1 //===-- JITEmitter.cpp - Write machine code to executable memory ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines a MachineCodeEmitter object that is used by the JIT to
11 // write machine code to memory and remember where relocatable values are.
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "jit"
17 #include "JITDwarfEmitter.h"
18 #include "llvm/Constant.h"
19 #include "llvm/Module.h"
20 #include "llvm/Type.h"
21 #include "llvm/CodeGen/MachineCodeEmitter.h"
22 #include "llvm/CodeGen/MachineFunction.h"
23 #include "llvm/CodeGen/MachineConstantPool.h"
24 #include "llvm/CodeGen/MachineJumpTableInfo.h"
25 #include "llvm/CodeGen/MachineModuleInfo.h"
26 #include "llvm/CodeGen/MachineRelocation.h"
27 #include "llvm/ExecutionEngine/JITMemoryManager.h"
28 #include "llvm/Target/TargetData.h"
29 #include "llvm/Target/TargetJITInfo.h"
30 #include "llvm/Target/TargetMachine.h"
31 #include "llvm/Target/TargetOptions.h"
32 #include "llvm/Support/Debug.h"
33 #include "llvm/Support/MutexGuard.h"
34 #include "llvm/System/Disassembler.h"
35 #include "llvm/Target/TargetInstrInfo.h"
36 #include "llvm/ADT/Statistic.h"
40 STATISTIC(NumBytes, "Number of bytes of machine code compiled");
41 STATISTIC(NumRelos, "Number of relocations applied");
42 static JIT *TheJIT = 0;
45 //===----------------------------------------------------------------------===//
46 // JIT lazy compilation code.
49 class JITResolverState {
51 /// FunctionToStubMap - Keep track of the stub created for a particular
52 /// function so that we can reuse them if necessary.
53 std::map<Function*, void*> FunctionToStubMap;
55 /// StubToFunctionMap - Keep track of the function that each stub
57 std::map<void*, Function*> StubToFunctionMap;
59 /// GlobalToLazyPtrMap - Keep track of the lazy pointer created for a
60 /// particular GlobalVariable so that we can reuse them if necessary.
61 std::map<GlobalValue*, void*> GlobalToLazyPtrMap;
64 std::map<Function*, void*>& getFunctionToStubMap(const MutexGuard& locked) {
65 assert(locked.holds(TheJIT->lock));
66 return FunctionToStubMap;
69 std::map<void*, Function*>& getStubToFunctionMap(const MutexGuard& locked) {
70 assert(locked.holds(TheJIT->lock));
71 return StubToFunctionMap;
74 std::map<GlobalValue*, void*>&
75 getGlobalToLazyPtrMap(const MutexGuard& locked) {
76 assert(locked.holds(TheJIT->lock));
77 return GlobalToLazyPtrMap;
81 /// JITResolver - Keep track of, and resolve, call sites for functions that
82 /// have not yet been compiled.
84 /// LazyResolverFn - The target lazy resolver function that we actually
85 /// rewrite instructions to use.
86 TargetJITInfo::LazyResolverFn LazyResolverFn;
88 JITResolverState state;
90 /// ExternalFnToStubMap - This is the equivalent of FunctionToStubMap for
91 /// external functions.
92 std::map<void*, void*> ExternalFnToStubMap;
94 //map addresses to indexes in the GOT
95 std::map<void*, unsigned> revGOTMap;
96 unsigned nextGOTIndex;
98 static JITResolver *TheJITResolver;
100 explicit JITResolver(JIT &jit) : nextGOTIndex(0) {
103 LazyResolverFn = jit.getJITInfo().getLazyResolverFunction(JITCompilerFn);
104 assert(TheJITResolver == 0 && "Multiple JIT resolvers?");
105 TheJITResolver = this;
112 /// getFunctionStub - This returns a pointer to a function stub, creating
113 /// one on demand as needed.
114 void *getFunctionStub(Function *F);
116 /// getExternalFunctionStub - Return a stub for the function at the
117 /// specified address, created lazily on demand.
