1 //===-- X86JITInfo.cpp - Implement the JIT interfaces for the X86 target --===//
3 // The LLVM Compiler Infrastructure
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.
8 //===----------------------------------------------------------------------===//
10 // This file implements the JIT interfaces for the X86 target.
12 //===----------------------------------------------------------------------===//
14 #define DEBUG_TYPE "jit"
15 #include "X86JITInfo.h"
16 #include "X86Relocations.h"
17 #include "llvm/CodeGen/MachineCodeEmitter.h"
18 #include "llvm/Config/alloca.h"
24 extern "C" void *_AddressOfReturnAddress(void);
25 #pragma intrinsic(_AddressOfReturnAddress)
28 void X86JITInfo::replaceMachineCodeForFunction(void *Old, void *New) {
29 unsigned char *OldByte = (unsigned char *)Old;
30 *OldByte++ = 0xE9; // Emit JMP opcode.
31 unsigned *OldWord = (unsigned *)OldByte;
32 unsigned NewAddr = (intptr_t)New;
33 unsigned OldAddr = (intptr_t)OldWord;
34 *OldWord = NewAddr - OldAddr - 4; // Emit PC-relative addr of New code.
38 /// JITCompilerFunction - This contains the address of the JIT function used to
39 /// compile a function lazily.
40 static TargetJITInfo::JITCompilerFn JITCompilerFunction;
42 // Provide a wrapper for X86CompilationCallback2 that saves non-traditional
43 // callee saved registers, for the fastcc calling convention.
45 #if defined(__x86_64__)
46 // No need to save EAX/EDX for X86-64.
47 void X86CompilationCallback(void);
51 ".globl _X86CompilationCallback\n"
52 "_X86CompilationCallback:\n"
57 // Save all int arg registers
64 // Align stack on 16-byte boundary. ESP might not be properly aligned
65 // (8 byte) if this is called from an indirect stub.
67 // Save all XMM arg registers
69 "movaps %xmm0, (%rsp)\n"
70 "movaps %xmm1, 16(%rsp)\n"
71 "movaps %xmm2, 32(%rsp)\n"
72 "movaps %xmm3, 48(%rsp)\n"
73 "movaps %xmm4, 64(%rsp)\n"
74 "movaps %xmm5, 80(%rsp)\n"
75 "movaps %xmm6, 96(%rsp)\n"
76 "movaps %xmm7, 112(%rsp)\n"
78 "movq %rbp, %rdi\n" // Pass prev frame and return address
79 "movq 8(%rbp), %rsi\n"
80 "call _X86CompilationCallback2\n"
81 // Restore all XMM arg registers
82 "movaps 112(%rsp), %xmm7\n"
83 "movaps 96(%rsp), %xmm6\n"
84 "movaps 80(%rsp), %xmm5\n"
85 "movaps 64(%rsp), %xmm4\n"
86 "movaps 48(%rsp), %xmm3\n"
87 "movaps 32(%rsp), %xmm2\n"
88 "movaps 16(%rsp), %xmm1\n"
89 "movaps (%rsp), %xmm0\n"
92 // Restore all int arg registers
103 #elif defined(__i386__) || defined(i386) || defined(_M_IX86)
105 void X86CompilationCallback(void);
109 #if defined(__CYGWIN__) || defined(__APPLE__) || defined(__MINGW32__)
110 ".globl _X86CompilationCallback\n"
111 "_X86CompilationCallback:\n"
113 ".globl X86CompilationCallback\n"
114 "X86CompilationCallback:\n"
117 "movl %esp, %ebp\n" // Standard prologue
118 #if FASTCC_NUM_INT_ARGS_INREGS > 0
120 "pushl %edx\n" // Save EAX/EDX
122 #if defined(__APPLE__)
123 "andl $-16, %esp\n" // Align ESP on 16-byte boundary
126 "movl 4(%ebp), %eax\n" // Pass prev frame and return address
127 "movl %eax, 4(%esp)\n"
128 "movl %ebp, (%esp)\n"
129 #if defined(__CYGWIN__) || defined(__MINGW32__) || defined(__APPLE__)
130 "call _X86CompilationCallback2\n"
132 "call X86CompilationCallback2\n"
134 "movl %ebp, %esp\n" // Restore ESP
135 #if FASTCC_NUM_INT_ARGS_INREGS > 0
143 void X86CompilationCallback2(void);
145 _declspec(naked) void X86CompilationCallback(void) {
149 call X86CompilationCallback2
157 #else // Not an i386 host
158 void X86CompilationCallback() {
159 std::cerr << "Cannot call X86CompilationCallback() on a non-x86 arch!\n";
165 /// X86CompilationCallback - This is the target-specific function invoked by the
166 /// function stub when we did not know the real target of a call. This function
167 /// must locate the start of the stub or call site and pass it into the JIT
168 /// compiler function.
