 int NewState;
400};
401
402/// Iterator that reports all the invoke state changes in a range of machine
403/// basic blocks. Changes to the null state are reported whenever a call that
404/// may unwind to caller is encountered. The MBB range is expected to be an
405/// entire function or funclet, and the start and end of the range are treated
406/// as being in the NullState even if there's not an unwind-to-caller call
407/// before the first invoke or after the last one (i.e., the first state change
408/// reported is the first change to something other than NullState, and a
409/// change back to NullState is always reported at the end of iteration).
410class InvokeStateChangeIterator {
411 InvokeStateChangeIterator(const WinEHFuncInfo &EHInfo,
412 MachineFunction::const_iterator MFI,
413 MachineFunction::const_iterator MFE,
414 MachineBasicBlock::const_iterator MBBI,
415 int BaseState)
416 : EHInfo(EHInfo), MFI(MFI), MFE(MFE), MBBI(MBBI), BaseState(BaseState) {
417 LastStateChange.PreviousEndLabel = nullptr;
418 LastStateChange.NewStartLabel = nullptr;
419 LastStateChange.NewState = BaseState;
420 scan();
421 }
422
423public:
424 static iterator_range<InvokeStateChangeIterator>
425 range(const WinEHFuncInfo &EHInfo, MachineFunction::const_iterator Begin,
426 MachineFunction::const_iterator End, int BaseState = NullState) {
427 // Reject empty ranges to simplify bookkeeping by ensuring that we can get
428 // the end of the last block.
429 assert(Begin != End)(static_cast<void> (0));
430 auto BlockBegin = Begin->begin();
431 auto BlockEnd = std::prev(End)->end();
432 return make_range(
433 InvokeStateChangeIterator(EHInfo, Begin, End, BlockBegin, BaseState),
434 InvokeStateChangeIterator(EHInfo, End, End, BlockEnd, BaseState));
435 }
436
437 // Iterator methods.
438 bool operator==(const InvokeStateChangeIterator &O) const {
439 assert(BaseState == O.BaseState)(static_cast<void> (0));
440 // Must be visiting same block.
441 if (MFI != O.MFI)
442 return false;
443 // Must be visiting same isntr.
444 if (MBBI != O.MBBI)
445 return false;
446 // At end of block/instr iteration, we can still have two distinct states:
447 // one to report the final EndLabel, and another indicating the end of the
448 // state change iteration. Check for CurrentEndLabel equality to
449 // distinguish these.
450 return CurrentEndLabel == O.CurrentEndLabel;
451 }
452
453 bool operator!=(const InvokeStateChangeIterator &O) const {
454 return !operator==(O);
455 }
456 InvokeStateChange &operator*() { return LastStateChange; }
457 InvokeStateChange *operator->() { return &LastStateChange; }
458 InvokeStateChangeIterator &operator++() { return scan(); }
459
460private:
461 InvokeStateChangeIterator &scan();
462
463 const WinEHFuncInfo &EHInfo;
464 const MCSymbol *CurrentEndLabel = nullptr;
465 MachineFunction::const_iterator MFI;
466 MachineFunction::const_iterator MFE;
467 MachineBasicBlock::const_iterator MBBI;
468 InvokeStateChange LastStateChange;
469 bool VisitingInvoke = false;
470 int BaseState;
471};
472
473} // end anonymous namespace
474
475InvokeStateChangeIterator &InvokeStateChangeIterator::scan() {
476 bool IsNewBlock = false;
477 for (; MFI != MFE; ++MFI, IsNewBlock = true) {
478 if (IsNewBlock)
479 MBBI = MFI->begin();
480 for (auto MBBE = MFI->end(); MBBI != MBBE; ++MBBI) {
481 const MachineInstr &MI = *MBBI;
482 if (!VisitingInvoke && LastStateChange.NewState != BaseState &&
483 MI.isCall() && !EHStreamer::callToNoUnwindFunction(&MI)) {
484 // Indicate a change of state to the null state. We don't have
485 // start/end EH labels handy but the caller won't expect them for
486 // null state regions.
487 LastStateChange.PreviousEndLabel = CurrentEndLabel;
488 LastStateChange.NewStartLabel = nullptr;
489 LastStateChange.NewState = BaseState;
490 CurrentEndLabel = nullptr;
491 // Don't re-visit this instr on the next scan
492 ++MBBI;
493 return *this;
494 }
495
496 // All other state changes are at EH labels before/after invokes.
497 if (!MI.isEHLabel())
498 continue;
499 MCSymbol *Label = MI.getOperand(0).getMCSymbol();
500 if (Label == CurrentEndLabel) {
501 VisitingInvoke = false;
502 continue;
503 }
504 auto InvokeMapIter = EHInfo.LabelToStateMap.find(Label);
505 // Ignore EH labels that aren't the ones inserted before an invoke
506 if (InvokeMapIter == EHInfo.LabelToStateMap.end())
507 continue;
508 auto &StateAndEnd = InvokeMapIter->second;
509 int NewState = StateAndEnd.first;
510 // Keep track of the fact that we're between EH start/end labels so
511 // we know not to treat the inoke we'll see as unwinding to caller.
512 VisitingInvoke = true;
513 if (NewState == LastStateChange.NewState) {
514 // The state isn't actually changing here. Record the new end and
515 // keep going.
516 CurrentEndLabel = StateAndEnd.second;
517 continue;
518 }
519 // Found a state change to report
520 LastStateChange.PreviousEndLabel = CurrentEndLabel;
521 LastStateChange.NewStartLabel = Label;
522 LastStateChange.NewState = NewState;
523 // Start keeping track of the new current end
524 CurrentEndLabel = StateAndEnd.second;
525 // Don't re-visit this instr on the next scan
526 ++MBBI;
527 return *this;
528 }
529 }
530 // Iteration hit the end of the block range.