118 void *getExternalFunctionStub(void *FnAddr);
120 /// getGlobalValueLazyPtr - Return a lazy pointer containing the specified
122 void *getGlobalValueLazyPtr(GlobalValue *V, void *GVAddress);
124 /// AddCallbackAtLocation - If the target is capable of rewriting an
125 /// instruction without the use of a stub, record the location of the use so
126 /// we know which function is being used at the location.
127 void *AddCallbackAtLocation(Function *F, void *Location) {
128 MutexGuard locked(TheJIT->lock);
129 /// Get the target-specific JIT resolver function.
130 state.getStubToFunctionMap(locked)[Location] = F;
131 return (void*)(intptr_t)LazyResolverFn;
134 /// getGOTIndexForAddress - Return a new or existing index in the GOT for
135 /// an address. This function only manages slots, it does not manage the
136 /// contents of the slots or the memory associated with the GOT.
137 unsigned getGOTIndexForAddr(void *addr);
139 /// JITCompilerFn - This function is called to resolve a stub to a compiled
140 /// address. If the LLVM Function corresponding to the stub has not yet
141 /// been compiled, this function compiles it first.
142 static void *JITCompilerFn(void *Stub);
146 JITResolver *JITResolver::TheJITResolver = 0;
148 #if (defined(__POWERPC__) || defined (__ppc__) || defined(_POWER)) && \
150 extern "C" void sys_icache_invalidate(const void *Addr, size_t len);
153 /// synchronizeICache - On some targets, the JIT emitted code must be
154 /// explicitly refetched to ensure correct execution.
155 static void synchronizeICache(const void *Addr, size_t len) {
156 #if (defined(__POWERPC__) || defined (__ppc__) || defined(_POWER)) && \
158 sys_icache_invalidate(Addr, len);
162 /// getFunctionStub - This returns a pointer to a function stub, creating
163 /// one on demand as needed.
164 void *JITResolver::getFunctionStub(Function *F) {
165 MutexGuard locked(TheJIT->lock);
167 // If we already have a stub for this function, recycle it.
168 void *&Stub = state.getFunctionToStubMap(locked)[F];
169 if (Stub) return Stub;
171 // Call the lazy resolver function unless we already KNOW it is an external
172 // function, in which case we just skip the lazy resolution step.
173 void *Actual = (void*)(intptr_t)LazyResolverFn;
174 if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode())
175 Actual = TheJIT->getPointerToFunction(F);
177 // Otherwise, codegen a new stub. For now, the stub will call the lazy
178 // resolver function.
179 Stub = TheJIT->getJITInfo().emitFunctionStub(F, Actual,
180 *TheJIT->getCodeEmitter());
182 if (Actual != (void*)(intptr_t)LazyResolverFn) {
183 // If we are getting the stub for an external function, we really want the
184 // address of the stub in the GlobalAddressMap for the JIT, not the address
185 // of the external function.
186 TheJIT->updateGlobalMapping(F, Stub);
189 DOUT << "JIT: Stub emitted at [" << Stub << "] for function '"
190 << F->getName() << "'\n";
192 // Finally, keep track of the stub-to-Function mapping so that the
193 // JITCompilerFn knows which function to compile!
194 state.getStubToFunctionMap(locked)[Stub] = F;
198 /// getGlobalValueLazyPtr - Return a lazy pointer containing the specified
200 void *JITResolver::getGlobalValueLazyPtr(GlobalValue *GV, void *GVAddress) {
201 MutexGuard locked(TheJIT->lock);
203 // If we already have a stub for this global variable, recycle it.
204 void *&LazyPtr = state.getGlobalToLazyPtrMap(locked)[GV];
205 if (LazyPtr) return LazyPtr;
207 // Otherwise, codegen a new lazy pointer.
