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();
}
/// 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);
}
}
/// isObviouslyBranchWithoutCleanups - Return true if a branch to the
/// specified destination obviously has no cleanups to run. 'false' is always
/// a conservatively correct answer for this method.
bool CodeGenFunction::isObviouslyBranchWithoutCleanups(JumpDest Dest) const {
assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
&& "stale jump destination");
// 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
return true;
// Otherwise, we might need some cleanups.
return false;
}
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 cleanup) {
// If we needed an EH block for any reason, that counts.
if (EHStack.find(cleanup)->hasEHBranches())
return true;
// Check whether any enclosed cleanups were needed.
for (EHScopeStack::stable_iterator
i = EHStack.getInnermostEHScope(); i != cleanup; ) {
assert(cleanup.strictlyEncloses(i));
EHScope &scope = *EHStack.find(i);
if (scope.hasEHBranches())
return true;
i = scope.getEnclosingEHScope();
}
return false;
}
/// 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.stable_begin())
&& "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 = nullptr;
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();
}
/// Activate a cleanup that was created in an inactivated state.
void CodeGenFunction::ActivateCleanup(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");
// Calculate whether the cleanup was used:
bool Used = false;
// - as a normal cleanup
if (Scope.isNormalCleanup()) {
bool NormalUsed = false;
if (Scope.getNormalBlock()) {
NormalUsed = true;
} else {
// 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()) {
NormalUsed = true;
break;
}
I = S.getEnclosingNormalCleanup();
}
}
if (NormalUsed)
Used = true;
else
Scope.setActivatedBeforeNormalUse(true);
}
// - as an EH cleanup
if (Scope.isEHCleanup()) {
bool EHUsed = false;
if (Scope.getEHBlock()) {
EHUsed = true;
} else {
// 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()) {
EHUsed = true;
break;
}
I = S.getEnclosingEHCleanup();
}
}
if (EHUsed)
Used = true;
else
Scope.setActivatedBeforeEHUse(true);
}
llvm::AllocaInst *Var = EHCleanupScope::activeSentinel();
if (Used) {
Var = CreateTempAlloca(Builder.getInt1Ty());
InitTempAlloca(Var, Builder.getFalse());
}
Scope.setActiveVar(Var);
}
