| //===-- Emitter.cpp - Write machine code to executable memory -------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines a MachineCodeEmitter object that is used by Jello to write |
| // machine code to memory and remember where relocatable values lie. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "jit" |
| #ifndef _POSIX_MAPPED_FILES |
| #define _POSIX_MAPPED_FILES |
| #endif |
| #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/Module.h" |
| #include "Support/Debug.h" |
| #include "Support/Statistic.h" |
| #include "Config/unistd.h" |
| #include "Config/sys/mman.h" |
| |
| namespace llvm { |
| |
| namespace { |
| Statistic<> NumBytes("jit", "Number of bytes of machine code compiled"); |
| VM *TheVM = 0; |
| |
| /// JITMemoryManager - Manage memory for the JIT code generation in a logical, |
| /// sane way. This splits a large block of MAP_NORESERVE'd memory into two |
| /// sections, one for function stubs, one for the functions themselves. We |
| /// have to do this because we may need to emit a function stub while in the |
| /// middle of emitting a function, and we don't know how large the function we |
| /// are emitting is. This never bothers to release the memory, because when |
| /// we are ready to destroy the JIT, the program exits. |
| class JITMemoryManager { |
| unsigned char *MemBase; // Base of block of memory, start of stub mem |
| unsigned char *FunctionBase; // Start of the function body area |
| unsigned char *CurStubPtr, *CurFunctionPtr; |
| public: |
| JITMemoryManager(); |
| |
| inline unsigned char *allocateStub(unsigned StubSize); |
| inline unsigned char *startFunctionBody(); |
| inline void endFunctionBody(unsigned char *FunctionEnd); |
| }; |
| } |
| |
| // getMemory - Return a pointer to the specified number of bytes, which is |
| // mapped as executable readable and writable. |
| static void *getMemory(unsigned NumBytes) { |
| if (NumBytes == 0) return 0; |
| static const long pageSize = sysconf(_SC_PAGESIZE); |
| unsigned NumPages = (NumBytes+pageSize-1)/pageSize; |
| |
| #if defined(i386) || defined(__i386__) || defined(__x86__) |
| /* Linux and *BSD tend to have these flags named differently. */ |
| #if defined(MAP_ANON) && !defined(MAP_ANONYMOUS) |
| # define MAP_ANONYMOUS MAP_ANON |
| #endif /* defined(MAP_ANON) && !defined(MAP_ANONYMOUS) */ |
| #elif defined(sparc) || defined(__sparc__) || defined(__sparcv9) |
| /* nothing */ |
| #else |
| std::cerr << "This architecture is not supported by the JIT!\n"; |
| abort(); |
| #endif |
| |
| #if defined(__linux__) |
| #define fd 0 |
| #else |
| #define fd -1 |
| #endif |
| |
| unsigned mmapFlags = MAP_PRIVATE|MAP_ANONYMOUS; |
| #ifdef MAP_NORESERVE |
| mmapFlags |= MAP_NORESERVE; |
| #endif |
| |
| void *pa = mmap(0, pageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC, |
| mmapFlags, fd, 0); |
| if (pa == MAP_FAILED) { |
| perror("mmap"); |
| abort(); |
| } |
| return pa; |
| } |
| |
| JITMemoryManager::JITMemoryManager() { |
| // Allocate a 16M block of memory... |
| MemBase = (unsigned char*)getMemory(16 << 20); |
| FunctionBase = MemBase + 512*1024; // Use 512k for stubs |
| |
| // Allocate stubs backwards from the function base, allocate functions forward |
| // from the function base. |
| CurStubPtr = CurFunctionPtr = FunctionBase; |
| } |
| |
| unsigned char *JITMemoryManager::allocateStub(unsigned StubSize) { |
| CurStubPtr -= StubSize; |
| if (CurStubPtr < MemBase) { |
| std::cerr << "JIT ran out of memory for function stubs!\n"; |
| abort(); |
| } |
| return CurStubPtr; |
| } |
| |
| unsigned char *JITMemoryManager::startFunctionBody() { |
| // Round up to an even multiple of 4 bytes, this should eventually be target |
| // specific. |
| return (unsigned char*)(((intptr_t)CurFunctionPtr + 3) & ~3); |
| } |
| |
| void JITMemoryManager::endFunctionBody(unsigned char *FunctionEnd) { |
| assert(FunctionEnd > CurFunctionPtr); |
| CurFunctionPtr = FunctionEnd; |
| } |
| |
| |
| |
| namespace { |
| /// Emitter - The JIT implementation of the MachineCodeEmitter, which is used |
| /// to output functions to memory for execution. |
| class Emitter : public MachineCodeEmitter { |
| JITMemoryManager MemMgr; |
| |
| // 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); |
| } |
| |
| void Emitter::startFunction(MachineFunction &F) { |
| CurByte = CurBlock = MemMgr.startFunctionBody(); |
| TheVM->addGlobalMapping(F.getFunction(), CurBlock); |
| } |
| |
| void Emitter::finishFunction(MachineFunction &F) { |
| MemMgr.endFunctionBody(CurByte); |
| 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) { |
| SavedCurBlock = CurBlock; SavedCurByte = CurByte; |
| CurByte = CurBlock = MemMgr.allocateStub(StubSize); |
| } |
| |
| 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) { |
| // 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); |
| } |
| |
| // getPointerToNamedFunction - This function is used as a global wrapper to |
| // VM::getPointerToNamedFunction for the purpose of resolving symbols when |
| // bugpoint is debugging the JIT. In that scenario, we are loading an .so and |
| // need to resolve function(s) that are being mis-codegenerated, so we need to |
| // resolve their addresses at runtime, and this is the way to do it. |
| extern "C" { |
| void *getPointerToNamedFunction(const char *Name) { |
| Module &M = TheVM->getModule(); |
| if (Function *F = M.getNamedFunction(Name)) |
| return TheVM->getPointerToFunction(F); |
| return TheVM->getPointerToNamedFunction(Name); |
| } |
| } |
| |
| } // End llvm namespace |