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//===--- SILGenProlog.cpp - Function prologue emission --------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
#include "SILGenFunction.h"
#include "Initialization.h"
#include "ManagedValue.h"
#include "Scope.h"
#include "swift/SIL/SILArgument.h"
#include "swift/AST/ParameterList.h"
#include "swift/Basic/Fallthrough.h"
using namespace swift;
using namespace Lowering;
SILValue SILGenFunction::emitSelfDecl(VarDecl *selfDecl) {
// Emit the implicit 'self' argument.
SILType selfType = getLoweredLoadableType(selfDecl->getType());
SILValue selfValue = new (SGM.M) SILArgument(F.begin(), selfType, selfDecl);
VarLocs[selfDecl] = VarLoc::get(selfValue);
SILLocation PrologueLoc(selfDecl);
PrologueLoc.markAsPrologue();
unsigned ArgNo = 1; // Hardcoded for destructors.
B.createDebugValue(PrologueLoc, selfValue, {selfDecl->isLet(), ArgNo});
return selfValue;
}
namespace {
/// Cleanup that writes back to an inout argument on function exit.
class CleanupWriteBackToInOut : public Cleanup {
VarDecl *var;
SILValue inoutAddr;
public:
CleanupWriteBackToInOut(VarDecl *var, SILValue inoutAddr)
: var(var), inoutAddr(inoutAddr) {}
void emit(SILGenFunction &gen, CleanupLocation l) override {
// Assign from the local variable to the inout address with an
// 'autogenerated' copyaddr.
l.markAutoGenerated();
gen.B.createCopyAddr(l, gen.VarLocs[var].value, inoutAddr,
IsNotTake, IsNotInitialization);
}
};
} // end anonymous namespace
namespace {
class StrongReleaseCleanup : public Cleanup {
SILValue box;
public:
StrongReleaseCleanup(SILValue box) : box(box) {}
void emit(SILGenFunction &gen, CleanupLocation l) override {
gen.B.emitStrongReleaseAndFold(l, box);
}
};
} // end anonymous namespace
namespace {
class EmitBBArguments : public CanTypeVisitor<EmitBBArguments,
/*RetTy*/ ManagedValue>
{
public:
SILGenFunction &gen;
SILBasicBlock *parent;
SILLocation loc;
bool functionArgs;
ArrayRef<SILParameterInfo> &parameters;
EmitBBArguments(SILGenFunction &gen, SILBasicBlock *parent,
SILLocation l, bool functionArgs,
ArrayRef<SILParameterInfo> &parameters)
: gen(gen), parent(parent), loc(l), functionArgs(functionArgs),
parameters(parameters) {}
ManagedValue getManagedValue(SILValue arg, CanType t,
SILParameterInfo parameterInfo) const {
switch (parameterInfo.getConvention()) {
case ParameterConvention::Direct_Deallocating:
// If we have a deallocating parameter, it is passed in at +0 and will not
// be deallocated since we do not allow for resurrection.
return ManagedValue::forUnmanaged(arg);
case ParameterConvention::Direct_Guaranteed:
case ParameterConvention::Indirect_In_Guaranteed:
// If we have a guaranteed parameter, it is passed in at +0, and its
// lifetime is guaranteed. We can potentially use the argument as-is
// if the parameter is bound as a 'let' without cleaning up.
return ManagedValue::forUnmanaged(arg);
case ParameterConvention::Direct_Unowned:
// An unowned parameter is passed at +0, like guaranteed, but it isn't
// kept alive by the caller, so we need to retain and manage it
// regardless.
return gen.emitManagedRetain(loc, arg);
case ParameterConvention::Indirect_Inout:
case ParameterConvention::Indirect_InoutAliasable:
// An inout parameter is +0 and guaranteed, but represents an lvalue.
return ManagedValue::forLValue(arg);
case ParameterConvention::Direct_Owned:
case ParameterConvention::Indirect_In:
// An owned or 'in' parameter is passed in at +1. We can claim ownership
// of the parameter and clean it up when it goes out of scope.
return gen.emitManagedRValueWithCleanup(arg);
}
llvm_unreachable("bad parameter convention");
}
ManagedValue visitType(CanType t) {
auto argType = gen.getLoweredType(t);
// Pop the next parameter info.
auto parameterInfo = parameters.front();
parameters = parameters.slice(1);
assert(argType == parent->getParent()
->mapTypeIntoContext(parameterInfo.getSILType()) &&
"argument does not have same type as specified by parameter info");
SILValue arg = new (gen.SGM.M)
SILArgument(parent, argType, loc.getAsASTNode<ValueDecl>());
ManagedValue mv = getManagedValue(arg, t, parameterInfo);
// If the value is a (possibly optional) ObjC block passed into the entry
// point of the function, then copy it so we can treat the value reliably
// as a heap object. Escape analysis can eliminate this copy if it's
// unneeded during optimization.
