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[cxx-interop] Support lifetime_capture_by in ClangImporter #77617

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Merged
merged 1 commit into from
Dec 18, 2024
Merged

[cxx-interop] Support lifetime_capture_by in ClangImporter #77617

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94 changes: 70 additions & 24 deletions lib/ClangImporter/ImportDecl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -25,11 +25,11 @@
#include "swift/AST/ConformanceLookup.h"
#include "swift/AST/Decl.h"
#include "swift/AST/DiagnosticsClangImporter.h"
#include "swift/ClangImporter/ClangImporter.h"
#include "swift/AST/ExistentialLayout.h"
#include "swift/AST/Expr.h"
#include "swift/AST/GenericEnvironment.h"
#include "swift/AST/GenericSignature.h"
#include "swift/AST/LifetimeDependence.h"
#include "swift/AST/Module.h"
#include "swift/AST/NameLookup.h"
#include "swift/AST/NameLookupRequests.h"
Expand All @@ -49,6 +49,7 @@
#include "swift/Basic/StringExtras.h"
#include "swift/Basic/Version.h"
#include "swift/ClangImporter/CXXMethodBridging.h"
#include "swift/ClangImporter/ClangImporter.h"
#include "swift/ClangImporter/ClangImporterRequests.h"
#include "swift/ClangImporter/ClangModule.h"
#include "swift/Parse/Lexer.h"
Expand All @@ -65,6 +66,7 @@
#include "clang/Sema/Lookup.h"

#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
Expand Down Expand Up @@ -3545,19 +3547,20 @@ namespace {
return true;
}

static bool
implicitObjectParamIsLifetimeBound(const clang::FunctionDecl *FD) {
template <typename T>
static const T *
getImplicitObjectParamAnnotation(const clang::FunctionDecl *FD) {
const clang::TypeSourceInfo *TSI = FD->getTypeSourceInfo();
if (!TSI)
return false;
return nullptr;
clang::AttributedTypeLoc ATL;
for (clang::TypeLoc TL = TSI->getTypeLoc();
(ATL = TL.getAsAdjusted<clang::AttributedTypeLoc>());
TL = ATL.getModifiedLoc()) {
if (ATL.getAttrAs<clang::LifetimeBoundAttr>())
return true;
if (auto attr = ATL.getAttrAs<T>())
return attr;
}
return false;
return nullptr;
}

Decl *importFunctionDecl(
Expand Down Expand Up @@ -3869,7 +3872,8 @@ namespace {
if (selfIsInOut)
func->setSelfAccessKind(SelfAccessKind::Mutating);
else {
if (implicitObjectParamIsLifetimeBound(decl))
if (getImplicitObjectParamAnnotation<clang::LifetimeBoundAttr>(
decl))
func->setSelfAccessKind(SelfAccessKind::Borrowing);
else
func->setSelfAccessKind(SelfAccessKind::NonMutating);
Expand Down Expand Up @@ -3961,26 +3965,68 @@ namespace {
auto swiftParams = result->getParameters();
bool hasSelf =
result->hasImplicitSelfDecl() && !isa<ConstructorDecl>(result);
SmallBitVector inheritLifetimeParamIndicesForReturn(swiftParams->size() +
hasSelf);
SmallBitVector scopedLifetimeParamIndicesForReturn(swiftParams->size() +
hasSelf);
for (auto [idx, param] : llvm::enumerate(decl->parameters())) {
if (param->hasAttr<clang::LifetimeBoundAttr>()) {
warnForEscapableReturnType();
if (swiftParams->get(idx)->getInterfaceType()->isEscapable())
scopedLifetimeParamIndicesForReturn[idx] = true;
else
inheritLifetimeParamIndicesForReturn[idx] = true;
}
}
if (implicitObjectParamIsLifetimeBound(decl)) {
const auto dependencyVecSize = swiftParams->size() + hasSelf;
SmallBitVector inheritLifetimeParamIndicesForReturn(dependencyVecSize);
SmallBitVector scopedLifetimeParamIndicesForReturn(dependencyVecSize);
std::map<unsigned, SmallBitVector> inheritedArgDependences;
auto processLifetimeBound = [&](unsigned idx, Type ty) {
warnForEscapableReturnType();
auto idx = result->getSelfIndex();
if (result->getImplicitSelfDecl()->getInterfaceType()->isEscapable())
if (ty->isEscapable())
scopedLifetimeParamIndicesForReturn[idx] = true;
else
inheritLifetimeParamIndicesForReturn[idx] = true;
};
auto processLifetimeCaptureBy =
[&](const clang::LifetimeCaptureByAttr *attr, unsigned idx, Type ty) {
// FIXME: support scoped lifetimes. This is not straightforward as
// const T& is imported as taking a value
// and we assume the address of T would not escape. An
// annotation in this case contradicts our assumptions. We
// should diagnose that, and support this for the non-const
// case.
if (ty->isEscapable())
return;
for (auto param : attr->params()) {
// FIXME: Swift assumes no escaping to globals. We should diagnose
// this.
if (param == clang::LifetimeCaptureByAttr::GLOBAL ||
param == clang::LifetimeCaptureByAttr::UNKNOWN ||
param == clang::LifetimeCaptureByAttr::INVALID)
continue;

