1 //===-- CGCleanup.h - Classes for cleanups IR generation --------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // These classes support the generation of LLVM IR for cleanups.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_LIB_CODEGEN_CGCLEANUP_H
15 #define LLVM_CLANG_LIB_CODEGEN_CGCLEANUP_H
17 #include "EHScopeStack.h"
20 #include "llvm/ADT/SmallPtrSet.h"
21 #include "llvm/ADT/SmallVector.h"
34 class CodeGenFunction;
36 /// The MS C++ ABI needs a pointer to RTTI data plus some flags to describe the
37 /// type of a catch handler, so we use this wrapper.
38 struct CatchTypeInfo {
43 /// A protected scope for zero-cost EH handling.
45 llvm::BasicBlock *CachedLandingPad;
46 llvm::BasicBlock *CachedEHDispatchBlock;
48 EHScopeStack::stable_iterator EnclosingEHScope;
50 class CommonBitFields {
54 enum { NumCommonBits = 3 };
57 class CatchBitFields {
58 friend class EHCatchScope;
59 unsigned : NumCommonBits;
61 unsigned NumHandlers : 32 - NumCommonBits;
64 class CleanupBitFields {
65 friend class EHCleanupScope;
66 unsigned : NumCommonBits;
68 /// Whether this cleanup needs to be run along normal edges.
69 unsigned IsNormalCleanup : 1;
71 /// Whether this cleanup needs to be run along exception edges.
72 unsigned IsEHCleanup : 1;
74 /// Whether this cleanup is currently active.
75 unsigned IsActive : 1;
77 /// Whether this cleanup is a lifetime marker
78 unsigned IsLifetimeMarker : 1;
80 /// Whether the normal cleanup should test the activation flag.
81 unsigned TestFlagInNormalCleanup : 1;
83 /// Whether the EH cleanup should test the activation flag.
84 unsigned TestFlagInEHCleanup : 1;
86 /// The amount of extra storage needed by the Cleanup.
87 /// Always a multiple of the scope-stack alignment.
88 unsigned CleanupSize : 12;
91 class FilterBitFields {
92 friend class EHFilterScope;
93 unsigned : NumCommonBits;
95 unsigned NumFilters : 32 - NumCommonBits;
99 CommonBitFields CommonBits;
100 CatchBitFields CatchBits;
101 CleanupBitFields CleanupBits;
102 FilterBitFields FilterBits;
106 enum Kind { Cleanup, Catch, Terminate, Filter, PadEnd };
108 EHScope(Kind kind, EHScopeStack::stable_iterator enclosingEHScope)
109 : CachedLandingPad(nullptr), CachedEHDispatchBlock(nullptr),
110 EnclosingEHScope(enclosingEHScope) {
111 CommonBits.Kind = kind;
114 Kind getKind() const { return static_cast<Kind>(CommonBits.Kind); }
116 llvm::BasicBlock *getCachedLandingPad() const {
117 return CachedLandingPad;
120 void setCachedLandingPad(llvm::BasicBlock *block) {
121 CachedLandingPad = block;
124 llvm::BasicBlock *getCachedEHDispatchBlock() const {
125 return CachedEHDispatchBlock;
128 void setCachedEHDispatchBlock(llvm::BasicBlock *block) {
129 CachedEHDispatchBlock = block;
132 bool hasEHBranches() const {
133 if (llvm::BasicBlock *block = getCachedEHDispatchBlock())
134 return !block->use_empty();
138 EHScopeStack::stable_iterator getEnclosingEHScope() const {
139 return EnclosingEHScope;
143 /// A scope which attempts to handle some, possibly all, types of
146 /// Objective C \@finally blocks are represented using a cleanup scope
147 /// after the catch scope.
148 class EHCatchScope : public EHScope {
149 // In effect, we have a flexible array member
150 // Handler Handlers[0];
151 // But that's only standard in C99, not C++, so we have to do
152 // annoying pointer arithmetic instead.
156 /// A type info value, or null (C++ null, not an LLVM null pointer)
160 /// The catch handler for this type.
