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SwiftͷδΣωϦΫε
Ͳ͏ͬͯಈ͍͍ͯΔͷ
͔ίϯύΠϥͷιʔε͔
Β୳Δ
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ࣗݾհ
• omochimetaru
• Qoncept, Inc
• ήʔϜ
• Swift
• SwiftίϯύΠϥ
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͜ͷൃදͷझࢫ
• δΣωϦΫεͷΈΛղઆ
• ίϯύΠϥΛྲྀߦΒͤΔ
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Generics
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Generics
// δΣωϦοΫؔ
func takeX(_ x: X)
// δΣωϦοΫܕ
class Box {
var value: T
}
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ͲΜͳܕͰͤΔ
func takeX(_ x: X)
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func takeX(_ x: X)
takeX(3)
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func takeX(_ x: X)
takeX(3)
takeX("hello")
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func takeX(_ x: X)
takeX(3)
takeX("hello")
struct Stone { ... }
takeX(Stone())
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func takeX(_ x: X)
takeX(3)
takeX("hello")
struct Stone { ... }
takeX(Stone())
class Cat { ... }
takeX(Cat())
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ෆࢥٞ
• Swift੩తܕ͚
• ͔͠͠, ࣮ߦ࣌·Ͱܕ͕Θ͔Βͳ͍
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ෆࢥٞ
• αΠζͷҧ͏Ҿͷड͚͠
struct Stone { ... }
class Cat { ... }
Stone() // 24όΠτ
Cat() // 8όΠτ
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ෆࢥٞ
• ࢀরܕ͚ͩͳΒΫϥεใʹΞΫηεͰ͖Δ
• SwiftͷδΣωϦΫεܕʹରԠ
• ܕʹͦͷΑ͏ͳϝλใ͕ແ͍
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Swiftͷٙ
• ݴޠ༷ͷٙ
• จॻ͕ͨ͘͞Μ͋Δ
• ݴޠ ࣮ ༷ͷٙ
• จॻ͕গͳ͍
• ͜ͷͷςʔϚͪ͜Β
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ݴޠ࣮༷ΛֶͿཧ༝
• ϓϩάϥϛϯάݴޠΛબ͢Δࡍͷஅࡐྉ
• ྫ͑ɺ Swift vs Objective-C
• ύϑΥʔϚϯε࠷దԽʹཱͭ
• ͍ॻ͖ํɺ͍ॻ͖ํɺͦͷཧ༝
• ָ͍͠
• ίϯύΠϥٕज़ͷਮ
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Swiftݴޠ࣮༷ͷֶͼํ
• จॻ
• গͳ͍
• ݹ͘ͳΔ
• ਅِͷ֬ೝ͕Ͱ͖ͳ͍
• ίϯύΠϥͷग़ྗ
• ίϯύΠϥͷιʔείʔυ
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ίϯύΠϥͷಈ͖
• Swiftଟஈ֊ʹม
• Swift → SIL → LLVM-IR → X86_64
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ίϯύΠϥͷग़ྗΛ؍
• ίϯύΠϥͷ్தঢ়ଶΛग़ྗ
• ࢼͨ͠έʔε͔͠Θ͔Βͳ͍
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ίϯύΠϥͷιʔείʔυΛಡΉ
• ཏతͳѲ͕Մೳ
• Φʔϓϯιʔε
• https://github.com/apple/swift
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Generics ͷ࣮
ग़ྗͷ؍
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ίϯύΠϧखॱͷ࠶ܝ
Swift → SIL → LLVM-IR → X86_64
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SIL ʹมͯ͠ΈΔ
func takeX(_ x: X) { ... }
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SIL ʹมͯ͠ΈΔ
// aaa.swift
func takeX(_ x: X) { ... }
$ swiftc -emit-sil aaa.swift > aaa.sil
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SIL Ͱͷ takeX
sil hidden @$S3aaa5takeXyyxlF :
$@convention(thin) (@in_guaranteed X) -> ()
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sil hidden @$S3aaa5takeXyyxlF :
$@convention(thin) (@in_guaranteed X) -> ()
: δΣωϦοΫύϥϝʔλɻ
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SILͷܕγεςϜ
• SILSwiftͷܕγεςϜΛ࣋ͭ
• δΣωϦΫε࣋ͭ
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LLVM-IR ʹมͯ͠ΈΔ
func takeX(_ x: X)
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LLVM-IR ʹมͯ͠ΈΔ
// aaa.swift
func takeX(_ x: X)
$ swiftc -emit-ir aaa.swift > aaa.ll
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LLVM-IR Ͱͷ takeX
; aaa.ll
define hidden swiftcc
void @"$S3aaa5takeXyyxlF"(
%swift.opaque* noalias nocapture,
%swift.type* %X)
ߏจ
define ଐੑ...
ฦΓͷܕ ໊ؔ (
ୈ1Ҿͷܕ ୈ1Ҿͷ໊લ,
ୈ2Ҿͷܕ ୈ2Ҿͷ໊લ, ...)