CanType objectType = t;
if (auto theObjTy = t.getAnyOptionalObjectType())
objectType = theObjTy;
if (functionArgs
&& isa<FunctionType>(objectType)
&& cast<FunctionType>(objectType)->getRepresentation()
== FunctionType::Representation::Block) {
SILValue blockCopy = gen.B.createCopyBlock(loc, mv.getValue());
mv = gen.emitManagedRValueWithCleanup(blockCopy);
}
return mv;
}
ManagedValue visitTupleType(CanTupleType t) {
SmallVector<ManagedValue, 4> elements;
auto &tl = gen.getTypeLowering(t);
bool canBeGuaranteed = tl.isLoadable();
// Collect the exploded elements.
for (auto fieldType : t.getElementTypes()) {
auto elt = visit(fieldType);
// If we can't borrow one of the elements as a guaranteed parameter, then
// we have to +1 the tuple.
if (elt.hasCleanup())
canBeGuaranteed = false;
elements.push_back(elt);
}
if (tl.isLoadable()) {
SmallVector<SILValue, 4> elementValues;
if (canBeGuaranteed) {
// If all of the elements were guaranteed, we can form a guaranteed tuple.
for (auto element : elements)
elementValues.push_back(element.getUnmanagedValue());
} else {
// Otherwise, we need to move or copy values into a +1 tuple.
for (auto element : elements) {
SILValue value = element.hasCleanup()
? element.forward(gen)
: element.copyUnmanaged(gen, loc).forward(gen);
elementValues.push_back(value);
}
}
auto tupleValue = gen.B.createTuple(loc, tl.getLoweredType(),
elementValues);
return canBeGuaranteed
? ManagedValue::forUnmanaged(tupleValue)
: gen.emitManagedRValueWithCleanup(tupleValue);
} else {
// If the type is address-only, we need to move or copy the elements into
// a tuple in memory.
// TODO: It would be a bit more efficient to use a preallocated buffer
// in this case.
auto buffer = gen.emitTemporaryAllocation(loc, tl.getLoweredType());
for (auto i : indices(elements)) {
auto element = elements[i];
auto elementBuffer = gen.B.createTupleElementAddr(loc, buffer,
i, element.getType().getAddressType());
if (element.hasCleanup())
element.forwardInto(gen, loc, elementBuffer);
else
element.copyInto(gen, elementBuffer, loc);
}
return gen.emitManagedRValueWithCleanup(buffer);
}
}
};
} // end anonymous namespace
namespace {
/// A helper for creating SILArguments and binding variables to the argument
/// names.
struct ArgumentInitHelper {
SILGenFunction &gen;
SILFunction &f;
SILGenBuilder &initB;
/// An ArrayRef that we use in our SILParameterList queue. Parameters are
/// sliced off of the front as they're emitted.
ArrayRef<SILParameterInfo> parameters;
unsigned ArgNo = 0;
ArgumentInitHelper(SILGenFunction &gen, SILFunction &f)
: gen(gen), f(f), initB(gen.B),
parameters(f.getLoweredFunctionType()->getParameters()) {
}
unsigned getNumArgs() const { return ArgNo; }
ManagedValue makeArgument(Type ty, SILBasicBlock *parent, SILLocation l) {
assert(ty && "no type?!");
// Create an RValue by emitting destructured arguments into a basic block.
CanType canTy = ty->getCanonicalType();
return EmitBBArguments(gen, parent, l, /*functionArgs*/ true,
parameters).visit(canTy);
}
/// Create a SILArgument and store its value into the given Initialization,
/// if not null.
void makeArgumentIntoBinding(Type ty, SILBasicBlock *parent, VarDecl *vd) {
SILLocation loc(vd);
loc.markAsPrologue();
ManagedValue argrv = makeArgument(ty, parent, loc);
// Create a shadow copy of inout parameters so they can be captured
// by closures. The InOutDeshadowing guaranteed optimization will
// eliminate the variable if it is not needed.
if (auto inOutTy = vd->getType()->getAs<InOutType>()) {
SILValue address = argrv.getUnmanagedValue();
CanType objectType = inOutTy->getObjectType()->getCanonicalType();
// As a special case, don't introduce a local variable for
// Builtin.UnsafeValueBuffer, which is not copyable.
