1 //===-- VM.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/Function.h"
17 #include "llvm/ModuleProvider.h"
18 #include "llvm/CodeGen/MachineCodeEmitter.h"
19 #include "llvm/CodeGen/MachineFunction.h"
20 #include "llvm/Target/TargetMachine.h"
28 /// setupPassManager - Initialize the VM PassManager object with all of the
29 /// passes needed for the target to generate code.
31 void VM::setupPassManager() {
32 // Compile LLVM Code down to machine code in the intermediate representation
33 if (TM.addPassesToJITCompile(PM)) {
34 std::cerr << "lli: target '" << TM.getName()
35 << "' doesn't support JIT compilation!\n";
39 // Turn the machine code intermediate representation into bytes in memory that
41 if (TM.addPassesToEmitMachineCode(PM, *MCE)) {
42 std::cerr << "lli: target '" << TM.getName()
43 << "' doesn't support machine code emission!\n";
48 /// runJITOnFunction - Run the FunctionPassManager full of
49 /// just-in-time compilation passes on F, hopefully filling in
50 /// GlobalAddress[F] with the address of F's machine code.
52 void VM::runJITOnFunction(Function *F) {
53 static bool isAlreadyCodeGenerating = false;
54 assert(!isAlreadyCodeGenerating && "Error: Recursive compilation detected!");
57 isAlreadyCodeGenerating = true;
59 isAlreadyCodeGenerating = false;
62 /// getPointerToFunction - This method is used to get the address of the
63 /// specified function, compiling it if neccesary.
65 void *VM::getPointerToFunction(Function *F) {
66 void *&Addr = GlobalAddress[F]; // Check if function already code gen'd
67 if (Addr) return Addr;
69 // Make sure we read in the function if it exists in this Module
70 MP->materializeFunction(F);
73 return Addr = getPointerToNamedFunction(F->getName());
76 assert(Addr && "Code generation didn't add function to GlobalAddress table!");
80 // getPointerToFunctionOrStub - If the specified function has been
81 // code-gen'd, return a pointer to the function. If not, compile it, or use
82 // a stub to implement lazy compilation if available.
84 void *VM::getPointerToFunctionOrStub(Function *F) {
85 // If we have already code generated the function, just return the address.
86 std::map<const GlobalValue*, void *>::iterator I = GlobalAddress.find(F);
87 if (I != GlobalAddress.end()) return I->second;
89 // If the target supports "stubs" for functions, get a stub now.
90 if (void *Ptr = TM.getJITStubForFunction(F, *MCE))
93 // Otherwise, if the target doesn't support it, just codegen the function.
94 return getPointerToFunction(F);
97 /// recompileAndRelinkFunction - This method is used to force a function
98 /// which has already been compiled, to be compiled again, possibly
99 /// after it has been modified. Then the entry to the old copy is overwritten
100 /// with a branch to the new copy. If there was no old copy, this acts
101 /// just like VM::getPointerToFunction().
103 void *VM::recompileAndRelinkFunction(Function *F) {
104 void *&Addr = GlobalAddress[F]; // Check if function already code gen'd
106 // If it's not already compiled (this is kind of weird) there is no
107 // reason to patch it up.
108 if (!Addr) { return getPointerToFunction (F); }
110 void *OldAddr = Addr;
112 MachineFunction::destruct(F);
114 assert(Addr && "Code generation didn't add function to GlobalAddress table!");
115 TM.replaceMachineCodeForFunction(OldAddr, Addr);