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//===-- Emitter.cpp - Write machine code to executable memory -------------===//
//
// This file defines a MachineCodeEmitter object that is used by Jello to write
// machine code to memory and remember where relocatable values lie.
//
//===----------------------------------------------------------------------===//
#include "VM.h"
#include "llvm/CodeGen/MachineCodeEmitter.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Function.h"
#include "Support/Statistic.h"
#include <stdio.h>
static VM *TheVM = 0;
namespace {
Statistic<> NumBytes("jello", "Number of bytes of machine code compiled");
class Emitter : public MachineCodeEmitter {
// CurBlock - The start of the current block of memory. CurByte - The
// current byte being emitted to.
unsigned char *CurBlock, *CurByte;
// When outputting a function stub in the context of some other function, we
// save CurBlock and CurByte here.
unsigned char *SavedCurBlock, *SavedCurByte;
// ConstantPoolAddresses - Contains the location for each entry in the
// constant pool.
std::vector<void*> ConstantPoolAddresses;
public:
Emitter(VM &vm) { TheVM = &vm; }
virtual void startFunction(MachineFunction &F);
virtual void finishFunction(MachineFunction &F);
virtual void emitConstantPool(MachineConstantPool *MCP);
virtual void startFunctionStub(const Function &F, unsigned StubSize);
virtual void* finishFunctionStub(const Function &F);
virtual void emitByte(unsigned char B);
virtual void emitWord(unsigned W);
virtual uint64_t getGlobalValueAddress(GlobalValue *V);
virtual uint64_t getGlobalValueAddress(const std::string &Name);
virtual uint64_t getConstantPoolEntryAddress(unsigned Entry);
virtual uint64_t getCurrentPCValue();
// forceCompilationOf - Force the compilation of the specified function, and
// return its address, because we REALLY need the address now.
//
// FIXME: This is JIT specific!
//
virtual uint64_t forceCompilationOf(Function *F);
};
}
MachineCodeEmitter *VM::createEmitter(VM &V) {
return new Emitter(V);
}
#define _POSIX_MAPPED_FILES
#include <unistd.h>
#include <sys/mman.h>
// FIXME: This should be rewritten to support a real memory manager for
// executable memory pages!
static void *getMemory(unsigned NumPages) {
void *pa;
if (NumPages == 0) return 0;
static const long pageSize = sysconf(_SC_PAGESIZE);
#if defined(i386) || defined(__i386__) || defined(__x86__)
#if defined(MAP_ANON) && !defined(MAP_ANONYMOUS)
# define MAP_ANONYMOUS MAP_ANON
#endif
pa = mmap(0, pageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_ANONYMOUS, 0, 0); /* fd = 0 */
#elif defined(sparc) || defined(__sparc__) || defined(__sparcv9)
static unsigned long Counter = 0;
pa = mmap((void*)(0x140000000UL+Counter), pageSize*NumPages,
PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_ANON|MAP_FIXED, -1, 0); /* fd = -1 */
Counter += pageSize*NumPages;
#else
std::cerr << "This architecture is not supported by the JIT\n";
abort();
#endif
if (pa == MAP_FAILED) {
perror("mmap");
abort();
}
return pa;
}
void Emitter::startFunction(MachineFunction &F) {
CurBlock = (unsigned char *)getMemory(16);
CurByte = CurBlock; // Start writing at the beginning of the fn.
TheVM->addGlobalMapping(F.getFunction(), CurBlock);
}
void Emitter::finishFunction(MachineFunction &F) {
ConstantPoolAddresses.clear();
NumBytes += CurByte-CurBlock;
DEBUG(std::cerr << "Finished CodeGen of [" << (void*)CurBlock
<< "] Function: " << F.getFunction()->getName()
<< ": " << CurByte-CurBlock << " bytes of text\n");
}
void Emitter::emitConstantPool(MachineConstantPool *MCP) {
const std::vector<Constant*> &Constants = MCP->getConstants();
for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
// For now we just allocate some memory on the heap, this can be
// dramatically improved.
const Type *Ty = ((Value*)Constants[i])->getType();
void *Addr = malloc(TheVM->getTargetData().getTypeSize(Ty));
TheVM->InitializeMemory(Constants[i], Addr);
ConstantPoolAddresses.push_back(Addr);
}
}
void Emitter::startFunctionStub(const Function &F, unsigned StubSize) {
static const long pageSize = sysconf(_SC_PAGESIZE);
SavedCurBlock = CurBlock; SavedCurByte = CurByte;
// FIXME: this is a huge waste of memory.
CurBlock = (unsigned char *)getMemory((StubSize+pageSize-1)/pageSize);
CurByte = CurBlock; // Start writing at the beginning of the fn.
}
void *Emitter::finishFunctionStub(const Function &F) {
NumBytes += CurByte-CurBlock;
DEBUG(std::cerr << "Finished CodeGen of [0x" << std::hex
<< (unsigned)(intptr_t)CurBlock
<< std::dec << "] Function stub for: " << F.getName()
<< ": " << CurByte-CurBlock << " bytes of text\n");
std::swap(CurBlock, SavedCurBlock);
CurByte = SavedCurByte;
return SavedCurBlock;
}
void Emitter::emitByte(unsigned char B) {
*CurByte++ = B; // Write the byte to memory
}
void Emitter::emitWord(unsigned W) {
// FIXME: This won't work if the endianness of the host and target don't
// agree! (For a JIT this can't happen though. :)
*(unsigned*)CurByte = W;
CurByte += sizeof(unsigned);
}
uint64_t Emitter::getGlobalValueAddress(GlobalValue *V) {
// Try looking up the function to see if it is already compiled, if not return
// 0.
return (intptr_t)TheVM->getPointerToGlobalIfAvailable(V);
}
uint64_t Emitter::getGlobalValueAddress(const std::string &Name) {
return (intptr_t)TheVM->getPointerToNamedFunction(Name);
}
// getConstantPoolEntryAddress - Return the address of the 'ConstantNum' entry
// in the constant pool that was last emitted with the 'emitConstantPool'
// method.
//
uint64_t Emitter::getConstantPoolEntryAddress(unsigned ConstantNum) {
assert(ConstantNum < ConstantPoolAddresses.size() &&
"Invalid ConstantPoolIndex!");
return (intptr_t)ConstantPoolAddresses[ConstantNum];
}
// getCurrentPCValue - This returns the address that the next emitted byte
// will be output to.
//
uint64_t Emitter::getCurrentPCValue() {
return (intptr_t)CurByte;
}
uint64_t Emitter::forceCompilationOf(Function *F) {
return (intptr_t)TheVM->getPointerToFunction(F);
}
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