if (isa<BuiltinUnsafeValueBufferType>(objectType)) {
// FIXME: mark a debug location?
gen.VarLocs[vd] = SILGenFunction::VarLoc::get(address);
gen.B.createDebugValueAddr(loc, address, {vd->isLet(), ArgNo});
return;
}
// Allocate the local variable for the inout.
auto initVar = gen.emitLocalVariableWithCleanup(vd, false, ArgNo);
// Initialize with the value from the inout with an "autogenerated"
// copyaddr.
loc.markAutoGenerated();
gen.B.createCopyAddr(loc, address, initVar->getAddress(),
IsNotTake, IsInitialization);
initVar->finishInitialization(gen);
// Set up a cleanup to write back to the inout.
gen.Cleanups.pushCleanup<CleanupWriteBackToInOut>(vd, address);
} else {
assert(vd->isLet() && "expected parameter to be immutable!");
// If the variable is immutable, we can bind the value as is.
// Leave the cleanup on the argument, if any, in place to consume the
// argument if we're responsible for it.
gen.VarLocs[vd] = SILGenFunction::VarLoc::get(argrv.getValue());
if (argrv.getType().isAddress())
gen.B.createDebugValueAddr(loc, argrv.getValue(), {vd->isLet(), ArgNo});
else
gen.B.createDebugValue(loc, argrv.getValue(), {vd->isLet(), ArgNo});
}
}
void emitParam(ParamDecl *PD) {
++ArgNo;
if (PD->hasName()) {
makeArgumentIntoBinding(PD->getType(), &*f.begin(), PD);
return;
}
emitAnonymousParam(PD->getType(), PD, PD);
}
void emitAnonymousParam(Type type, SILLocation paramLoc, ParamDecl *PD) {
assert(!PD || PD->getType()->isEqual(type));
// Allow non-materializable tuples to be bound to anonymous parameters.
if (!type->isMaterializable()) {
if (auto tupleType = type->getAs<TupleType>()) {
for (auto eltType : tupleType->getElementTypes()) {
emitAnonymousParam(eltType, paramLoc, nullptr);
}
return;
}
}
// A value bound to _ is unused and can be immediately released.
Scope discardScope(gen.Cleanups, CleanupLocation(PD));
// Manage the parameter.
ManagedValue argrv = makeArgument(type, &*f.begin(), paramLoc);
// Don't do anything else if we don't have a parameter.
if (!PD) return;
// Emit debug information for the argument.
SILLocation loc(PD);
loc.markAsPrologue();
if (argrv.getType().isAddress())
gen.B.createDebugValueAddr(loc, argrv.getValue(), {PD->isLet(), ArgNo});
else
gen.B.createDebugValue(loc, argrv.getValue(), {PD->isLet(), ArgNo});
}
};
} // end anonymous namespace
static void makeArgument(Type ty, ParamDecl *decl,
SmallVectorImpl<SILValue> &args, SILGenFunction &gen) {
assert(ty && "no type?!");
// Destructure tuple arguments.
if (TupleType *tupleTy = ty->getAs<TupleType>()) {
for (auto fieldType : tupleTy->getElementTypes())
makeArgument(fieldType, decl, args, gen);
} else {
auto arg = new (gen.F.getModule()) SILArgument(gen.F.begin(),
gen.getLoweredType(ty),decl);
args.push_back(arg);
}
}
void SILGenFunction::bindParametersForForwarding(const ParameterList *params,
SmallVectorImpl<SILValue> &parameters) {
for (auto param : *params) {
makeArgument(param->getType(), param, parameters, *this);
}
}
static void emitCaptureArguments(SILGenFunction &gen, CapturedValue capture,
unsigned ArgNo) {
auto *VD = capture.getDecl();
auto type = VD->getType();
SILLocation Loc(VD);
Loc.markAsPrologue();
switch (gen.SGM.Types.getDeclCaptureKind(capture)) {
case CaptureKind::None:
break;
case CaptureKind::Constant: {
auto &lowering = gen.getTypeLowering(VD->getType());
// Constant decls are captured by value.