531 if (LastStateChange.NewState != BaseState) {
532 // Report the end of the last new state
533 LastStateChange.PreviousEndLabel = CurrentEndLabel;
534 LastStateChange.NewStartLabel = nullptr;
535 LastStateChange.NewState = BaseState;
536 // Leave CurrentEndLabel non-null to distinguish this state from end.
537 assert(CurrentEndLabel != nullptr)(static_cast<void> (0));
538 return *this;
539 }
540 // We've reported all state changes and hit the end state.
541 CurrentEndLabel = nullptr;
542 return *this;
543}
544
545/// Emit the language-specific data that __C_specific_handler expects. This
546/// handler lives in the x64 Microsoft C runtime and allows catching or cleaning
547/// up after faults with __try, __except, and __finally. The typeinfo values
548/// are not really RTTI data, but pointers to filter functions that return an
549/// integer (1, 0, or -1) indicating how to handle the exception. For __finally
550/// blocks and other cleanups, the landing pad label is zero, and the filter
551/// function is actually a cleanup handler with the same prototype. A catch-all
552/// entry is modeled with a null filter function field and a non-zero landing
553/// pad label.
554///
555/// Possible filter function return values:
556/// EXCEPTION_EXECUTE_HANDLER (1):
557/// Jump to the landing pad label after cleanups.
558/// EXCEPTION_CONTINUE_SEARCH (0):
559/// Continue searching this table or continue unwinding.
560/// EXCEPTION_CONTINUE_EXECUTION (-1):
561/// Resume execution at the trapping PC.
562///
563/// Inferred table structure:
564/// struct Table {
565/// int NumEntries;
566/// struct Entry {
567/// imagerel32 LabelStart; // Inclusive
568/// imagerel32 LabelEnd; // Exclusive
569/// imagerel32 FilterOrFinally; // One means catch-all.
570/// imagerel32 LabelLPad; // Zero means __finally.
571/// } Entries[NumEntries];
572/// };
573void WinException::emitCSpecificHandlerTable(const MachineFunction *MF) {
574 auto &OS = *Asm->OutStreamer;
575 MCContext &Ctx = Asm->OutContext;
576 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
577
578 bool VerboseAsm = OS.isVerboseAsm();
579 auto AddComment = [&](const Twine &Comment) {
580 if (VerboseAsm)
581 OS.AddComment(Comment);
582 };
583
584 if (!isAArch64) {
585 // Emit a label assignment with the SEH frame offset so we can use it for
586 // llvm.eh.recoverfp.
587 StringRef FLinkageName =
588 GlobalValue::dropLLVMManglingEscape(MF->getFunction().getName());
589 MCSymbol *ParentFrameOffset =
590 Ctx.getOrCreateParentFrameOffsetSymbol(FLinkageName);
591 const MCExpr *MCOffset =
592 MCConstantExpr::create(FuncInfo.SEHSetFrameOffset, Ctx);
593 Asm->OutStreamer->emitAssignment(ParentFrameOffset, MCOffset);
594 }
595
596 // Use the assembler to compute the number of table entries through label
597 // difference and division.
598 MCSymbol *TableBegin =
599 Ctx.createTempSymbol("lsda_begin", /*AlwaysAddSuffix=*/true);
600 MCSymbol *TableEnd =
601 Ctx.createTempSymbol("lsda_end", /*AlwaysAddSuffix=*/true);
602 const MCExpr *LabelDiff = getOffset(TableEnd, TableBegin);
603 const MCExpr *EntrySize = MCConstantExpr::create(16, Ctx);
604 const MCExpr *EntryCount = MCBinaryExpr::createDiv(LabelDiff, EntrySize, Ctx);
605 AddComment("Number of call sites");
606 OS.emitValue(EntryCount, 4);
607
608 OS.emitLabel(TableBegin);
609
610 // Iterate over all the invoke try ranges. Unlike MSVC, LLVM currently only
611 // models exceptions from invokes. LLVM also allows arbitrary reordering of
612 // the code, so our tables end up looking a bit different. Rather than
613 // trying to match MSVC's tables exactly, we emit a denormalized table. For
614 // each range of invokes in the same state, we emit table entries for all
615 // the actions that would be taken in that state. This means our tables are
616 // slightly bigger, which is OK.
617 const MCSymbol *LastStartLabel = nullptr;
618 int LastEHState = -1;
619 // Break out before we enter into a finally funclet.
620 // FIXME: We need to emit separate EH tables for cleanups.
621 MachineFunction::const_iterator End = MF->end();
622 MachineFunction::const_iterator Stop = std::next(MF->begin());
623 while (Stop != End && !Stop->isEHFuncletEntry())
624 ++Stop;
625 for (const auto &StateChange :
626 InvokeStateChangeIterator::range(FuncInfo, MF->begin(), Stop)) {
627 // Emit all the actions for the state we just transitioned out of
628 // if it was not the null state
629 if (LastEHState != -1)
630 emitSEHActionsForRange(FuncInfo, LastStartLabel,
631 StateChange.PreviousEndLabel, LastEHState);
632 LastStartLabel = StateChange.NewStartLabel;
633 LastEHState = StateChange.NewState;
634 }
635
636 OS.emitLabel(TableEnd);
637}
638
639void WinException::emitSEHActionsForRange(const WinEHFuncInfo &FuncInfo,
640 const MCSymbol *BeginLabel,
641 const MCSymbol *EndLabel, int State) {
642 auto &OS = *Asm->OutStreamer;
643 MCContext &Ctx = Asm->OutContext;
644 bool VerboseAsm = OS.isVerboseAsm();
645 auto AddComment = [&](const Twine &Comment) {
646 if (VerboseAsm)
647 OS.AddComment(Comment);
648 };
649
650 assert(BeginLabel && EndLabel)(static_cast<void> (0));
651 while (State != -1) {
652 const SEHUnwindMapEntry &UME = FuncInfo.SEHUnwindMap[State];
653 const MCExpr *FilterOrFinally;
654 const MCExpr *ExceptOrNull;
655 auto *Handler = UME.Handler.get<MachineBasicBlock *>();
656 if (UME.IsFinally) {
657 FilterOrFinally = create32bitRef(getMCSymbolForMBB(Asm, Handler));
658 ExceptOrNull = MCConstantExpr::create(0, Ctx);
659 } else {
660 // For an except, the filter can be 1 (catch-all) or a function
661 // label.
