TargetJITInfo.h revision 55b5053b8e22cf165d1f0ce3aa9a04707e368a15
1//===- Target/TargetJITInfo.h - Target Information for JIT ------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by the LLVM research group and is distributed under 6// the University of Illinois Open Source 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 <vector> 22 23namespace llvm { 24 class Function; 25 class FunctionPassManager; 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 /// addPassesToJITCompile - Add passes to the specified pass manager to 37 /// implement a fast code generator for this target. 38 /// 39 virtual void addPassesToJITCompile(FunctionPassManager &PM) = 0; 40 41 /// replaceMachineCodeForFunction - Make it so that calling the function 42 /// whose machine code is at OLD turns into a call to NEW, perhaps by 43 /// overwriting OLD with a branch to NEW. This is used for self-modifying 44 /// code. 45 /// 46 virtual void replaceMachineCodeForFunction(void *Old, void *New) = 0; 47 48 /// emitFunctionStub - Use the specified MachineCodeEmitter object to emit a 49 /// small native function that simply calls the function at the specified 50 /// address. Return the address of the resultant function. 51 virtual void *emitFunctionStub(void *Fn, MachineCodeEmitter &MCE) { 52 assert(0 && "This target doesn't implement emitFunctionStub!"); 53 return 0; 54 } 55 56 /// LazyResolverFn - This typedef is used to represent the function that 57 /// unresolved call points should invoke. This is a target specific 58 /// function that knows how to walk the stack and find out which stub the 59 /// call is coming from. 60 typedef void (*LazyResolverFn)(); 61 62 /// JITCompilerFn - This typedef is used to represent the JIT function that 63 /// lazily compiles the function corresponding to a stub. The JIT keeps 64 /// track of the mapping between stubs and LLVM Functions, the target 65 /// provides the ability to figure out the address of a stub that is called 66 /// by the LazyResolverFn. 67 typedef void* (*JITCompilerFn)(void *); 68 69 /// getLazyResolverFunction - This method is used to initialize the JIT, 70 /// giving the target the function that should be used to compile a 71 /// function, and giving the JIT the target function used to do the lazy 72 /// resolving. 73 virtual LazyResolverFn getLazyResolverFunction(JITCompilerFn) { 74 assert(0 && "Not implemented for this target!"); 75 return 0; 76 } 77 78 /// relocate - Before the JIT can run a block of code that has been emitted, 79 /// it must rewrite the code to contain the actual addresses of any 80 /// referenced global symbols. 81 virtual void relocate(void *Function, MachineRelocation *MR, 82 unsigned NumRelocs, unsigned char* GOTBase) { 83 assert(NumRelocs == 0 && "This target does not have relocations!"); 84 } 85 86 /// resolveBBRefs - Resolve branches to BasicBlocks for the JIT emitted 87 /// function. 88 virtual void resolveBBRefs(MachineCodeEmitter &MCE) {} 89 90 /// addBBRef - Add a BasicBlock reference to be resolved after the function 91 /// is emitted. 92 void addBBRef(MachineBasicBlock *BB, intptr_t PC) { 93 BBRefs.push_back(std::make_pair(BB, PC)); 94 } 95 96 /// needsGOT - Allows a target to specify that it would like the 97 // JIT to manage a GOT for it. 98 bool needsGOT() const { return useGOT; } 99 100 protected: 101 bool useGOT; 102 103 // Tracks which instruction references which BasicBlock 104 std::vector<std::pair<MachineBasicBlock*, intptr_t> > BBRefs; 105 106 }; 107} // End llvm namespace 108 109#endif 110