TargetJITInfo.h revision a3f99f90338d89354384ca25f53ca4450a1a9d18 
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 JITCodeEmitter;
27  class MachineRelocation;
28
29  /// TargetJITInfo - Target specific information required by the Just-In-Time
30  /// code generator.
31  class TargetJITInfo {
32  public:
33    virtual ~TargetJITInfo() {}
34
35    /// replaceMachineCodeForFunction - Make it so that calling the function
36    /// whose machine code is at OLD turns into a call to NEW, perhaps by
37    /// overwriting OLD with a branch to NEW.  This is used for self-modifying
38    /// code.
39    ///
40    virtual void replaceMachineCodeForFunction(void *Old, void *New) = 0;
41
42    /// emitGlobalValueIndirectSym - Use the specified JITCodeEmitter object
43    /// to emit an indirect symbol which contains the address of the specified
44    /// ptr.
45    virtual void *emitGlobalValueIndirectSym(const GlobalValue* GV, void *ptr,
46                                             JITCodeEmitter &JCE) {
47      assert(0 && "This target doesn't implement emitGlobalValueIndirectSym!");
48      return 0;
49    }
50
51    /// emitFunctionStub - Use the specified JITCodeEmitter 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                                   JITCodeEmitter &JCE) {
56      assert(0 && "This target doesn't implement emitFunctionStub!");
57      return 0;
58    }
59
60    /// emitFunctionStubAtAddr - Use the specified JITCodeEmitter object to
61    /// emit a small native function that simply calls Fn. Emit the stub into
62    /// the supplied buffer.
63    virtual void emitFunctionStubAtAddr(const Function* F, void *Fn,
64                                        void *Buffer, JITCodeEmitter &JCE) {
65      assert(0 && "This target doesn't implement emitFunctionStubAtAddr!");
66    }
67
68    /// getPICJumpTableEntry - Returns the value of the jumptable entry for the
69    /// specific basic block.
70    virtual uintptr_t getPICJumpTableEntry(uintptr_t BB, uintptr_t JTBase) {
71      assert(0 && "This target doesn't implement getPICJumpTableEntry!");
72      return 0;
73    }
74
75    /// LazyResolverFn - This typedef is used to represent the function that
76    /// unresolved call points should invoke.  This is a target specific
77    /// function that knows how to walk the stack and find out which stub the
78    /// call is coming from.
79    typedef void (*LazyResolverFn)();
80
81    /// JITCompilerFn - This typedef is used to represent the JIT function that
82    /// lazily compiles the function corresponding to a stub.  The JIT keeps
83    /// track of the mapping between stubs and LLVM Functions, the target
84    /// provides the ability to figure out the address of a stub that is called
85    /// by the LazyResolverFn.
86    typedef void* (*JITCompilerFn)(void *);
87
88    /// getLazyResolverFunction - This method is used to initialize the JIT,
89    /// giving the target the function that should be used to compile a
90    /// function, and giving the JIT the target function used to do the lazy
91    /// resolving.
92    virtual LazyResolverFn getLazyResolverFunction(JITCompilerFn) {
93      assert(0 && "Not implemented for this target!");
94      return 0;
95    }
96
97    /// relocate - Before the JIT can run a block of code that has been emitted,
98    /// it must rewrite the code to contain the actual addresses of any
99    /// referenced global symbols.
100    virtual void relocate(void *Function, MachineRelocation *MR,
101                          unsigned NumRelocs, unsigned char* GOTBase) {
102      assert(NumRelocs == 0 && "This target does not have relocations!");
103    }
104
105
106    /// allocateThreadLocalMemory - Each target has its own way of
107    /// handling thread local variables. This method returns a value only
108    /// meaningful to the target.
109    virtual char* allocateThreadLocalMemory(size_t size) {
110      assert(0 && "This target does not implement thread local storage!");
111      return 0;
112    }
113
114    /// needsGOT - Allows a target to specify that it would like the
115    /// JIT to manage a GOT for it.
116    bool needsGOT() const { return useGOT; }
117
118    /// hasCustomConstantPool - Allows a target to specify that constant
119    /// pool address resolution is handled by the target.
120    virtual bool hasCustomConstantPool() const { return false; }
121
122    /// hasCustomJumpTables - Allows a target to specify that jumptables
123    /// are emitted by the target.
124    virtual bool hasCustomJumpTables() const { return false; }
125
126    /// allocateSeparateGVMemory - If true, globals should be placed in
127    /// separately allocated heap memory rather than in the same
128    /// code memory allocated by JITCodeEmitter.
129    virtual bool allocateSeparateGVMemory() const { return false; }
130  protected:
131    bool useGOT;
132  };
133} // End llvm namespace
134
135#endif
136