662 FilterOrFinally = UME.Filter ? create32bitRef(UME.Filter)
663 : MCConstantExpr::create(1, Ctx);
664 ExceptOrNull = create32bitRef(Handler->getSymbol());
665 }
666
667 AddComment("LabelStart");
668 OS.emitValue(getLabel(BeginLabel), 4);
669 AddComment("LabelEnd");
670 OS.emitValue(getLabelPlusOne(EndLabel), 4);
671 AddComment(UME.IsFinally ? "FinallyFunclet" : UME.Filter ? "FilterFunction"
672 : "CatchAll");
673 OS.emitValue(FilterOrFinally, 4);
674 AddComment(UME.IsFinally ? "Null" : "ExceptionHandler");
675 OS.emitValue(ExceptOrNull, 4);
676
677 assert(UME.ToState < State && "states should decrease")(static_cast<void> (0));
678 State = UME.ToState;
679 }
680}
681
682void WinException::emitCXXFrameHandler3Table(const MachineFunction *MF) {
683 const Function &F = MF->getFunction();
684 auto &OS = *Asm->OutStreamer;
685 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
686
687 StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName());
688
689 SmallVector<std::pair<const MCExpr *, int>, 4> IPToStateTable;
690 MCSymbol *FuncInfoXData = nullptr;
691 if (shouldEmitPersonality) {
692 // If we're 64-bit, emit a pointer to the C++ EH data, and build a map from
693 // IPs to state numbers.
694 FuncInfoXData =
695 Asm->OutContext.getOrCreateSymbol(Twine("$cppxdata$", FuncLinkageName));
696 computeIP2StateTable(MF, FuncInfo, IPToStateTable);
697 } else {
698 FuncInfoXData = Asm->OutContext.getOrCreateLSDASymbol(FuncLinkageName);
699 }
700
701 int UnwindHelpOffset = 0;
702 if (Asm->MAI->usesWindowsCFI())
703 UnwindHelpOffset =
704 getFrameIndexOffset(FuncInfo.UnwindHelpFrameIdx, FuncInfo);
705
706 MCSymbol *UnwindMapXData = nullptr;
707 MCSymbol *TryBlockMapXData = nullptr;
708 MCSymbol *IPToStateXData = nullptr;
709 if (!FuncInfo.CxxUnwindMap.empty())
710 UnwindMapXData = Asm->OutContext.getOrCreateSymbol(
711 Twine("$stateUnwindMap$", FuncLinkageName));
712 if (!FuncInfo.TryBlockMap.empty())
713 TryBlockMapXData =
714 Asm->OutContext.getOrCreateSymbol(Twine("$tryMap$", FuncLinkageName));
715 if (!IPToStateTable.empty())
716 IPToStateXData =
717 Asm->OutContext.getOrCreateSymbol(Twine("$ip2state$", FuncLinkageName));
718
719 bool VerboseAsm = OS.isVerboseAsm();
720 auto AddComment = [&](const Twine &Comment) {
721 if (VerboseAsm)
722 OS.AddComment(Comment);
723 };
724
725 // FuncInfo {
726 // uint32_t MagicNumber
727 // int32_t MaxState;
728 // UnwindMapEntry *UnwindMap;
729 // uint32_t NumTryBlocks;
730 // TryBlockMapEntry *TryBlockMap;
731 // uint32_t IPMapEntries; // always 0 for x86
732 // IPToStateMapEntry *IPToStateMap; // always 0 for x86
733 // uint32_t UnwindHelp; // non-x86 only
734 // ESTypeList *ESTypeList;
735 // int32_t EHFlags;
736 // }
737 // EHFlags & 1 -> Synchronous exceptions only, no async exceptions.
738 // EHFlags & 2 -> ???
739 // EHFlags & 4 -> The function is noexcept(true), unwinding can't continue.
