mirror of
https://github.com/c64scene-ar/llvm-6502.git
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6020ddd57e
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9184 91177308-0d34-0410-b5e6-96231b3b80d8
261 lines
8.9 KiB
C++
261 lines
8.9 KiB
C++
//===-- Emitter.cpp - Write machine code to executable memory -------------===//
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//
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// This file defines a MachineCodeEmitter object that is used by Jello to write
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// machine code to memory and remember where relocatable values lie.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "jit"
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#ifndef _POSIX_MAPPED_FILES
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#define _POSIX_MAPPED_FILES
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#endif
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#include "VM.h"
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#include "llvm/CodeGen/MachineCodeEmitter.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineConstantPool.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Module.h"
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#include "Support/Debug.h"
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#include "Support/Statistic.h"
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#include "Config/unistd.h"
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#include "Config/sys/mman.h"
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namespace {
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Statistic<> NumBytes("jello", "Number of bytes of machine code compiled");
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VM *TheVM = 0;
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/// JITMemoryManager - Manage memory for the JIT code generation in a logical,
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/// sane way. This splits a large block of MAP_NORESERVE'd memory into two
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/// sections, one for function stubs, one for the functions themselves. We
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/// have to do this because we may need to emit a function stub while in the
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/// middle of emitting a function, and we don't know how large the function we
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/// are emitting is. This never bothers to release the memory, because when
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/// we are ready to destroy the JIT, the program exits.
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class JITMemoryManager {
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unsigned char *MemBase; // Base of block of memory, start of stub mem
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unsigned char *FunctionBase; // Start of the function body area
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unsigned char *CurStubPtr, *CurFunctionPtr;
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public:
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JITMemoryManager();
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inline unsigned char *allocateStub(unsigned StubSize);
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inline unsigned char *startFunctionBody();
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inline void endFunctionBody(unsigned char *FunctionEnd);
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};
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}
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// getMemory - Return a pointer to the specified number of bytes, which is
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// mapped as executable readable and writable.
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static void *getMemory(unsigned NumBytes) {
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if (NumBytes == 0) return 0;
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static const long pageSize = sysconf(_SC_PAGESIZE);
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unsigned NumPages = (NumBytes+pageSize-1)/pageSize;
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#if defined(i386) || defined(__i386__) || defined(__x86__)
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/* Linux and *BSD tend to have these flags named differently. */
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#if defined(MAP_ANON) && !defined(MAP_ANONYMOUS)
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# define MAP_ANONYMOUS MAP_ANON
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#endif /* defined(MAP_ANON) && !defined(MAP_ANONYMOUS) */
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#elif defined(sparc) || defined(__sparc__) || defined(__sparcv9)
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/* nothing */
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#else
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std::cerr << "This architecture is not supported by the JIT!\n";
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abort();
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#endif
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#if defined(__linux__)
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#define fd 0
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#else
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#define fd -1
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#endif
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unsigned mmapFlags = MAP_PRIVATE|MAP_ANONYMOUS;
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#ifdef MAP_NORESERVE
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mmapFlags |= MAP_NORESERVE;
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#endif
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void *pa = mmap(0, pageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC,
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mmapFlags, fd, 0);
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if (pa == MAP_FAILED) {
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perror("mmap");
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abort();
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}
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return pa;
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}
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JITMemoryManager::JITMemoryManager() {
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// Allocate a 16M block of memory...
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MemBase = (unsigned char*)getMemory(16 << 20);
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FunctionBase = MemBase + 512*1024; // Use 512k for stubs
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// Allocate stubs backwards from the function base, allocate functions forward
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// from the function base.
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CurStubPtr = CurFunctionPtr = FunctionBase;
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}
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unsigned char *JITMemoryManager::allocateStub(unsigned StubSize) {
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CurStubPtr -= StubSize;
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if (CurStubPtr < MemBase) {
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std::cerr << "JIT ran out of memory for function stubs!\n";
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abort();
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}
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return CurStubPtr;
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}
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unsigned char *JITMemoryManager::startFunctionBody() {
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// Round up to an even multiple of 4 bytes, this should eventually be target
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// specific.
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return (unsigned char*)(((intptr_t)CurFunctionPtr + 3) & ~3);
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}
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void JITMemoryManager::endFunctionBody(unsigned char *FunctionEnd) {
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assert(FunctionEnd > CurFunctionPtr);
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CurFunctionPtr = FunctionEnd;
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}
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namespace {
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/// Emitter - The JIT implementation of the MachineCodeEmitter, which is used
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/// to output functions to memory for execution.
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class Emitter : public MachineCodeEmitter {
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JITMemoryManager MemMgr;
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// CurBlock - The start of the current block of memory. CurByte - The
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// current byte being emitted to.
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unsigned char *CurBlock, *CurByte;
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// When outputting a function stub in the context of some other function, we
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// save CurBlock and CurByte here.
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unsigned char *SavedCurBlock, *SavedCurByte;
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// ConstantPoolAddresses - Contains the location for each entry in the
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// constant pool.
