void StmtEmitter::visitForEachStmt(ForEachStmt *S) {
// Emit the 'iterator' variable that we'll be using for iteration.
LexicalScope OuterForScope(SGF.Cleanups, SGF, CleanupLocation(S));
SGF.visitPatternBindingDecl(S->getIterator());
// If we ever reach an unreachable point, stop emitting statements.
// This will need revision if we ever add goto.
if (!SGF.B.hasValidInsertionPoint()) return;
// If generator's optional result is address-only, create a stack allocation
// to hold the results. This will be initialized on every entry into the loop
// header and consumed by the loop body. On loop exit, the terminating value
// will be in the buffer.
auto optTy = S->getIteratorNext()->getType()->getCanonicalType();
auto &optTL = SGF.getTypeLowering(optTy);
SILValue nextBufOrValue;
if (optTL.isAddressOnly())
nextBufOrValue = SGF.emitTemporaryAllocation(S, optTL.getLoweredType());
// Create a new basic block and jump into it.
JumpDest loopDest = createJumpDest(S->getBody());
SGF.B.emitBlock(loopDest.getBlock(), S);
// Set the destinations for 'break' and 'continue'.
JumpDest endDest = createJumpDest(S->getBody());
SGF.BreakContinueDestStack.push_back({ S, endDest, loopDest });
// Advance the generator. Use a scope to ensure that any temporary stack
// allocations in the subexpression are immediately released.
if (optTL.isAddressOnly()) {
Scope InnerForScope(SGF.Cleanups, CleanupLocation(S->getIteratorNext()));
auto nextInit = SGF.useBufferAsTemporary(nextBufOrValue, optTL);
SGF.emitExprInto(S->getIteratorNext(), nextInit.get());
nextInit->getManagedAddress().forward(SGF);
} else {
Scope InnerForScope(SGF.Cleanups, CleanupLocation(S->getIteratorNext()));
nextBufOrValue =
SGF.emitRValueAsSingleValue(S->getIteratorNext()).forward(SGF);
}
// Continue if the value is present.
Condition Cond = SGF.emitCondition(
SGF.emitDoesOptionalHaveValue(S, nextBufOrValue), S,
/*hasFalseCode=*/false, /*invertValue=*/false);
if (Cond.hasTrue()) {
Cond.enterTrue(SGF);
SGF.emitProfilerIncrement(S->getBody());
// Emit the loop body.
// The declared variable(s) for the current element are destroyed
// at the end of each loop iteration.
{
Scope InnerForScope(SGF.Cleanups, CleanupLocation(S->getBody()));
// Emit the initialization for the pattern. If any of the bound patterns
// fail (because this is a 'for case' pattern with a refutable pattern,
// the code should jump to the continue block.
InitializationPtr initLoopVars
= SGF.emitPatternBindingInitialization(S->getPattern(), loopDest);
ManagedValue val;
// If we had a loadable "next" generator value, we know it is present.
// Get the value out of the optional, and wrap it up with a cleanup so
// that any exits out of this scope properly clean it up.
if (optTL.isLoadable()) {
val = SGF.emitManagedRValueWithCleanup(nextBufOrValue);
} else {
val = SGF.emitManagedBufferWithCleanup(nextBufOrValue);
}
val = SGF.emitUncheckedGetOptionalValueFrom(S, val, optTL,
SGFContext(initLoopVars.get()));
if (!val.isInContext())
RValue(SGF, S, optTy.getAnyOptionalObjectType(), val)
.forwardInto(SGF, S, initLoopVars.get());
// Now that the pattern has been initialized, check any where condition.
// If it fails, loop around as if 'continue' happened.
if (auto *Where = S->getWhere()) {
auto cond = SGF.emitCondition(Where, /*hasFalse*/false, /*invert*/true);
// If self is null, branch to the epilog.
cond.enterTrue(SGF);
SGF.Cleanups.emitBranchAndCleanups(loopDest, Where, { });
cond.exitTrue(SGF);
cond.complete(SGF);
}
visit(S->getBody());
}
// Loop back to the header.
if (SGF.B.hasValidInsertionPoint()) {
// Associate the loop body's closing brace with this branch.
RegularLocation L(S->getBody());
L.pointToEnd();
SGF.B.createBranch(L, loopDest.getBlock());
}
Cond.exitTrue(SGF);
}
// Complete the conditional execution.
Cond.complete(SGF);
emitOrDeleteBlock(SGF, endDest, S);
SGF.BreakContinueDestStack.pop_back();
// We do not need to destroy the value in the 'nextBuf' slot here, because
// either the 'for' loop finished naturally and the buffer contains '.None',
// or we exited by 'break' and the value in the buffer was consumed.
}
void StmtEmitter::visitForStmt(ForStmt *S) {
// Enter a new scope.
LexicalScope ForScope(SGF.Cleanups, SGF, CleanupLocation(S));
// Emit any local 'var' variables declared in the initializer.
for (auto D : S->getInitializerVarDecls()) {
SGF.visit(D);
}
if (auto *Initializer = S->getInitializer().getPtrOrNull()) {
SGF.emitIgnoredExpr(Initializer);
}
// If we ever reach an unreachable point, stop emitting statements.
// This will need revision if we ever add goto.
if (!SGF.B.hasValidInsertionPoint()) return;
// Create a new basic block and jump into it.
SILBasicBlock *loopBB = createBasicBlock();
SGF.B.emitBlock(loopBB, S);
JumpDest endDest = createJumpDest(S->getBody());
// Evaluate the condition with the false edge leading directly
// to the continuation block.
Condition Cond = S->getCond().isNonNull() ?
SGF.emitCondition(S->getCond().get(), /*hasFalseCode*/ false) :
Condition(loopBB, 0, 0, S); // Infinite loop.
// If there's a true edge, emit the body in it.
if (Cond.hasTrue()) {
Cond.enterTrue(SGF);
SGF.emitProfilerIncrement(S->getBody());
// Set the destinations for 'break' and 'continue'.
JumpDest incDest = createJumpDest(S->getBody());
SGF.BreakContinueDestStack.push_back({S, endDest, incDest});
visit(S->getBody());
SGF.BreakContinueDestStack.pop_back();
emitOrDeleteBlock(SGF, incDest, S);
if (SGF.B.hasValidInsertionPoint() && S->getIncrement().isNonNull()) {
FullExpr Scope(SGF.Cleanups, CleanupLocation(S->getIncrement().get()));
// Ignore the result of the increment expression.
SGF.emitIgnoredExpr(S->getIncrement().get());
}
if (SGF.B.hasValidInsertionPoint()) {
// Associate the loop body's closing brace with this branch.
RegularLocation L(S->getBody());
L.pointToEnd();
SGF.B.createBranch(L, loopBB);
}
Cond.exitTrue(SGF);
}
// Complete the conditional execution.
Cond.complete(SGF);
emitOrDeleteBlock(SGF, endDest, S);
}