1 //===-- Emitter.cpp - Write machine code to executable memory -------------===//
3 // This file defines a MachineCodeEmitter object that is used by Jello to write
4 // machine code to memory and remember where relocatable values lie.
6 //===----------------------------------------------------------------------===//
9 #include "Config/sys/mman.h"
10 #include "llvm/CodeGen/MachineCodeEmitter.h"
11 #include "llvm/CodeGen/MachineFunction.h"
12 #include "llvm/CodeGen/MachineConstantPool.h"
13 #include "llvm/Target/TargetData.h"
14 #include "llvm/Module.h"
15 #include "Support/Statistic.h"
19 Statistic<> NumBytes("jello", "Number of bytes of machine code compiled");
22 class Emitter : public MachineCodeEmitter {
23 // CurBlock - The start of the current block of memory. CurByte - The
24 // current byte being emitted to.
25 unsigned char *CurBlock, *CurByte;
27 // When outputting a function stub in the context of some other function, we
28 // save CurBlock and CurByte here.
29 unsigned char *SavedCurBlock, *SavedCurByte;
31 // ConstantPoolAddresses - Contains the location for each entry in the
33 std::vector<void*> ConstantPoolAddresses;
35 Emitter(VM &vm) { TheVM = &vm; }
37 virtual void startFunction(MachineFunction &F);
38 virtual void finishFunction(MachineFunction &F);
39 virtual void emitConstantPool(MachineConstantPool *MCP);
40 virtual void startFunctionStub(const Function &F, unsigned StubSize);
41 virtual void* finishFunctionStub(const Function &F);
42 virtual void emitByte(unsigned char B);
43 virtual void emitWord(unsigned W);
45 virtual uint64_t getGlobalValueAddress(GlobalValue *V);
46 virtual uint64_t getGlobalValueAddress(const std::string &Name);
47 virtual uint64_t getConstantPoolEntryAddress(unsigned Entry);
48 virtual uint64_t getCurrentPCValue();
50 // forceCompilationOf - Force the compilation of the specified function, and
51 // return its address, because we REALLY need the address now.
53 // FIXME: This is JIT specific!
55 virtual uint64_t forceCompilationOf(Function *F);
59 MachineCodeEmitter *VM::createEmitter(VM &V) {
60 return new Emitter(V);
64 #define _POSIX_MAPPED_FILES
68 // FIXME: This should be rewritten to support a real memory manager for
69 // executable memory pages!
70 static void *getMemory(unsigned NumPages) {
72 if (NumPages == 0) return 0;
73 static const long pageSize = sysconf(_SC_PAGESIZE);
75 #if defined(i386) || defined(__i386__) || defined(__x86__)
76 /* Linux and *BSD tend to have these flags named differently. */
77 #if defined(MAP_ANON) && !defined(MAP_ANONYMOUS)
78 # define MAP_ANONYMOUS MAP_ANON
80 pa = mmap(0, pageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC,
81 MAP_PRIVATE|MAP_ANONYMOUS, 0, 0); /* fd = 0 */
82 #elif defined(sparc) || defined(__sparc__) || defined(__sparcv9)
83 static unsigned long Counter = 0;
84 pa = mmap((void*)(0x140000000UL+Counter), pageSize*NumPages,
85 PROT_READ|PROT_WRITE|PROT_EXEC,
86 MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, -1, 0); /* fd = -1 */
87 Counter += pageSize*NumPages;
89 std::cerr << "This architecture is not supported by the JIT\n";
93 if (pa == MAP_FAILED) {
101 void Emitter::startFunction(MachineFunction &F) {
102 CurBlock = (unsigned char *)getMemory(16);
103 CurByte = CurBlock; // Start writing at the beginning of the fn.
104 TheVM->addGlobalMapping(F.getFunction(), CurBlock);
107 void Emitter::finishFunction(MachineFunction &F) {
108 ConstantPoolAddresses.clear();
109 NumBytes += CurByte-CurBlock;
111 DEBUG(std::cerr << "Finished CodeGen of [" << (void*)CurBlock
112 << "] Function: " << F.getFunction()->getName()
113 << ": " << CurByte-CurBlock << " bytes of text\n");
116 void Emitter::emitConstantPool(MachineConstantPool *MCP) {
117 const std::vector<Constant*> &Constants = MCP->getConstants();
118 for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
119 // For now we just allocate some memory on the heap, this can be
120 // dramatically improved.