161 llvm::BasicBlock *Block;
163 bool isCatchAll() const { return Type.RTTI == nullptr; }
167 friend class EHScopeStack;
169 Handler *getHandlers() {
170 return reinterpret_cast<Handler*>(this+1);
173 const Handler *getHandlers() const {
174 return reinterpret_cast<const Handler*>(this+1);
178 static size_t getSizeForNumHandlers(unsigned N) {
179 return sizeof(EHCatchScope) + N * sizeof(Handler);
182 EHCatchScope(unsigned numHandlers,
183 EHScopeStack::stable_iterator enclosingEHScope)
184 : EHScope(Catch, enclosingEHScope) {
185 CatchBits.NumHandlers = numHandlers;
186 assert(CatchBits.NumHandlers == numHandlers && "NumHandlers overflow?");
189 unsigned getNumHandlers() const {
190 return CatchBits.NumHandlers;
193 void setCatchAllHandler(unsigned I, llvm::BasicBlock *Block) {
194 setHandler(I, CatchTypeInfo{nullptr, 0}, Block);
197 void setHandler(unsigned I, llvm::Constant *Type, llvm::BasicBlock *Block) {
198 assert(I < getNumHandlers());
199 getHandlers()[I].Type = CatchTypeInfo{Type, 0};
200 getHandlers()[I].Block = Block;
203 void setHandler(unsigned I, CatchTypeInfo Type, llvm::BasicBlock *Block) {
204 assert(I < getNumHandlers());
205 getHandlers()[I].Type = Type;
206 getHandlers()[I].Block = Block;
209 const Handler &getHandler(unsigned I) const {
210 assert(I < getNumHandlers());
211 return getHandlers()[I];
214 // Clear all handler blocks.
215 // FIXME: it's better to always call clearHandlerBlocks in DTOR and have a
216 // 'takeHandler' or some such function which removes ownership from the
217 // EHCatchScope object if the handlers should live longer than EHCatchScope.
218 void clearHandlerBlocks() {
219 for (unsigned I = 0, N = getNumHandlers(); I != N; ++I)
220 delete getHandler(I).Block;
223 typedef const Handler *iterator;
224 iterator begin() const { return getHandlers(); }
225 iterator end() const { return getHandlers() + getNumHandlers(); }
227 static bool classof(const EHScope *Scope) {
228 return Scope->getKind() == Catch;
232 /// A cleanup scope which generates the cleanup blocks lazily.
233 class LLVM_ALIGNAS(/*alignof(uint64_t)*/ 8) EHCleanupScope : public EHScope {
234 /// The nearest normal cleanup scope enclosing this one.
235 EHScopeStack::stable_iterator EnclosingNormal;
237 /// The nearest EH scope enclosing this one.
238 EHScopeStack::stable_iterator EnclosingEH;
240 /// The dual entry/exit block along the normal edge. This is lazily
241 /// created if needed before the cleanup is popped.
242 llvm::BasicBlock *NormalBlock;
244 /// An optional i1 variable indicating whether this cleanup has been
246 llvm::AllocaInst *ActiveFlag;
248 /// Extra information required for cleanups that have resolved
249 /// branches through them. This has to be allocated on the side
250 /// because everything on the cleanup stack has be trivially
253 /// The destinations of normal branch-afters and branch-throughs.
254 llvm::SmallPtrSet<llvm::BasicBlock*, 4> Branches;
256 /// Normal branch-afters.
257 SmallVector<std::pair<llvm::BasicBlock*,llvm::ConstantInt*>, 4>
260 mutable struct ExtInfo *ExtInfo;
262 /// The number of fixups required by enclosing scopes (not including
263 /// this one). If this is the top cleanup scope, all the fixups
264 /// from this index onwards belong to this scope.
267 struct ExtInfo &getExtInfo() {
268 if (!ExtInfo) ExtInfo = new struct ExtInfo();
272 const struct ExtInfo &getExtInfo() const {
273 if (!ExtInfo) ExtInfo = new struct ExtInfo();
278 /// Gets the size required for a lazy cleanup scope with the given
279 /// cleanup-data requirements.
