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Disable AST type caching for SILFunctionTypes since the mapping isn't #2245

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Merged
merged 1 commit into from
Dec 15, 2020
Merged

Disable AST type caching for SILFunctionTypes since the mapping isn't #2245

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18 changes: 11 additions & 7 deletions lldb/source/Plugins/TypeSystem/Swift/SwiftASTContext.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4180,7 +4180,7 @@ void SwiftASTContext::CacheDemangledTypeFailure(ConstString name) {
/// What we should really do is only mangle AST types in DebugInfo, but that
/// requires some more plumbing on the Swift side to properly handle generic
/// specializations.
swift::Type convertSILFunctionTypesToASTFunctionTypes(swift::Type t) {
static swift::Type ConvertSILFunctionTypesToASTFunctionTypes(swift::Type t) {
return t.transform([](swift::Type t) -> swift::Type {
if (auto *silFn = t->getAs<swift::SILFunctionType>())
return swift::FunctionType::get({}, t->getASTContext().TheEmptyTupleType);
Expand Down Expand Up @@ -4300,14 +4300,18 @@ swift::TypeBase *SwiftASTContext::ReconstructType(ConstString mangled_typename,
.getPointer();

if (found_type) {
found_type =
convertSILFunctionTypesToASTFunctionTypes(found_type).getPointer();
CacheDemangledType(mangled_typename, found_type);
CompilerType result_type = ToCompilerType(found_type);
assert(&found_type->getASTContext() == ast_ctx);
swift::TypeBase *ast_type =
ConvertSILFunctionTypesToASTFunctionTypes(found_type).getPointer();
// This transformation is lossy: all SILFunction types are mapped
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Can we just get rid of this mapping? IIRC, the old type reconstruction code didn't handle SILFunctionType at all, always returning () -> (). When I implemented full type reconstruction, there were a few places in lldb that weren't set up to handle a SILFunctionType so I added this hack to get the old behavior back. We should just remove it.

// to the same AST type. We thus cannot cache the result, since
// the mapping isn't bijective.
if (ast_type == found_type)
CacheDemangledType(mangled_typename, ast_type);
CompilerType result_type = ToCompilerType(ast_type);
assert(&ast_type->getASTContext() == ast_ctx);
LOG_PRINTF(LIBLLDB_LOG_TYPES, "(\"%s\") -- found %s", mangled_cstr,
result_type.GetTypeName().GetCString());
return found_type;
return ast_type;
}

LOG_PRINTF(LIBLLDB_LOG_TYPES, "(\"%s\") -- not found", mangled_cstr);
Expand Down
6 changes: 6 additions & 0 deletions lldb/source/Plugins/TypeSystem/Swift/TypeSystemSwiftTypeRef.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1420,6 +1420,12 @@ static bool ContainsSugaredParen(swift::Demangle::NodePointer node) {
/// Compare two swift types from different type systems by comparing their
/// (canonicalized) mangled name.
template <> bool Equivalent<CompilerType>(CompilerType l, CompilerType r) {
// See comments in SwiftASTContext::ReconstructType(). For
// SILFunctionTypes the mapping isn't bijective.
auto *ast_ctx = llvm::cast<SwiftASTContext>(r.GetTypeSystem());
if (((void *)ast_ctx->ReconstructType(l.GetMangledTypeName())) ==
r.GetOpaqueQualType())
return true;
ConstString lhs = l.GetMangledTypeName();
ConstString rhs = r.GetMangledTypeName();
if (lhs == ConstString("$sSiD") && rhs == ConstString("$sSuD"))
Expand Down