Fun with parameter attributes: For several of the "synthetic" parameters added to D functions, we can apply noalias and nocapture. They are sret parameters, 'nest' pointers passed to nested functions, and _argptr: Nocapture: - Sret and nest are nocapture because they don't represent D-level variables, and thus the callee can't (validly) obtain a pointer to them, let alone keep it around after it returns. - _argptr is nocapture because although the callee has access to it as a pointer, that pointer is invalidated when it returns. All three are noalias because they're function-local variables - Sret and _argptr are noalias because they're freshly alloca'd memory only used for a single function call that's not allowed to keep an aliasing pointer to it around (since the parameter is nocapture). - 'Nest' is noalias because the callee only ever has access to one such pointer per parent function, and every parent function has a different one. This commit also ensures attributes set on sret, _arguments and _argptr are propagated to calls to such functions. It also adds one exception to the general rule that attributes on function types should propagate to calls: the type of a delegate's function pointer has a 'nest' parameter, but this can either be a true 'nest' (for delegates to nested functions) or a 'this' (for delegates to member functions). Since 'this' is neither noalias nor nocapture, and there's generally no way to tell which one it is, we remove these attributes at the call site if the callee is a delegate.

#ifndef LDC_GEN_TODEBUG_H
#define LDC_GEN_TODEBUG_H

void RegisterDwarfSymbols(llvm::Module* mod);

/**
 * Emit the Dwarf compile_unit global for a Module m.
 * @param m
 * @return the Dwarf compile_unit.
 */
llvm::DICompileUnit DtoDwarfCompileUnit(Module* m);

/**
 * Emit the Dwarf subprogram global for a function declaration fd.
 * @param fd
 * @return the Dwarf subprogram global.
 */
llvm::DISubprogram DtoDwarfSubProgram(FuncDeclaration* fd);

/**
 * Emit the Dwarf subprogram global for a internal function.
 * This is used for generated functions like moduleinfoctors, 
 * module ctors/dtors and unittests.
 * @return the Dwarf subprogram global.
 */
llvm::DISubprogram DtoDwarfSubProgramInternal(const char* prettyname, const char* mangledname);

void DtoDwarfFuncStart(FuncDeclaration* fd);
void DtoDwarfFuncEnd(FuncDeclaration* fd);

void DtoDwarfStopPoint(unsigned ln);

/**
 * Emits all things necessary for making debug info for a local variable vd.
 * @param ll LLVM Value of the variable.
 * @param vd Variable declaration to emit debug info for.
 */
void DtoDwarfLocalVariable(LLValue* ll, VarDeclaration* vd);

/**
 * Emits all things necessary for making debug info for a global variable vd.
 * @param ll 
 * @param vd 
 * @return 
 */
llvm::DIGlobalVariable DtoDwarfGlobalVariable(LLGlobalVariable* ll, VarDeclaration* vd);

#endif // LDC_GEN_TODEBUG_H