LLVM API Documentation

LLVMContext.h
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00001 //===-- llvm/LLVMContext.h - Class for managing "global" state --*- C++ -*-===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file is distributed under the University of Illinois Open Source
00006 // License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file declares LLVMContext, a container of "global" state in LLVM, such
00011 // as the global type and constant uniquing tables.
00012 //
00013 //===----------------------------------------------------------------------===//
00014 
00015 #ifndef LLVM_IR_LLVMCONTEXT_H
00016 #define LLVM_IR_LLVMCONTEXT_H
00017 
00018 #include "llvm-c/Core.h"
00019 #include "llvm/Support/CBindingWrapping.h"
00020 #include "llvm/Support/Compiler.h"
00021 
00022 namespace llvm {
00023 
00024 class LLVMContextImpl;
00025 class StringRef;
00026 class Twine;
00027 class Instruction;
00028 class Module;
00029 class SMDiagnostic;
00030 class DiagnosticInfo;
00031 template <typename T> class SmallVectorImpl;
00032 class Function;
00033 class DebugLoc;
00034 
00035 /// This is an important class for using LLVM in a threaded context.  It
00036 /// (opaquely) owns and manages the core "global" data of LLVM's core
00037 /// infrastructure, including the type and constant uniquing tables.
00038 /// LLVMContext itself provides no locking guarantees, so you should be careful
00039 /// to have one context per thread.
00040 class LLVMContext {
00041 public:
00042   LLVMContextImpl *const pImpl;
00043   LLVMContext();
00044   ~LLVMContext();
00045 
00046   // Pinned metadata names, which always have the same value.  This is a
00047   // compile-time performance optimization, not a correctness optimization.
00048   enum {
00049     MD_dbg = 0,  // "dbg"
00050     MD_tbaa = 1, // "tbaa"
00051     MD_prof = 2,  // "prof"
00052     MD_fpmath = 3,  // "fpmath"
00053     MD_range = 4, // "range"
00054     MD_tbaa_struct = 5, // "tbaa.struct"
00055     MD_invariant_load = 6, // "invariant.load"
00056     MD_alias_scope = 7, // "alias.scope"
00057     MD_noalias = 8 // "noalias"
00058   };
00059 
00060   /// getMDKindID - Return a unique non-zero ID for the specified metadata kind.
00061   /// This ID is uniqued across modules in the current LLVMContext.
00062   unsigned getMDKindID(StringRef Name) const;
00063 
00064   /// getMDKindNames - Populate client supplied SmallVector with the name for
00065   /// custom metadata IDs registered in this LLVMContext.
00066   void getMDKindNames(SmallVectorImpl<StringRef> &Result) const;
00067 
00068 
00069   typedef void (*InlineAsmDiagHandlerTy)(const SMDiagnostic&, void *Context,
00070                                          unsigned LocCookie);
00071 
00072   /// Defines the type of a diagnostic handler.
00073   /// \see LLVMContext::setDiagnosticHandler.
00074   /// \see LLVMContext::diagnose.
00075   typedef void (*DiagnosticHandlerTy)(const DiagnosticInfo &DI, void *Context);
00076 
00077   /// Defines the type of a yield callback.
00078   /// \see LLVMContext::setYieldCallback.
00079   typedef void (*YieldCallbackTy)(LLVMContext *Context, void *OpaqueHandle);
00080 
00081   /// setInlineAsmDiagnosticHandler - This method sets a handler that is invoked
00082   /// when problems with inline asm are detected by the backend.  The first
00083   /// argument is a function pointer and the second is a context pointer that
00084   /// gets passed into the DiagHandler.
00085   ///
00086   /// LLVMContext doesn't take ownership or interpret either of these
00087   /// pointers.
00088   void setInlineAsmDiagnosticHandler(InlineAsmDiagHandlerTy DiagHandler,
00089                                      void *DiagContext = nullptr);
00090 
00091   /// getInlineAsmDiagnosticHandler - Return the diagnostic handler set by
00092   /// setInlineAsmDiagnosticHandler.
00093   InlineAsmDiagHandlerTy getInlineAsmDiagnosticHandler() const;
00094 
00095   /// getInlineAsmDiagnosticContext - Return the diagnostic context set by
00096   /// setInlineAsmDiagnosticHandler.
00097   void *getInlineAsmDiagnosticContext() const;
00098 
00099   /// setDiagnosticHandler - This method sets a handler that is invoked
00100   /// when the backend needs to report anything to the user.  The first
00101   /// argument is a function pointer and the second is a context pointer that
00102   /// gets passed into the DiagHandler.
