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[IRGen][interop] do not add 'nocapture' to not bitwise takable types

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The use of 'nocapture' for parameters and return values is incorrect for C++ types, as they can actually capture a pointer into its own value (e.g. std::string in libstdc++)

rdar://115062687
This commit is contained in:
Alex Lorenz
2023-09-12 18:18:10 -07:00
parent 79cdadf93d
commit 4858cb6225
161 changed files with 396 additions and 384 deletions
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34
lib/IRGen/GenCall.cpp
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@@ -266,7 +266,10 @@ static void addIndirectValueParameterAttributes(IRGenModule &IGM,
llvm::AttrBuilder b(IGM.getLLVMContext());
// Value parameter pointers can't alias or be captured.
b.addAttribute(llvm::Attribute::NoAlias);
b.addAttribute(llvm::Attribute::NoCapture);
// Bitwise takable value types are guaranteed not to capture
// a pointer into itself.
if (ti.isBitwiseTakable(ResilienceExpansion::Maximal))
b.addAttribute(llvm::Attribute::NoCapture);
// The parameter must reference dereferenceable memory of the type.
addDereferenceableAttributeToBuilder(IGM, b, ti);
@@ -278,9 +281,11 @@ static void addPackParameterAttributes(IRGenModule &IGM,
llvm::AttributeList &attrs,
unsigned argIndex) {
llvm::AttrBuilder b(IGM.getLLVMContext());
// Pack parameter pointers can't alias or be captured.
// Pack parameter pointers can't alias.
// Note: they are not marked `nocapture` as one
// pack parameter could be a value type (e.g. a C++ type)
// that captures its own pointer in itself.
b.addAttribute(llvm::Attribute::NoAlias);
b.addAttribute(llvm::Attribute::NoCapture);
// TODO: we could mark this dereferenceable when the pack has fixed
// components.
// TODO: add an alignment attribute
@@ -301,8 +306,10 @@ static void addInoutParameterAttributes(IRGenModule &IGM, SILType paramSILType,
// attribute if it's a pointer being passed inout.
b.addAttribute(llvm::Attribute::NoAlias);
}
// Aliasing inouts can't be captured without doing unsafe stuff.
b.addAttribute(llvm::Attribute::NoCapture);
// Bitwise takable value types are guaranteed not to capture
// a pointer into itself.
if (ti.isBitwiseTakable(ResilienceExpansion::Maximal))
b.addAttribute(llvm::Attribute::NoCapture);
// The inout must reference dereferenceable memory of the type.
addDereferenceableAttributeToBuilder(IGM, b, ti);
@@ -341,10 +348,14 @@ llvm::CallingConv::ID irgen::expandCallingConv(IRGenModule &IGM,
static void addIndirectResultAttributes(IRGenModule &IGM,
llvm::AttributeList &attrs,
unsigned paramIndex, bool allowSRet,
llvm::Type *storageType) {
llvm::Type *storageType,
const TypeInfo &typeInfo) {
llvm::AttrBuilder b(IGM.getLLVMContext());
b.addAttribute(llvm::Attribute::NoAlias);
b.addAttribute(llvm::Attribute::NoCapture);
// Bitwise takable value types are guaranteed not to capture
// a pointer into itself.
if (typeInfo.isBitwiseTakable(ResilienceExpansion::Maximal))
b.addAttribute(llvm::Attribute::NoCapture);
if (allowSRet) {
assert(storageType);
b.addStructRetAttr(storageType);
@@ -509,7 +520,7 @@ llvm::Type *SignatureExpansion::addIndirectResult() {
const TypeInfo &resultTI = IGM.getTypeInfo(resultType);
auto storageTy = resultTI.getStorageType();
addIndirectResultAttributes(IGM, Attrs, ParamIRTypes.size(), claimSRet(),
storageTy);
storageTy, resultTI);
addPointerParameter(storageTy);
return IGM.VoidTy;
}
@@ -568,11 +579,12 @@ void SignatureExpansion::expandIndirectResults() {
auto useSRet = claimSRet();
// We need to use opaque types or non fixed size storage types because llvm
// does type based analysis based on the type of sret arguments.
if (useSRet && !isa<FixedTypeInfo>(IGM.getTypeInfo(indirectResultType))) {
const TypeInfo &typeInfo = IGM.getTypeInfo(indirectResultType);
if (useSRet && !isa<FixedTypeInfo>(typeInfo)) {
storageTy = IGM.OpaqueTy;
}
addIndirectResultAttributes(IGM, Attrs, ParamIRTypes.size(), useSRet,
storageTy);
storageTy, typeInfo);
addPointerParameter(storageTy);
}
}
@@ -1459,7 +1471,7 @@ void SignatureExpansion::expandExternalSignatureTypes() {
param, IGM.getMaximalTypeExpansionContext());
auto &paramTI = cast<FixedTypeInfo>(IGM.getTypeInfo(paramTy));
addIndirectResultAttributes(IGM, Attrs, getCurParamIndex(), claimSRet(),
paramTI.getStorageType());
paramTI.getStorageType(), paramTI);
break;
}
}