TargetJITInfo.h revision 46281865724c8836de538995e97168db3b06edfc
1//===- Target/TargetJITInfo.h - Target Information for JIT ------*- 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 exposes an abstract interface used by the Just-In-Time code 11// generator to perform target-specific activities, such as emitting stubs. If 12// a TargetMachine supports JIT code generation, it should provide one of these 13// objects through the getJITInfo() method. 14// 15//===----------------------------------------------------------------------===// 16 17#ifndef LLVM_TARGET_TARGETJITINFO_H 18#define LLVM_TARGET_TARGETJITINFO_H 19 20#include <cassert> 21#include "llvm/Support/DataTypes.h" 22 23namespace llvm { 24 class Function; 25 class GlobalValue; 26 class MachineBasicBlock; 27 class MachineCodeEmitter; 28 class MachineRelocation; 29 30 /// TargetJITInfo - Target specific information required by the Just-In-Time 31 /// code generator. 32 class TargetJITInfo { 33 public: 34 virtual ~TargetJITInfo() {} 35 36 /// replaceMachineCodeForFunction - Make it so that calling the function 37 /// whose machine code is at OLD turns into a call to NEW, perhaps by 38 /// overwriting OLD with a branch to NEW. This is used for self-modifying 39 /// code. 40 /// 41 virtual void replaceMachineCodeForFunction(void *Old, void *New) = 0; 42 43 /// emitGlobalValueLazyPtr - Use the specified MachineCodeEmitter object to 44 /// emit a lazy pointer which contains the address of the specified ptr. 45 virtual void *emitGlobalValueLazyPtr(const GlobalValue* GV, void *ptr, 46 MachineCodeEmitter &MCE) { 47 assert(0 && "This target doesn't implement emitGlobalValueLazyPtr!"); 48 return 0; 49 } 50 51 /// emitFunctionStub - Use the specified MachineCodeEmitter object to emit a 52 /// small native function that simply calls the function at the specified 53 /// address. Return the address of the resultant function. 54 virtual void *emitFunctionStub(const Function* F, void *Fn, 55 MachineCodeEmitter &MCE) { 56 assert(0 && "This target doesn't implement emitFunctionStub!"); 57 return 0; 58 } 59 60 /// getPICJumpTableEntry - Returns the value of the jumptable entry for the 61 /// specific basic block. 62 virtual intptr_t getPICJumpTableEntry(intptr_t BB, intptr_t JTBase) { 63 assert(0 && "This target doesn't implement getPICJumpTableEntry!"); 64 return 0; 65 } 66 67 /// LazyResolverFn - This typedef is used to represent the function that 68 /// unresolved call points should invoke. This is a target specific 69 /// function that knows how to walk the stack and find out which stub the 70 /// call is coming from. 71 typedef void (*LazyResolverFn)(); 72 73 /// JITCompilerFn - This typedef is used to represent the JIT function that 74 /// lazily compiles the function corresponding to a stub. The JIT keeps 75 /// track of the mapping between stubs and LLVM Functions, the target 76 /// provides the ability to figure out the address of a stub that is called 77 /// by the LazyResolverFn. 78 typedef void* (*JITCompilerFn)(void *); 79 80 /// getLazyResolverFunction - This method is used to initialize the JIT, 81 /// giving the target the function that should be used to compile a 82 /// function, and giving the JIT the target function used to do the lazy 83 /// resolving. 84 virtual LazyResolverFn getLazyResolverFunction(JITCompilerFn) { 85 assert(0 && "Not implemented for this target!"); 86 return 0; 87 } 88 89 /// relocate - Before the JIT can run a block of code that has been emitted, 90 /// it must rewrite the code to contain the actual addresses of any 91 /// referenced global symbols. 92 virtual void relocate(void *Function, MachineRelocation *MR, 93 unsigned NumRelocs, unsigned char* GOTBase) { 94 assert(NumRelocs == 0 && "This target does not have relocations!"); 95 } 96 97 98 /// allocateThreadLocalMemory - Each target has its own way of 99 /// handling thread local variables. This method returns a value only 100 /// meaningful to the target. 101 virtual char* allocateThreadLocalMemory(size_t size) { 102 assert(0 && "This target does not implement thread local storage!"); 103 return 0; 104 } 105 106 /// needsGOT - Allows a target to specify that it would like the 107 // JIT to manage a GOT for it. 108 bool needsGOT() const { return useGOT; } 109 110 protected: 111 bool useGOT; 112 }; 113} // End llvm namespace 114 115#endif 116