Move all the cleanups framework code into a single file.
Pure motion.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@124484 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGCleanup.cpp b/lib/CodeGen/CGCleanup.cpp
new file mode 100644
index 0000000..3c4d80f
--- /dev/null
+++ b/lib/CodeGen/CGCleanup.cpp
@@ -0,0 +1,1144 @@
+//===--- CGCleanup.cpp - Bookkeeping and code emission for cleanups -------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains code dealing with the IR generation for cleanups
+// and related information.
+//
+// A "cleanup" is a piece of code which needs to be executed whenever
+// control transfers out of a particular scope. This can be
+// conditionalized to occur only on exceptional control flow, only on
+// normal control flow, or both.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CodeGenFunction.h"
+#include "CGCleanup.h"
+
+using namespace clang;
+using namespace CodeGen;
+
+bool DominatingValue<RValue>::saved_type::needsSaving(RValue rv) {
+ if (rv.isScalar())
+ return DominatingLLVMValue::needsSaving(rv.getScalarVal());
+ if (rv.isAggregate())
+ return DominatingLLVMValue::needsSaving(rv.getAggregateAddr());
+ return true;
+}
+
+DominatingValue<RValue>::saved_type
+DominatingValue<RValue>::saved_type::save(CodeGenFunction &CGF, RValue rv) {
+ if (rv.isScalar()) {
+ llvm::Value *V = rv.getScalarVal();
+
+ // These automatically dominate and don't need to be saved.
+ if (!DominatingLLVMValue::needsSaving(V))
+ return saved_type(V, ScalarLiteral);
+
+ // Everything else needs an alloca.
+ llvm::Value *addr = CGF.CreateTempAlloca(V->getType(), "saved-rvalue");
+ CGF.Builder.CreateStore(V, addr);
+ return saved_type(addr, ScalarAddress);
+ }
+
+ if (rv.isComplex()) {
+ CodeGenFunction::ComplexPairTy V = rv.getComplexVal();
+ const llvm::Type *ComplexTy =
+ llvm::StructType::get(CGF.getLLVMContext(),
+ V.first->getType(), V.second->getType(),
+ (void*) 0);
+ llvm::Value *addr = CGF.CreateTempAlloca(ComplexTy, "saved-complex");
+ CGF.StoreComplexToAddr(V, addr, /*volatile*/ false);
+ return saved_type(addr, ComplexAddress);
+ }
+
+ assert(rv.isAggregate());
+ llvm::Value *V = rv.getAggregateAddr(); // TODO: volatile?
+ if (!DominatingLLVMValue::needsSaving(V))
+ return saved_type(V, AggregateLiteral);
+
+ llvm::Value *addr = CGF.CreateTempAlloca(V->getType(), "saved-rvalue");
+ CGF.Builder.CreateStore(V, addr);
+ return saved_type(addr, AggregateAddress);
+}
+
+/// Given a saved r-value produced by SaveRValue, perform the code
+/// necessary to restore it to usability at the current insertion
+/// point.
+RValue DominatingValue<RValue>::saved_type::restore(CodeGenFunction &CGF) {
+ switch (K) {
+ case ScalarLiteral:
+ return RValue::get(Value);
+ case ScalarAddress:
+ return RValue::get(CGF.Builder.CreateLoad(Value));
+ case AggregateLiteral:
+ return RValue::getAggregate(Value);
+ case AggregateAddress:
+ return RValue::getAggregate(CGF.Builder.CreateLoad(Value));
+ case ComplexAddress:
+ return RValue::getComplex(CGF.LoadComplexFromAddr(Value, false));
+ }
+
+ llvm_unreachable("bad saved r-value kind");
+ return RValue();
+}
+
+/// Push an entry of the given size onto this protected-scope stack.
+char *EHScopeStack::allocate(size_t Size) {
+ if (!StartOfBuffer) {
+ unsigned Capacity = 1024;
+ while (Capacity < Size) Capacity *= 2;
+ StartOfBuffer = new char[Capacity];
+ StartOfData = EndOfBuffer = StartOfBuffer + Capacity;
+ } else if (static_cast<size_t>(StartOfData - StartOfBuffer) < Size) {
+ unsigned CurrentCapacity = EndOfBuffer - StartOfBuffer;
+ unsigned UsedCapacity = CurrentCapacity - (StartOfData - StartOfBuffer);
+
+ unsigned NewCapacity = CurrentCapacity;
+ do {
+ NewCapacity *= 2;
+ } while (NewCapacity < UsedCapacity + Size);
+
+ char *NewStartOfBuffer = new char[NewCapacity];
+ char *NewEndOfBuffer = NewStartOfBuffer + NewCapacity;
+ char *NewStartOfData = NewEndOfBuffer - UsedCapacity;
+ memcpy(NewStartOfData, StartOfData, UsedCapacity);
+ delete [] StartOfBuffer;
+ StartOfBuffer = NewStartOfBuffer;
+ EndOfBuffer = NewEndOfBuffer;
+ StartOfData = NewStartOfData;
+ }
+
+ assert(StartOfBuffer + Size <= StartOfData);
+ StartOfData -= Size;
+ return StartOfData;
+}
+
+EHScopeStack::stable_iterator
+EHScopeStack::getEnclosingEHCleanup(iterator it) const {
+ assert(it != end());
+ do {
+ if (isa<EHCleanupScope>(*it)) {
+ if (cast<EHCleanupScope>(*it).isEHCleanup())
+ return stabilize(it);
+ return cast<EHCleanupScope>(*it).getEnclosingEHCleanup();
+ }
+ ++it;
+ } while (it != end());
+ return stable_end();
+}
+
+
+void *EHScopeStack::pushCleanup(CleanupKind Kind, size_t Size) {
+ assert(((Size % sizeof(void*)) == 0) && "cleanup type is misaligned");
+ char *Buffer = allocate(EHCleanupScope::getSizeForCleanupSize(Size));
+ bool IsNormalCleanup = Kind & NormalCleanup;
+ bool IsEHCleanup = Kind & EHCleanup;
+ bool IsActive = !(Kind & InactiveCleanup);
+ EHCleanupScope *Scope =
+ new (Buffer) EHCleanupScope(IsNormalCleanup,
+ IsEHCleanup,
+ IsActive,
+ Size,
+ BranchFixups.size(),
+ InnermostNormalCleanup,
+ InnermostEHCleanup);
+ if (IsNormalCleanup)
+ InnermostNormalCleanup = stable_begin();
+ if (IsEHCleanup)
+ InnermostEHCleanup = stable_begin();
+
+ return Scope->getCleanupBuffer();
+}
+
+void EHScopeStack::popCleanup() {
+ assert(!empty() && "popping exception stack when not empty");
+
+ assert(isa<EHCleanupScope>(*begin()));
+ EHCleanupScope &Cleanup = cast<EHCleanupScope>(*begin());
+ InnermostNormalCleanup = Cleanup.getEnclosingNormalCleanup();
+ InnermostEHCleanup = Cleanup.getEnclosingEHCleanup();
+ StartOfData += Cleanup.getAllocatedSize();
+
+ if (empty()) NextEHDestIndex = FirstEHDestIndex;
+
+ // Destroy the cleanup.