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define hidden swiftcc
void @"$S3aaa5takeXyyxlF"(
%swift.opaque* noalias nocapture,
%swift.type* %X)
• ୈ1Ҿͷܕ %swift.opaque*
• * ϙΠϯλ
• opaqueʮෆ໌ͳԿ͔ʯ
• Swiftʹ͓͚ΔҾ x: X ͱରԠʁ
• ৗʹϙΠϯλͳΒαΠζҰఆ
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define hidden swiftcc
void @"$S3aaa5takeXyyxlF"(
%swift.opaque* noalias nocapture,
%swift.type* %X)
• ୈ2Ҿͷܕ %swift.type*
• ୈ2Ҿͷ໊લ %X
• Swiftʹ͓͚Δܕύϥϝʔλ ͱରԠʁ
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δΣωϦΫεͷ͘͠Έ
• X ܕͷৗʹϙΠϯλ͠
• Swiftͷܕύϥϝʔλ → Ҿ %X
• ʹ͍ͭͯͷϝλใʁ
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༧͕ͨ͘͞Μ
• ܕ͔͠ௐ͍ͯͳ͍
• ݺͼग़͠ଆௐΒΕΔ
• ݺͼग़͞ΕଆௐΒΕΔ
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ΫΠζ
func take2X(_ x1: X, _ x2: X)
• LLVM-IR Ͱ %swift.type* ͍ͭ͘ʁ
• X x1 ͱ x2 ͕͋Δ͔Βɺ2ͭʁ
• 1͔ͭͩΒɺ1ͭʁ
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LLVM-IR Ͱͷ take2X
define hidden swiftcc
void @"$S3aaa6take2Xyyx_xtlF"(
%swift.opaque* noalias nocapture,
%swift.opaque* noalias nocapture,
%swift.type* %X)
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؍ख๏ͷ݀
• ؍ͨ͠ࣄ͔͠Θ͔Βͳ͍ɻ
• Ҿ͕3ͭͷ߹ʁ
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Genericsͷ࣮
ίϯύΠϥͷιʔεΛಡΉ
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IRGen
SIL → LLVM-IR ͷมϞδϡʔϧ
swift/lib/IRGen
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swift/lib/IRGen/GenDecl.cpp
llvm::Function *
IRGenModule::getAddrOfSILFunction(SILFunction *f,
ForDefinition_t forDefinition)
SILͷؔʹରԠ͢ΔLLVM-IRͷؔΛऔಘɺ
·ͨੜ͢Δؔɻ
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llvm::Function *IRGenModule::getAddrOfSILFunction(SILFunction *f,
ForDefinition_t forDefinition) {
LinkEntity entity = LinkEntity::forSILFunction(f);
// Check whether we've created the function already.
// FIXME: We should integrate this into the LinkEntity cache more cleanly.
llvm::Function *fn = Module.getFunction(f->getName());
if (fn) {
if (forDefinition) updateLinkageForDefinition(*this, fn, entity);
return fn;
}
// If it's a Clang declaration, ask Clang to generate the IR declaration.
// This might generate new functions, so we should do it before computing
// the insert-before point.
llvm::Constant *clangAddr = nullptr;
if (auto clangDecl = f->getClangDecl()) {
auto globalDecl = getClangGlobalDeclForFunction(clangDecl);
clangAddr = getAddrOfClangGlobalDecl(globalDecl, forDefinition);
}
bool isDefinition = f->isDefinition();
bool hasOrderNumber = isDefinition;
unsigned orderNumber = ~0U;
llvm::Function *insertBefore = nullptr;
// If the SIL function has a definition, we should have an order
// number for it; make sure to insert it in that position relative
// to other ordered functions.
if (hasOrderNumber) {
orderNumber = IRGen.getFunctionOrder(f);
if (auto emittedFunctionIterator
= EmittedFunctionsByOrder.findLeastUpperBound(orderNumber))
insertBefore = *emittedFunctionIterator;
}
// If it's a Clang declaration, check whether Clang gave us a declaration.
if (clangAddr) {
fn = dyn_cast(clangAddr->stripPointerCasts());
// If we have a function, move it to the appropriate position.
if (fn) {
if (hasOrderNumber) {
auto &fnList = Module.getFunctionList();
fnList.remove(fn);
fnList.insert(llvm::Module::iterator(insertBefore), fn);
EmittedFunctionsByOrder.insert(orderNumber, fn);
}
return fn;
}
// Otherwise, if we have a lazy definition for it, be sure to queue that up.
} else if (isDefinition && !forDefinition && !f->isPossiblyUsedExternally() &&
!hasCodeCoverageInstrumentation(*f, getSILModule())) {
IRGen.addLazyFunction(f);
}
Signature signature = getSignature(f->getLoweredFunctionType());
auto &attrs = signature.getMutableAttributes();
LinkInfo link = LinkInfo::get(*this, entity, forDefinition);
switch (f->getInlineStrategy()) {
case NoInline:
attrs = attrs.addAttribute(signature.getType()->getContext(),
llvm::AttributeList::FunctionIndex,
llvm::Attribute::NoInline);
break;
case AlwaysInline:
// FIXME: We do not currently transfer AlwaysInline since doing so results
// in test failures, which must be investigated first.
case InlineDefault:
break;
}
if (isReadOnlyFunction(f)) {
attrs = attrs.addAttribute(signature.getType()->getContext(),
llvm::AttributeList::FunctionIndex,
llvm::Attribute::ReadOnly);
}
fn = createFunction(*this, link, signature, insertBefore,
f->getOptimizationMode());
// If `hasCReferences` is true, then the function is either marked with
// @_silgen_name OR @_cdecl. If it is the latter, it must have a definition
// associated with it. The combination of the two allows us to identify the
// @_silgen_name functions. These are locally defined function thunks used in
// the standard library. Do not give them DLLImport DLL Storage.