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std::vector<void*> ConstantPoolAddresses;
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public:
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Emitter(VM &vm) { TheVM = &vm; }
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virtual void startFunction(MachineFunction &F);
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virtual void finishFunction(MachineFunction &F);
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virtual void emitConstantPool(MachineConstantPool *MCP);
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virtual void startFunctionStub(const Function &F, unsigned StubSize);
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virtual void* finishFunctionStub(const Function &F);
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virtual void emitByte(unsigned char B);
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virtual void emitWord(unsigned W);
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virtual uint64_t getGlobalValueAddress(GlobalValue *V);
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virtual uint64_t getGlobalValueAddress(const std::string &Name);
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virtual uint64_t getConstantPoolEntryAddress(unsigned Entry);
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virtual uint64_t getCurrentPCValue();
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// forceCompilationOf - Force the compilation of the specified function, and
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// return its address, because we REALLY need the address now.
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//
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// FIXME: This is JIT specific!
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//
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virtual uint64_t forceCompilationOf(Function *F);
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};
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}
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MachineCodeEmitter *VM::createEmitter(VM &V) {
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return new Emitter(V);
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}
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void Emitter::startFunction(MachineFunction &F) {
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CurByte = CurBlock = MemMgr.startFunctionBody();
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TheVM->addGlobalMapping(F.getFunction(), CurBlock);
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}
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void Emitter::finishFunction(MachineFunction &F) {
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MemMgr.endFunctionBody(CurByte);
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ConstantPoolAddresses.clear();
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NumBytes += CurByte-CurBlock;
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DEBUG(std::cerr << "Finished CodeGen of [" << (void*)CurBlock
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<< "] Function: " << F.getFunction()->getName()
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<< ": " << CurByte-CurBlock << " bytes of text\n");
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}
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void Emitter::emitConstantPool(MachineConstantPool *MCP) {
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const std::vector<Constant*> &Constants = MCP->getConstants();
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for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
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// For now we just allocate some memory on the heap, this can be
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// dramatically improved.
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const Type *Ty = ((Value*)Constants[i])->getType();
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void *Addr = malloc(TheVM->getTargetData().getTypeSize(Ty));
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TheVM->InitializeMemory(Constants[i], Addr);
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ConstantPoolAddresses.push_back(Addr);
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}
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}
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void Emitter::startFunctionStub(const Function &F, unsigned StubSize) {
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SavedCurBlock = CurBlock; SavedCurByte = CurByte;
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CurByte = CurBlock = MemMgr.allocateStub(StubSize);
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}
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void *Emitter::finishFunctionStub(const Function &F) {
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NumBytes += CurByte-CurBlock;
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DEBUG(std::cerr << "Finished CodeGen of [0x" << std::hex
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<< (unsigned)(intptr_t)CurBlock
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<< std::dec << "] Function stub for: " << F.getName()
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<< ": " << CurByte-CurBlock << " bytes of text\n");
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std::swap(CurBlock, SavedCurBlock);
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CurByte = SavedCurByte;
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return SavedCurBlock;
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}
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void Emitter::emitByte(unsigned char B) {
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*CurByte++ = B; // Write the byte to memory
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}
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void Emitter::emitWord(unsigned W) {
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// This won't work if the endianness of the host and target don't agree! (For
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// a JIT this can't happen though. :)
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*(unsigned*)CurByte = W;
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CurByte += sizeof(unsigned);
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}
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uint64_t Emitter::getGlobalValueAddress(GlobalValue *V) {
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// Try looking up the function to see if it is already compiled, if not return
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// 0.
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return (intptr_t)TheVM->getPointerToGlobalIfAvailable(V);
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}
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uint64_t Emitter::getGlobalValueAddress(const std::string &Name) {
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return (intptr_t)TheVM->getPointerToNamedFunction(Name);
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}
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// getConstantPoolEntryAddress - Return the address of the 'ConstantNum' entry
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// in the constant pool that was last emitted with the 'emitConstantPool'
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// method.
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//
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uint64_t Emitter::getConstantPoolEntryAddress(unsigned ConstantNum) {
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assert(ConstantNum < ConstantPoolAddresses.size() &&
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"Invalid ConstantPoolIndex!");
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return (intptr_t)ConstantPoolAddresses[ConstantNum];
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}
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// getCurrentPCValue - This returns the address that the next emitted byte
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// will be output to.
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//
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uint64_t Emitter::getCurrentPCValue() {
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return (intptr_t)CurByte;
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}
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uint64_t Emitter::forceCompilationOf(Function *F) {
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return (intptr_t)TheVM->getPointerToFunction(F);
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}
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// getPointerToNamedFunction - This function is used as a global wrapper to
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// VM::getPointerToNamedFunction for the purpose of resolving symbols when
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// bugpoint is debugging the JIT. In that scenario, we are loading an .so and
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// need to resolve function(s) that are being mis-codegenerated, so we need to
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// resolve their addresses at runtime, and this is the way to do it.
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extern "C" {
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void *getPointerToNamedFunction(const char *Name) {
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Module &M = TheVM->getModule();
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if (Function *F = M.getNamedFunction(Name))
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return TheVM->getPointerToFunction(F);
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return TheVM->getPointerToNamedFunction(Name);
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}
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}
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