+ Cleanup.~EHCleanupScope();
+
+ // Check whether we can shrink the branch-fixups stack.
+ if (!BranchFixups.empty()) {
+ // If we no longer have any normal cleanups, all the fixups are
+ // complete.
+ if (!hasNormalCleanups())
+ BranchFixups.clear();
+
+ // Otherwise we can still trim out unnecessary nulls.
+ else
+ popNullFixups();
+ }
+}
+
+EHFilterScope *EHScopeStack::pushFilter(unsigned NumFilters) {
+ char *Buffer = allocate(EHFilterScope::getSizeForNumFilters(NumFilters));
+ CatchDepth++;
+ return new (Buffer) EHFilterScope(NumFilters);
+}
+
+void EHScopeStack::popFilter() {
+ assert(!empty() && "popping exception stack when not empty");
+
+ EHFilterScope &Filter = cast<EHFilterScope>(*begin());
+ StartOfData += EHFilterScope::getSizeForNumFilters(Filter.getNumFilters());
+
+ if (empty()) NextEHDestIndex = FirstEHDestIndex;
+
+ assert(CatchDepth > 0 && "mismatched filter push/pop");
+ CatchDepth--;
+}
+
+EHCatchScope *EHScopeStack::pushCatch(unsigned NumHandlers) {
+ char *Buffer = allocate(EHCatchScope::getSizeForNumHandlers(NumHandlers));
+ CatchDepth++;
+ EHCatchScope *Scope = new (Buffer) EHCatchScope(NumHandlers);
+ for (unsigned I = 0; I != NumHandlers; ++I)
+ Scope->getHandlers()[I].Index = getNextEHDestIndex();
+ return Scope;
+}
+
+void EHScopeStack::pushTerminate() {
+ char *Buffer = allocate(EHTerminateScope::getSize());
+ CatchDepth++;
+ new (Buffer) EHTerminateScope(getNextEHDestIndex());
+}
+
+/// Remove any 'null' fixups on the stack. However, we can't pop more
+/// fixups than the fixup depth on the innermost normal cleanup, or
+/// else fixups that we try to add to that cleanup will end up in the
+/// wrong place. We *could* try to shrink fixup depths, but that's
+/// actually a lot of work for little benefit.
+void EHScopeStack::popNullFixups() {
+ // We expect this to only be called when there's still an innermost
+ // normal cleanup; otherwise there really shouldn't be any fixups.
+ assert(hasNormalCleanups());
+
+ EHScopeStack::iterator it = find(InnermostNormalCleanup);
+ unsigned MinSize = cast<EHCleanupScope>(*it).getFixupDepth();
+ assert(BranchFixups.size() >= MinSize && "fixup stack out of order");
+
+ while (BranchFixups.size() > MinSize &&
+ BranchFixups.back().Destination == 0)
+ BranchFixups.pop_back();
+}
+
+void CodeGenFunction::initFullExprCleanup() {
+ // Create a variable to decide whether the cleanup needs to be run.
+ llvm::AllocaInst *active
+ = CreateTempAlloca(Builder.getInt1Ty(), "cleanup.cond");
+
+ // Initialize it to false at a site that's guaranteed to be run
+ // before each evaluation.
+ llvm::BasicBlock *block = OutermostConditional->getStartingBlock();
+ new llvm::StoreInst(Builder.getFalse(), active, &block->back());
+
+ // Initialize it to true at the current location.
+ Builder.CreateStore(Builder.getTrue(), active);
+
+ // Set that as the active flag in the cleanup.
+ EHCleanupScope &cleanup = cast<EHCleanupScope>(*EHStack.begin());
+ assert(cleanup.getActiveFlag() == 0 && "cleanup already has active flag?");
+ cleanup.setActiveFlag(active);
+
+ if (cleanup.isNormalCleanup()) cleanup.setTestFlagInNormalCleanup();
+ if (cleanup.isEHCleanup()) cleanup.setTestFlagInEHCleanup();
+}
+
+EHScopeStack::Cleanup::~Cleanup() {
+ llvm_unreachable("Cleanup is indestructable");
+}
+
+/// All the branch fixups on the EH stack have propagated out past the
+/// outermost normal cleanup; resolve them all by adding cases to the
+/// given switch instruction.
+static void ResolveAllBranchFixups(CodeGenFunction &CGF,
+ llvm::SwitchInst *Switch,
+ llvm::BasicBlock *CleanupEntry) {
+ llvm::SmallPtrSet<llvm::BasicBlock*, 4> CasesAdded;
+
+ for (unsigned I = 0, E = CGF.EHStack.getNumBranchFixups(); I != E; ++I) {
+ // Skip this fixup if its destination isn't set.
+ BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I);
+ if (Fixup.Destination == 0) continue;
+
+ // If there isn't an OptimisticBranchBlock, then InitialBranch is
+ // still pointing directly to its destination; forward it to the
+ // appropriate cleanup entry. This is required in the specific
+ // case of
+ // { std::string s; goto lbl; }
+ // lbl:
+ // i.e. where there's an unresolved fixup inside a single cleanup
+ // entry which we're currently popping.
+ if (Fixup.OptimisticBranchBlock == 0) {
+ new llvm::StoreInst(CGF.Builder.getInt32(Fixup.DestinationIndex),
+ CGF.getNormalCleanupDestSlot(),
+ Fixup.InitialBranch);
+ Fixup.InitialBranch->setSuccessor(0, CleanupEntry);
+ }
+
+ // Don't add this case to the switch statement twice.
+ if (!CasesAdded.insert(Fixup.Destination)) continue;
+
+ Switch->addCase(CGF.Builder.getInt32(Fixup.DestinationIndex),
+ Fixup.Destination);
+ }
+
+ CGF.EHStack.clearFixups();
+}
+
+/// Transitions the terminator of the given exit-block of a cleanup to
+/// be a cleanup switch.
+static llvm::SwitchInst *TransitionToCleanupSwitch(CodeGenFunction &CGF,
+ llvm::BasicBlock *Block) {
+ // If it's a branch, turn it into a switch whose default
+ // destination is its original target.
+ llvm::TerminatorInst *Term = Block->getTerminator();
+ assert(Term && "can't transition block without terminator");
+
+ if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
+ assert(Br->isUnconditional());
+ llvm::LoadInst *Load =
+ new llvm::LoadInst(CGF.getNormalCleanupDestSlot(), "cleanup.dest", Term);
+ llvm::SwitchInst *Switch =
+ llvm::SwitchInst::Create(Load, Br->getSuccessor(0), 4, Block);
+ Br->eraseFromParent();
+ return Switch;
+ } else {
+ return cast<llvm::SwitchInst>(Term);
+ }
+}
+
+void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) {
+ assert(Block && "resolving a null target block");
+ if (!EHStack.getNumBranchFixups()) return;
+
+ assert(EHStack.hasNormalCleanups() &&
+ "branch fixups exist with no normal cleanups on stack");
+
+ llvm::SmallPtrSet<llvm::BasicBlock*, 4> ModifiedOptimisticBlocks;
+ bool ResolvedAny = false;
+
+ for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) {
+ // Skip this fixup if its destination doesn't match.
+ BranchFixup &Fixup = EHStack.getBranchFixup(I);
+ if (Fixup.Destination != Block) continue;
+
+ Fixup.Destination = 0;
+ ResolvedAny = true;
+
+ // If it doesn't have an optimistic branch block, LatestBranch is
+ // already pointing to the right place.
+ llvm::BasicBlock *BranchBB = Fixup.OptimisticBranchBlock;
+ if (!BranchBB)
+ continue;
+
+ // Don't process the same optimistic branch block twice.
+ if (!ModifiedOptimisticBlocks.insert(BranchBB))
+ continue;
+
+ llvm::SwitchInst *Switch = TransitionToCleanupSwitch(*this, BranchBB);
+
+ // Add a case to the switch.
+ Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Block);
+ }
+
+ if (ResolvedAny)
+ EHStack.popNullFixups();
+}
+
+/// Pops cleanup blocks until the given savepoint is reached.
+void CodeGenFunction::PopCleanupBlocks(EHScopeStack::stable_iterator Old) {
+ assert(Old.isValid());
+
+ while (EHStack.stable_begin() != Old) {
+ EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
+
+ // As long as Old strictly encloses the scope's enclosing normal
+ // cleanup, we're going to emit another normal cleanup which
+ // fallthrough can propagate through.
+ bool FallThroughIsBranchThrough =
+ Old.strictlyEncloses(Scope.getEnclosingNormalCleanup());
+
+ PopCleanupBlock(FallThroughIsBranchThrough);
+ }
+}
+
+static llvm::BasicBlock *CreateNormalEntry(CodeGenFunction &CGF,
+ EHCleanupScope &Scope) {
+ assert(Scope.isNormalCleanup());
+ llvm::BasicBlock *Entry = Scope.getNormalBlock();
+ if (!Entry) {
+ Entry = CGF.createBasicBlock("cleanup");
+ Scope.setNormalBlock(Entry);
+ }
+ return Entry;
+}
+
+static llvm::BasicBlock *CreateEHEntry(CodeGenFunction &CGF,
+ EHCleanupScope &Scope) {
+ assert(Scope.isEHCleanup());
+ llvm::BasicBlock *Entry = Scope.getEHBlock();
+ if (!Entry) {
+ Entry = CGF.createBasicBlock("eh.cleanup");
+ Scope.setEHBlock(Entry);
+ }
+ return Entry;
+}
+
+/// Attempts to reduce a cleanup's entry block to a fallthrough. This
+/// is basically llvm::MergeBlockIntoPredecessor, except
+/// simplified/optimized for the tighter constraints on cleanup blocks.
+///
+/// Returns the new block, whatever it is.
+static llvm::BasicBlock *SimplifyCleanupEntry(CodeGenFunction &CGF,
+ llvm::BasicBlock *Entry) {
+ llvm::BasicBlock *Pred = Entry->getSinglePredecessor();
+ if (!Pred) return Entry;
+
+ llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Pred->getTerminator());
+ if (!Br || Br->isConditional()) return Entry;
+ assert(Br->getSuccessor(0) == Entry);
+
+ // If we were previously inserting at the end of the cleanup entry
+ // block, we'll need to continue inserting at the end of the
+ // predecessor.
+ bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry;
+ assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end());
+
+ // Kill the branch.
+ Br->eraseFromParent();
+
+ // Merge the blocks.
