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 CLANG_CODEGEN_CGCLEANUP_H
15 #define CLANG_CODEGEN_CGCLEANUP_H
17 #include "EHScopeStack.h"
18 #include "llvm/ADT/SmallPtrSet.h"
19 #include "llvm/ADT/SmallVector.h"
31 /// A protected scope for zero-cost EH handling.
33 llvm::BasicBlock *CachedLandingPad;
34 llvm::BasicBlock *CachedEHDispatchBlock;
36 EHScopeStack::stable_iterator EnclosingEHScope;
38 class CommonBitFields {
42 enum { NumCommonBits = 2 };
45 class CatchBitFields {
46 friend class EHCatchScope;
47 unsigned : NumCommonBits;
49 unsigned NumHandlers : 32 - NumCommonBits;
52 class CleanupBitFields {
53 friend class EHCleanupScope;
54 unsigned : NumCommonBits;
56 /// Whether this cleanup needs to be run along normal edges.
57 unsigned IsNormalCleanup : 1;
59 /// Whether this cleanup needs to be run along exception edges.
60 unsigned IsEHCleanup : 1;
62 /// Whether this cleanup is currently active.
63 unsigned IsActive : 1;
65 /// Whether the normal cleanup should test the activation flag.
66 unsigned TestFlagInNormalCleanup : 1;
68 /// Whether the EH cleanup should test the activation flag.
69 unsigned TestFlagInEHCleanup : 1;
71 /// The amount of extra storage needed by the Cleanup.
72 /// Always a multiple of the scope-stack alignment.
73 unsigned CleanupSize : 12;
75 /// The number of fixups required by enclosing scopes (not including
76 /// this one). If this is the top cleanup scope, all the fixups
77 /// from this index onwards belong to this scope.
78 unsigned FixupDepth : 32 - 17 - NumCommonBits; // currently 13
81 class FilterBitFields {
82 friend class EHFilterScope;
83 unsigned : NumCommonBits;
85 unsigned NumFilters : 32 - NumCommonBits;
89 CommonBitFields CommonBits;
90 CatchBitFields CatchBits;
91 CleanupBitFields CleanupBits;
92 FilterBitFields FilterBits;
96 enum Kind { Cleanup, Catch, Terminate, Filter };
98 EHScope(Kind kind, EHScopeStack::stable_iterator enclosingEHScope)
99 : CachedLandingPad(0), CachedEHDispatchBlock(0),
100 EnclosingEHScope(enclosingEHScope) {
101 CommonBits.Kind = kind;
104 Kind getKind() const { return static_cast<Kind>(CommonBits.Kind); }
106 llvm::BasicBlock *getCachedLandingPad() const {
107 return CachedLandingPad;
110 void setCachedLandingPad(llvm::BasicBlock *block) {
111 CachedLandingPad = block;
114 llvm::BasicBlock *getCachedEHDispatchBlock() const {
115 return CachedEHDispatchBlock;
118 void setCachedEHDispatchBlock(llvm::BasicBlock *block) {
119 CachedEHDispatchBlock = block;
122 bool hasEHBranches() const {
123 if (llvm::BasicBlock *block = getCachedEHDispatchBlock())
124 return !block->use_empty();
128 EHScopeStack::stable_iterator getEnclosingEHScope() const {
129 return EnclosingEHScope;
133 /// A scope which attempts to handle some, possibly all, types of
136 /// Objective C \@finally blocks are represented using a cleanup scope
137 /// after the catch scope.
138 class EHCatchScope : public EHScope {
139 // In effect, we have a flexible array member
140 // Handler Handlers[0];
141 // But that's only standard in C99, not C++, so we have to do
142 // annoying pointer arithmetic instead.
146 /// A type info value, or null (C++ null, not an LLVM null pointer)
150 /// The catch handler for this type.
