1 //===-- JIT.cpp - LLVM Just in Time Compiler ------------------------------===//
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 tool implements a just-in-time compiler for LLVM, allowing direct
11 // execution of LLVM bytecode in an efficient manner.
13 //===----------------------------------------------------------------------===//
16 #include "llvm/DerivedTypes.h"
17 #include "llvm/Function.h"
18 #include "llvm/GlobalVariable.h"
19 #include "llvm/ModuleProvider.h"
20 #include "llvm/CodeGen/MachineCodeEmitter.h"
21 #include "llvm/CodeGen/MachineFunction.h"
22 #include "llvm/ExecutionEngine/GenericValue.h"
23 #include "llvm/Target/TargetMachine.h"
24 #include "llvm/Target/TargetJITInfo.h"
25 #include "Support/DynamicLinker.h"
30 JIT::JIT(ModuleProvider *MP, TargetMachine &tm, TargetJITInfo &tji)
31 : ExecutionEngine(MP), TM(tm), TJI(tji), PM(MP) {
32 setTargetData(TM.getTargetData());
35 MCE = createEmitter(*this);
38 PM.add (new TargetData (TM.getTargetData ()));
40 // Compile LLVM Code down to machine code in the intermediate representation
41 TJI.addPassesToJITCompile(PM);
43 // Turn the machine code intermediate representation into bytes in memory that
45 if (TM.addPassesToEmitMachineCode(PM, *MCE)) {
46 std::cerr << "lli: target '" << TM.getName()
47 << "' doesn't support machine code emission!\n";
57 /// run - Start execution with the specified function and arguments.
59 GenericValue JIT::runFunction(Function *F,
60 const std::vector<GenericValue> &ArgValues) {
61 assert(F && "Function *F was null at entry to run()");
64 void *FPtr = getPointerToFunction(F);
65 assert(FPtr && "Pointer to fn's code was null after getPointerToFunction");
66 const Type *RetTy = F->getReturnType();
67 const FunctionType *FTy = F->getFunctionType();
69 // Handle some common cases first.
70 if (RetTy == Type::IntTy || RetTy == Type::UIntTy || RetTy == Type::VoidTy) {
71 switch (ArgValues.size()) {
73 if (FTy->getNumParams() == 3 &&
74 (FTy->getParamType(0) == Type::IntTy ||
75 FTy->getParamType(0) == Type::UIntTy) &&
76 isa<PointerType>(FTy->getParamType(1)) &&
77 isa<PointerType>(FTy->getParamType(2))) {
78 int (*PF)(int, char **, const char **) =
79 (int(*)(int, char **, const char **))FPtr;
82 rv.IntVal = PF(ArgValues[0].IntVal, (char **)GVTOP(ArgValues[1]),
83 (const char **)GVTOP(ArgValues[2]));
88 if (FTy->getNumParams() == 1 &&
89 (FTy->getParamType(0) == Type::IntTy ||
90 FTy->getParamType(0) == Type::UIntTy)) {
91 int (*PF)(int) = (int(*)(int))FPtr;
92 rv.IntVal = PF(ArgValues[0].IntVal);
97 int (*PF)() = (int(*)())FPtr;
103 // FIXME: This code should handle a couple of common cases efficiently, but
104 // it should also implement the general case by code-gening a new anonymous
105 // nullary function to call.
106 std::cerr << "Sorry, unimplemented feature in the LLVM JIT. See LLVM"
107 << " PR#419\n for details.\n";
112 /// runJITOnFunction - Run the FunctionPassManager full of
113 /// just-in-time compilation passes on F, hopefully filling in
114 /// GlobalAddress[F] with the address of F's machine code.
116 void JIT::runJITOnFunction(Function *F) {
117 static bool isAlreadyCodeGenerating = false;
118 assert(!isAlreadyCodeGenerating && "Error: Recursive compilation detected!");
121 isAlreadyCodeGenerating = true;
123 isAlreadyCodeGenerating = false;
125 // If the function referred to a global variable that had not yet been
126 // emitted, it allocates memory for the global, but doesn't emit it yet. Emit
127 // all of these globals now.
128 while (!PendingGlobals.empty()) {
129 const GlobalVariable *GV = PendingGlobals.back();
130 PendingGlobals.pop_back();
131 EmitGlobalVariable(GV);
135 /// getPointerToFunction - This method is used to get the address of the
136 /// specified function, compiling it if neccesary.
138 void *JIT::getPointerToFunction(Function *F) {
139 if (void *Addr = getPointerToGlobalIfAvailable(F))
140 return Addr; // Check if function already code gen'd
142 // Make sure we read in the function if it exists in this Module
144 MP->materializeFunction(F);
145 } catch ( std::string& errmsg ) {
146 std::cerr << "Error reading bytecode file: " << errmsg << "\n";
149 std::cerr << "Error reading bytecode file!\n";
153 if (F->isExternal()) {
154 void *Addr = getPointerToNamedFunction(F->getName());
155 addGlobalMapping(F, Addr);
161 void *Addr = getPointerToGlobalIfAvailable(F);
162 assert(Addr && "Code generation didn't add function to GlobalAddress table!");
166 // getPointerToFunctionOrStub - If the specified function has been
167 // code-gen'd, return a pointer to the function. If not, compile it, or use
168 // a stub to implement lazy compilation if available.
170 void *JIT::getPointerToFunctionOrStub(Function *F) {
171 // If we have already code generated the function, just return the address.
172 if (void *Addr = getPointerToGlobalIfAvailable(F))
175 // If the target supports "stubs" for functions, get a stub now.
176 if (void *Ptr = TJI.getJITStubForFunction(F, *MCE))
179 // Otherwise, if the target doesn't support it, just codegen the function.
180 return getPointerToFunction(F);
183 /// getOrEmitGlobalVariable - Return the address of the specified global
184 /// variable, possibly emitting it to memory if needed. This is used by the
186 void *JIT::getOrEmitGlobalVariable(const GlobalVariable *GV) {
187 void *Ptr = getPointerToGlobalIfAvailable(GV);
190 // If the global is external, just remember the address.
191 if (GV->isExternal()) {
192 Ptr = GetAddressOfSymbol(GV->getName().c_str());
194 std::cerr << "Could not resolve external global address: "
195 << GV->getName() << "\n";
199 // If the global hasn't been emitted to memory yet, allocate space. We will
200 // actually initialize the global after current function has finished
202 Ptr =new char[getTargetData().getTypeSize(GV->getType()->getElementType())];
203 PendingGlobals.push_back(GV);
205 addGlobalMapping(GV, Ptr);
210 /// recompileAndRelinkFunction - This method is used to force a function
211 /// which has already been compiled, to be compiled again, possibly
212 /// after it has been modified. Then the entry to the old copy is overwritten
213 /// with a branch to the new copy. If there was no old copy, this acts
214 /// just like JIT::getPointerToFunction().
216 void *JIT::recompileAndRelinkFunction(Function *F) {
217 void *OldAddr = getPointerToGlobalIfAvailable(F);
219 // If it's not already compiled there is no reason to patch it up.
220 if (OldAddr == 0) { return getPointerToFunction(F); }
222 // Delete the old function mapping.
223 addGlobalMapping(F, 0);
225 // Recodegen the function
228 // Update state, forward the old function to the new function.
229 void *Addr = getPointerToGlobalIfAvailable(F);
230 assert(Addr && "Code generation didn't add function to GlobalAddress table!");
231 TJI.replaceMachineCodeForFunction(OldAddr, Addr);