if (isa<clang::CXXMethodDecl>(decl) &&
param == clang::LifetimeCaptureByAttr::THIS) {
auto [it, inserted] = inheritedArgDependences.try_emplace(
result->getSelfIndex(), SmallBitVector(dependencyVecSize));
it->second[idx] = true;
} else {
auto [it, inserted] = inheritedArgDependences.try_emplace(
param - isa<clang::CXXMethodDecl>(decl),
SmallBitVector(dependencyVecSize));
it->second[idx] = true;
}
}
};
for (auto [idx, param] : llvm::enumerate(decl->parameters())) {
if (param->hasAttr<clang::LifetimeBoundAttr>())
processLifetimeBound(idx, swiftParams->get(idx)->getInterfaceType());
if (const auto *attr = param->getAttr<clang::LifetimeCaptureByAttr>())
processLifetimeCaptureBy(attr, idx,
swiftParams->get(idx)->getInterfaceType());
}
if (getImplicitObjectParamAnnotation<clang::LifetimeBoundAttr>(decl))
processLifetimeBound(result->getSelfIndex(),
result->getImplicitSelfDecl()->getInterfaceType());
if (auto attr =
getImplicitObjectParamAnnotation<clang::LifetimeCaptureByAttr>(
decl))
processLifetimeCaptureBy(
attr, result->getSelfIndex(),
result->getImplicitSelfDecl()->getInterfaceType());

for (auto& [idx, inheritedDepVec]: inheritedArgDependences) {
lifetimeDependencies.push_back(LifetimeDependenceInfo(inheritedDepVec.any() ? IndexSubset::get(Impl.SwiftContext,
inheritedDepVec): nullptr, nullptr, idx, /*isImmortal=*/false));
}

if (inheritLifetimeParamIndicesForReturn.any() ||
Expand Down
34 changes: 33 additions & 1 deletion test/Interop/Cxx/class/nonescapable-lifetimebound.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,29 @@ View returnsImmortal() SWIFT_RETURNS_INDEPENDENT_VALUE {
return View();
}

void copyView(View view1 [[clang::lifetime_capture_by(view2)]], View &view2) {
view2 = view1;
}

struct SWIFT_NONESCAPABLE CaptureView {
CaptureView() : view(nullptr) {}
CaptureView(View p [[clang::lifetimebound]]) : view(p) {}

void captureView(View v [[clang::lifetime_capture_by(this)]]) {
view = v;
}

void handOut(View &v) const [[clang::lifetime_capture_by(v)]] {
v = view;
}

View view;
};

CaptureView getCaptureView(const Owner& owner [[clang::lifetimebound]]) {
return CaptureView(View{&owner.data});
}

// CHECK: sil [clang makeOwner] {{.*}}: $@convention(c) () -> Owner
// CHECK: sil [clang getView] {{.*}} : $@convention(c) (@in_guaranteed Owner) -> @lifetime(borrow 0) @autoreleased View
// CHECK: sil [clang getViewFromFirst] {{.*}} : $@convention(c) (@in_guaranteed Owner, @in_guaranteed Owner) -> @lifetime(borrow 0) @autoreleased View
Expand All @@ -92,6 +115,10 @@ View returnsImmortal() SWIFT_RETURNS_INDEPENDENT_VALUE {
// CHECK: sil [clang View.init] {{.*}} : $@convention(c) () -> @lifetime(immortal) @out View
// CHECK: sil [clang OtherView.init] {{.*}} : $@convention(c) (@guaranteed View) -> @lifetime(copy 0) @out OtherView
// CHECK: sil [clang returnsImmortal] {{.*}} : $@convention(c) () -> @lifetime(immortal) @autoreleased View
// CHECK: sil [clang copyView] {{.*}} : $@convention(c) (View, @lifetime(copy 0) @inout View) -> ()
// CHECK: sil [clang getCaptureView] {{.*}} : $@convention(c) (@in_guaranteed Owner) -> @lifetime(borrow 0) @autoreleased CaptureView
// CHECK: sil [clang CaptureView.captureView] {{.*}} : $@convention(cxx_method) (View, @lifetime(copy 0) @inout CaptureView) -> ()
// CHECK: sil [clang CaptureView.handOut] {{.*}} : $@convention(cxx_method) (@lifetime(copy 1) @inout View, @in_guaranteed CaptureView) -> ()

// CHECK-NO-LIFETIMES: nonescapable.h:36:6: error: returning ~Escapable type requires '-enable-experimental-feature LifetimeDependence'
// CHECK-NO-LIFETIMES: nonescapable.h:40:6: error: returning ~Escapable type requires '-enable-experimental-feature LifetimeDependence'
Expand All @@ -104,6 +131,7 @@ View returnsImmortal() SWIFT_RETURNS_INDEPENDENT_VALUE {
// CHECK-NO-LIFETIMES: nonescapable.h:13:5: error: returning ~Escapable type requires '-enable-experimental-feature LifetimeDependence'
// CHECK-NO-LIFETIMES: nonescapable.h:14:5: error: returning ~Escapable type requires '-enable-experimental-feature LifetimeDependence'
// CHECK-NO-LIFETIMES: nonescapable.h:68:6: error: returning ~Escapable type requires '-enable-experimental-feature LifetimeDependence'
// CHECK-NO-LIFETIMES: nonescapable.h:91:13: error: returning ~Escapable type requires '-enable-experimental-feature LifetimeDependence'
// CHECK-NO-LIFETIMES-NOT: error

//--- test.swift
Expand All @@ -113,7 +141,7 @@ import Test
public func test() {
let o = makeOwner()
let o2 = makeOwner()
let v1 = getView(o)
var v1 = getView(o)
let v2 = getViewFromFirst(o, o2)
let _ = getViewFromEither(o, o2)
let _ = o.handOutView()
Expand All @@ -122,4 +150,8 @@ public func test() {
let defaultView = View()
let _ = OtherView(defaultView)
let _ = returnsImmortal()
copyView(v2, &v1)
var cv = getCaptureView(o)
cv.captureView(v1)
cv.handOut(&v1)
}