151 llvm::BasicBlock *Block;
153 bool isCatchAll() const { return Type == 0; }
157 friend class EHScopeStack;
159 Handler *getHandlers() {
160 return reinterpret_cast<Handler*>(this+1);
163 const Handler *getHandlers() const {
164 return reinterpret_cast<const Handler*>(this+1);
168 static size_t getSizeForNumHandlers(unsigned N) {
169 return sizeof(EHCatchScope) + N * sizeof(Handler);
172 EHCatchScope(unsigned numHandlers,
173 EHScopeStack::stable_iterator enclosingEHScope)
174 : EHScope(Catch, enclosingEHScope) {
175 CatchBits.NumHandlers = numHandlers;
178 unsigned getNumHandlers() const {
179 return CatchBits.NumHandlers;
182 void setCatchAllHandler(unsigned I, llvm::BasicBlock *Block) {
183 setHandler(I, /*catchall*/ 0, Block);
186 void setHandler(unsigned I, llvm::Value *Type, llvm::BasicBlock *Block) {
187 assert(I < getNumHandlers());
188 getHandlers()[I].Type = Type;
189 getHandlers()[I].Block = Block;
192 const Handler &getHandler(unsigned I) const {
193 assert(I < getNumHandlers());
194 return getHandlers()[I];
197 typedef const Handler *iterator;
198 iterator begin() const { return getHandlers(); }
199 iterator end() const { return getHandlers() + getNumHandlers(); }
201 static bool classof(const EHScope *Scope) {
202 return Scope->getKind() == Catch;
206 /// A cleanup scope which generates the cleanup blocks lazily.
207 class EHCleanupScope : public EHScope {
208 /// The nearest normal cleanup scope enclosing this one.
209 EHScopeStack::stable_iterator EnclosingNormal;
211 /// The nearest EH scope enclosing this one.
212 EHScopeStack::stable_iterator EnclosingEH;
214 /// The dual entry/exit block along the normal edge. This is lazily
215 /// created if needed before the cleanup is popped.
216 llvm::BasicBlock *NormalBlock;
218 /// An optional i1 variable indicating whether this cleanup has been
220 llvm::AllocaInst *ActiveFlag;
222 /// Extra information required for cleanups that have resolved
223 /// branches through them. This has to be allocated on the side
224 /// because everything on the cleanup stack has be trivially
227 /// The destinations of normal branch-afters and branch-throughs.
228 llvm::SmallPtrSet<llvm::BasicBlock*, 4> Branches;
230 /// Normal branch-afters.
231 SmallVector<std::pair<llvm::BasicBlock*,llvm::ConstantInt*>, 4>
234 mutable struct ExtInfo *ExtInfo;
236 struct ExtInfo &getExtInfo() {
237 if (!ExtInfo) ExtInfo = new struct ExtInfo();
241 const struct ExtInfo &getExtInfo() const {
242 if (!ExtInfo) ExtInfo = new struct ExtInfo();
247 /// Gets the size required for a lazy cleanup scope with the given
248 /// cleanup-data requirements.
249 static size_t getSizeForCleanupSize(size_t Size) {
250 return sizeof(EHCleanupScope) + Size;
253 size_t getAllocatedSize() const {
254 return sizeof(EHCleanupScope) + CleanupBits.CleanupSize;
257 EHCleanupScope(bool isNormal, bool isEH, bool isActive,
258 unsigned cleanupSize, unsigned fixupDepth,
259 EHScopeStack::stable_iterator enclosingNormal,
260 EHScopeStack::stable_iterator enclosingEH)
261 : EHScope(EHScope::Cleanup, enclosingEH), EnclosingNormal(enclosingNormal),
262 NormalBlock(0), ActiveFlag(0), ExtInfo(0) {
263 CleanupBits.IsNormalCleanup = isNormal;
264 CleanupBits.IsEHCleanup = isEH;
265 CleanupBits.IsActive = isActive;
266 CleanupBits.TestFlagInNormalCleanup = false;
267 CleanupBits.TestFlagInEHCleanup = false;
268 CleanupBits.CleanupSize = cleanupSize;
269 CleanupBits.FixupDepth = fixupDepth;
271 assert(CleanupBits.CleanupSize == cleanupSize && "cleanup size overflow");
278 bool isNormalCleanup() const { return CleanupBits.IsNormalCleanup; }
279 llvm::BasicBlock *getNormalBlock() const { return NormalBlock; }
280 void setNormalBlock(llvm::BasicBlock *BB) { NormalBlock = BB; }
282 bool isEHCleanup() const { return CleanupBits.IsEHCleanup; }
