Home | History | Annotate | Download | only in IR 
      1 //===-- llvm/LLVMContext.h - Class for managing "global" state --*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file declares LLVMContext, a container of "global" state in LLVM, such
     11 // as the global type and constant uniquing tables.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #ifndef LLVM_IR_LLVMCONTEXT_H
     16 #define LLVM_IR_LLVMCONTEXT_H
     17 
     18 #include "llvm-c/Core.h"
     19 #include "llvm/Support/CBindingWrapping.h"
     20 #include "llvm/Support/Compiler.h"
     21 
     22 namespace llvm {
     23 
     24 class LLVMContextImpl;
     25 class StringRef;
     26 class Twine;
     27 class Instruction;
     28 class Module;
     29 class SMDiagnostic;
     30 class DiagnosticInfo;
     31 template <typename T> class SmallVectorImpl;
     32 class Function;
     33 class DebugLoc;
     34 
     35 /// This is an important class for using LLVM in a threaded context.  It
     36 /// (opaquely) owns and manages the core "global" data of LLVM's core
     37 /// infrastructure, including the type and constant uniquing tables.
     38 /// LLVMContext itself provides no locking guarantees, so you should be careful
     39 /// to have one context per thread.
     40 class LLVMContext {
     41 public:
     42   LLVMContextImpl *const pImpl;
     43   LLVMContext();
     44   ~LLVMContext();
     45 
     46   // Pinned metadata names, which always have the same value.  This is a
     47   // compile-time performance optimization, not a correctness optimization.
     48   enum {
     49     MD_dbg = 0,  // "dbg"
     50     MD_tbaa = 1, // "tbaa"
     51     MD_prof = 2,  // "prof"
     52     MD_fpmath = 3,  // "fpmath"
     53     MD_range = 4, // "range"
     54     MD_tbaa_struct = 5, // "tbaa.struct"
     55     MD_invariant_load = 6 // "invariant.load"
     56   };
     57 
     58   /// getMDKindID - Return a unique non-zero ID for the specified metadata kind.
     59   /// This ID is uniqued across modules in the current LLVMContext.
     60   unsigned getMDKindID(StringRef Name) const;
     61 
     62   /// getMDKindNames - Populate client supplied SmallVector with the name for
     63   /// custom metadata IDs registered in this LLVMContext.
     64   void getMDKindNames(SmallVectorImpl<StringRef> &Result) const;
     65 
     66 
     67   typedef void (*InlineAsmDiagHandlerTy)(const SMDiagnostic&, void *Context,
     68                                          unsigned LocCookie);
     69 
     70   /// Defines the type of a diagnostic handler.
     71   /// \see LLVMContext::setDiagnosticHandler.
     72   /// \see LLVMContext::diagnose.
     73   typedef void (*DiagnosticHandlerTy)(const DiagnosticInfo &DI, void *Context);
     74 
     75   /// Defines the type of a yield callback.
     76   /// \see LLVMContext::setYieldCallback.
     77   typedef void (*YieldCallbackTy)(LLVMContext *Context, void *OpaqueHandle);
     78 
     79   /// setInlineAsmDiagnosticHandler - This method sets a handler that is invoked
     80   /// when problems with inline asm are detected by the backend.  The first
     81   /// argument is a function pointer and the second is a context pointer that
     82   /// gets passed into the DiagHandler.
     83   ///
     84   /// LLVMContext doesn't take ownership or interpret either of these
     85   /// pointers.
     86   void setInlineAsmDiagnosticHandler(InlineAsmDiagHandlerTy DiagHandler,
     87                                      void *DiagContext = nullptr);
     88 
     89   /// getInlineAsmDiagnosticHandler - Return the diagnostic handler set by
     90   /// setInlineAsmDiagnosticHandler.
     91   InlineAsmDiagHandlerTy getInlineAsmDiagnosticHandler() const;
     92 
     93   /// getInlineAsmDiagnosticContext - Return the diagnostic context set by
     94   /// setInlineAsmDiagnosticHandler.
     95   void *getInlineAsmDiagnosticContext() const;
     96 
     97   /// setDiagnosticHandler - This method sets a handler that is invoked
     98   /// when the backend needs to report anything to the user.  The first
     99   /// argument is a function pointer and the second is a context pointer that
    100   /// gets passed into the DiagHandler.
    101   ///
    102   /// LLVMContext doesn't take ownership or interpret either of these
    103   /// pointers.