280 static size_t getSizeForCleanupSize(size_t Size) {
281 return sizeof(EHCleanupScope) + Size;
284 size_t getAllocatedSize() const {
285 return sizeof(EHCleanupScope) + CleanupBits.CleanupSize;
288 EHCleanupScope(bool isNormal, bool isEH, bool isActive,
289 unsigned cleanupSize, unsigned fixupDepth,
290 EHScopeStack::stable_iterator enclosingNormal,
291 EHScopeStack::stable_iterator enclosingEH)
292 : EHScope(EHScope::Cleanup, enclosingEH),
293 EnclosingNormal(enclosingNormal), NormalBlock(nullptr),
294 ActiveFlag(nullptr), ExtInfo(nullptr), FixupDepth(fixupDepth) {
295 CleanupBits.IsNormalCleanup = isNormal;
296 CleanupBits.IsEHCleanup = isEH;
297 CleanupBits.IsActive = isActive;
298 CleanupBits.IsLifetimeMarker = false;
299 CleanupBits.TestFlagInNormalCleanup = false;
300 CleanupBits.TestFlagInEHCleanup = false;
301 CleanupBits.CleanupSize = cleanupSize;
303 assert(CleanupBits.CleanupSize == cleanupSize && "cleanup size overflow");
309 // Objects of EHCleanupScope are not destructed. Use Destroy().
310 ~EHCleanupScope() = delete;
312 bool isNormalCleanup() const { return CleanupBits.IsNormalCleanup; }
313 llvm::BasicBlock *getNormalBlock() const { return NormalBlock; }
314 void setNormalBlock(llvm::BasicBlock *BB) { NormalBlock = BB; }
316 bool isEHCleanup() const { return CleanupBits.IsEHCleanup; }
318 bool isActive() const { return CleanupBits.IsActive; }
319 void setActive(bool A) { CleanupBits.IsActive = A; }
321 bool isLifetimeMarker() const { return CleanupBits.IsLifetimeMarker; }
322 void setLifetimeMarker() { CleanupBits.IsLifetimeMarker = true; }
324 bool hasActiveFlag() const { return ActiveFlag != nullptr; }
325 Address getActiveFlag() const {
326 return Address(ActiveFlag, CharUnits::One());
328 void setActiveFlag(Address Var) {
329 assert(Var.getAlignment().isOne());
330 ActiveFlag = cast<llvm::AllocaInst>(Var.getPointer());
333 void setTestFlagInNormalCleanup() {
334 CleanupBits.TestFlagInNormalCleanup = true;
336 bool shouldTestFlagInNormalCleanup() const {
337 return CleanupBits.TestFlagInNormalCleanup;
340 void setTestFlagInEHCleanup() {
341 CleanupBits.TestFlagInEHCleanup = true;
343 bool shouldTestFlagInEHCleanup() const {
344 return CleanupBits.TestFlagInEHCleanup;
347 unsigned getFixupDepth() const { return FixupDepth; }
348 EHScopeStack::stable_iterator getEnclosingNormalCleanup() const {
349 return EnclosingNormal;
352 size_t getCleanupSize() const { return CleanupBits.CleanupSize; }
353 void *getCleanupBuffer() { return this + 1; }
355 EHScopeStack::Cleanup *getCleanup() {
356 return reinterpret_cast<EHScopeStack::Cleanup*>(getCleanupBuffer());
359 /// True if this cleanup scope has any branch-afters or branch-throughs.
360 bool hasBranches() const { return ExtInfo && !ExtInfo->Branches.empty(); }
362 /// Add a branch-after to this cleanup scope. A branch-after is a
363 /// branch from a point protected by this (normal) cleanup to a
364 /// point in the normal cleanup scope immediately containing it.
366 /// for (;;) { A a; break; }
367 /// contains a branch-after.
369 /// Branch-afters each have their own destination out of the
370 /// cleanup, guaranteed distinct from anything else threaded through
371 /// it. Therefore branch-afters usually force a switch after the
373 void addBranchAfter(llvm::ConstantInt *Index,
374 llvm::BasicBlock *Block) {
375 struct ExtInfo &ExtInfo = getExtInfo();
376 if (ExtInfo.Branches.insert(Block).second)
377 ExtInfo.BranchAfters.push_back(std::make_pair(Block, Index));
380 /// Return the number of unique branch-afters on this scope.