00103   ///
00104   /// LLVMContext doesn't take ownership or interpret either of these
00105   /// pointers.
00106   void setDiagnosticHandler(DiagnosticHandlerTy DiagHandler,
00107                             void *DiagContext = nullptr);
00108 
00109   /// getDiagnosticHandler - Return the diagnostic handler set by
00110   /// setDiagnosticHandler.
00111   DiagnosticHandlerTy getDiagnosticHandler() const;
00112 
00113   /// getDiagnosticContext - Return the diagnostic context set by
00114   /// setDiagnosticContext.
00115   void *getDiagnosticContext() const;
00116 
00117   /// diagnose - Report a message to the currently installed diagnostic handler.
00118   /// This function returns, in particular in the case of error reporting
00119   /// (DI.Severity == RS_Error), so the caller should leave the compilation
00120   /// process in a self-consistent state, even though the generated code
00121   /// need not be correct.
00122   /// The diagnostic message will be implicitly prefixed with a severity
00123   /// keyword according to \p DI.getSeverity(), i.e., "error: "
00124   /// for RS_Error, "warning: " for RS_Warning, and "note: " for RS_Note.
00125   void diagnose(const DiagnosticInfo &DI);
00126 
00127   /// \brief Registers a yield callback with the given context.
00128   ///
00129   /// The yield callback function may be called by LLVM to transfer control back
00130   /// to the client that invoked the LLVM compilation. This can be used to yield
00131   /// control of the thread, or perform periodic work needed by the client.
00132   /// There is no guaranteed frequency at which callbacks must occur; in fact,
00133   /// the client is not guaranteed to ever receive this callback. It is at the
00134   /// sole discretion of LLVM to do so and only if it can guarantee that
00135   /// suspending the thread won't block any forward progress in other LLVM
00136   /// contexts in the same process.
00137   ///
00138   /// At a suspend point, the state of the current LLVM context is intentionally
00139   /// undefined. No assumptions about it can or should be made. Only LLVM
00140   /// context API calls that explicitly state that they can be used during a
00141   /// yield callback are allowed to be used. Any other API calls into the
00142   /// context are not supported until the yield callback function returns
00143   /// control to LLVM. Other LLVM contexts are unaffected by this restriction.
00144   void setYieldCallback(YieldCallbackTy Callback, void *OpaqueHandle);
00145 
00146   /// \brief Calls the yield callback (if applicable).
00147   ///
00148   /// This transfers control of the current thread back to the client, which may
00149   /// suspend the current thread. Only call this method when LLVM doesn't hold
00150   /// any global mutex or cannot block the execution in another LLVM context.
00151   void yield();
00152 
00153   /// emitError - Emit an error message to the currently installed error handler
00154   /// with optional location information.  This function returns, so code should
00155   /// be prepared to drop the erroneous construct on the floor and "not crash".
00156   /// The generated code need not be correct.  The error message will be
00157   /// implicitly prefixed with "error: " and should not end with a ".".
00158   void emitError(unsigned LocCookie, const Twine &ErrorStr);
00159   void emitError(const Instruction *I, const Twine &ErrorStr);
00160   void emitError(const Twine &ErrorStr);
00161 
00162 private:
00163   LLVMContext(LLVMContext&) LLVM_DELETED_FUNCTION;
00164   void operator=(LLVMContext&) LLVM_DELETED_FUNCTION;
00165 
00166   /// addModule - Register a module as being instantiated in this context.  If
00167   /// the context is deleted, the module will be deleted as well.
00168   void addModule(Module*);
00169 
00170   /// removeModule - Unregister a module from this context.
00171   void removeModule(Module*);
00172 
00173   // Module needs access to the add/removeModule methods.
00174   friend class Module;
00175 };
00176 
00177 /// getGlobalContext - Returns a global context.  This is for LLVM clients that
00178 /// only care about operating on a single thread.
00179 extern LLVMContext &getGlobalContext();
00180 
00181 // Create wrappers for C Binding types (see CBindingWrapping.h).
00182 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(LLVMContext, LLVMContextRef)
00183 
00184 /* Specialized opaque context conversions.
00185  */
00186 inline LLVMContext **unwrap(LLVMContextRef* Tys) {
00187   return reinterpret_cast<LLVMContext**>(Tys);
00188 }
00189 
00190 inline LLVMContextRef *wrap(const LLVMContext **Tys) {
00191   return reinterpret_cast<LLVMContextRef*>(const_cast<LLVMContext**>(Tys));
00192 }
00193 
00194 }
00195 
00196 #endif