LLVMContext.h

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//===-- llvm/LLVMContext.h - Class for managing "global" state --*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares LLVMContext, a container of "global" state in LLVM, such
// as the global type and constant uniquing tables.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_IR_LLVMCONTEXT_H
#define LLVM_IR_LLVMCONTEXT_H

#include "llvm-c/Core.h"
#include "llvm/Support/CBindingWrapping.h"
#include "llvm/Support/Compiler.h"

namespace llvm {

class LLVMContextImpl;
class StringRef;
class Twine;
class Instruction;
class Module;
class SMDiagnostic;
class DiagnosticInfo;
template <typename T> class SmallVectorImpl;
class Function;
class DebugLoc;

/// This is an important class for using LLVM in a threaded context.  It
/// (opaquely) owns and manages the core "global" data of LLVM's core
/// infrastructure, including the type and constant uniquing tables.
/// LLVMContext itself provides no locking guarantees, so you should be careful
/// to have one context per thread.
class LLVMContext {
public:
  LLVMContextImpl *const pImpl;
  LLVMContext();
  ~LLVMContext();

  // Pinned metadata names, which always have the same value.  This is a
  // compile-time performance optimization, not a correctness optimization.
  enum {
    MD_dbg = 0,  // "dbg"
    MD_tbaa = 1, // "tbaa"
    MD_prof = 2,  // "prof"
    MD_fpmath = 3,  // "fpmath"
    MD_range = 4, // "range"
    MD_tbaa_struct = 5, // "tbaa.struct"
    MD_invariant_load = 6, // "invariant.load"
    MD_alias_scope = 7, // "alias.scope"
    MD_noalias = 8 // "noalias"
  };

  /// getMDKindID - Return a unique non-zero ID for the specified metadata kind.
  /// This ID is uniqued across modules in the current LLVMContext.
  unsigned getMDKindID(StringRef Name) const;

  /// getMDKindNames - Populate client supplied SmallVector with the name for
  /// custom metadata IDs registered in this LLVMContext.
  void getMDKindNames(SmallVectorImpl<StringRef> &Result) const;


  typedef void (*InlineAsmDiagHandlerTy)(const SMDiagnostic&, void *Context,
                                         unsigned LocCookie);

  /// Defines the type of a diagnostic handler.
  /// \see LLVMContext::setDiagnosticHandler.
  /// \see LLVMContext::diagnose.
  typedef void (*DiagnosticHandlerTy)(const DiagnosticInfo &DI, void *Context);

  /// Defines the type of a yield callback.
  /// \see LLVMContext::setYieldCallback.
  typedef void (*YieldCallbackTy)(LLVMContext *Context, void *OpaqueHandle);

  /// setInlineAsmDiagnosticHandler - This method sets a handler that is invoked
  /// when problems with inline asm are detected by the backend.  The first
  /// argument is a function pointer and the second is a context pointer that
  /// gets passed into the DiagHandler.
  ///
  /// LLVMContext doesn't take ownership or interpret either of these
  /// pointers.
  void setInlineAsmDiagnosticHandler(InlineAsmDiagHandlerTy DiagHandler,
                                     void *DiagContext = nullptr);

  /// getInlineAsmDiagnosticHandler - Return the diagnostic handler set by
  /// setInlineAsmDiagnosticHandler.
  InlineAsmDiagHandlerTy getInlineAsmDiagnosticHandler() const;

  /// getInlineAsmDiagnosticContext - Return the diagnostic context set by
  /// setInlineAsmDiagnosticHandler.
  void *getInlineAsmDiagnosticContext() const;

  /// setDiagnosticHandler - This method sets a handler that is invoked
  /// when the backend needs to report anything to the user.  The first
  /// argument is a function pointer and the second is a context pointer that
  /// gets passed into the DiagHandler.
  ///
  /// LLVMContext doesn't take ownership or interpret either of these
  /// pointers.
  void setDiagnosticHandler(DiagnosticHandlerTy DiagHandler,
                            void *DiagContext = nullptr);