283 llvm::BasicBlock *getEHBlock() const { return getCachedEHDispatchBlock(); }
284 void setEHBlock(llvm::BasicBlock *BB) { setCachedEHDispatchBlock(BB); }
286 bool isActive() const { return CleanupBits.IsActive; }
287 void setActive(bool A) { CleanupBits.IsActive = A; }
289 llvm::AllocaInst *getActiveFlag() const { return ActiveFlag; }
290 void setActiveFlag(llvm::AllocaInst *Var) { ActiveFlag = Var; }
292 void setTestFlagInNormalCleanup() {
293 CleanupBits.TestFlagInNormalCleanup = true;
295 bool shouldTestFlagInNormalCleanup() const {
296 return CleanupBits.TestFlagInNormalCleanup;
299 void setTestFlagInEHCleanup() {
300 CleanupBits.TestFlagInEHCleanup = true;
302 bool shouldTestFlagInEHCleanup() const {
303 return CleanupBits.TestFlagInEHCleanup;
306 unsigned getFixupDepth() const { return CleanupBits.FixupDepth; }
307 EHScopeStack::stable_iterator getEnclosingNormalCleanup() const {
308 return EnclosingNormal;
311 size_t getCleanupSize() const { return CleanupBits.CleanupSize; }
312 void *getCleanupBuffer() { return this + 1; }
314 EHScopeStack::Cleanup *getCleanup() {
315 return reinterpret_cast<EHScopeStack::Cleanup*>(getCleanupBuffer());
318 /// True if this cleanup scope has any branch-afters or branch-throughs.
319 bool hasBranches() const { return ExtInfo && !ExtInfo->Branches.empty(); }
321 /// Add a branch-after to this cleanup scope. A branch-after is a
322 /// branch from a point protected by this (normal) cleanup to a
323 /// point in the normal cleanup scope immediately containing it.
325 /// for (;;) { A a; break; }
326 /// contains a branch-after.
328 /// Branch-afters each have their own destination out of the
329 /// cleanup, guaranteed distinct from anything else threaded through
330 /// it. Therefore branch-afters usually force a switch after the
332 void addBranchAfter(llvm::ConstantInt *Index,
333 llvm::BasicBlock *Block) {
334 struct ExtInfo &ExtInfo = getExtInfo();
335 if (ExtInfo.Branches.insert(Block))
336 ExtInfo.BranchAfters.push_back(std::make_pair(Block, Index));
339 /// Return the number of unique branch-afters on this scope.
340 unsigned getNumBranchAfters() const {
341 return ExtInfo ? ExtInfo->BranchAfters.size() : 0;
344 llvm::BasicBlock *getBranchAfterBlock(unsigned I) const {
345 assert(I < getNumBranchAfters());
346 return ExtInfo->BranchAfters[I].first;
349 llvm::ConstantInt *getBranchAfterIndex(unsigned I) const {
350 assert(I < getNumBranchAfters());
351 return ExtInfo->BranchAfters[I].second;
354 /// Add a branch-through to this cleanup scope. A branch-through is
355 /// a branch from a scope protected by this (normal) cleanup to an
356 /// enclosing scope other than the immediately-enclosing normal
359 /// In the following example, the branch through B's scope is a
360 /// branch-through, while the branch through A's scope is a
362 /// for (;;) { A a; B b; break; }
364 /// All branch-throughs have a common destination out of the
365 /// cleanup, one possibly shared with the fall-through. Therefore
366 /// branch-throughs usually don't force a switch after the cleanup.
368 /// \return true if the branch-through was new to this scope
369 bool addBranchThrough(llvm::BasicBlock *Block) {
370 return getExtInfo().Branches.insert(Block);
373 /// Determines if this cleanup scope has any branch throughs.
374 bool hasBranchThroughs() const {
375 if (!ExtInfo) return false;
376 return (ExtInfo->BranchAfters.size() != ExtInfo->Branches.size());
379 static bool classof(const EHScope *Scope) {
380 return (Scope->getKind() == Cleanup);
384 /// An exceptions scope which filters exceptions thrown through it.
385 /// Only exceptions matching the filter types will be permitted to be
388 /// This is used to implement C++ exception specifications.