if (useDllStorage() && f->hasCReferences() && !forDefinition)
fn->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass);
// If we have an order number for this function, set it up as appropriate.
if (hasOrderNumber) {
EmittedFunctionsByOrder.insert(orderNumber, fn);
}
return fn;
}
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llvm::Function *IRGenModule::getAddrOfSILFunction(SILFunction *f,
ForDefinition_t forDefinition) {
...
llvm::Function *fn = Module.getFunction(f->getName());
if (fn) {
...
return fn;
}
...
Signature signature = getSignature(f->getLoweredFunctionType());
...
fn = createFunction(*this, link, signature, insertBefore,
f->getOptimizationMode());
...
return fn;
}
Ωϟογϡύλʔϯ
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llvm::Function *IRGenModule::getAddrOfSILFunction(SILFunction *f,
ForDefinition_t forDefinition) {
...
llvm::Function *fn = Module.getFunction(f->getName());
if (fn) {
...
return fn;
}
...
Signature signature = getSignature(f->getLoweredFunctionType());
...
fn = createFunction(*this, link, signature, insertBefore,
f->getOptimizationMode());
...
return fn;
}
SILؔͷܕˠLLVM-IRؔͷܕ
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Signature
IRGenModule::getSignature(CanSILFunctionType type) {
auto &sigInfo = getFuncSignatureInfoForLowered(*this, type);
return sigInfo.getSignature(*this);
}
ॲཧΛܕʹΓग़͍ͯ͠Δ
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Signature FuncSignatureInfo::getSignature(IRGenModule &IGM) const {
// If it's already been filled in, we're done.
if (TheSignature.isValid())
return TheSignature;
// Update the cache and return.
TheSignature = Signature::getUncached(IGM, FormalType);
assert(TheSignature.isValid());
return TheSignature;
}
Ωϟογϡύλʔϯ
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Signature Signature::getUncached(IRGenModule &IGM,
CanSILFunctionType formalType) {
GenericContextScope scope(IGM, formalType->getGenericSignature());
SignatureExpansion expansion(IGM, formalType);
expansion.expandFunctionType();
return expansion.getSignature();
}
ॲཧΛܕʹΓग़͍ͯ͠Δ
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Signature Signature::getUncached(IRGenModule &IGM,
CanSILFunctionType formalType) {
GenericContextScope scope(IGM, formalType->getGenericSignature());
SignatureExpansion expansion(IGM, formalType);
expansion.expandFunctionType();
return expansion.getSignature();
}
ؔͷܕΛੜ
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void SignatureExpansion::expandFunctionType() {
switch (FnType->getLanguage()) {
case SILFunctionLanguage::Swift: {
expandResult();
expandParameters();
return;
}
case SILFunctionLanguage::C:
expandExternalSignatureTypes();
return;
}
llvm_unreachable("bad abstract calling convention");
}
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void SignatureExpansion::expandFunctionType() {
switch (FnType->getLanguage()) {
case SILFunctionLanguage::Swift: {
expandResult();
expandParameters();
return;
}
case SILFunctionLanguage::C:
expandExternalSignatureTypes();
return;
}
llvm_unreachable("bad abstract calling convention");
}
ฦΓͷܕΛੜ
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void SignatureExpansion::expandFunctionType() {
switch (FnType->getLanguage()) {
case SILFunctionLanguage::Swift: {
expandResult();
expandParameters();
return;
}
case SILFunctionLanguage::C:
expandExternalSignatureTypes();
return;
}
llvm_unreachable("bad abstract calling convention");
}
ҾͷܕΛੜ
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void SignatureExpansion::expandParameters() {
assert(FnType->getRepresentation() != SILFunctionTypeRepresentation::Block
&& "block with non-C calling conv?!");
// First, if this is a coroutine, add the coroutine-context parameter.
switch (FnType->getCoroutineKind()) {
case SILCoroutineKind::None:
break;
case SILCoroutineKind::YieldOnce:
case SILCoroutineKind::YieldMany:
addCoroutineContextParameter();
break;
}
// Next, the formal parameters. But 'self' is treated as the
// context if it has pointer representation.
auto params = FnType->getParameters();
bool hasSelfContext = false;
if (hasSelfContextParameter(FnType)) {
hasSelfContext = true;
params = params.drop_back();
}
for (auto param : params) {
expand(param);
}
// Next, the generic signature.
if (hasPolymorphicParameters(FnType))
expandPolymorphicSignature(IGM, FnType, ParamIRTypes);
// Context is next.
if (hasSelfContext) {
auto curLength = ParamIRTypes.size(); (void) curLength;
if (claimSelf())
IGM.addSwiftSelfAttributes(Attrs, curLength);
expand(FnType->getSelfParameter());
assert(ParamIRTypes.size() == curLength + 1 &&
"adding 'self' added unexpected number of parameters");
} else {
auto needsContext = [=]() -> bool {
switch (FnType->getRepresentation()) {
case SILFunctionType::Representation::Block:
llvm_unreachable("adding block parameter in Swift CC expansion?");
// Always leave space for a context argument if we have an error result.