+ Pred->getInstList().splice(Pred->end(), Entry->getInstList());
+
+ // Replace all uses of the entry with the predecessor, in case there
+ // are phis in the cleanup.
+ Entry->replaceAllUsesWith(Pred);
+
+ // Kill the entry block.
+ Entry->eraseFromParent();
+
+ if (WasInsertBlock)
+ CGF.Builder.SetInsertPoint(Pred);
+
+ return Pred;
+}
+
+static void EmitCleanup(CodeGenFunction &CGF,
+ EHScopeStack::Cleanup *Fn,
+ bool ForEH,
+ llvm::Value *ActiveFlag) {
+ // EH cleanups always occur within a terminate scope.
+ if (ForEH) CGF.EHStack.pushTerminate();
+
+ // If there's an active flag, load it and skip the cleanup if it's
+ // false.
+ llvm::BasicBlock *ContBB = 0;
+ if (ActiveFlag) {
+ ContBB = CGF.createBasicBlock("cleanup.done");
+ llvm::BasicBlock *CleanupBB = CGF.createBasicBlock("cleanup.action");
+ llvm::Value *IsActive
+ = CGF.Builder.CreateLoad(ActiveFlag, "cleanup.is_active");
+ CGF.Builder.CreateCondBr(IsActive, CleanupBB, ContBB);
+ CGF.EmitBlock(CleanupBB);
+ }
+
+ // Ask the cleanup to emit itself.
+ Fn->Emit(CGF, ForEH);
+ assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?");
+
+ // Emit the continuation block if there was an active flag.
+ if (ActiveFlag)
+ CGF.EmitBlock(ContBB);
+
+ // Leave the terminate scope.
+ if (ForEH) CGF.EHStack.popTerminate();
+}
+
+static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit,
+ llvm::BasicBlock *From,
+ llvm::BasicBlock *To) {
+ // Exit is the exit block of a cleanup, so it always terminates in
+ // an unconditional branch or a switch.
+ llvm::TerminatorInst *Term = Exit->getTerminator();
+
+ if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
+ assert(Br->isUnconditional() && Br->getSuccessor(0) == From);
+ Br->setSuccessor(0, To);
+ } else {
+ llvm::SwitchInst *Switch = cast<llvm::SwitchInst>(Term);
+ for (unsigned I = 0, E = Switch->getNumSuccessors(); I != E; ++I)
+ if (Switch->getSuccessor(I) == From)
+ Switch->setSuccessor(I, To);
+ }
+}
+
+/// Pops a cleanup block. If the block includes a normal cleanup, the
+/// current insertion point is threaded through the cleanup, as are
+/// any branch fixups on the cleanup.
+void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
+ assert(!EHStack.empty() && "cleanup stack is empty!");
+ assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!");
+ EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
+ assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups());
+
+ // Remember activation information.
+ bool IsActive = Scope.isActive();
+ llvm::Value *NormalActiveFlag =
+ Scope.shouldTestFlagInNormalCleanup() ? Scope.getActiveFlag() : 0;
+ llvm::Value *EHActiveFlag =
+ Scope.shouldTestFlagInEHCleanup() ? Scope.getActiveFlag() : 0;
+
+ // Check whether we need an EH cleanup. This is only true if we've
+ // generated a lazy EH cleanup block.
+ bool RequiresEHCleanup = Scope.hasEHBranches();
+
+ // Check the three conditions which might require a normal cleanup:
+
+ // - whether there are branch fix-ups through this cleanup
+ unsigned FixupDepth = Scope.getFixupDepth();
+ bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth;
+
+ // - whether there are branch-throughs or branch-afters
+ bool HasExistingBranches = Scope.hasBranches();
+
+ // - whether there's a fallthrough
+ llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock();
+ bool HasFallthrough = (FallthroughSource != 0 && IsActive);
+
+ // Branch-through fall-throughs leave the insertion point set to the
+ // end of the last cleanup, which points to the current scope. The
+ // rest of IR gen doesn't need to worry about this; it only happens
+ // during the execution of PopCleanupBlocks().
+ bool HasPrebranchedFallthrough =
+ (FallthroughSource && FallthroughSource->getTerminator());
+
+ // If this is a normal cleanup, then having a prebranched
+ // fallthrough implies that the fallthrough source unconditionally
+ // jumps here.
+ assert(!Scope.isNormalCleanup() || !HasPrebranchedFallthrough ||
+ (Scope.getNormalBlock() &&
+ FallthroughSource->getTerminator()->getSuccessor(0)
+ == Scope.getNormalBlock()));
+
+ bool RequiresNormalCleanup = false;
+ if (Scope.isNormalCleanup() &&
+ (HasFixups || HasExistingBranches || HasFallthrough)) {
+ RequiresNormalCleanup = true;
+ }
+
+ // Even if we don't need the normal cleanup, we might still have
+ // prebranched fallthrough to worry about.
+ if (Scope.isNormalCleanup() && !RequiresNormalCleanup &&
+ HasPrebranchedFallthrough) {
+ assert(!IsActive);
+
+ llvm::BasicBlock *NormalEntry = Scope.getNormalBlock();
+
+ // If we're branching through this cleanup, just forward the
+ // prebranched fallthrough to the next cleanup, leaving the insert
+ // point in the old block.
+ if (FallthroughIsBranchThrough) {
+ EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup());
+ llvm::BasicBlock *EnclosingEntry =
+ CreateNormalEntry(*this, cast<EHCleanupScope>(S));
+
+ ForwardPrebranchedFallthrough(FallthroughSource,
+ NormalEntry, EnclosingEntry);
+ assert(NormalEntry->use_empty() &&
+ "uses of entry remain after forwarding?");
+ delete NormalEntry;
+
+ // Otherwise, we're branching out; just emit the next block.
+ } else {
+ EmitBlock(NormalEntry);
+ SimplifyCleanupEntry(*this, NormalEntry);
+ }
+ }
+
+ // If we don't need the cleanup at all, we're done.