170 extern "C" void X86CompilationCallback2() {
171 assert(sizeof(size_t) == 4); // FIXME: handle Win64
172 unsigned *RetAddrLoc = (unsigned *)_AddressOfReturnAddress();
173 RetAddrLoc += 3; // skip over ret addr, edx, eax
174 unsigned RetAddr = *RetAddrLoc;
176 extern "C" void X86CompilationCallback2(intptr_t *StackPtr, intptr_t RetAddr) {
177 intptr_t *RetAddrLoc = &StackPtr[1];
179 assert(*RetAddrLoc == RetAddr &&
180 "Could not find return address on the stack!");
182 // It's a stub if there is an interrupt marker after the call.
183 bool isStub = ((unsigned char*)RetAddr)[0] == 0xCD;
185 // The call instruction should have pushed the return value onto the stack...
186 RetAddr -= 4; // Backtrack to the reference itself...
189 DEBUG(std::cerr << "In callback! Addr=" << (void*)RetAddr
190 << " ESP=" << (void*)StackPtr
191 << ": Resolving call to function: "
192 << TheVM->getFunctionReferencedName((void*)RetAddr) << "\n");
195 // Sanity check to make sure this really is a call instruction.
196 assert(((unsigned char*)RetAddr)[-1] == 0xE8 &&"Not a call instr!");
198 intptr_t NewVal = (intptr_t)JITCompilerFunction((void*)RetAddr);
200 // Rewrite the call target... so that we don't end up here every time we
202 *(unsigned *)RetAddr = (unsigned)(NewVal-RetAddr-4);
205 // If this is a stub, rewrite the call into an unconditional branch
206 // instruction so that two return addresses are not pushed onto the stack
207 // when the requested function finally gets called. This also makes the
208 // 0xCD byte (interrupt) dead, so the marker doesn't effect anything.
209 ((unsigned char*)RetAddr)[-1] = 0xE9;
212 // Change the return address to reexecute the call instruction...
216 TargetJITInfo::LazyResolverFn
217 X86JITInfo::getLazyResolverFunction(JITCompilerFn F) {
218 JITCompilerFunction = F;
219 return X86CompilationCallback;
222 void *X86JITInfo::emitFunctionStub(void *Fn, MachineCodeEmitter &MCE) {
223 // Note, we cast to intptr_t here to silence a -pedantic warning that
224 // complains about casting a function pointer to a normal pointer.
225 if (Fn != (void*)(intptr_t)X86CompilationCallback) {
226 MCE.startFunctionStub(5);
228 MCE.emitWordLE((intptr_t)Fn-MCE.getCurrentPCValue()-4);
229 return MCE.finishFunctionStub(0);
232 MCE.startFunctionStub(6);
233 MCE.emitByte(0xE8); // Call with 32 bit pc-rel destination...
235 MCE.emitWordLE((intptr_t)Fn-MCE.getCurrentPCValue()-4);
237 MCE.emitByte(0xCD); // Interrupt - Just a marker identifying the stub!
238 return MCE.finishFunctionStub(0);
241 /// relocate - Before the JIT can run a block of code that has been emitted,
242 /// it must rewrite the code to contain the actual addresses of any
243 /// referenced global symbols.
244 void X86JITInfo::relocate(void *Function, MachineRelocation *MR,
245 unsigned NumRelocs, unsigned char* GOTBase) {
246 for (unsigned i = 0; i != NumRelocs; ++i, ++MR) {
247 void *RelocPos = (char*)Function + MR->getMachineCodeOffset();
248 intptr_t ResultPtr = (intptr_t)MR->getResultPointer();
249 switch ((X86::RelocationType)MR->getRelocationType()) {
250 case X86::reloc_pcrel_word: {
251 // PC relative relocation, add the relocated value to the value already in
252 // memory, after we adjust it for where the PC is.
253 ResultPtr = ResultPtr-(intptr_t)RelocPos-4-MR->getConstantVal();
254 *((unsigned*)RelocPos) += (unsigned)ResultPtr;
257 case X86::reloc_absolute_word:
258 // Absolute relocation, just add the relocated value to the value already
260 *((unsigned*)RelocPos) += (unsigned)ResultPtr;