1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
//===-- Intercept.cpp - System function interception routines -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// If a function call occurs to an external function, the JIT is designed to use
// the dynamic loader interface to find a function to call. This is useful for
// calling system calls and library functions that are not available in LLVM.
// Some system calls, however, need to be handled specially. For this reason,
// we intercept some of them here and use our own stubs to handle them.
//
//===----------------------------------------------------------------------===//
#include "JIT.h"
#include "llvm/System/DynamicLibrary.h"
#include <iostream>
#include <sys/stat.h>
using namespace llvm;
// AtExitHandlers - List of functions to call when the program exits,
// registered with the atexit() library function.
static std::vector<void (*)()> AtExitHandlers;
/// runAtExitHandlers - Run any functions registered by the program's
/// calls to atexit(3), which we intercept and store in
/// AtExitHandlers.
///
static void runAtExitHandlers() {
while (!AtExitHandlers.empty()) {
void (*Fn)() = AtExitHandlers.back();
AtExitHandlers.pop_back();
Fn();
}
}
//===----------------------------------------------------------------------===//
// Function stubs that are invoked instead of certain library calls
//===----------------------------------------------------------------------===//
// Force the following functions to be linked in to anything that uses the
// JIT. This is a hack designed to work around the all-too-clever Glibc
// strategy of making these functions work differently when inlined vs. when
// not inlined, and hiding their real definitions in a separate archive file
// that the dynamic linker can't see. For more info, search for
// 'libc_nonshared.a' on Google, or read http://llvm.cs.uiuc.edu/PR274.
#if defined(__linux__)
void *FunctionPointers[] = {
(void *) stat,
(void *) fstat,
(void *) lstat,
(void *) stat64,
(void *) fstat64,
(void *) lstat64,
(void *) atexit,
(void *) mknod
};
#endif // __linux__
// __mainFunc - If the program does not have a linked in __main function, allow
// it to run, but print a warning.
static void __mainFunc() {
fprintf(stderr, "WARNING: Program called __main but was not linked to "
"libcrtend.a.\nThis probably won't hurt anything unless the "
"program is written in C++.\n");
}
// jit_exit - Used to intercept the "exit" library call.
static void jit_exit(int Status) {
runAtExitHandlers(); // Run atexit handlers...
exit(Status);
}
// jit_atexit - Used to intercept the "atexit" library call.
static int jit_atexit(void (*Fn)(void)) {
AtExitHandlers.push_back(Fn); // Take note of atexit handler...
return 0; // Always successful
}
//===----------------------------------------------------------------------===//
//
/// getPointerToNamedFunction - This method returns the address of the specified
/// function by using the dynamic loader interface. As such it is only useful
/// for resolving library symbols, not code generated symbols.
///
void *JIT::getPointerToNamedFunction(const std::string &Name) {
// Check to see if this is one of the functions we want to intercept...
if (Name == "exit") return (void*)&jit_exit;
if (Name == "atexit") return (void*)&jit_atexit;
// If the program does not have a linked in __main function, allow it to run,
// but print a warning.
if (Name == "__main") return (void*)&__mainFunc;
// If it's an external function, look it up in the process image...
void *Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(Name);
if (Ptr) return Ptr;
// If this is darwin, it has some funky issues, try to solve them here. Some
// important symbols are marked 'private external' which doesn't allow
// SearchForAddressOfSymbol to find them. As such, we special case them here,
// there is only a small handful of them.
#ifdef __APPLE__
{
extern void *__ashldi3; if (Name == "__ashldi3") return &__ashldi3;
extern void *__ashrdi3; if (Name == "__ashrdi3") return &__ashrdi3;
extern void *__cmpdi2; if (Name == "__cmpdi2") return &__cmpdi2;
extern void *__divdi3; if (Name == "__divdi3") return &__divdi3;
extern void *__eprintf; if (Name == "__eprintf") return &__eprintf;
extern void *__fixdfdi; if (Name == "__fixdfdi") return &__fixdfdi;
extern void *__fixsfdi; if (Name == "__fixsfdi") return &__fixsfdi;
extern void *__fixunsdfdi; if (Name == "__fixunsdfdi") return &__fixunsdfdi;
extern void *__fixunssfdi; if (Name == "__fixunssfdi") return &__fixunssfdi;
extern void *__floatdidf; if (Name == "__floatdidf") return &__floatdidf;
extern void *__floatdisf; if (Name == "__floatdisf") return &__floatdisf;
extern void *__lshrdi3; if (Name == "__lshrdi3") return &__lshrdi3;
extern void *__moddi3; if (Name == "__moddi3") return &__moddi3;
extern void *__udivdi3; if (Name == "__udivdi3") return &__udivdi3;
extern void *__umoddi3; if (Name == "__umoddi3") return &__umoddi3;
}
#endif
std::cerr << "ERROR: Program used external function '" << Name
<< "' which could not be resolved!\n";
abort();
return 0;
}
|