case SILFunctionType::Representation::CFunctionPointer:
case SILFunctionType::Representation::Method:
case SILFunctionType::Representation::WitnessMethod:
case SILFunctionType::Representation::ObjCMethod:
case SILFunctionType::Representation::Thin:
case SILFunctionType::Representation::Closure:
return FnType->hasErrorResult();
case SILFunctionType::Representation::Thick:
return true;
}
llvm_unreachable("bad representation kind");
};
if (needsContext()) {
if (claimSelf())
IGM.addSwiftSelfAttributes(Attrs, ParamIRTypes.size());
ParamIRTypes.push_back(IGM.RefCountedPtrTy);
}
}
// Error results are last. We always pass them as a pointer to the
// formal error type; LLVM will magically turn this into a non-pointer
// if we set the right attribute.
if (FnType->hasErrorResult()) {
if (claimError())
IGM.addSwiftErrorAttributes(Attrs, ParamIRTypes.size());
llvm::Type *errorType = IGM.getStorageType(
getSILFuncConventions().getSILType(FnType->getErrorResult()));
ParamIRTypes.push_back(errorType->getPointerTo());
}
// Witness methods have some extra parameter types.
if (FnType->getRepresentation() ==
SILFunctionTypeRepresentation::WitnessMethod) {
expandTrailingWitnessSignature(IGM, FnType, ParamIRTypes);
}
}
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void SignatureExpansion::expandParameters() {
...
auto params = FnType->getParameters();
...
for (auto param : params) {
expand(param);
}
// Next, the generic signature.
if (hasPolymorphicParameters(FnType))
expandPolymorphicSignature(IGM, FnType, ParamIRTypes);
...
}
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void SignatureExpansion::expandParameters() {
...
auto params = FnType->getParameters();
...
for (auto param : params) {
expand(param);
}
// Next, the generic signature.
if (hasPolymorphicParameters(FnType))
expandPolymorphicSignature(IGM, FnType, ParamIRTypes);
...
}
SILؔͷҾͦΕͧΕʹ͍ͭͯɺ
LLVM-IRؔͷҾΛੜ
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void SignatureExpansion::expandParameters() {
...
auto params = FnType->getParameters();
...
for (auto param : params) {
expand(param);
}
// Next, the generic signature.
if (hasPolymorphicParameters(FnType))
expandPolymorphicSignature(IGM, FnType, ParamIRTypes);
...
}
δΣωϦΫεͷใʹ͍ͭͯɺ
LLVM-IRؔͷҾΛੜ
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void irgen::expandPolymorphicSignature(IRGenModule &IGM,
CanSILFunctionType polyFn,
SmallVectorImpl &out) {
ExpandPolymorphicSignature(IGM, polyFn).expand(out);
}
ॲཧΛܕʹΓग़͍ͯ͠Δ
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class ExpandPolymorphicSignature : public PolymorphicConvention {
...
void expand(SmallVectorImpl &out) {
...
enumerateUnfulfilledRequirements([&](GenericRequirement reqt) {
out.push_back(reqt.Protocol ? IGM.WitnessTablePtrTy
: IGM.TypeMetadataPtrTy);
});
}
...
}
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class ExpandPolymorphicSignature : public PolymorphicConvention {
...
void expand(SmallVectorImpl &out) {
...
enumerateUnfulfilledRequirements([&](GenericRequirement reqt) {
out.push_back(reqt.Protocol ? IGM.WitnessTablePtrTy
: IGM.TypeMetadataPtrTy);
});
}
...
}
δΣωϦοΫύϥϝʔλͱɺϓϩτίϧ੍ʹ͍ͭͯ܁Γฦ
͢ɻ
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class ExpandPolymorphicSignature : public PolymorphicConvention {
...
void expand(SmallVectorImpl &out) {
...
enumerateUnfulfilledRequirements([&](GenericRequirement reqt) {
out.push_back(reqt.Protocol ? IGM.WitnessTablePtrTy
: IGM.TypeMetadataPtrTy);
});
}
...
}
IGM.TypeMetadataPtrTy = %swift.type*
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͜͜·Ͱ·ͱΊ
ܕύϥϝʔλίϯύΠϧޙܕͷใΛද͢ͷҾʹͳΔ
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X ͷऔѻ
• X ΛऔΓѻ͏ͨΊͷใ͕ɺҾͰ͞ΕΔ
• ͲΜͳใʁ
• X ΛऔΓѻ͏ ͱԿ͔ʁ
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X ʹରͯ͠Կ͕Ͱ͖Δʁ
func takeX(_ x: X) {
...