740 OS.emitValueToAlignment(4);
741 OS.emitLabel(FuncInfoXData);
742
743 AddComment("MagicNumber");
744 OS.emitInt32(0x19930522);
745
746 AddComment("MaxState");
747 OS.emitInt32(FuncInfo.CxxUnwindMap.size());
748
749 AddComment("UnwindMap");
750 OS.emitValue(create32bitRef(UnwindMapXData), 4);
751
752 AddComment("NumTryBlocks");
753 OS.emitInt32(FuncInfo.TryBlockMap.size());
754
755 AddComment("TryBlockMap");
756 OS.emitValue(create32bitRef(TryBlockMapXData), 4);
757
758 AddComment("IPMapEntries");
759 OS.emitInt32(IPToStateTable.size());
760
761 AddComment("IPToStateXData");
762 OS.emitValue(create32bitRef(IPToStateXData), 4);
763
764 if (Asm->MAI->usesWindowsCFI()) {
765 AddComment("UnwindHelp");
766 OS.emitInt32(UnwindHelpOffset);
767 }
768
769 AddComment("ESTypeList");
770 OS.emitInt32(0);
771
772 AddComment("EHFlags");
773 OS.emitInt32(1);
774
775 // UnwindMapEntry {
776 // int32_t ToState;
777 // void (*Action)();
778 // };
779 if (UnwindMapXData) {
780 OS.emitLabel(UnwindMapXData);
781 for (const CxxUnwindMapEntry &UME : FuncInfo.CxxUnwindMap) {
782 MCSymbol *CleanupSym =
783 getMCSymbolForMBB(Asm, UME.Cleanup.dyn_cast<MachineBasicBlock *>());
784 AddComment("ToState");
785 OS.emitInt32(UME.ToState);
786
787 AddComment("Action");
788 OS.emitValue(create32bitRef(CleanupSym), 4);
789 }
790 }
791
792 // TryBlockMap {
793 // int32_t TryLow;
794 // int32_t TryHigh;
795 // int32_t CatchHigh;
796 // int32_t NumCatches;
797 // HandlerType *HandlerArray;
798 // };
799 if (TryBlockMapXData) {
800 OS.emitLabel(TryBlockMapXData);
801 SmallVector<MCSymbol *, 1> HandlerMaps;
802 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
803 const WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
804
805 MCSymbol *HandlerMapXData = nullptr;
806 if (!TBME.HandlerArray.empty())
807 HandlerMapXData =
808 Asm->OutContext.getOrCreateSymbol(Twine("$handlerMap$")
809 .concat(Twine(I))
810 .concat("$")
811 .concat(FuncLinkageName));
812 HandlerMaps.push_back(HandlerMapXData);
813
814 // TBMEs should form intervals.
815 assert(0 <= TBME.TryLow && "bad trymap interval")(static_cast<void> (0));
816 assert(TBME.TryLow <= TBME.TryHigh && "bad trymap interval")(static_cast<void> (0));
817 assert(TBME.TryHigh < TBME.CatchHigh && "bad trymap interval")(static_cast<void> (0));
818 assert(TBME.CatchHigh < int(FuncInfo.CxxUnwindMap.size()) &&(static_cast<void> (0))
819 "bad trymap interval")(static_cast<void> (0));
820
821 AddComment("TryLow");
822 OS.emitInt32(TBME.TryLow);
823
824 AddComment("TryHigh");
825 OS.emitInt32(TBME.TryHigh);
826
827 AddComment("CatchHigh");
828 OS.emitInt32(TBME.CatchHigh);
829
830 AddComment("NumCatches");
831 OS.emitInt32(TBME.HandlerArray.size());
832
833 AddComment("HandlerArray");
834 OS.emitValue(create32bitRef(HandlerMapXData), 4);
835 }
836
837 // All funclets use the same parent frame offset currently.
838 unsigned ParentFrameOffset = 0;
839 if (shouldEmitPersonality) {
840 const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
841 ParentFrameOffset = TFI->getWinEHParentFrameOffset(*MF);
842 }
843
844 for (size_t I = 0, E = FuncInfo.TryBlockMap.size(); I != E; ++I) {
845 const WinEHTryBlockMapEntry &TBME = FuncInfo.TryBlockMap[I];
846 MCSymbol *HandlerMapXData = HandlerMaps[I];
847 if (!HandlerMapXData)
848 continue;
849 // HandlerType {
850 // int32_t Adjectives;
851 // TypeDescriptor *Type;
852 // int32_t CatchObjOffset;
853 // void (*Handler)();
854 // int32_t ParentFrameOffset; // x64 and AArch64 only
855 // };
856 OS.emitLabel(HandlerMapXData);
857 for (const WinEHHandlerType &HT : TBME.HandlerArray) {
858 // Get the frame escape label with the offset of the catch object. If
859 // the index is INT_MAX, then there is no catch object, and we should
860 // emit an offset of zero, indicating that no copy will occur.
861 const MCExpr *FrameAllocOffsetRef = nullptr;
862 if (HT.CatchObj.FrameIndex != INT_MAX2147483647) {
863 int Offset = getFrameIndexOffset(HT.CatchObj.FrameIndex, FuncInfo);
864 assert(Offset != 0 && "Illegal offset for catch object!")(static_cast<void> (0));
865 FrameAllocOffsetRef = MCConstantExpr::create(Offset, Asm->OutContext);
866 } else {
867 FrameAllocOffsetRef = MCConstantExpr::create(0, Asm->OutContext);
868 }
869
870 MCSymbol *HandlerSym =
871 getMCSymbolForMBB(Asm, HT.Handler.dyn_cast<MachineBasicBlock *>());
872
873 AddComment("Adjectives");
874 OS.emitInt32(HT.Adjectives);
875
876 AddComment("Type");
877 OS.emitValue(create32bitRef(HT.TypeDescriptor), 4);
878
879 AddComment("CatchObjOffset");
880 OS.emitValue(FrameAllocOffsetRef, 4);
881
882 AddComment("Handler");
883 OS.emitValue(create32bitRef(HandlerSym), 4);
884
885 if (shouldEmitPersonality) {
886 AddComment("ParentFrameOffset");
887 OS.emitInt32(ParentFrameOffset);
888 }
889 }
890 }
891 }
892
893 // IPToStateMapEntry {
894 // void *IP;
895 // int32_t State;
896 // };
897 if (IPToStateXData) {
898 OS.emitLabel(IPToStateXData);
899 for (auto &IPStatePair : IPToStateTable) {
900 AddComment("IP");
901 OS.emitValue(IPStatePair.first, 4);
902 AddComment("ToState");
903 OS.emitInt32(IPStatePair.second);
904 }
905 }
906}
907
908void WinException::computeIP2StateTable(
909 const MachineFunction *MF, const WinEHFuncInfo &FuncInfo,
910 SmallVectorImpl<std::pair<const MCExpr *, int>> &IPToStateTable) {
911
912 for (MachineFunction::const_iterator FuncletStart = MF->begin(),
913 FuncletEnd = MF->begin(),
914 End = MF->end();
915 FuncletStart != End; FuncletStart = FuncletEnd) {
916 // Find the end of the funclet
917 while (++FuncletEnd != End) {
918 if (FuncletEnd->isEHFuncletEntry()) {
919 break;
920 }
921 }
922
923 // Don't emit ip2state entries for cleanup funclets. Any interesting
924 // exceptional actions in cleanups must be handled in a separate IR
925 // function.
