TargetJITInfo.h revision 8fe95356dd487a79145ec07a9f46cd743b4c9bdd 
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    /// hasCustomConstantPool - Allows a target to specify that constant
111    /// pool address resolution is handled by the target.
112    virtual bool hasCustomConstantPool() const { return false; }
113  protected:
114    bool useGOT;
115  };
116} // End llvm namespace
117
118#endif
119