381 unsigned getNumBranchAfters() const {
382 return ExtInfo ? ExtInfo->BranchAfters.size() : 0;
385 llvm::BasicBlock *getBranchAfterBlock(unsigned I) const {
386 assert(I < getNumBranchAfters());
387 return ExtInfo->BranchAfters[I].first;
390 llvm::ConstantInt *getBranchAfterIndex(unsigned I) const {
391 assert(I < getNumBranchAfters());
392 return ExtInfo->BranchAfters[I].second;
395 /// Add a branch-through to this cleanup scope. A branch-through is
396 /// a branch from a scope protected by this (normal) cleanup to an
397 /// enclosing scope other than the immediately-enclosing normal
400 /// In the following example, the branch through B's scope is a
401 /// branch-through, while the branch through A's scope is a
403 /// for (;;) { A a; B b; break; }
405 /// All branch-throughs have a common destination out of the
406 /// cleanup, one possibly shared with the fall-through. Therefore
407 /// branch-throughs usually don't force a switch after the cleanup.
409 /// \return true if the branch-through was new to this scope
410 bool addBranchThrough(llvm::BasicBlock *Block) {
411 return getExtInfo().Branches.insert(Block).second;
414 /// Determines if this cleanup scope has any branch throughs.
415 bool hasBranchThroughs() const {
416 if (!ExtInfo) return false;
417 return (ExtInfo->BranchAfters.size() != ExtInfo->Branches.size());
420 static bool classof(const EHScope *Scope) {
421 return (Scope->getKind() == Cleanup);
424 // NOTE: there's a bunch of different data classes tacked on after an
425 // EHCleanupScope. It is asserted (in EHScopeStack::pushCleanup*) that
426 // they don't require greater alignment than ScopeStackAlignment. So,
427 // EHCleanupScope ought to have alignment equal to that -- not more
428 // (would be misaligned by the stack allocator), and not less (would
429 // break the appended classes).
430 static_assert(alignof(EHCleanupScope) == EHScopeStack::ScopeStackAlignment,
431 "EHCleanupScope expected alignment");
433 /// An exceptions scope which filters exceptions thrown through it.
434 /// Only exceptions matching the filter types will be permitted to be
437 /// This is used to implement C++ exception specifications.
438 class EHFilterScope : public EHScope {
439 // Essentially ends in a flexible array member:
440 // llvm::Value *FilterTypes[0];
442 llvm::Value **getFilters() {
443 return reinterpret_cast<llvm::Value**>(this+1);
446 llvm::Value * const *getFilters() const {
447 return reinterpret_cast<llvm::Value* const *>(this+1);
451 EHFilterScope(unsigned numFilters)
452 : EHScope(Filter, EHScopeStack::stable_end()) {
453 FilterBits.NumFilters = numFilters;
454 assert(FilterBits.NumFilters == numFilters && "NumFilters overflow");
457 static size_t getSizeForNumFilters(unsigned numFilters) {
458 return sizeof(EHFilterScope) + numFilters * sizeof(llvm::Value*);
461 unsigned getNumFilters() const { return FilterBits.NumFilters; }
463 void setFilter(unsigned i, llvm::Value *filterValue) {
464 assert(i < getNumFilters());
465 getFilters()[i] = filterValue;
468 llvm::Value *getFilter(unsigned i) const {
469 assert(i < getNumFilters());
470 return getFilters()[i];
473 static bool classof(const EHScope *scope) {
474 return scope->getKind() == Filter;
478 /// An exceptions scope which calls std::terminate if any exception
480 class EHTerminateScope : public EHScope {
482 EHTerminateScope(EHScopeStack::stable_iterator enclosingEHScope)
483 : EHScope(Terminate, enclosingEHScope) {}
484 static size_t getSize() { return sizeof(EHTerminateScope); }
486 static bool classof(const EHScope *scope) {
487 return scope->getKind() == Terminate;
491 class EHPadEndScope : public EHScope {
493 EHPadEndScope(EHScopeStack::stable_iterator enclosingEHScope)
494 : EHScope(PadEnd, enclosingEHScope) {}
495 static size_t getSize() { return sizeof(EHPadEndScope); }
497 static bool classof(const EHScope *scope) {
498 return scope->getKind() == PadEnd;
502 /// A non-stable pointer into the scope stack.