926 if (FuncletStart->isCleanupFuncletEntry())
927 continue;
928
929 MCSymbol *StartLabel;
930 int BaseState;
931 if (FuncletStart == MF->begin()) {
932 BaseState = NullState;
933 StartLabel = Asm->getFunctionBegin();
934 } else {
935 auto *FuncletPad =
936 cast<FuncletPadInst>(FuncletStart->getBasicBlock()->getFirstNonPHI());
937 assert(FuncInfo.FuncletBaseStateMap.count(FuncletPad) != 0)(static_cast<void> (0));
938 BaseState = FuncInfo.FuncletBaseStateMap.find(FuncletPad)->second;
939 StartLabel = getMCSymbolForMBB(Asm, &*FuncletStart);
940 }
941 assert(StartLabel && "need local function start label")(static_cast<void> (0));
942 IPToStateTable.push_back(
943 std::make_pair(create32bitRef(StartLabel), BaseState));
944
945 for (const auto &StateChange : InvokeStateChangeIterator::range(
946 FuncInfo, FuncletStart, FuncletEnd, BaseState)) {
947 // Compute the label to report as the start of this entry; use the EH
948 // start label for the invoke if we have one, otherwise (this is a call
949 // which may unwind to our caller and does not have an EH start label, so)
950 // use the previous end label.
951 const MCSymbol *ChangeLabel = StateChange.NewStartLabel;
952 if (!ChangeLabel)
953 ChangeLabel = StateChange.PreviousEndLabel;
954 // Emit an entry indicating that PCs after 'Label' have this EH state.
955 // NOTE: On ARM architectures, the StateFromIp automatically takes into
956 // account that the return address is after the call instruction (whose EH
957 // state we should be using), but on other platforms we need to +1 to the
958 // label so that we are using the correct EH state.
959 const MCExpr *LabelExpression = (isAArch64 || isThumb)
960 ? getLabel(ChangeLabel)
961 : getLabelPlusOne(ChangeLabel);
962 IPToStateTable.push_back(
963 std::make_pair(LabelExpression, StateChange.NewState));
964 // FIXME: assert that NewState is between CatchLow and CatchHigh.
965 }
966 }
967}
968
969void WinException::emitEHRegistrationOffsetLabel(const WinEHFuncInfo &FuncInfo,
970 StringRef FLinkageName) {
971 // Outlined helpers called by the EH runtime need to know the offset of the EH
972 // registration in order to recover the parent frame pointer. Now that we know
973 // we've code generated the parent, we can emit the label assignment that
974 // those helpers use to get the offset of the registration node.
975
976 // Compute the parent frame offset. The EHRegNodeFrameIndex will be invalid if
977 // after optimization all the invokes were eliminated. We still need to emit
978 // the parent frame offset label, but it should be garbage and should never be
979 // used.
980 int64_t Offset = 0;
981 int FI = FuncInfo.EHRegNodeFrameIndex;
982 if (FI != INT_MAX2147483647) {
983 const TargetFrameLowering *TFI = Asm->MF->getSubtarget().getFrameLowering();
984 Offset = TFI->getNonLocalFrameIndexReference(*Asm->MF, FI).getFixed();
985 }
986
987 MCContext &Ctx = Asm->OutContext;
988 MCSymbol *ParentFrameOffset =
989 Ctx.getOrCreateParentFrameOffsetSymbol(FLinkageName);
990 Asm->OutStreamer->emitAssignment(ParentFrameOffset,
991 MCConstantExpr::create(Offset, Ctx));
992}
993
994/// Emit the language-specific data that _except_handler3 and 4 expect. This is
995/// functionally equivalent to the __C_specific_handler table, except it is
996/// indexed by state number instead of IP.
997void WinException::emitExceptHandlerTable(const MachineFunction *MF) {
998 MCStreamer &OS = *Asm->OutStreamer;
999 const Function &F = MF->getFunction();
1000 StringRef FLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName());
1001
1002 bool VerboseAsm = OS.isVerboseAsm();
1003 auto AddComment = [&](const Twine &Comment) {
1004 if (VerboseAsm)
1005 OS.AddComment(Comment);
1006 };
1007
1008 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
1009 emitEHRegistrationOffsetLabel(FuncInfo, FLinkageName);
1010
1011 // Emit the __ehtable label that we use for llvm.x86.seh.lsda.
1012 MCSymbol *LSDALabel = Asm->OutContext.getOrCreateLSDASymbol(FLinkageName);
1013 OS.emitValueToAlignment(4);
1014 OS.emitLabel(LSDALabel);
1015
1016 const auto *Per = cast<Function>(F.getPersonalityFn()->stripPointerCasts());
1017 StringRef PerName = Per->getName();
1018 int BaseState = -1;
1019 if (PerName == "_except_handler4") {
1020 // The LSDA for _except_handler4 starts with this struct, followed by the
1021 // scope table:
1022 //
1023 // struct EH4ScopeTable {
1024 // int32_t GSCookieOffset;
1025 // int32_t GSCookieXOROffset;
1026 // int32_t EHCookieOffset;
1027 // int32_t EHCookieXOROffset;
1028 // ScopeTableEntry ScopeRecord[];
1029 // };
1030 //
1031 // Offsets are %ebp relative.