SILType ty = lowering.getLoweredType();
SILValue val = new (gen.SGM.M) SILArgument(gen.F.begin(), ty, VD);
// If the original variable was settable, then Sema will have treated the
// VarDecl as an lvalue, even in the closure's use. As such, we need to
// allow formation of the address for this captured value. Create a
// temporary within the closure to provide this address.
if (VD->isSettable(VD->getDeclContext())) {
auto addr = gen.emitTemporaryAllocation(VD, ty);
gen.B.createStore(VD, val, addr);
val = addr;
}
gen.VarLocs[VD] = SILGenFunction::VarLoc::get(val);
if (auto *AllocStack = dyn_cast<AllocStackInst>(val))
AllocStack->setArgNo(ArgNo);
else
gen.B.createDebugValue(Loc, val, {/*Constant*/true, ArgNo});
// TODO: Closure contexts should always be guaranteed.
if (!gen.SGM.M.getOptions().EnableGuaranteedClosureContexts
&& !lowering.isTrivial())
gen.enterDestroyCleanup(val);
break;
}
case CaptureKind::Box: {
// LValues are captured as a retained @box that owns
// the captured value.
SILType ty = gen.getLoweredType(type).getAddressType();
SILType boxTy = SILType::getPrimitiveObjectType(
SILBoxType::get(ty.getSwiftRValueType()));
SILValue box = new (gen.SGM.M) SILArgument(gen.F.begin(), boxTy, VD);
SILValue addr = gen.B.createProjectBox(VD, box);
gen.VarLocs[VD] = SILGenFunction::VarLoc::get(addr, box);
gen.B.createDebugValueAddr(Loc, addr, {/*Constant*/false, ArgNo});
if (!gen.SGM.M.getOptions().EnableGuaranteedClosureContexts)
gen.Cleanups.pushCleanup<StrongReleaseCleanup>(box);
break;
}
case CaptureKind::StorageAddress: {
// Non-escaping stored decls are captured as the address of the value.
SILType ty = gen.getLoweredType(type).getAddressType();
SILValue addr = new (gen.SGM.M) SILArgument(gen.F.begin(), ty, VD);
gen.VarLocs[VD] = SILGenFunction::VarLoc::get(addr);
gen.B.createDebugValueAddr(Loc, addr, {/*Constant*/true, ArgNo});
break;
}
}
}
void SILGenFunction::emitProlog(AnyFunctionRef TheClosure,
ArrayRef<ParameterList*> paramPatterns,
Type resultType) {
unsigned ArgNo =
emitProlog(paramPatterns, resultType, TheClosure.getAsDeclContext());
// Emit the capture argument variables. These are placed last because they
// become the first curry level of the SIL function.
auto captureInfo = SGM.Types.getLoweredLocalCaptures(TheClosure);
for (auto capture : captureInfo.getCaptures()) {
if (capture.isDynamicSelfMetadata()) {
auto selfMetatype = MetatypeType::get(
captureInfo.getDynamicSelfType()->getSelfType(),
MetatypeRepresentation::Thick)
->getCanonicalType();
SILType ty = SILType::getPrimitiveObjectType(selfMetatype);
SILValue val = new (SGM.M) SILArgument(F.begin(), ty);
(void) val;
return;
}
emitCaptureArguments(*this, capture, ++ArgNo);
}
}
static void emitIndirectResultParameters(SILGenFunction &gen, Type resultType,
DeclContext *DC) {
// Expand tuples.
if (auto tupleType = resultType->getAs<TupleType>()) {
for (auto eltType : tupleType->getElementTypes()) {
emitIndirectResultParameters(gen, eltType, DC);
}
return;
}
// If the return type is address-only, emit the indirect return argument.
const TypeLowering &resultTI = gen.getTypeLowering(resultType);
if (!resultTI.isReturnedIndirectly()) return;
auto &ctx = gen.getASTContext();
auto var = new (ctx) ParamDecl(/*IsLet*/ false, SourceLoc(), SourceLoc(),
ctx.getIdentifier("$return_value"), SourceLoc(),
ctx.getIdentifier("$return_value"), resultType,
DC);
auto arg =
new (gen.SGM.M) SILArgument(gen.F.begin(), resultTI.getLoweredType(), var);
(void) arg;
}
unsigned SILGenFunction::emitProlog(ArrayRef<ParameterList*> paramLists,
Type resultType, DeclContext *DC) {
// Create the indirect result parameters.
emitIndirectResultParameters(*this, resultType, DC);
// Emit the argument variables in calling convention order.
ArgumentInitHelper emitter(*this, F);
for (ParameterList *paramList : reversed(paramLists)) {
// Add the SILArguments and use them to initialize the local argument
// values.
for (auto &param : *paramList)
emitter.emitParam(param);
}
return emitter.getNumArgs();
}