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IRGen: Add implementation for dynamically replaceable functions

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A dynamically replaceable function calls through a global variable that
holds the function pointer.

struct ChainEntry {
   void *(funPtr)();
   struct ChainEntry *next;
}

ChainEntry dynamicallyReplaceableVar;

void dynamicallyReplaceableFunction() {
  dynamicallyReplaceableVar.funPtr()
}

dynamic replacements will be chainable so the global variable also
functions as the root entry in the chain of replacements.

A dynamic replacement functions can call the previous implementation by
going through its chain entry.

ChainEntry chainEntryOf_dynamic_replacement_for_foo;

void dynamic_replacement_for_foo() {
   // call the previous (original) implementation.
   chainEntryOf_dynamic_replacement_for_foo.funPtr();
}
This commit is contained in:
Arnold Schwaighofer
2018-08-24 07:07:09 -07:00
parent 5f4e183302
commit ebbe3aed1c
14 changed files with 343 additions and 41 deletions
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62
lib/IRGen/Linking.cpp
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@@ -264,8 +264,45 @@ std::string LinkEntity::mangleAsString() const {
return Result;
}
case Kind::SILFunction:
return getSILFunction()->getName();
case Kind::SILFunction: {
std::string Result(getSILFunction()->getName());
if (isDynamicallyReplaceable()) {
Result.append("TI");
}
return Result;
}
case Kind::DynamicallyReplaceableFunctionImpl: {
assert(isa<AbstractFunctionDecl>(getDecl()));
std::string Result;
if (auto *Constructor = dyn_cast<ConstructorDecl>(getDecl())) {
Result = mangler.mangleConstructorEntity(Constructor, true,
/*isCurried=*/false);
} else {
Result = mangler.mangleEntity(getDecl(), /*isCurried=*/false);
}
Result.append("TI");
return Result;
}
case Kind::DynamicallyReplaceableFunctionVariable: {
std::string Result(getSILFunction()->getName());
Result.append("TX");
return Result;
}
case Kind::DynamicallyReplaceableFunctionVariableAST: {
assert(isa<AbstractFunctionDecl>(getDecl()));
std::string Result;
if (auto *Constructor = dyn_cast<ConstructorDecl>(getDecl())) {
Result = mangler.mangleConstructorEntity(Constructor, true,
/*isCurried=*/false);
} else {
Result = mangler.mangleEntity(getDecl(), /*isCurried=*/false);
}
Result.append("TX");
return Result;
}
case Kind::SILGlobalVariable:
return getSILGlobalVariable()->getName();
@@ -494,6 +531,14 @@ SILLinkage LinkEntity::getLinkage(ForDefinition_t forDefinition) const {
case Kind::SILFunction:
return getSILFunction()->getEffectiveSymbolLinkage();
case Kind::DynamicallyReplaceableFunctionImpl:
return getSILLinkage(getDeclLinkage(getDecl()), forDefinition);
case Kind::DynamicallyReplaceableFunctionVariable:
return getSILFunction()->getEffectiveSymbolLinkage();
case Kind::DynamicallyReplaceableFunctionVariableAST:
return getSILLinkage(getDeclLinkage(getDecl()), forDefinition);
case Kind::SILGlobalVariable:
return getSILGlobalVariable()->getLinkage();
@@ -623,6 +668,8 @@ bool LinkEntity::isAvailableExternally(IRGenModule &IGM) const {
case Kind::TypeMetadataPattern:
case Kind::DefaultAssociatedConformanceAccessor:
return false;
case Kind::DynamicallyReplaceableFunctionVariable:
return true;
case Kind::SILFunction:
return ::isAvailableExternally(IGM, getSILFunction());
@@ -647,6 +694,8 @@ bool LinkEntity::isAvailableExternally(IRGenModule &IGM) const {
case Kind::ReflectionFieldDescriptor:
case Kind::ReflectionAssociatedTypeDescriptor:
case Kind::CoroutineContinuationPrototype:
case Kind::DynamicallyReplaceableFunctionVariableAST:
case Kind::DynamicallyReplaceableFunctionImpl:
llvm_unreachable("Relative reference to unsupported link entity");
}
llvm_unreachable("bad link entity kind");
@@ -728,6 +777,8 @@ llvm::Type *LinkEntity::getDefaultDeclarationType(IRGenModule &IGM) const {
case Kind::MethodDescriptorAllocator:
return IGM.MethodDescriptorStructTy;
case Kind::DynamicallyReplaceableFunctionVariable:
return IGM.DynamicReplacementLinkEntryTy;
default:
llvm_unreachable("declaration LLVM type not specified");
}
@@ -768,6 +819,7 @@ Alignment LinkEntity::getAlignment(IRGenModule &IGM) const {
case Kind::ProtocolWitnessTablePattern:
case Kind::ObjCMetaclass:
case Kind::SwiftMetaclassStub:
case Kind::DynamicallyReplaceableFunctionVariable:
return IGM.getPointerAlignment();
case Kind::SILFunction:
return Alignment(1);
@@ -783,6 +835,7 @@ bool LinkEntity::isWeakImported(ModuleDecl *module) const {
return getSILGlobalVariable()->getDecl()->isWeakImported(module);
return false;
case Kind::DynamicallyReplaceableFunctionVariable:
case Kind::SILFunction: {
// For imported functions check the Clang declaration.
if (auto clangOwner = getSILFunction()->getClangNodeOwner())
@@ -833,6 +886,8 @@ bool LinkEntity::isWeakImported(ModuleDecl *module) const {
case Kind::ProtocolDescriptor:
case Kind::ProtocolRequirementsBaseDescriptor:
case Kind::AssociatedTypeDescriptor:
case Kind::DynamicallyReplaceableFunctionVariableAST:
case Kind::DynamicallyReplaceableFunctionImpl:
return getDecl()->isWeakImported(module);
// TODO: Revisit some of the below, for weak conformances.
@@ -905,12 +960,15 @@ const SourceFile *LinkEntity::getSourceFileForEmission() const {
case Kind::AssociatedTypeDescriptor:
case Kind::AssociatedConformanceDescriptor:
case Kind::DefaultAssociatedConformanceAccessor:
case Kind::DynamicallyReplaceableFunctionVariableAST:
case Kind::DynamicallyReplaceableFunctionImpl:
sf = getSourceFileForDeclContext(getDecl()->getDeclContext());
if (!sf)
return nullptr;
break;
case Kind::SILFunction:
case Kind::DynamicallyReplaceableFunctionVariable:
sf = getSourceFileForDeclContext(getSILFunction()->getDeclContext());
if (!sf)
return nullptr;