+ if (!RequiresNormalCleanup && !RequiresEHCleanup) {
+ EHStack.popCleanup(); // safe because there are no fixups
+ assert(EHStack.getNumBranchFixups() == 0 ||
+ EHStack.hasNormalCleanups());
+ return;
+ }
+
+ // Copy the cleanup emission data out. Note that SmallVector
+ // guarantees maximal alignment for its buffer regardless of its
+ // type parameter.
+ llvm::SmallVector<char, 8*sizeof(void*)> CleanupBuffer;
+ CleanupBuffer.reserve(Scope.getCleanupSize());
+ memcpy(CleanupBuffer.data(),
+ Scope.getCleanupBuffer(), Scope.getCleanupSize());
+ CleanupBuffer.set_size(Scope.getCleanupSize());
+ EHScopeStack::Cleanup *Fn =
+ reinterpret_cast<EHScopeStack::Cleanup*>(CleanupBuffer.data());
+
+ // We want to emit the EH cleanup after the normal cleanup, but go
+ // ahead and do the setup for the EH cleanup while the scope is still
+ // alive.
+ llvm::BasicBlock *EHEntry = 0;
+ llvm::SmallVector<llvm::Instruction*, 2> EHInstsToAppend;
+ if (RequiresEHCleanup) {
+ EHEntry = CreateEHEntry(*this, Scope);
+
+ // Figure out the branch-through dest if necessary.
+ llvm::BasicBlock *EHBranchThroughDest = 0;
+ if (Scope.hasEHBranchThroughs()) {
+ assert(Scope.getEnclosingEHCleanup() != EHStack.stable_end());
+ EHScope &S = *EHStack.find(Scope.getEnclosingEHCleanup());
+ EHBranchThroughDest = CreateEHEntry(*this, cast<EHCleanupScope>(S));
+ }
+
+ // If we have exactly one branch-after and no branch-throughs, we
+ // can dispatch it without a switch.
+ if (!Scope.hasEHBranchThroughs() &&
+ Scope.getNumEHBranchAfters() == 1) {
+ assert(!EHBranchThroughDest);
+
+ // TODO: remove the spurious eh.cleanup.dest stores if this edge
+ // never went through any switches.
+ llvm::BasicBlock *BranchAfterDest = Scope.getEHBranchAfterBlock(0);
+ EHInstsToAppend.push_back(llvm::BranchInst::Create(BranchAfterDest));
+
+ // Otherwise, if we have any branch-afters, we need a switch.
+ } else if (Scope.getNumEHBranchAfters()) {
+ // The default of the switch belongs to the branch-throughs if
+ // they exist.
+ llvm::BasicBlock *Default =
+ (EHBranchThroughDest ? EHBranchThroughDest : getUnreachableBlock());
+
+ const unsigned SwitchCapacity = Scope.getNumEHBranchAfters();
+
+ llvm::LoadInst *Load =
+ new llvm::LoadInst(getEHCleanupDestSlot(), "cleanup.dest");
+ llvm::SwitchInst *Switch =
+ llvm::SwitchInst::Create(Load, Default, SwitchCapacity);
+
+ EHInstsToAppend.push_back(Load);
+ EHInstsToAppend.push_back(Switch);
+
+ for (unsigned I = 0, E = Scope.getNumEHBranchAfters(); I != E; ++I)
+ Switch->addCase(Scope.getEHBranchAfterIndex(I),
+ Scope.getEHBranchAfterBlock(I));
+
+ // Otherwise, we have only branch-throughs; jump to the next EH
+ // cleanup.
+ } else {
+ assert(EHBranchThroughDest);
+ EHInstsToAppend.push_back(llvm::BranchInst::Create(EHBranchThroughDest));
+ }
+ }
+
+ if (!RequiresNormalCleanup) {
+ EHStack.popCleanup();
+ } else {
+ // If we have a fallthrough and no other need for the cleanup,
+ // emit it directly.
+ if (HasFallthrough && !HasPrebranchedFallthrough &&
+ !HasFixups && !HasExistingBranches) {
+
+ // Fixups can cause us to optimistically create a normal block,
+ // only to later have no real uses for it. Just delete it in
+ // this case.
+ // TODO: we can potentially simplify all the uses after this.
+ if (Scope.getNormalBlock()) {
+ Scope.getNormalBlock()->replaceAllUsesWith(getUnreachableBlock());
+ delete Scope.getNormalBlock();
+ }
+
+ EHStack.popCleanup();
+
+ EmitCleanup(*this, Fn, /*ForEH*/ false, NormalActiveFlag);
+
+ // Otherwise, the best approach is to thread everything through
+ // the cleanup block and then try to clean up after ourselves.
+ } else {
+ // Force the entry block to exist.
+ llvm::BasicBlock *NormalEntry = CreateNormalEntry(*this, Scope);
+
+ // I. Set up the fallthrough edge in.
+
+ // If there's a fallthrough, we need to store the cleanup
+ // destination index. For fall-throughs this is always zero.
+ if (HasFallthrough) {
+ if (!HasPrebranchedFallthrough)
+ Builder.CreateStore(Builder.getInt32(0), getNormalCleanupDestSlot());
+
+ // Otherwise, clear the IP if we don't have fallthrough because
+ // the cleanup is inactive. We don't need to save it because
+ // it's still just FallthroughSource.
+ } else if (FallthroughSource) {
+ assert(!IsActive && "source without fallthrough for active cleanup");
+ Builder.ClearInsertionPoint();
+ }
+
+ // II. Emit the entry block. This implicitly branches to it if
+ // we have fallthrough. All the fixups and existing branches
+ // should already be branched to it.
+ EmitBlock(NormalEntry);
+
+ // III. Figure out where we're going and build the cleanup
+ // epilogue.