1032 //
1033 // The GS cookie is present only if the function needs stack protection.
1034 // GSCookieOffset = -2 means that GS cookie is not used.
1035 //
1036 // The EH cookie is always present.
1037 //
1038 // Check is done the following way:
1039 // (ebp+CookieXOROffset) ^ [ebp+CookieOffset] == _security_cookie
1040
1041 // Retrieve the Guard Stack slot.
1042 int GSCookieOffset = -2;
1043 const MachineFrameInfo &MFI = MF->getFrameInfo();
1044 if (MFI.hasStackProtectorIndex()) {
1045 Register UnusedReg;
1046 const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
1047 int SSPIdx = MFI.getStackProtectorIndex();
1048 GSCookieOffset =
1049 TFI->getFrameIndexReference(*MF, SSPIdx, UnusedReg).getFixed();
1050 }
1051
1052 // Retrieve the EH Guard slot.
1053 // TODO(etienneb): Get rid of this value and change it for and assertion.
1054 int EHCookieOffset = 9999;
1055 if (FuncInfo.EHGuardFrameIndex != INT_MAX2147483647) {
1056 Register UnusedReg;
1057 const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
1058 int EHGuardIdx = FuncInfo.EHGuardFrameIndex;
1059 EHCookieOffset =
1060 TFI->getFrameIndexReference(*MF, EHGuardIdx, UnusedReg).getFixed();
1061 }
1062
1063 AddComment("GSCookieOffset");
1064 OS.emitInt32(GSCookieOffset);
1065 AddComment("GSCookieXOROffset");
1066 OS.emitInt32(0);
1067 AddComment("EHCookieOffset");
1068 OS.emitInt32(EHCookieOffset);
1069 AddComment("EHCookieXOROffset");
1070 OS.emitInt32(0);
1071 BaseState = -2;
1072 }
1073
1074 assert(!FuncInfo.SEHUnwindMap.empty())(static_cast<void> (0));
1075 for (const SEHUnwindMapEntry &UME : FuncInfo.SEHUnwindMap) {
1076 auto *Handler = UME.Handler.get<MachineBasicBlock *>();
1077 const MCSymbol *ExceptOrFinally =
1078 UME.IsFinally ? getMCSymbolForMBB(Asm, Handler) : Handler->getSymbol();
1079 // -1 is usually the base state for "unwind to caller", but for
1080 // _except_handler4 it's -2. Do that replacement here if necessary.
1081 int ToState = UME.ToState == -1 ? BaseState : UME.ToState;
1082 AddComment("ToState");
1083 OS.emitInt32(ToState);
1084 AddComment(UME.IsFinally ? "Null" : "FilterFunction");
1085 OS.emitValue(create32bitRef(UME.Filter), 4);
1086 AddComment(UME.IsFinally ? "FinallyFunclet" : "ExceptionHandler");
1087 OS.emitValue(create32bitRef(ExceptOrFinally), 4);
1088 }
1089}
1090
1091static int getTryRank(const WinEHFuncInfo &FuncInfo, int State) {
1092 int Rank = 0;
1093 while (State != -1) {
1094 ++Rank;
1095 State = FuncInfo.ClrEHUnwindMap[State].TryParentState;
1096 }
1097 return Rank;
1098}
1099
1100static int getTryAncestor(const WinEHFuncInfo &FuncInfo, int Left, int Right) {
1101 int LeftRank = getTryRank(FuncInfo, Left);
1102 int RightRank = getTryRank(FuncInfo, Right);
1103
1104 while (LeftRank < RightRank) {
1105 Right = FuncInfo.ClrEHUnwindMap[Right].TryParentState;
1106 --RightRank;
1107 }
1108
1109 while (RightRank < LeftRank) {
1110 Left = FuncInfo.ClrEHUnwindMap[Left].TryParentState;
1111 --LeftRank;
1112 }
1113
1114 while (Left != Right) {
1115 Left = FuncInfo.ClrEHUnwindMap[Left].TryParentState;
1116 Right = FuncInfo.ClrEHUnwindMap[Right].TryParentState;
1117 }
1118
1119 return Left;
1120}
1121
1122void WinException::emitCLRExceptionTable(const MachineFunction *MF) {
1123 // CLR EH "states" are really just IDs that identify handlers/funclets;
1124 // states, handlers, and funclets all have 1:1 mappings between them, and a
1125 // handler/funclet's "state" is its index in the ClrEHUnwindMap.
1126 MCStreamer &OS = *Asm->OutStreamer;
1127 const WinEHFuncInfo &FuncInfo = *MF->getWinEHFuncInfo();
1128 MCSymbol *FuncBeginSym = Asm->getFunctionBegin();
1129 MCSymbol *FuncEndSym = Asm->getFunctionEnd();
1130
1131 // A ClrClause describes a protected region.
1132 struct ClrClause {
1133 const MCSymbol *StartLabel; // Start of protected region
1134 const MCSymbol *EndLabel; // End of protected region
1135 int State; // Index of handler protecting the protected region
1136 int EnclosingState; // Index of funclet enclosing the protected region
1137 };
1138 SmallVector<ClrClause, 8> Clauses;
1139
1140 // Build a map from handler MBBs to their corresponding states (i.e. their
1141 // indices in the ClrEHUnwindMap).