208 LazyPtr = TheJIT->getJITInfo().emitGlobalValueLazyPtr(GV, GVAddress,
209 *TheJIT->getCodeEmitter());
211 DOUT << "JIT: Stub emitted at [" << LazyPtr << "] for GV '"
212 << GV->getName() << "'\n";
217 /// getExternalFunctionStub - Return a stub for the function at the
218 /// specified address, created lazily on demand.
219 void *JITResolver::getExternalFunctionStub(void *FnAddr) {
220 // If we already have a stub for this function, recycle it.
221 void *&Stub = ExternalFnToStubMap[FnAddr];
222 if (Stub) return Stub;
224 Stub = TheJIT->getJITInfo().emitFunctionStub(0, FnAddr,
225 *TheJIT->getCodeEmitter());
227 DOUT << "JIT: Stub emitted at [" << Stub
228 << "] for external function at '" << FnAddr << "'\n";
232 unsigned JITResolver::getGOTIndexForAddr(void* addr) {
233 unsigned idx = revGOTMap[addr];
235 idx = ++nextGOTIndex;
236 revGOTMap[addr] = idx;
237 DOUT << "Adding GOT entry " << idx << " for addr " << addr << "\n";
242 /// JITCompilerFn - This function is called when a lazy compilation stub has
243 /// been entered. It looks up which function this stub corresponds to, compiles
244 /// it if necessary, then returns the resultant function pointer.
245 void *JITResolver::JITCompilerFn(void *Stub) {
246 JITResolver &JR = *TheJITResolver;
248 MutexGuard locked(TheJIT->lock);
250 // The address given to us for the stub may not be exactly right, it might be
251 // a little bit after the stub. As such, use upper_bound to find it.
252 std::map<void*, Function*>::iterator I =
253 JR.state.getStubToFunctionMap(locked).upper_bound(Stub);
254 assert(I != JR.state.getStubToFunctionMap(locked).begin() &&
255 "This is not a known stub!");
256 Function *F = (--I)->second;
258 // If we have already code generated the function, just return the address.
259 void *Result = TheJIT->getPointerToGlobalIfAvailable(F);
262 // Otherwise we don't have it, do lazy compilation now.
264 // If lazy compilation is disabled, emit a useful error message and abort.
265 if (TheJIT->isLazyCompilationDisabled()) {
266 cerr << "LLVM JIT requested to do lazy compilation of function '"
267 << F->getName() << "' when lazy compiles are disabled!\n";
271 // We might like to remove the stub from the StubToFunction map.
272 // We can't do that! Multiple threads could be stuck, waiting to acquire the
273 // lock above. As soon as the 1st function finishes compiling the function,
274 // the next one will be released, and needs to be able to find the function
276 //JR.state.getStubToFunctionMap(locked).erase(I);
278 DOUT << "JIT: Lazily resolving function '" << F->getName()
279 << "' In stub ptr = " << Stub << " actual ptr = "
282 Result = TheJIT->getPointerToFunction(F);
285 // We don't need to reuse this stub in the future, as F is now compiled.
286 JR.state.getFunctionToStubMap(locked).erase(F);
288 // FIXME: We could rewrite all references to this stub if we knew them.
290 // What we will do is set the compiled function address to map to the
291 // same GOT entry as the stub so that later clients may update the GOT
292 // if they see it still using the stub address.
293 // Note: this is done so the Resolver doesn't have to manage GOT memory
294 // Do this without allocating map space if the target isn't using a GOT
295 if(JR.revGOTMap.find(Stub) != JR.revGOTMap.end())
296 JR.revGOTMap[Result] = JR.revGOTMap[Stub];
301 //===----------------------------------------------------------------------===//
302 // Function Index Support
304 // On MacOS we generate an index of currently JIT'd functions so that
305 // performance tools can determine a symbol name and accurate code range for a
306 // PC value. Because performance tools are generally asynchronous, the code
307 // below is written with the hope that it could be interrupted at any time and
308 // have useful answers. However, we don't go crazy with atomic operations, we
309 // just do a "reasonable effort".