}
• ϝιουݺͳ͍
• initͰ͖ͳ͍
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X ʹରͯ͠Ͱ͖Δ͜ͱ
func take(_ x: X) {
let x2: X = x
}
• ֓Ͷ͜ΕͰશͯ
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func take(_ x: X) {
let x2: X = x
}
• x2ͷྖҬͷ֬อ
• x2ͷίϐʔ
• x2ͷഁغ (ؔग़࣌)
• x2ͷྖҬͷղ์ (ؔग़࣌)
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ྖҬͷ֬อʹඞཁͳใ
• ܕͷαΠζͱΞϥΠϝϯτ
• ղ์֬อ࣌ͷใͷΈͰOK
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ίϐʔͱഁغʹඞཁͳૢ࡞
ࢀরܕͷ߹: retain countૢ࡞
ܕͷ߹: stored property ͝ͱʹૢ࡞
struct Entry {
var id: Int
var name: String
var view: UIView
}
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Value Witness Table
• ܕΛऔΓѻ͏ͨΊͷؔΛఆٛͨ͠ςʔϒϧ
• ܕ͝ͱʹ1ͭఆٛ
• ϝλλΠϓ(Int.self ͳͲ)͔ΒऔΓग़ͤΔ
https://github.com/apple/swift/blob/master/docs/ABI/
TypeMetadata.rst
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Value Witness Table ͷٙࣅίʔυ
var vwt = VWT()
vwt[0] = ...
vwt[1] = destroy
vwt[2] = initializeWithCopy
vwt[3] = assignWithCopy
vwt[4] = initializeWithTake
vwt[5] = assignWithTake
vwt[6] = ...
vwt[7] = ...
vwt[8] = size
vwt[9] = flags (alignment)
vwt[10] = stride
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4ͭͷίϐʔ
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• ίϐʔઌ ͕ະॳظԽ͔Ͳ͏͔ɻ
• ະॳظԽ: initialize
• ॳظԽࡁΈ: assign
• ίϐʔݩ Λഁغ͢Δ͔Ͳ͏͔ɻ
• ഁغ͠ͳ͍: copy
• ഁغ͢Δ: take
• 2x2ͷΈ߹ΘͤͰ4छྨ
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Έ߹Θͤͷྫ
initializeWithTake
• initialize: ະॳظԽͷίϐʔઌΛॳظԽ͢Δ
• take: ίϐʔݩഁغ͢Δ
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Value Witness Table ΛௐΔ
• ༻͢Δଆ, ݺͼग़͞Εଆ
• ݺͼग़͠ଆ
• ςʔϒϧͷੜॲཧ
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Value Witness Table
༻͢Δଆ, Swift
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func takeX(_ x: X) {
let x2 = x
}
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Value Witness Table
༻͢Δଆ, SIL
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Value Witness Table
༻͢Δଆ, LLVM-IR
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define hidden swiftcc void @"$S3aaa5takeXyyxlF"(%swift.opaque* noalias nocapture, %swift.type* %X) #0 {
entry:
%X1 = alloca %swift.type*, align 8
%x2.addr = alloca i8*, align 8
%1 = bitcast i8** %x2.addr to %swift.opaque**
store %swift.opaque* null, %swift.opaque** %1, align 8
store %swift.type* %X, %swift.type** %X1, align 8
%2 = bitcast %swift.type* %X to i8***
%3 = getelementptr inbounds i8**, i8*** %2, i64 -1
%X.valueWitnesses = load i8**, i8*** %3, align 8, !invariant.load !13, !dereferenceable !14
%4 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 8
%5 = load i8*, i8** %4, align 8, !invariant.load !13
%size = ptrtoint i8* %5 to i64
%x2 = alloca i8, i64 %size, align 16
call void @llvm.lifetime.start.p0i8(i64 -1, i8* %x2)
%6 = bitcast i8* %x2 to %swift.opaque*
store i8* %x2, i8** %x2.addr, align 8
%7 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 2
%8 = load i8*, i8** %7, align 8, !invariant.load !13
%initializeWithCopy = bitcast i8* %8 to %swift.opaque* (%swift.opaque*, %swift.opaque*, %swift.type*)*
%9 = call %swift.opaque* %initializeWithCopy(%swift.opaque* noalias %6, %swift.opaque* noalias %0, %swift.type* %X) #3
%10 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 1
%11 = load i8*, i8** %10, align 8, !invariant.load !13
%destroy = bitcast i8* %11 to void (%swift.opaque*, %swift.type*)*
call void %destroy(%swift.opaque* noalias %6, %swift.type* %X) #3
%12 = bitcast %swift.opaque* %6 to i8*
call void @llvm.lifetime.end.p0i8(i64 -1, i8* %12)
ret void
}
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define hidden swiftcc void @"$S3aaa5takeXyyxlF"(
%swift.opaque* noalias nocapture, %swift.type* %X) #0 {
entry:
%X1 = alloca %swift.type*, align 8
%x2.addr = alloca i8*, align 8
%1 = bitcast i8** %x2.addr to %swift.opaque**
store %swift.opaque* null, %swift.opaque** %1, align 8
store %swift.type* %X, %swift.type** %X1, align 8
%2 = bitcast %swift.type* %X to i8***
%3 = getelementptr inbounds i8**, i8*** %2, i64 -1
%X.valueWitnesses = load i8**, i8*** %3, align 8,
!invariant.load !13, !dereferenceable !14
%4 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 8
%5 = load i8*, i8** %4, align 8, !invariant.load !13
%size = ptrtoint i8* %5 to i64
%x2 = alloca i8, i64 %size, align 16
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define hidden swiftcc void @"$S3aaa5takeXyyxlF"(
%swift.opaque* noalias nocapture, %swift.type* %X) #0 {
entry:
%X1 = alloca %swift.type*, align 8
%x2.addr = alloca i8*, align 8
%1 = bitcast i8** %x2.addr to %swift.opaque**
store %swift.opaque* null, %swift.opaque** %1, align 8
store %swift.type* %X, %swift.type** %X1, align 8
%2 = bitcast %swift.type* %X to i8***
%3 = getelementptr inbounds i8**, i8*** %2, i64 -1
%X.valueWitnesses = load i8**, i8*** %3, align 8,
!invariant.load !13, !dereferenceable !14
%4 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 8
%5 = load i8*, i8** %4, align 8, !invariant.load !13
%size = ptrtoint i8* %5 to i64
%x2 = alloca i8, i64 %size, align 16
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var vwt = VWT()
vwt[0] = ...