1142 int NumStates = FuncInfo.ClrEHUnwindMap.size();
1143 assert(NumStates > 0 && "Don't need exception table!")(static_cast<void> (0));
1144 DenseMap<const MachineBasicBlock *, int> HandlerStates;
1145 for (int State = 0; State < NumStates; ++State) {
10
←
Assuming 'State' is >= 'NumStates'
→
11
←
Loop condition is false. Execution continues on line 1156
→
1146 MachineBasicBlock *HandlerBlock =
1147 FuncInfo.ClrEHUnwindMap[State].Handler.get<MachineBasicBlock *>();
1148 HandlerStates[HandlerBlock] = State;
1149 // Use this loop through all handlers to verify our assumption (used in
1150 // the MinEnclosingState computation) that enclosing funclets have lower
1151 // state numbers than their enclosed funclets.
1152 assert(FuncInfo.ClrEHUnwindMap[State].HandlerParentState < State &&(static_cast<void> (0))
1153 "ill-formed state numbering")(static_cast<void> (0));
1154 }
1155 // Map the main function to the NullState.
1156 HandlerStates[&MF->front()] = NullState;
1157
1158 // Write out a sentinel indicating the end of the standard (Windows) xdata
1159 // and the start of the additional (CLR) info.
1160 OS.emitInt32(0xffffffff);
1161 // Write out the number of funclets
1162 OS.emitInt32(NumStates);
1163
1164 // Walk the machine blocks/instrs, computing and emitting a few things:
1165 // 1. Emit a list of the offsets to each handler entry, in lexical order.
1166 // 2. Compute a map (EndSymbolMap) from each funclet to the symbol at its end.
1167 // 3. Compute the list of ClrClauses, in the required order (inner before
1168 // outer, earlier before later; the order by which a forward scan with
1169 // early termination will find the innermost enclosing clause covering
1170 // a given address).
1171 // 4. A map (MinClauseMap) from each handler index to the index of the
1172 // outermost funclet/function which contains a try clause targeting the
1173 // key handler. This will be used to determine IsDuplicate-ness when
1174 // emitting ClrClauses. The NullState value is used to indicate that the
1175 // top-level function contains a try clause targeting the key handler.
1176 // HandlerStack is a stack of (PendingStartLabel, PendingState) pairs for
1177 // try regions we entered before entering the PendingState try but which
1178 // we haven't yet exited.
1179 SmallVector<std::pair<const MCSymbol *, int>, 4> HandlerStack;
1180 // EndSymbolMap and MinClauseMap are maps described above.
1181 std::unique_ptr<MCSymbol *[]> EndSymbolMap(new MCSymbol *[NumStates]);
12
←
Memory is allocated
→
1182 SmallVector<int, 4> MinClauseMap((size_t)NumStates, NumStates);
1183
1184 // Visit the root function and each funclet.
1185 for (MachineFunction::const_iterator FuncletStart = MF->begin(),
13
←
Loop condition is true. Entering loop body
→
1186 FuncletEnd = MF->begin(),
1187 End = MF->end();
1188 FuncletStart != End; FuncletStart = FuncletEnd) {
1189 int FuncletState = HandlerStates[&*FuncletStart];
1190 // Find the end of the funclet
1191 MCSymbol *EndSymbol = FuncEndSym;
1192 while (++FuncletEnd != End) {
14
←
Loop condition is false. Execution continues on line 1200
→
1193 if (FuncletEnd->isEHFuncletEntry()) {
1194 EndSymbol = getMCSymbolForMBB(Asm, &*FuncletEnd);
1195 break;
1196 }
1197 }
1198 // Emit the function/funclet end and, if this is a funclet (and not the
1199 // root function), record it in the EndSymbolMap.
1200 OS.emitValue(getOffset(EndSymbol, FuncBeginSym), 4);
1201 if (FuncletState != NullState) {
15
←
Assuming 'FuncletState' is not equal to 'NullState'
→
16
←
Taking true branch
→
1202 // Record the end of the handler.
1203 EndSymbolMap[FuncletState] = EndSymbol;
17
←
Use of zero-allocated memory
1204 }
1205
1206 // Walk the state changes in this function/funclet and compute its clauses.
1207 // Funclets always start in the null state.
1208 const MCSymbol *CurrentStartLabel = nullptr;
1209 int CurrentState = NullState;
1210 assert(HandlerStack.empty())(static_cast<void> (0));
1211 for (const auto &StateChange :
1212 InvokeStateChangeIterator::range(FuncInfo, FuncletStart, FuncletEnd)) {
1213 // Close any try regions we're not still under
1214 int StillPendingState =
1215 getTryAncestor(FuncInfo, CurrentState, StateChange.NewState);
1216 while (CurrentState != StillPendingState) {
1217 assert(CurrentState != NullState &&(static_cast<void> (0))
1218 "Failed to find still-pending state!")(static_cast<void> (0));
1219 // Close the pending clause
1220 Clauses.push_back({CurrentStartLabel, StateChange.PreviousEndLabel,
1221 CurrentState, FuncletState});
1222 // Now the next-outer try region is current
1223 CurrentState = FuncInfo.ClrEHUnwindMap[CurrentState].TryParentState;
1224 // Pop the new start label from the handler stack if we've exited all
1225 // inner try regions of the corresponding try region.
1226 if (HandlerStack.back().second == CurrentState)
1227 CurrentStartLabel = HandlerStack.pop_back_val().first;
1228 }
1229
1230 if (StateChange.NewState != CurrentState) {
1231 // For each clause we're starting, update the MinClauseMap so we can
1232 // know which is the topmost funclet containing a clause targeting
1233 // it.