311 #define ENABLE_JIT_SYMBOL_TABLE 1
314 /// JitSymbolEntry - Each function that is JIT compiled results in one of these
315 /// being added to an array of symbols. This indicates the name of the function
316 /// as well as the address range it occupies. This allows the client to map
317 /// from a PC value to the name of the function.
318 struct JitSymbolEntry {
319 const char *FnName; // FnName - a strdup'd string.
325 struct JitSymbolTable {
326 /// NextPtr - This forms a linked list of JitSymbolTable entries. This
327 /// pointer is not used right now, but might be used in the future. Consider
328 /// it reserved for future use.
329 JitSymbolTable *NextPtr;
331 /// Symbols - This is an array of JitSymbolEntry entries. Only the first
332 /// 'NumSymbols' symbols are valid.
333 JitSymbolEntry *Symbols;
335 /// NumSymbols - This indicates the number entries in the Symbols array that
339 /// NumAllocated - This indicates the amount of space we have in the Symbols
340 /// array. This is a private field that should not be read by external tools.
341 unsigned NumAllocated;
344 #if ENABLE_JIT_SYMBOL_TABLE
345 JitSymbolTable *__jitSymbolTable;
348 static void AddFunctionToSymbolTable(const char *FnName,
349 void *FnStart, intptr_t FnSize) {
350 assert(FnName != 0 && FnStart != 0 && "Bad symbol to add");
351 JitSymbolTable **SymTabPtrPtr = 0;
352 #if !ENABLE_JIT_SYMBOL_TABLE
355 SymTabPtrPtr = &__jitSymbolTable;
358 // If this is the first entry in the symbol table, add the JitSymbolTable
360 if (*SymTabPtrPtr == 0) {
361 JitSymbolTable *New = new JitSymbolTable();
365 New->NumAllocated = 0;
369 JitSymbolTable *SymTabPtr = *SymTabPtrPtr;
371 // If we have space in the table, reallocate the table.
372 if (SymTabPtr->NumSymbols >= SymTabPtr->NumAllocated) {
373 // If we don't have space, reallocate the table.
374 unsigned NewSize = std::max(64U, SymTabPtr->NumAllocated*2);
375 JitSymbolEntry *NewSymbols = new JitSymbolEntry[NewSize];
376 JitSymbolEntry *OldSymbols = SymTabPtr->Symbols;
378 // Copy the old entries over.
379 memcpy(NewSymbols, OldSymbols,
380 SymTabPtr->NumSymbols*sizeof(OldSymbols[0]));
382 // Swap the new symbols in, delete the old ones.
383 SymTabPtr->Symbols = NewSymbols;
384 SymTabPtr->NumAllocated = NewSize;
385 delete [] OldSymbols;
388 // Otherwise, we have enough space, just tack it onto the end of the array.
389 JitSymbolEntry &Entry = SymTabPtr->Symbols[SymTabPtr->NumSymbols];
390 Entry.FnName = strdup(FnName);
391 Entry.FnStart = FnStart;
392 Entry.FnSize = FnSize;
393 ++SymTabPtr->NumSymbols;
396 static void RemoveFunctionFromSymbolTable(void *FnStart) {
397 assert(FnStart && "Invalid function pointer");
398 JitSymbolTable **SymTabPtrPtr = 0;
399 #if !ENABLE_JIT_SYMBOL_TABLE
402 SymTabPtrPtr = &__jitSymbolTable;
405 JitSymbolTable *SymTabPtr = *SymTabPtrPtr;
406 JitSymbolEntry *Symbols = SymTabPtr->Symbols;
408 // Scan the table to find its index. The table is not sorted, so do a linear
411 for (Index = 0; Symbols[Index].FnStart != FnStart; ++Index)
412 assert(Index != SymTabPtr->NumSymbols && "Didn't find function!");
414 // Once we have an index, we know to nuke this entry, overwrite it with the
415 // entry at the end of the array, making the last entry redundant.
416 const char *OldName = Symbols[Index].FnName;
417 Symbols[Index] = Symbols[SymTabPtr->NumSymbols-1];
418 free((void*)OldName);
420 // Drop the number of symbols in the table.
