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"
29 /// setupPassManager - Initialize the VM PassManager object with all of the
30 /// passes needed for the target to generate code.
32 void VM::setupPassManager() {
33 // Compile LLVM Code down to machine code in the intermediate representation
34 if (TM.addPassesToJITCompile(PM)) {
35 std::cerr << "lli: target '" << TM.getName()
36 << "' doesn't support JIT compilation!\n";
40 // Turn the machine code intermediate representation into bytes in memory that
42 if (TM.addPassesToEmitMachineCode(PM, *MCE)) {
43 std::cerr << "lli: target '" << TM.getName()
44 << "' doesn't support machine code emission!\n";
49 /// runJITOnFunction - Run the FunctionPassManager full of
50 /// just-in-time compilation passes on F, hopefully filling in
51 /// GlobalAddress[F] with the address of F's machine code.
53 void VM::runJITOnFunction(Function *F) {
54 static bool isAlreadyCodeGenerating = false;
55 assert(!isAlreadyCodeGenerating && "Error: Recursive compilation detected!");
58 isAlreadyCodeGenerating = true;
60 isAlreadyCodeGenerating = false;
63 /// getPointerToFunction - This method is used to get the address of the
64 /// specified function, compiling it if neccesary.
66 void *VM::getPointerToFunction(Function *F) {
67 void *&Addr = GlobalAddress[F]; // Check if function already code gen'd
68 if (Addr) return Addr;
70 // Make sure we read in the function if it exists in this Module
71 MP->materializeFunction(F);
74 return Addr = getPointerToNamedFunction(F->getName());
77 assert(Addr && "Code generation didn't add function to GlobalAddress table!");
81 /// recompileAndRelinkFunction - This method is used to force a function
82 /// which has already been compiled, to be compiled again, possibly
83 /// after it has been modified. Then the entry to the old copy is overwritten
84 /// with a branch to the new copy. If there was no old copy, this acts
85 /// just like VM::getPointerToFunction().
87 void *VM::recompileAndRelinkFunction(Function *F) {
88 void *&Addr = GlobalAddress[F]; // Check if function already code gen'd
90 // If it's not already compiled (this is kind of weird) there is no
91 // reason to patch it up.
92 if (!Addr) { return getPointerToFunction (F); }
96 MachineFunction::destruct(F);
98 assert(Addr && "Code generation didn't add function to GlobalAddress table!");
99 TM.replaceMachineCodeForFunction(OldAddr, Addr);
103 } // End llvm namespace