+
+ bool HasEnclosingCleanups =
+ (Scope.getEnclosingNormalCleanup() != EHStack.stable_end());
+
+ // Compute the branch-through dest if we need it:
+ // - if there are branch-throughs threaded through the scope
+ // - if fall-through is a branch-through
+ // - if there are fixups that will be optimistically forwarded
+ // to the enclosing cleanup
+ llvm::BasicBlock *BranchThroughDest = 0;
+ if (Scope.hasBranchThroughs() ||
+ (FallthroughSource && FallthroughIsBranchThrough) ||
+ (HasFixups && HasEnclosingCleanups)) {
+ assert(HasEnclosingCleanups);
+ EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup());
+ BranchThroughDest = CreateNormalEntry(*this, cast<EHCleanupScope>(S));
+ }
+
+ llvm::BasicBlock *FallthroughDest = 0;
+ llvm::SmallVector<llvm::Instruction*, 2> InstsToAppend;
+
+ // If there's exactly one branch-after and no other threads,
+ // we can route it without a switch.
+ if (!Scope.hasBranchThroughs() && !HasFixups && !HasFallthrough &&
+ Scope.getNumBranchAfters() == 1) {
+ assert(!BranchThroughDest || !IsActive);
+
+ // TODO: clean up the possibly dead stores to the cleanup dest slot.
+ llvm::BasicBlock *BranchAfter = Scope.getBranchAfterBlock(0);
+ InstsToAppend.push_back(llvm::BranchInst::Create(BranchAfter));
+
+ // Build a switch-out if we need it:
+ // - if there are branch-afters threaded through the scope
+ // - if fall-through is a branch-after
+ // - if there are fixups that have nowhere left to go and
+ // so must be immediately resolved
+ } else if (Scope.getNumBranchAfters() ||
+ (HasFallthrough && !FallthroughIsBranchThrough) ||
+ (HasFixups && !HasEnclosingCleanups)) {
+
+ llvm::BasicBlock *Default =
+ (BranchThroughDest ? BranchThroughDest : getUnreachableBlock());
+
+ // TODO: base this on the number of branch-afters and fixups
+ const unsigned SwitchCapacity = 10;
+
+ llvm::LoadInst *Load =
+ new llvm::LoadInst(getNormalCleanupDestSlot(), "cleanup.dest");
+ llvm::SwitchInst *Switch =
+ llvm::SwitchInst::Create(Load, Default, SwitchCapacity);
+
+ InstsToAppend.push_back(Load);
+ InstsToAppend.push_back(Switch);
+
+ // Branch-after fallthrough.
+ if (FallthroughSource && !FallthroughIsBranchThrough) {
+ FallthroughDest = createBasicBlock("cleanup.cont");
+ if (HasFallthrough)
+ Switch->addCase(Builder.getInt32(0), FallthroughDest);
+ }
+
+ for (unsigned I = 0, E = Scope.getNumBranchAfters(); I != E; ++I) {
+ Switch->addCase(Scope.getBranchAfterIndex(I),
+ Scope.getBranchAfterBlock(I));
+ }
+
+ // If there aren't any enclosing cleanups, we can resolve all
+ // the fixups now.
+ if (HasFixups && !HasEnclosingCleanups)
+ ResolveAllBranchFixups(*this, Switch, NormalEntry);
+ } else {
+ // We should always have a branch-through destination in this case.
+ assert(BranchThroughDest);
+ InstsToAppend.push_back(llvm::BranchInst::Create(BranchThroughDest));
+ }
+
+ // IV. Pop the cleanup and emit it.
+ EHStack.popCleanup();
+ assert(EHStack.hasNormalCleanups() == HasEnclosingCleanups);
+
+ EmitCleanup(*this, Fn, /*ForEH*/ false, NormalActiveFlag);
+
+ // Append the prepared cleanup prologue from above.
+ llvm::BasicBlock *NormalExit = Builder.GetInsertBlock();
+ for (unsigned I = 0, E = InstsToAppend.size(); I != E; ++I)
+ NormalExit->getInstList().push_back(InstsToAppend[I]);
+
+ // Optimistically hope that any fixups will continue falling through.
+ for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
+ I < E; ++I) {
+ BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I);
+ if (!Fixup.Destination) continue;
+ if (!Fixup.OptimisticBranchBlock) {
+ new llvm::StoreInst(Builder.getInt32(Fixup.DestinationIndex),
+ getNormalCleanupDestSlot(),
+ Fixup.InitialBranch);
+ Fixup.InitialBranch->setSuccessor(0, NormalEntry);
+ }
+ Fixup.OptimisticBranchBlock = NormalExit;
+ }
+
+ // V. Set up the fallthrough edge out.
+
+ // Case 1: a fallthrough source exists but shouldn't branch to
+ // the cleanup because the cleanup is inactive.
+ if (!HasFallthrough && FallthroughSource) {
+ assert(!IsActive);
+
+ // If we have a prebranched fallthrough, that needs to be
+ // forwarded to the right block.
+ if (HasPrebranchedFallthrough) {
+ llvm::BasicBlock *Next;
+ if (FallthroughIsBranchThrough) {
+ Next = BranchThroughDest;
+ assert(!FallthroughDest);
+ } else {
+ Next = FallthroughDest;
+ }
+
+ ForwardPrebranchedFallthrough(FallthroughSource, NormalEntry, Next);
+ }
+ Builder.SetInsertPoint(FallthroughSource);
+
+ // Case 2: a fallthrough source exists and should branch to the
+ // cleanup, but we're not supposed to branch through to the next
+ // cleanup.
+ } else if (HasFallthrough && FallthroughDest) {
+ assert(!FallthroughIsBranchThrough);
+ EmitBlock(FallthroughDest);
+
+ // Case 3: a fallthrough source exists and should branch to the
+ // cleanup and then through to the next.
+ } else if (HasFallthrough) {
+ // Everything is already set up for this.
+
+ // Case 4: no fallthrough source exists.
