view ir/irfunction.h @ 1117:4c20fcc4252b

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.
author Frits van Bommel <fvbommel wxs.nl>
date Sat, 14 Mar 2009 22:15:31 +0100
parents dc608dc33081
children 40caa8207b3e
line wrap: on
line source

#ifndef LDC_IR_IRFUNCTION_H
#define LDC_IR_IRFUNCTION_H

#include "gen/llvm.h"
#include "ir/ir.h"
#include "ir/irlandingpad.h"

#include <vector>
#include <stack>
#include <map>

// represents a function
struct IrFunction : IrBase
{
    llvm::Function* func;
    llvm::Instruction* allocapoint;
    FuncDeclaration* decl;
    TypeFunction* type;

    bool queued;
    bool defined;
    
    llvm::Value* retArg; // return in ptr arg
    llvm::Value* thisArg; // class/struct 'this' arg
    llvm::Value* nestArg; // nested function 'this' arg
    
    llvm::Value* nestedVar; // nested var alloca
    
    llvm::Value* _arguments;
    llvm::Value* _argptr;
    
    llvm::DISubprogram diSubprogram;

    // pushes a unique label scope of the given name
    void pushUniqueLabelScope(const char* name);
    // pops a label scope
    void popLabelScope();

    // gets the string under which the label's BB
    // is stored in the labelToBB map.
    // essentially prefixes ident by the strings in labelScopes
    std::string getScopedLabelName(const char* ident);

    // label to basic block lookup
    typedef std::map<std::string, llvm::BasicBlock*> LabelToBBMap;
    LabelToBBMap labelToBB;

    // landing pads for try statements
    IRLandingPad landingPad;

    IrFunction(FuncDeclaration* fd);

    // annotations
    void setNeverInline();
    void setAlwaysInline();

private:
    // prefix for labels and gotos
    // used for allowing labels to be emitted twice
    std::vector<std::string> labelScopes;

    // next unique id stack
    std::stack<int> nextUnique;
};

#endif