503 class EHScopeStack::iterator {
506 friend class EHScopeStack;
507 explicit iterator(char *Ptr) : Ptr(Ptr) {}
510 iterator() : Ptr(nullptr) {}
512 EHScope *get() const {
513 return reinterpret_cast<EHScope*>(Ptr);
516 EHScope *operator->() const { return get(); }
517 EHScope &operator*() const { return *get(); }
519 iterator &operator++() {
521 switch (get()->getKind()) {
523 Size = EHCatchScope::getSizeForNumHandlers(
524 static_cast<const EHCatchScope *>(get())->getNumHandlers());
527 case EHScope::Filter:
528 Size = EHFilterScope::getSizeForNumFilters(
529 static_cast<const EHFilterScope *>(get())->getNumFilters());
532 case EHScope::Cleanup:
533 Size = static_cast<const EHCleanupScope *>(get())->getAllocatedSize();
536 case EHScope::Terminate:
537 Size = EHTerminateScope::getSize();
540 case EHScope::PadEnd:
541 Size = EHPadEndScope::getSize();
544 Ptr += llvm::alignTo(Size, ScopeStackAlignment);
549 iterator copy = *this;
554 iterator operator++(int) {
555 iterator copy = *this;
560 bool encloses(iterator other) const { return Ptr >= other.Ptr; }
561 bool strictlyEncloses(iterator other) const { return Ptr > other.Ptr; }
563 bool operator==(iterator other) const { return Ptr == other.Ptr; }
564 bool operator!=(iterator other) const { return Ptr != other.Ptr; }
567 inline EHScopeStack::iterator EHScopeStack::begin() const {
568 return iterator(StartOfData);
571 inline EHScopeStack::iterator EHScopeStack::end() const {
572 return iterator(EndOfBuffer);
575 inline void EHScopeStack::popCatch() {
576 assert(!empty() && "popping exception stack when not empty");
578 EHCatchScope &scope = cast<EHCatchScope>(*begin());
579 InnermostEHScope = scope.getEnclosingEHScope();
580 deallocate(EHCatchScope::getSizeForNumHandlers(scope.getNumHandlers()));
583 inline void EHScopeStack::popTerminate() {
584 assert(!empty() && "popping exception stack when not empty");
586 EHTerminateScope &scope = cast<EHTerminateScope>(*begin());
587 InnermostEHScope = scope.getEnclosingEHScope();
588 deallocate(EHTerminateScope::getSize());
591 inline EHScopeStack::iterator EHScopeStack::find(stable_iterator sp) const {
592 assert(sp.isValid() && "finding invalid savepoint");
593 assert(sp.Size <= stable_begin().Size && "finding savepoint after pop");
594 return iterator(EndOfBuffer - sp.Size);
597 inline EHScopeStack::stable_iterator
598 EHScopeStack::stabilize(iterator ir) const {
599 assert(StartOfData <= ir.Ptr && ir.Ptr <= EndOfBuffer);
600 return stable_iterator(EndOfBuffer - ir.Ptr);
603 /// The exceptions personality for a function.
604 struct EHPersonality {
605 const char *PersonalityFn;
607 // If this is non-null, this personality requires a non-standard
608 // function for rethrowing an exception after a catchall cleanup.
609 // This function must have prototype void(void*).
610 const char *CatchallRethrowFn;
612 static const EHPersonality &get(CodeGenModule &CGM, const FunctionDecl *FD);
613 static const EHPersonality &get(CodeGenFunction &CGF);
615 static const EHPersonality GNU_C;
616 static const EHPersonality GNU_C_SJLJ;
617 static const EHPersonality GNU_C_SEH;
618 static const EHPersonality GNU_ObjC;
619 static const EHPersonality GNU_ObjC_SJLJ;
620 static const EHPersonality GNU_ObjC_SEH;
621 static const EHPersonality GNUstep_ObjC;
622 static const EHPersonality GNU_ObjCXX;
623 static const EHPersonality NeXT_ObjC;
624 static const EHPersonality GNU_CPlusPlus;
625 static const EHPersonality GNU_CPlusPlus_SJLJ;
626 static const EHPersonality GNU_CPlusPlus_SEH;
627 static const EHPersonality MSVC_except_handler;
628 static const EHPersonality MSVC_C_specific_handler;
629 static const EHPersonality MSVC_CxxFrameHandler3;
631 /// Does this personality use landingpads or the family of pad instructions
632 /// designed to form funclets?
633 bool usesFuncletPads() const { return isMSVCPersonality(); }
635 bool isMSVCPersonality() const {
636 return this == &MSVC_except_handler || this == &MSVC_C_specific_handler ||
637 this == &MSVC_CxxFrameHandler3;
640 bool isMSVCXXPersonality() const { return this == &MSVC_CxxFrameHandler3; }