+ } else {
+ Builder.ClearInsertionPoint();
+ }
+
+ // VI. Assorted cleaning.
+
+ // Check whether we can merge NormalEntry into a single predecessor.
+ // This might invalidate (non-IR) pointers to NormalEntry.
+ llvm::BasicBlock *NewNormalEntry =
+ SimplifyCleanupEntry(*this, NormalEntry);
+
+ // If it did invalidate those pointers, and NormalEntry was the same
+ // as NormalExit, go back and patch up the fixups.
+ if (NewNormalEntry != NormalEntry && NormalEntry == NormalExit)
+ for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
+ I < E; ++I)
+ CGF.EHStack.getBranchFixup(I).OptimisticBranchBlock = NewNormalEntry;
+ }
+ }
+
+ assert(EHStack.hasNormalCleanups() || EHStack.getNumBranchFixups() == 0);
+
+ // Emit the EH cleanup if required.
+ if (RequiresEHCleanup) {
+ CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
+
+ EmitBlock(EHEntry);
+ EmitCleanup(*this, Fn, /*ForEH*/ true, EHActiveFlag);
+
+ // Append the prepared cleanup prologue from above.
+ llvm::BasicBlock *EHExit = Builder.GetInsertBlock();
+ for (unsigned I = 0, E = EHInstsToAppend.size(); I != E; ++I)
+ EHExit->getInstList().push_back(EHInstsToAppend[I]);
+
+ Builder.restoreIP(SavedIP);
+
+ SimplifyCleanupEntry(*this, EHEntry);
+ }
+}
+
+/// Terminate the current block by emitting a branch which might leave
+/// the current cleanup-protected scope. The target scope may not yet
+/// be known, in which case this will require a fixup.
+///
+/// As a side-effect, this method clears the insertion point.
+void CodeGenFunction::EmitBranchThroughCleanup(JumpDest Dest) {
+ assert(Dest.getScopeDepth().encloses(EHStack.getInnermostNormalCleanup())
+ && "stale jump destination");
+
+ if (!HaveInsertPoint())
+ return;
+
+ // Create the branch.
+ llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock());
+
+ // Calculate the innermost active normal cleanup.
+ EHScopeStack::stable_iterator
+ TopCleanup = EHStack.getInnermostActiveNormalCleanup();
+
+ // If we're not in an active normal cleanup scope, or if the
+ // destination scope is within the innermost active normal cleanup
+ // scope, we don't need to worry about fixups.
+ if (TopCleanup == EHStack.stable_end() ||
+ TopCleanup.encloses(Dest.getScopeDepth())) { // works for invalid
+ Builder.ClearInsertionPoint();
+ return;
+ }
+
+ // If we can't resolve the destination cleanup scope, just add this
+ // to the current cleanup scope as a branch fixup.
+ if (!Dest.getScopeDepth().isValid()) {
+ BranchFixup &Fixup = EHStack.addBranchFixup();
+ Fixup.Destination = Dest.getBlock();
+ Fixup.DestinationIndex = Dest.getDestIndex();
+ Fixup.InitialBranch = BI;
+ Fixup.OptimisticBranchBlock = 0;
+
+ Builder.ClearInsertionPoint();
+ return;
+ }
+
+ // Otherwise, thread through all the normal cleanups in scope.
+
+ // Store the index at the start.
+ llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex());
+ new llvm::StoreInst(Index, getNormalCleanupDestSlot(), BI);
+
+ // Adjust BI to point to the first cleanup block.
+ {
+ EHCleanupScope &Scope =
+ cast<EHCleanupScope>(*EHStack.find(TopCleanup));
+ BI->setSuccessor(0, CreateNormalEntry(*this, Scope));
+ }
+
+ // Add this destination to all the scopes involved.
+ EHScopeStack::stable_iterator I = TopCleanup;
+ EHScopeStack::stable_iterator E = Dest.getScopeDepth();
+ if (E.strictlyEncloses(I)) {
+ while (true) {
+ EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I));
+ assert(Scope.isNormalCleanup());
+ I = Scope.getEnclosingNormalCleanup();
+
+ // If this is the last cleanup we're propagating through, tell it
+ // that there's a resolved jump moving through it.
+ if (!E.strictlyEncloses(I)) {
+ Scope.addBranchAfter(Index, Dest.getBlock());
+ break;
+ }
+
+ // Otherwise, tell the scope that there's a jump propoagating
+ // through it. If this isn't new information, all the rest of
+ // the work has been done before.
+ if (!Scope.addBranchThrough(Dest.getBlock()))
+ break;
+ }
+ }
+
+ Builder.ClearInsertionPoint();
+}
+
+void CodeGenFunction::EmitBranchThroughEHCleanup(UnwindDest Dest) {
+ // We should never get invalid scope depths for an UnwindDest; that
+ // implies that the destination wasn't set up correctly.
+ assert(Dest.getScopeDepth().isValid() && "invalid scope depth on EH dest?");
+
+ if (!HaveInsertPoint())
+ return;
+
+ // Create the branch.
+ llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock());
+
+ // Calculate the innermost active cleanup.
+ EHScopeStack::stable_iterator
+ InnermostCleanup = EHStack.getInnermostActiveEHCleanup();
+
+ // If the destination is in the same EH cleanup scope as us, we
+ // don't need to thread through anything.
+ if (InnermostCleanup.encloses(Dest.getScopeDepth())) {
+ Builder.ClearInsertionPoint();
+ return;
+ }
+ assert(InnermostCleanup != EHStack.stable_end());
+
+ // Store the index at the start.
+ llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex());
+ new llvm::StoreInst(Index, getEHCleanupDestSlot(), BI);
+
+ // Adjust BI to point to the first cleanup block.
+ {
+ EHCleanupScope &Scope =
+ cast<EHCleanupScope>(*EHStack.find(InnermostCleanup));
+ BI->setSuccessor(0, CreateEHEntry(*this, Scope));
+ }
+
+ // Add this destination to all the scopes involved.