vwt[1] = destroy
vwt[2] = initializeWithCopy
vwt[3] = assignWithCopy
vwt[4] = initializeWithTake
vwt[5] = assignWithTake
vwt[6] = ...
vwt[7] = ...
vwt[8] = size
vwt[9] = flags (alignment)
vwt[10] = stride
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%x2 = alloca i8, i64 %size, align 16
call void @llvm.lifetime.start.p0i8(i64 -1, i8* %x2)
%6 = bitcast i8* %x2 to %swift.opaque*
store i8* %x2, i8** %x2.addr, align 8
%7 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 2
%8 = load i8*, i8** %7, align 8, !invariant.load !13
%initializeWithCopy = bitcast i8* %8 to
%swift.opaque* (%swift.opaque*, %swift.opaque*, %swift.type*)*
%9 = call %swift.opaque* %initializeWithCopy(
%swift.opaque* noalias %6, %swift.opaque* noalias %0, %swift.type* %X) #3
%10 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 1
%11 = load i8*, i8** %10, align 8, !invariant.load !13
%destroy = bitcast i8* %11 to void (%swift.opaque*, %swift.type*)*
call void %destroy(%swift.opaque* noalias %6, %swift.type* %X) #3
%12 = bitcast %swift.opaque* %6 to i8*
call void @llvm.lifetime.end.p0i8(i64 -1, i8* %12)
ret void
}
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var vwt = VWT()
vwt[0] = ...
vwt[1] = destroy
vwt[2] = initializeWithCopy
vwt[3] = assignWithCopy
vwt[4] = initializeWithTake
vwt[5] = assignWithTake
vwt[6] = ...
vwt[7] = ...
vwt[8] = size
vwt[9] = flags (alignment)
vwt[10] = stride
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%x2 = alloca i8, i64 %size, align 16
call void @llvm.lifetime.start.p0i8(i64 -1, i8* %x2)
%6 = bitcast i8* %x2 to %swift.opaque*
store i8* %x2, i8** %x2.addr, align 8
%7 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 2
%8 = load i8*, i8** %7, align 8, !invariant.load !13
%initializeWithCopy = bitcast i8* %8 to
%swift.opaque* (%swift.opaque*, %swift.opaque*, %swift.type*)*
%9 = call %swift.opaque* %initializeWithCopy(
%swift.opaque* noalias %6, %swift.opaque* noalias %0, %swift.type* %X) #3
%10 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 1
%11 = load i8*, i8** %10, align 8, !invariant.load !13
%destroy = bitcast i8* %11 to void (%swift.opaque*, %swift.type*)*
call void %destroy(%swift.opaque* noalias %6, %swift.type* %X) #3
%12 = bitcast %swift.opaque* %6 to i8*
call void @llvm.lifetime.end.p0i8(i64 -1, i8* %12)
ret void
}
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var vwt = VWT()
vwt[0] = ...
vwt[1] = destroy
vwt[2] = initializeWithCopy
vwt[3] = assignWithCopy
vwt[4] = initializeWithTake
vwt[5] = assignWithTake
vwt[6] = ...
vwt[7] = ...
vwt[8] = size
vwt[9] = flags (alignment)
vwt[10] = stride
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Value Witness Table
༻͢Δଆ, ίϯύΠϥ
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IRGenSILFunction
VisitorύλʔϯͰSIL໋ྩ͝ͱʹม
void IRGenSILFunction::visitCopyAddrInst(swift::CopyAddrInst *i)
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void IRGenSILFunction::visitCopyAddrInst(swift::CopyAddrInst *i) {
SILType addrTy = i->getSrc()->getType();
const TypeInfo &addrTI = getTypeInfo(addrTy);
Address src = getLoweredAddress(i->getSrc());
// See whether we have a deferred fixed-size buffer initialization.
auto &loweredDest = getLoweredValue(i->getDest());
assert(!loweredDest.isUnallocatedAddressInBuffer());
Address dest = loweredDest.getAnyAddress();
if (i->isInitializationOfDest()) {
if (i->isTakeOfSrc()) {
addrTI.initializeWithTake(*this, dest, src, addrTy, false);
} else {
addrTI.initializeWithCopy(*this, dest, src, addrTy, false);
}
} else {
if (i->isTakeOfSrc()) {
addrTI.assignWithTake(*this, dest, src, addrTy, false);
} else {
addrTI.assignWithCopy(*this, dest, src, addrTy, false);
}
}
}
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void IRGenSILFunction::visitCopyAddrInst(swift::CopyAddrInst *i) {
SILType addrTy = i->getSrc()->getType();
const TypeInfo &addrTI = getTypeInfo(addrTy);
Address src = getLoweredAddress(i->getSrc());
// See whether we have a deferred fixed-size buffer initialization.
