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//===-- jello.cpp - LLVM Just in Time Compiler ----------------------------===//
//
// This tool implements a just-in-time compiler for LLVM, allowing direct
// execution of LLVM bytecode in an efficient manner.
//
//===----------------------------------------------------------------------===//
#include "VM.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/CodeGen/MachineCodeEmitter.h"
#include "llvm/Function.h"
#include <dlfcn.h> // dlsym access
VM::~VM() {
delete MCE;
delete &TM;
}
/// setupPassManager - Initialize the VM PassManager object with all of the
/// passes needed for the target to generate code.
///
void VM::setupPassManager() {
// Compile LLVM Code down to machine code in the intermediate representation
if (TM.addPassesToJITCompile(PM)) {
std::cerr << "lli: target '" << TM.getName()
<< "' doesn't support JIT compilation!\n";
abort();
}
// Turn the machine code intermediate representation into bytes in memory that
// may be executed.
//
if (TM.addPassesToEmitMachineCode(PM, *MCE)) {
std::cerr << "lli: target '" << TM.getName()
<< "' doesn't support machine code emission!\n";
abort();
}
}
void *VM::resolveFunctionReference(void *RefAddr) {
Function *F = FunctionRefs[RefAddr];
assert(F && "Reference address not known!");
void *Addr = getPointerToFunction(F);
assert(Addr && "Pointer to function unknown!");
FunctionRefs.erase(RefAddr);
return Addr;
}
const std::string &VM::getFunctionReferencedName(void *RefAddr) {
return FunctionRefs[RefAddr]->getName();
}
static void NoopFn() {}
/// getPointerToNamedFunction - This method returns the address of the specified
/// function by using the dlsym function call. As such it is only useful for
/// resolving library symbols, not code generated symbols.
///
void *VM::getPointerToNamedFunction(const std::string &Name) {
// If it's an external function, look it up in the process image...
void *Ptr = dlsym(0, Name.c_str());
if (Ptr == 0) {
std::cerr << "WARNING: Cannot resolve fn '" << Name
<< "' using a dummy noop function instead!\n";
Ptr = (void*)NoopFn;
}
return Ptr;
}
/// getPointerToFunction - This method is used to get the address of the
/// specified function, compiling it if neccesary.
///
void *VM::getPointerToFunction(const Function *F) {
void *&Addr = GlobalAddress[F]; // Function already code gen'd
if (Addr) return Addr;
if (F->isExternal())
return Addr = getPointerToNamedFunction(F->getName());
static bool isAlreadyCodeGenerating = false;
if (isAlreadyCodeGenerating) {
// Generate a function stub instead of reentering...
void *SAddr = emitStubForFunction(*F);
assert(SAddr && "Target machine doesn't support function stub generation!");
return SAddr;
}
// FIXME: JIT all of the functions in the module. Eventually this will JIT
// functions on demand. This has the effect of populating all of the
// non-external functions into the GlobalAddress table.
isAlreadyCodeGenerating = true;
PM.run(getModule());
isAlreadyCodeGenerating = false;
assert(Addr && "Code generation didn't add function to GlobalAddress table!");
return Addr;
}
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