121 const Type *Ty = ((Value*)Constants[i])->getType();
122 void *Addr = malloc(TheVM->getTargetData().getTypeSize(Ty));
123 TheVM->InitializeMemory(Constants[i], Addr);
124 ConstantPoolAddresses.push_back(Addr);
128 void Emitter::startFunctionStub(const Function &F, unsigned StubSize) {
129 static const long pageSize = sysconf(_SC_PAGESIZE);
130 SavedCurBlock = CurBlock; SavedCurByte = CurByte;
131 // FIXME: this is a huge waste of memory.
132 CurBlock = (unsigned char *)getMemory((StubSize+pageSize-1)/pageSize);
133 CurByte = CurBlock; // Start writing at the beginning of the fn.
136 void *Emitter::finishFunctionStub(const Function &F) {
137 NumBytes += CurByte-CurBlock;
138 DEBUG(std::cerr << "Finished CodeGen of [0x" << std::hex
139 << (unsigned)(intptr_t)CurBlock
140 << std::dec << "] Function stub for: " << F.getName()
141 << ": " << CurByte-CurBlock << " bytes of text\n");
142 std::swap(CurBlock, SavedCurBlock);
143 CurByte = SavedCurByte;
144 return SavedCurBlock;
147 void Emitter::emitByte(unsigned char B) {
148 *CurByte++ = B; // Write the byte to memory
151 void Emitter::emitWord(unsigned W) {
152 // FIXME: This won't work if the endianness of the host and target don't
153 // agree! (For a JIT this can't happen though. :)
154 *(unsigned*)CurByte = W;
155 CurByte += sizeof(unsigned);
159 uint64_t Emitter::getGlobalValueAddress(GlobalValue *V) {
160 // Try looking up the function to see if it is already compiled, if not return
162 return (intptr_t)TheVM->getPointerToGlobalIfAvailable(V);
164 uint64_t Emitter::getGlobalValueAddress(const std::string &Name) {
165 return (intptr_t)TheVM->getPointerToNamedFunction(Name);
168 // getConstantPoolEntryAddress - Return the address of the 'ConstantNum' entry
169 // in the constant pool that was last emitted with the 'emitConstantPool'
172 uint64_t Emitter::getConstantPoolEntryAddress(unsigned ConstantNum) {
173 assert(ConstantNum < ConstantPoolAddresses.size() &&
174 "Invalid ConstantPoolIndex!");
175 return (intptr_t)ConstantPoolAddresses[ConstantNum];
178 // getCurrentPCValue - This returns the address that the next emitted byte
179 // will be output to.
181 uint64_t Emitter::getCurrentPCValue() {
182 return (intptr_t)CurByte;
185 uint64_t Emitter::forceCompilationOf(Function *F) {
186 return (intptr_t)TheVM->getPointerToFunction(F);
189 // getPointerToNamedFunction - This function is used as a global wrapper to
190 // VM::getPointerToNamedFunction for the purpose of resolving symbols when
191 // bugpoint is debugging the JIT. In that scenario, we are loading an .so and
192 // need to resolve function(s) that are being mis-codegenerated, so we need to
193 // resolve their addresses at runtime, and this is the way to do it.
195 void *getPointerToNamedFunction(const char *Name) {
196 Module &M = TheVM->getModule();
197 if (Function *F = M.getNamedFunction(Name))
198 return TheVM->getPointerToFunction(F);
199 return TheVM->getPointerToNamedFunction(Name);