auto &loweredDest = getLoweredValue(i->getDest());
assert(!loweredDest.isUnallocatedAddressInBuffer());
Address dest = loweredDest.getAnyAddress();
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if (i->isInitializationOfDest()) {
if (i->isTakeOfSrc()) {
addrTI.initializeWithTake(*this, dest, src, addrTy, false);
} else {
addrTI.initializeWithCopy(*this, dest, src, addrTy, false);
}
} else {
if (i->isTakeOfSrc()) {
addrTI.assignWithTake(*this, dest, src, addrTy, false);
} else {
addrTI.assignWithCopy(*this, dest, src, addrTy, false);
}
}
}
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TypeInfo
ΫϥεܧঝΛͬͯܕͷྨ͝ͱʹ
ίϯύΠϧॲཧΛΓସ͑Δɻ
struct: LoadableStructTypeInfo
class: ClassTypeInfo
: OpaqueArchetypeTypeInfo
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OpaqueArchetypeTypeInfo
initializeWithCopyΫϥεͷ
ResilientTypeInfoͷ࣮Λܧঝɻ
template
class ResilientTypeInfo {
...
void initializeWithCopy(IRGenFunction &IGF, Address dest, Address src,
SILType T, bool isOutlined) const override {
emitInitializeWithCopyCall(IGF, T, dest, src);
}
...
};
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void irgen::emitInitializeWithCopyCall(IRGenFunction &IGF,
SILType T,
Address dest,
Address src) {
llvm::Value *metadata;
auto fn = IGF.emitValueWitnessFunctionRef(T, metadata,
ValueWitness::InitializeWithCopy);
auto destPtr = emitCastToOpaquePtr(IGF, dest);
auto srcPtr = emitCastToOpaquePtr(IGF, src);
IGF.Builder.CreateCall(fn, {destPtr, srcPtr, metadata});
}
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C++
auto fn = IGF.emitValueWitnessFunctionRef(T, metadata,
ValueWitness::InitializeWithCopy);
auto destPtr = emitCastToOpaquePtr(IGF, dest);
auto srcPtr = emitCastToOpaquePtr(IGF, src);
IGF.Builder.CreateCall(fn, {destPtr, srcPtr, metadata});
LLVM-IR
%7 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 2
%8 = load i8*, i8** %7, align 8, !invariant.load !13
%initializeWithCopy = bitcast i8* %8 to
%swift.opaque* (%swift.opaque*, %swift.opaque*, %swift.type*)*
%9 = call %swift.opaque* %initializeWithCopy(
%swift.opaque* noalias %6, %swift.opaque* noalias %0, %swift.type* %X) #3
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C++
auto fn = IGF.emitValueWitnessFunctionRef(T, metadata,
ValueWitness::InitializeWithCopy);
auto destPtr = emitCastToOpaquePtr(IGF, dest);
auto srcPtr = emitCastToOpaquePtr(IGF, src);
IGF.Builder.CreateCall(fn, {destPtr, srcPtr, metadata});
LLVM-IR
%7 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 2
%8 = load i8*, i8** %7, align 8, !invariant.load !13
%initializeWithCopy = bitcast i8* %8 to
%swift.opaque* (%swift.opaque*, %swift.opaque*, %swift.type*)*
%9 = call %swift.opaque* %initializeWithCopy(
%swift.opaque* noalias %6, %swift.opaque* noalias %0, %swift.type* %X) #3
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FunctionPointer
IRGenFunction::emitValueWitnessFunctionRef(SILType type,
llvm::Value *&metadataSlot,
ValueWitness index) {
assert(isValueWitnessFunction(index));
auto key = LocalTypeDataKind::forValueWitness(index);
if (auto witness = tryGetLocalTypeDataForLayout(type, key)) {
metadataSlot = emitTypeMetadataRefForLayout(type);
auto signature = IGM.getValueWitnessSignature(index);
return FunctionPointer(witness, signature);
}
auto vwtable = emitValueWitnessTableRef(type, &metadataSlot);
auto witness = emitLoadOfValueWitnessFunction(*this, vwtable, index);
setScopedLocalTypeDataForLayout(type, key, witness.getPointer());
return witness;
}
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FunctionPointer
IRGenFunction::emitValueWitnessFunctionRef(SILType type,
llvm::Value *&metadataSlot,
ValueWitness index) {
...
auto vwtable = emitValueWitnessTableRef(type, &metadataSlot);
auto witness = emitLoadOfValueWitnessFunction(*this, vwtable, index);
...