1234 for (int EnteredState = StateChange.NewState;
1235 EnteredState != CurrentState;
1236 EnteredState =
1237 FuncInfo.ClrEHUnwindMap[EnteredState].TryParentState) {
1238 int &MinEnclosingState = MinClauseMap[EnteredState];
1239 if (FuncletState < MinEnclosingState)
1240 MinEnclosingState = FuncletState;
1241 }
1242 // Save the previous current start/label on the stack and update to
1243 // the newly-current start/state.
1244 HandlerStack.emplace_back(CurrentStartLabel, CurrentState);
1245 CurrentStartLabel = StateChange.NewStartLabel;
1246 CurrentState = StateChange.NewState;
1247 }
1248 }
1249 assert(HandlerStack.empty())(static_cast<void> (0));
1250 }
1251
1252 // Now emit the clause info, starting with the number of clauses.
1253 OS.emitInt32(Clauses.size());
1254 for (ClrClause &Clause : Clauses) {
1255 // Emit a CORINFO_EH_CLAUSE :
1256 /*
1257 struct CORINFO_EH_CLAUSE
1258 {
1259 CORINFO_EH_CLAUSE_FLAGS Flags; // actually a CorExceptionFlag
1260 DWORD TryOffset;
1261 DWORD TryLength; // actually TryEndOffset
1262 DWORD HandlerOffset;
1263 DWORD HandlerLength; // actually HandlerEndOffset
1264 union
1265 {
1266 DWORD ClassToken; // use for catch clauses
1267 DWORD FilterOffset; // use for filter clauses
1268 };
1269 };
1270
1271 enum CORINFO_EH_CLAUSE_FLAGS
1272 {
1273 CORINFO_EH_CLAUSE_NONE = 0,
1274 CORINFO_EH_CLAUSE_FILTER = 0x0001, // This clause is for a filter
1275 CORINFO_EH_CLAUSE_FINALLY = 0x0002, // This clause is a finally clause
1276 CORINFO_EH_CLAUSE_FAULT = 0x0004, // This clause is a fault clause
1277 };
1278 typedef enum CorExceptionFlag
1279 {
1280 COR_ILEXCEPTION_CLAUSE_NONE,
1281 COR_ILEXCEPTION_CLAUSE_FILTER = 0x0001, // This is a filter clause
1282 COR_ILEXCEPTION_CLAUSE_FINALLY = 0x0002, // This is a finally clause
1283 COR_ILEXCEPTION_CLAUSE_FAULT = 0x0004, // This is a fault clause
1284 COR_ILEXCEPTION_CLAUSE_DUPLICATED = 0x0008, // duplicated clause. This
1285 // clause was duplicated
1286 // to a funclet which was
1287 // pulled out of line
1288 } CorExceptionFlag;
1289 */
1290 // Add 1 to the start/end of the EH clause; the IP associated with a
1291 // call when the runtime does its scan is the IP of the next instruction
1292 // (the one to which control will return after the call), so we need
1293 // to add 1 to the end of the clause to cover that offset. We also add
1294 // 1 to the start of the clause to make sure that the ranges reported
1295 // for all clauses are disjoint. Note that we'll need some additional
1296 // logic when machine traps are supported, since in that case the IP
1297 // that the runtime uses is the offset of the faulting instruction
1298 // itself; if such an instruction immediately follows a call but the
1299 // two belong to different clauses, we'll need to insert a nop between
1300 // them so the runtime can distinguish the point to which the call will
1301 // return from the point at which the fault occurs.
1302
1303 const MCExpr *ClauseBegin =
1304 getOffsetPlusOne(Clause.StartLabel, FuncBeginSym);
1305 const MCExpr *ClauseEnd = getOffsetPlusOne(Clause.EndLabel, FuncBeginSym);
1306
1307 const ClrEHUnwindMapEntry &Entry = FuncInfo.ClrEHUnwindMap[Clause.State];
1308 MachineBasicBlock *HandlerBlock = Entry.Handler.get<MachineBasicBlock *>();
1309 MCSymbol *BeginSym = getMCSymbolForMBB(Asm, HandlerBlock);
1310 const MCExpr *HandlerBegin = getOffset(BeginSym, FuncBeginSym);
1311 MCSymbol *EndSym = EndSymbolMap[Clause.State];
1312 const MCExpr *HandlerEnd = getOffset(EndSym, FuncBeginSym);
1313
1314 uint32_t Flags = 0;
1315 switch (Entry.HandlerType) {
1316 case ClrHandlerType::Catch:
1317 // Leaving bits 0-2 clear indicates catch.
1318 break;
1319 case ClrHandlerType::Filter:
1320 Flags |= 1;
1321 break;
1322 case ClrHandlerType::Finally:
1323 Flags |= 2;
1324 break;
1325 case ClrHandlerType::Fault:
1326 Flags |= 4;
1327 break;
1328 }
1329 if (Clause.EnclosingState != MinClauseMap[Clause.State]) {
1330 // This is a "duplicate" clause; the handler needs to be entered from a
1331 // frame above the one holding the invoke.
1332 assert(Clause.EnclosingState > MinClauseMap[Clause.State])(static_cast<void> (0));
1333 Flags |= 8;
1334 }
1335 OS.emitInt32(Flags);
1336
1337 // Write the clause start/end
1338 OS.emitValue(ClauseBegin, 4);
1339 OS.emitValue(ClauseEnd, 4);
1340
1341 // Write out the handler start/end
1342 OS.emitValue(HandlerBegin, 4);
1343 OS.emitValue(HandlerEnd, 4);
1344
1345 // Write out the type token or filter offset
1346 assert(Entry.HandlerType != ClrHandlerType::Filter && "NYI: filters")(static_cast<void> (0));
1347 OS.emitInt32(Entry.TypeToken);
1348 }
1349}