To be useful, the type metadata described in the previous section needs to be associated with variables of the source program. For a global variable, this is pretty easy. The [...]
To create the debug metadata for the function, we have to create a type for the signature first, and then the metadata for the function itself. This is similar to [...]
The file is a module in tinylang, which makes it the compilation unit for LLVM. This carries a lot of information: bool IsOptimized = false;llvm::StringRef CUFlags;unsigned ObjCRunTimeVersion = 0;llvm::StringRef SplitName;llvm::DICompileUnit::DebugEmissionKind [...]
To allow source-level debugging, we have to add debug information. Support for debug information in LLVM uses debug metadata to describe the types of the source language and other static [...]
llvm::MDNode *CGTBAA::getTypeInfo(TypeDeclaration *Ty) {if (llvm::MDNode *N = MetadataCache[Ty])return N;if (auto *Pervasive =llvm::dyn_cast(Ty)) {StringRef Name = Pervasive->getName();return createScalarTypeNode(Pervasive, Name, getRoot());}if (auto *Pointer =llvm::dyn_cast(Ty)) {StringRef Name = “any pointer”;return createScalarTypeNode(Pointer, Name, getRoot());}if [...]
To support TBAA, we must add a new CGTBAA class. This class is responsible for generating the metadata nodes. Furthermore, we make the CGTBAA class a member of the CGModule [...]
To create the metadata, we must use the llvm::MDBuilder class, which is declared in the llvm/IR/MDBuilder.h header file. The data itself is stored in instances of the llvm::MDNode and llvm::MDString [...]
With these definitions, we can now define a relation on the access tags, which is used to evaluate if two pointers may alias each other or not. Let’s take a [...]
To demonstrate the problem, let’s look at the following function:void doSomething(int *p, float *q) { *p = 42; *q = 3.1425;} The optimizer cannot decide if the pointers, p and q, point [...]
The IR for the division is generated inside the visit(BinaryOp &) method. Instead of just generating a sdiv instruction, we must generate an IR to compare the divisor with 0. [...]