return witness;
}
ValueWitness::InitializeWithCopy == 2
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static FunctionPointer emitLoadOfValueWitnessFunction(IRGenFunction &IGF,
llvm::Value *table,
ValueWitness index) {
assert(isValueWitnessFunction(index));
llvm::Value *witness = emitInvariantLoadOfOpaqueWitness(IGF, table, index);
auto label = getValueWitnessLabel(index);
auto signature = IGF.IGM.getValueWitnessSignature(index);
auto type = signature.getType()->getPointerTo();
witness = IGF.Builder.CreateBitCast(witness, type, label);
return FunctionPointer(witness, signature);
}
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C++
llvm::Value *witness = emitInvariantLoadOfOpaqueWitness(IGF, table, index);
auto label = getValueWitnessLabel(index);
auto signature = IGF.IGM.getValueWitnessSignature(index);
auto type = signature.getType()->getPointerTo();
witness = IGF.Builder.CreateBitCast(witness, type, label);
return FunctionPointer(witness, signature);
LLVM-IR
%7 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 2
%8 = load i8*, i8** %7, align 8, !invariant.load !13
%initializeWithCopy = bitcast i8* %8 to
%swift.opaque* (%swift.opaque*, %swift.opaque*, %swift.type*)*
%9 = call %swift.opaque* %initializeWithCopy(
%swift.opaque* noalias %6, %swift.opaque* noalias %0, %swift.type* %X) #3
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C++
llvm::Value *witness = emitInvariantLoadOfOpaqueWitness(IGF, table, index);
auto label = getValueWitnessLabel(index);
auto signature = IGF.IGM.getValueWitnessSignature(index);
auto type = signature.getType()->getPointerTo();
witness = IGF.Builder.CreateBitCast(witness, type, label);
return FunctionPointer(witness, signature);
LLVM-IR
%7 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 2
%8 = load i8*, i8** %7, align 8, !invariant.load !13
%initializeWithCopy = bitcast i8* %8 to
%swift.opaque* (%swift.opaque*, %swift.opaque*, %swift.type*)*
%9 = call %swift.opaque* %initializeWithCopy(
%swift.opaque* noalias %6, %swift.opaque* noalias %0, %swift.type* %X) #3
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llvm::Value *irgen::emitInvariantLoadOfOpaqueWitness(IRGenFunction &IGF,
llvm::Value *table,
WitnessIndex index) {
assert(table->getType() == IGF.IGM.WitnessTablePtrTy);
// GEP to the appropriate index, avoiding spurious IR in the trivial case.
llvm::Value *slot = table;
if (index.getValue() != 0)
slot = IGF.Builder.CreateConstInBoundsGEP1_32(
/*Ty=*/nullptr, table, index.getValue());
auto witness =
IGF.Builder.CreateLoad(Address(slot, IGF.IGM.getPointerAlignment()));
IGF.setInvariantLoad(witness);
return witness;
}
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C++; index.getValue() == 2
// GEP to the appropriate index, avoiding spurious IR in the trivial case.
llvm::Value *slot = table;
if (index.getValue() != 0)
slot = IGF.Builder.CreateConstInBoundsGEP1_32(
/*Ty=*/nullptr, table, index.getValue());
auto witness =
IGF.Builder.CreateLoad(Address(slot, IGF.IGM.getPointerAlignment()));
IGF.setInvariantLoad(witness);
return witness;
LLVM-IR
%7 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 2
%8 = load i8*, i8** %7, align 8, !invariant.load !13
%initializeWithCopy = bitcast i8* %8 to
%swift.opaque* (%swift.opaque*, %swift.opaque*, %swift.type*)*
%9 = call %swift.opaque* %initializeWithCopy(
%swift.opaque* noalias %6, %swift.opaque* noalias %0, %swift.type* %X) #3
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C++
// GEP to the appropriate index, avoiding spurious IR in the trivial case.
llvm::Value *slot = table;
if (index.getValue() != 0)
slot = IGF.Builder.CreateConstInBoundsGEP1_32(
/*Ty=*/nullptr, table, index.getValue());
auto witness =
IGF.Builder.CreateLoad(Address(slot, IGF.IGM.getPointerAlignment()));
IGF.setInvariantLoad(witness);
return witness;
LLVM-IR
%7 = getelementptr inbounds i8*, i8** %X.valueWitnesses, i32 2
%8 = load i8*, i8** %7, align 8, !invariant.load !13
%initializeWithCopy = bitcast i8* %8 to
%swift.opaque* (%swift.opaque*, %swift.opaque*, %swift.type*)*
%9 = call %swift.opaque* %initializeWithCopy(
%swift.opaque* noalias %6, %swift.opaque* noalias %0, %swift.type* %X) #3
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Value Witness Table
• ݺͼग़͠ଆ
• ςʔϒϧͷੜ
λΠϜΞοϓ
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·ͱΊ
• δΣωϦοΫύϥϝʔλ࣮ߦ࣌ʹܕใͷҾʹͳΔ
• ܕใʹ Value Witness Table ͕ೖ͍ͬͯͯɺ
औΓѻ͏ͨΊͷؔ܈͕ೖ͍ͬͯΔɻ
• Swift࣮தؒग़ྗͱίϯύΠϥιʔεͷ྆ํ͔Βֶ΅͏ɻ
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એ
Θ͍Θ͍swiftc: SwiftίϯύΠϥͷษڧձ
https://iosdiscord.connpass.com/event/92738/
࣍ճ ୈ5ճ 9/12
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એ
Θ͍Θ͍swiftc: SwiftίϯύΠϥͷษڧձ
https://iosdiscord.connpass.com/event/92738/
࣍ճ ୈ5ճ 9/12
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એ
Θ͍Θ͍swiftc: SwiftίϯύΠϥͷษڧձ
https://iosdiscord.connpass.com/event/92738/
͜ͷ͋ͱ͙͢ʂ
࣍࣍ճ ୈ5ճ 9/12
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