+ for (EHScopeStack::stable_iterator
+ I = InnermostCleanup, E = Dest.getScopeDepth(); ; ) {
+ assert(E.strictlyEncloses(I));
+ EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I));
+ assert(Scope.isEHCleanup());
+ I = Scope.getEnclosingEHCleanup();
+
+ // If this is the last cleanup we're propagating through, add this
+ // as a branch-after.
+ if (I == E) {
+ Scope.addEHBranchAfter(Index, Dest.getBlock());
+ break;
+ }
+
+ // Otherwise, add it as a branch-through. If this isn't new
+ // information, all the rest of the work has been done before.
+ if (!Scope.addEHBranchThrough(Dest.getBlock()))
+ break;
+ }
+
+ Builder.ClearInsertionPoint();
+}
+
+static bool IsUsedAsNormalCleanup(EHScopeStack &EHStack,
+ EHScopeStack::stable_iterator C) {
+ // If we needed a normal block for any reason, that counts.
+ if (cast<EHCleanupScope>(*EHStack.find(C)).getNormalBlock())
+ return true;
+
+ // Check whether any enclosed cleanups were needed.
+ for (EHScopeStack::stable_iterator
+ I = EHStack.getInnermostNormalCleanup();
+ I != C; ) {
+ assert(C.strictlyEncloses(I));
+ EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I));
+ if (S.getNormalBlock()) return true;
+ I = S.getEnclosingNormalCleanup();
+ }
+
+ return false;
+}
+
+static bool IsUsedAsEHCleanup(EHScopeStack &EHStack,
+ EHScopeStack::stable_iterator C) {
+ // If we needed an EH block for any reason, that counts.
+ if (cast<EHCleanupScope>(*EHStack.find(C)).getEHBlock())
+ return true;
+
+ // Check whether any enclosed cleanups were needed.
+ for (EHScopeStack::stable_iterator
+ I = EHStack.getInnermostEHCleanup(); I != C; ) {
+ assert(C.strictlyEncloses(I));
+ EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I));
+ if (S.getEHBlock()) return true;
+ I = S.getEnclosingEHCleanup();
+ }
+
+ return false;
+}
+
+enum ForActivation_t {
+ ForActivation,
+ ForDeactivation
+};
+
+/// The given cleanup block is changing activation state. Configure a
+/// cleanup variable if necessary.
+///
+/// It would be good if we had some way of determining if there were
+/// extra uses *after* the change-over point.
+static void SetupCleanupBlockActivation(CodeGenFunction &CGF,
+ EHScopeStack::stable_iterator C,
+ ForActivation_t Kind) {
+ EHCleanupScope &Scope = cast<EHCleanupScope>(*CGF.EHStack.find(C));
+
+ // We always need the flag if we're activating the cleanup, because
+ // we have to assume that the current location doesn't necessarily
+ // dominate all future uses of the cleanup.
+ bool NeedFlag = (Kind == ForActivation);
+
+ // Calculate whether the cleanup was used:
+
+ // - as a normal cleanup
+ if (Scope.isNormalCleanup() && IsUsedAsNormalCleanup(CGF.EHStack, C)) {
+ Scope.setTestFlagInNormalCleanup();
+ NeedFlag = true;
+ }
+
+ // - as an EH cleanup
+ if (Scope.isEHCleanup() && IsUsedAsEHCleanup(CGF.EHStack, C)) {
+ Scope.setTestFlagInEHCleanup();
+ NeedFlag = true;
+ }
+
+ // If it hasn't yet been used as either, we're done.
+ if (!NeedFlag) return;
+
+ llvm::AllocaInst *Var = Scope.getActiveFlag();
+ if (!Var) {
+ Var = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), "cleanup.isactive");
+ Scope.setActiveFlag(Var);
+
+ // Initialize to true or false depending on whether it was
+ // active up to this point.
+ CGF.InitTempAlloca(Var, CGF.Builder.getInt1(Kind == ForDeactivation));
+ }
+
+ CGF.Builder.CreateStore(CGF.Builder.getInt1(Kind == ForActivation), Var);
+}
+
+/// Activate a cleanup that was created in an inactivated state.
+void CodeGenFunction::ActivateCleanupBlock(EHScopeStack::stable_iterator C) {
+ assert(C != EHStack.stable_end() && "activating bottom of stack?");
+ EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
+ assert(!Scope.isActive() && "double activation");
+
+ SetupCleanupBlockActivation(*this, C, ForActivation);
+
+ Scope.setActive(true);
+}
+
+/// Deactive a cleanup that was created in an active state.
+void CodeGenFunction::DeactivateCleanupBlock(EHScopeStack::stable_iterator C) {
+ assert(C != EHStack.stable_end() && "deactivating bottom of stack?");
+ EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
+ assert(Scope.isActive() && "double deactivation");
+
+ // If it's the top of the stack, just pop it.
+ if (C == EHStack.stable_begin()) {
+ // If it's a normal cleanup, we need to pretend that the
+ // fallthrough is unreachable.
+ CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
+ PopCleanupBlock();
+ Builder.restoreIP(SavedIP);
+ return;
+ }
+
+ // Otherwise, follow the general case.
+ SetupCleanupBlockActivation(*this, C, ForDeactivation);
+
+ Scope.setActive(false);
+}
+
+llvm::Value *CodeGenFunction::getNormalCleanupDestSlot() {
+ if (!NormalCleanupDest)
+ NormalCleanupDest =
+ CreateTempAlloca(Builder.getInt32Ty(), "cleanup.dest.slot");
+ return NormalCleanupDest;
+}
+
+llvm::Value *CodeGenFunction::getEHCleanupDestSlot() {
+ if (!EHCleanupDest)
+ EHCleanupDest =
+ CreateTempAlloca(Builder.getInt32Ty(), "eh.cleanup.dest.slot");
+ return EHCleanupDest;
+}