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//===-- VM.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/Function.h"
#include "llvm/ModuleProvider.h"
#include "llvm/CodeGen/MachineCodeEmitter.h"
#include "llvm/Target/TargetMachine.h"
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();
}
}
/// runJITOnFunction - Run the FunctionPassManager full of
/// just-in-time compilation passes on F, hopefully filling in
/// GlobalAddress[F] with the address of F's machine code.
///
void VM::runJITOnFunction (Function *F) {
static bool isAlreadyCodeGenerating = false;
assert(!isAlreadyCodeGenerating && "ERROR: RECURSIVE COMPILATION DETECTED!");
// JIT the function
isAlreadyCodeGenerating = true;
PM.run(*F);
isAlreadyCodeGenerating = false;
}
/// getPointerToFunction - This method is used to get the address of the
/// specified function, compiling it if neccesary.
///
void *VM::getPointerToFunction(Function *F) {
void *&Addr = GlobalAddress[F]; // Check if function already code gen'd
if (Addr) return Addr;
// Make sure we read in the function if it exists in this Module
MP->materializeFunction(F);
if (F->isExternal())
return Addr = getPointerToNamedFunction(F->getName());
runJITOnFunction (F);
assert(Addr && "Code generation didn't add function to GlobalAddress table!");
return Addr;
}
/// recompileAndRelinkFunction - This method is used to force a function
/// which has already been compiled, to be compiled again, possibly
/// after it has been modified. Then the entry to the old copy is overwritten
/// with a branch to the new copy. If there was no old copy, this acts
/// just like VM::getPointerToFunction().
///
void *VM::recompileAndRelinkFunction(Function *F) {
void *&Addr = GlobalAddress[F]; // Check if function already code gen'd
// If it's not already compiled (this is kind of weird) there is no
// reason to patch it up.
if (!Addr) { return getPointerToFunction (F); }
void *OldAddr = Addr;
Addr = 0;
runJITOnFunction (F);
assert(Addr && "Code generation didn't add function to GlobalAddress table!");
TM.replaceMachineCodeForFunction (OldAddr, Addr);
return Addr;
}
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