389 class EHFilterScope : public EHScope {
390 // Essentially ends in a flexible array member:
391 // llvm::Value *FilterTypes[0];
393 llvm::Value **getFilters() {
394 return reinterpret_cast<llvm::Value**>(this+1);
397 llvm::Value * const *getFilters() const {
398 return reinterpret_cast<llvm::Value* const *>(this+1);
402 EHFilterScope(unsigned numFilters)
403 : EHScope(Filter, EHScopeStack::stable_end()) {
404 FilterBits.NumFilters = numFilters;
407 static size_t getSizeForNumFilters(unsigned numFilters) {
408 return sizeof(EHFilterScope) + numFilters * sizeof(llvm::Value*);
411 unsigned getNumFilters() const { return FilterBits.NumFilters; }
413 void setFilter(unsigned i, llvm::Value *filterValue) {
414 assert(i < getNumFilters());
415 getFilters()[i] = filterValue;
418 llvm::Value *getFilter(unsigned i) const {
419 assert(i < getNumFilters());
420 return getFilters()[i];
423 static bool classof(const EHScope *scope) {
424 return scope->getKind() == Filter;
428 /// An exceptions scope which calls std::terminate if any exception
430 class EHTerminateScope : public EHScope {
432 EHTerminateScope(EHScopeStack::stable_iterator enclosingEHScope)
433 : EHScope(Terminate, enclosingEHScope) {}
434 static size_t getSize() { return sizeof(EHTerminateScope); }
436 static bool classof(const EHScope *scope) {
437 return scope->getKind() == Terminate;
441 /// A non-stable pointer into the scope stack.
442 class EHScopeStack::iterator {
445 friend class EHScopeStack;
446 explicit iterator(char *Ptr) : Ptr(Ptr) {}
449 iterator() : Ptr(0) {}
451 EHScope *get() const {
452 return reinterpret_cast<EHScope*>(Ptr);
455 EHScope *operator->() const { return get(); }
456 EHScope &operator*() const { return *get(); }
458 iterator &operator++() {
459 switch (get()->getKind()) {
461 Ptr += EHCatchScope::getSizeForNumHandlers(
462 static_cast<const EHCatchScope*>(get())->getNumHandlers());
465 case EHScope::Filter:
466 Ptr += EHFilterScope::getSizeForNumFilters(
467 static_cast<const EHFilterScope*>(get())->getNumFilters());
470 case EHScope::Cleanup:
471 Ptr += static_cast<const EHCleanupScope*>(get())
472 ->getAllocatedSize();
475 case EHScope::Terminate:
476 Ptr += EHTerminateScope::getSize();
484 iterator copy = *this;
489 iterator operator++(int) {
490 iterator copy = *this;
495 bool encloses(iterator other) const { return Ptr >= other.Ptr; }
496 bool strictlyEncloses(iterator other) const { return Ptr > other.Ptr; }
498 bool operator==(iterator other) const { return Ptr == other.Ptr; }
499 bool operator!=(iterator other) const { return Ptr != other.Ptr; }
502 inline EHScopeStack::iterator EHScopeStack::begin() const {
503 return iterator(StartOfData);
506 inline EHScopeStack::iterator EHScopeStack::end() const {
507 return iterator(EndOfBuffer);
510 inline void EHScopeStack::popCatch() {
511 assert(!empty() && "popping exception stack when not empty");
513 EHCatchScope &scope = cast<EHCatchScope>(*begin());
514 InnermostEHScope = scope.getEnclosingEHScope();
515 StartOfData += EHCatchScope::getSizeForNumHandlers(scope.getNumHandlers());
518 inline void EHScopeStack::popTerminate() {
519 assert(!empty() && "popping exception stack when not empty");
521 EHTerminateScope &scope = cast<EHTerminateScope>(*begin());
522 InnermostEHScope = scope.getEnclosingEHScope();
523 StartOfData += EHTerminateScope::getSize();
526 inline EHScopeStack::iterator EHScopeStack::find(stable_iterator sp) const {
527 assert(sp.isValid() && "finding invalid savepoint");
528 assert(sp.Size <= stable_begin().Size && "finding savepoint after pop");
529 return iterator(EndOfBuffer - sp.Size);
532 inline EHScopeStack::stable_iterator
533 EHScopeStack::stabilize(iterator ir) const {
534 assert(StartOfData <= ir.Ptr && ir.Ptr <= EndOfBuffer);
535 return stable_iterator(EndOfBuffer - ir.Ptr);