    104   void setDiagnosticHandler(DiagnosticHandlerTy DiagHandler,
    105                             void *DiagContext = nullptr);
    106 
    107   /// getDiagnosticHandler - Return the diagnostic handler set by
    108   /// setDiagnosticHandler.
    109   DiagnosticHandlerTy getDiagnosticHandler() const;
    110 
    111   /// getDiagnosticContext - Return the diagnostic context set by
    112   /// setDiagnosticContext.
    113   void *getDiagnosticContext() const;
    114 
    115   /// diagnose - Report a message to the currently installed diagnostic handler.
    116   /// This function returns, in particular in the case of error reporting
    117   /// (DI.Severity == RS_Error), so the caller should leave the compilation
    118   /// process in a self-consistent state, even though the generated code
    119   /// need not be correct.
    120   /// The diagnostic message will be implicitly prefixed with a severity
    121   /// keyword according to \p DI.getSeverity(), i.e., "error: "
    122   /// for RS_Error, "warning: " for RS_Warning, and "note: " for RS_Note.
    123   void diagnose(const DiagnosticInfo &DI);
    124 
    125   /// \brief Registers a yield callback with the given context.
    126   ///
    127   /// The yield callback function may be called by LLVM to transfer control back
    128   /// to the client that invoked the LLVM compilation. This can be used to yield
    129   /// control of the thread, or perform periodic work needed by the client.
    130   /// There is no guaranteed frequency at which callbacks must occur; in fact,
    131   /// the client is not guaranteed to ever receive this callback. It is at the
    132   /// sole discretion of LLVM to do so and only if it can guarantee that
    133   /// suspending the thread won't block any forward progress in other LLVM
    134   /// contexts in the same process.
    135   ///
    136   /// At a suspend point, the state of the current LLVM context is intentionally
    137   /// undefined. No assumptions about it can or should be made. Only LLVM
    138   /// context API calls that explicitly state that they can be used during a
    139   /// yield callback are allowed to be used. Any other API calls into the
    140   /// context are not supported until the yield callback function returns
    141   /// control to LLVM. Other LLVM contexts are unaffected by this restriction.
    142   void setYieldCallback(YieldCallbackTy Callback, void *OpaqueHandle);
    143 
    144   /// \brief Calls the yield callback (if applicable).
    145   ///
    146   /// This transfers control of the current thread back to the client, which may
    147   /// suspend the current thread. Only call this method when LLVM doesn't hold
    148   /// any global mutex or cannot block the execution in another LLVM context.
    149   void yield();
    150 
    151   /// emitError - Emit an error message to the currently installed error handler
    152   /// with optional location information.  This function returns, so code should
    153   /// be prepared to drop the erroneous construct on the floor and "not crash".
    154   /// The generated code need not be correct.  The error message will be
    155   /// implicitly prefixed with "error: " and should not end with a ".".
    156   void emitError(unsigned LocCookie, const Twine &ErrorStr);
    157   void emitError(const Instruction *I, const Twine &ErrorStr);
    158   void emitError(const Twine &ErrorStr);
    159 
    160 private:
    161   LLVMContext(LLVMContext&) LLVM_DELETED_FUNCTION;
    162   void operator=(LLVMContext&) LLVM_DELETED_FUNCTION;
    163 
    164   /// addModule - Register a module as being instantiated in this context.  If
    165   /// the context is deleted, the module will be deleted as well.
    166   void addModule(Module*);
    167 
    168   /// removeModule - Unregister a module from this context.
    169   void removeModule(Module*);
    170 
    171   // Module needs access to the add/removeModule methods.
    172   friend class Module;
    173 };
    174 
    175 /// getGlobalContext - Returns a global context.  This is for LLVM clients that
    176 /// only care about operating on a single thread.
    177 extern LLVMContext &getGlobalContext();
    178 
    179 // Create wrappers for C Binding types (see CBindingWrapping.h).
    180 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(LLVMContext, LLVMContextRef)
    181 
    182 /* Specialized opaque context conversions.
    183  */
    184 inline LLVMContext **unwrap(LLVMContextRef* Tys) {
    185   return reinterpret_cast<LLVMContext**>(Tys);
    186 }
    187 
    188 inline LLVMContextRef *wrap(const LLVMContext **Tys) {
    189   return reinterpret_cast<LLVMContextRef*>(const_cast<LLVMContext**>(Tys));
    190 }
    191 
    192 }
    193 
    194 #endif
    195