  /// getDiagnosticHandler - Return the diagnostic handler set by
  /// setDiagnosticHandler.
  DiagnosticHandlerTy getDiagnosticHandler() const;

  /// getDiagnosticContext - Return the diagnostic context set by
  /// setDiagnosticContext.
  void *getDiagnosticContext() const;

  /// \brief Report a message to the currently installed diagnostic handler.
  ///
  /// This function returns, in particular in the case of error reporting
  /// (DI.Severity == \a DS_Error), so the caller should leave the compilation
  /// process in a self-consistent state, even though the generated code
  /// need not be correct.
  ///
  /// The diagnostic message will be implicitly prefixed with a severity keyword
  /// according to \p DI.getSeverity(), i.e., "error: " for \a DS_Error,
  /// "warning: " for \a DS_Warning, and "note: " for \a DS_Note.
  void diagnose(const DiagnosticInfo &DI);

  /// \brief Registers a yield callback with the given context.
  ///
  /// The yield callback function may be called by LLVM to transfer control back
  /// to the client that invoked the LLVM compilation. This can be used to yield
  /// control of the thread, or perform periodic work needed by the client.
  /// There is no guaranteed frequency at which callbacks must occur; in fact,
  /// the client is not guaranteed to ever receive this callback. It is at the
  /// sole discretion of LLVM to do so and only if it can guarantee that
  /// suspending the thread won't block any forward progress in other LLVM
  /// contexts in the same process.
  ///
  /// At a suspend point, the state of the current LLVM context is intentionally
  /// undefined. No assumptions about it can or should be made. Only LLVM
  /// context API calls that explicitly state that they can be used during a
  /// yield callback are allowed to be used. Any other API calls into the
  /// context are not supported until the yield callback function returns
  /// control to LLVM. Other LLVM contexts are unaffected by this restriction.
  void setYieldCallback(YieldCallbackTy Callback, void *OpaqueHandle);

  /// \brief Calls the yield callback (if applicable).
  ///
  /// This transfers control of the current thread back to the client, which may
  /// suspend the current thread. Only call this method when LLVM doesn't hold
  /// any global mutex or cannot block the execution in another LLVM context.
  void yield();

  /// emitError - Emit an error message to the currently installed error handler
  /// with optional location information.  This function returns, so code should
  /// be prepared to drop the erroneous construct on the floor and "not crash".
  /// The generated code need not be correct.  The error message will be
  /// implicitly prefixed with "error: " and should not end with a ".".
  void emitError(unsigned LocCookie, const Twine &ErrorStr);
  void emitError(const Instruction *I, const Twine &ErrorStr);
  void emitError(const Twine &ErrorStr);

private:
  LLVMContext(LLVMContext&) LLVM_DELETED_FUNCTION;
  void operator=(LLVMContext&) LLVM_DELETED_FUNCTION;

  /// addModule - Register a module as being instantiated in this context.  If
  /// the context is deleted, the module will be deleted as well.
  void addModule(Module*);

  /// removeModule - Unregister a module from this context.
  void removeModule(Module*);

  // Module needs access to the add/removeModule methods.
  friend class Module;
};

/// getGlobalContext - Returns a global context.  This is for LLVM clients that
/// only care about operating on a single thread.
extern LLVMContext &getGlobalContext();

// Create wrappers for C Binding types (see CBindingWrapping.h).
DEFINE_SIMPLE_CONVERSION_FUNCTIONS(LLVMContext, LLVMContextRef)

/* Specialized opaque context conversions.
 */
inline LLVMContext **unwrap(LLVMContextRef* Tys) {
  return reinterpret_cast<LLVMContext**>(Tys);
}

inline LLVMContextRef *wrap(const LLVMContext **Tys) {
  return reinterpret_cast<LLVMContextRef*>(const_cast<LLVMContext**>(Tys));
}

}

#endif