[CHERIoT] Add the __builtin_cheriot_sealing_type clang built-in
#169
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clang/lib/CodeGen/CGBuiltin.cpp
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| if (!GV) { | ||
| llvm::StructType *opaqueType = llvm::StructType::create( | ||
| CGM.getModule().getContext(), "__Opaque_" + SealingTypeName); |
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Do we need to define a new type here? The global should just be opaque.
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It appears to me that there is no built-in opaque struct type that can be used this way. So, this PR now produces a new type only once. I also added a comment explaining the role of the global.
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clang/lib/CodeGen/CGBuiltin.cpp
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| auto PrefixedImportName = | ||
| CHERIoTSealingKeyTypeAttr::getSealingTypeSymbolName(CompartmentName, | ||
| SealingTypeName); | ||
| auto *Mod = &CGM.getModule(); |
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No need to take the address here
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= CGM.getModule() uses a deleted constructor:
llvm-project/clang/lib/CodeGen/CGBuiltin.cpp:6166:10: error: call to implicitly-deleted copy constructor of 'llvm::Module'
6166 | auto Mod = CGM.getModule();
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The way to do it is auto &Mod = CGM.getModule();
| struct CompartmentExport { | ||
| /// The compartment name for the object. | ||
| std::string CompartmentName; | ||
| std::variant<FunctionCompartmentExport, SealingKeyCompartmentExport> Object; |
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Alternatively, you could just have two vectors, one for FunctionCompartmentExport's and one for SealingKeyCompartmentExport's ;-)
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Latest commit also adds a warning emitted when the built-in is used but no compartment name is given. |
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Any particular reason it's a warning rather than an error? |
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I made into an error with the latest commit. Indeed, it would not make any sense to generate symbols in the |
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This PR introduces a new
__builtin_cheriot_sealing_typebuilt-in command in clang, that should replace theCHERIOT_EMIT_STATIC_SEALING_TYPEmacro, as referenced in #6:Note that, differently from the suggested syntax in the issue quoted above, the built-in uses a string to specify the name of the type, rather than using a raw identifier. This choice was made in order to avoid inserting custom code in the parser.
The side effects of this call is that two new entries,
and
are generated, respectively in the
.compartment_importsand.compartment_exportssections. The value of the import is a sequence of two words: the address of the export and0. The value of the export reproduces the value generated in the original macro.