1 //===- Target/TargetJITInfo.h - Target Information for JIT ------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
15 //===----------------------------------------------------------------------===//
17 #ifndef LLVM_TARGET_TARGETJITINFO_H
18 #define LLVM_TARGET_TARGETJITINFO_H
21 #include "llvm/Support/DataTypes.h"
26 class MachineBasicBlock;
27 class MachineCodeEmitter;
28 class MachineRelocation;
30 /// TargetJITInfo - Target specific information required by the Just-In-Time
34 virtual ~TargetJITInfo() {}
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
41 virtual void replaceMachineCodeForFunction(void *Old, void *New) = 0;
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!");
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!");
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!");
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)();
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 *);
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
84 virtual LazyResolverFn getLazyResolverFunction(JITCompilerFn) {
85 assert(0 && "Not implemented for this target!");
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!");
97 /// needsGOT - Allows a target to specify that it would like the
98 // JIT to manage a GOT for it.
99 bool needsGOT() const { return useGOT; }
104 } // End llvm namespace