421 --SymTabPtr->NumSymbols;
423 // Finally, if we deleted the final symbol, deallocate the table itself.
424 if (SymTabPtr->NumSymbols == 0)
432 //===----------------------------------------------------------------------===//
436 /// JITEmitter - The JIT implementation of the MachineCodeEmitter, which is
437 /// used to output functions to memory for execution.
438 class JITEmitter : public MachineCodeEmitter {
439 JITMemoryManager *MemMgr;
441 // When outputting a function stub in the context of some other function, we
442 // save BufferBegin/BufferEnd/CurBufferPtr here.
443 unsigned char *SavedBufferBegin, *SavedBufferEnd, *SavedCurBufferPtr;
445 /// Relocations - These are the relocations that the function needs, as
447 std::vector<MachineRelocation> Relocations;
449 /// MBBLocations - This vector is a mapping from MBB ID's to their address.
450 /// It is filled in by the StartMachineBasicBlock callback and queried by
451 /// the getMachineBasicBlockAddress callback.
452 std::vector<intptr_t> MBBLocations;
454 /// ConstantPool - The constant pool for the current function.
456 MachineConstantPool *ConstantPool;
458 /// ConstantPoolBase - A pointer to the first entry in the constant pool.
460 void *ConstantPoolBase;
462 /// JumpTable - The jump tables for the current function.
464 MachineJumpTableInfo *JumpTable;
466 /// JumpTableBase - A pointer to the first entry in the jump table.
470 /// Resolver - This contains info about the currently resolved functions.
471 JITResolver Resolver;
473 /// DE - The dwarf emitter for the jit.
476 /// LabelLocations - This vector is a mapping from Label ID's to their
478 std::vector<intptr_t> LabelLocations;
480 /// MMI - Machine module info for exception informations
481 MachineModuleInfo* MMI;
484 JITEmitter(JIT &jit, JITMemoryManager *JMM) : Resolver(jit) {
485 MemMgr = JMM ? JMM : JITMemoryManager::CreateDefaultMemManager();
486 if (jit.getJITInfo().needsGOT()) {
487 MemMgr->AllocateGOT();
488 DOUT << "JIT is managing a GOT\n";
491 if (ExceptionHandling) DE = new JITDwarfEmitter(jit);
495 if (ExceptionHandling) delete DE;
498 JITResolver &getJITResolver() { return Resolver; }
500 virtual void startFunction(MachineFunction &F);
501 virtual bool finishFunction(MachineFunction &F);
503 void emitConstantPool(MachineConstantPool *MCP);
504 void initJumpTableInfo(MachineJumpTableInfo *MJTI);
505 void emitJumpTableInfo(MachineJumpTableInfo *MJTI);
507 virtual void startFunctionStub(const GlobalValue* F, unsigned StubSize,
508 unsigned Alignment = 1);
509 virtual void* finishFunctionStub(const GlobalValue *F);
511 virtual void addRelocation(const MachineRelocation &MR) {
512 Relocations.push_back(MR);
515 virtual void StartMachineBasicBlock(MachineBasicBlock *MBB) {
516 if (MBBLocations.size() <= (unsigned)MBB->getNumber())
517 MBBLocations.resize((MBB->getNumber()+1)*2);
518 MBBLocations[MBB->getNumber()] = getCurrentPCValue();
521 virtual intptr_t getConstantPoolEntryAddress(unsigned Entry) const;
522 virtual intptr_t getJumpTableEntryAddress(unsigned Entry) const;
524 virtual intptr_t getMachineBasicBlockAddress(MachineBasicBlock *MBB) const {
525 assert(MBBLocations.size() > (unsigned)MBB->getNumber() &&
526 MBBLocations[MBB->getNumber()] && "MBB not emitted!");
527 return MBBLocations[MBB->getNumber()];
530 /// deallocateMemForFunction - Deallocate all memory for the specified
532 void deallocateMemForFunction(Function *F) {
533 MemMgr->deallocateMemForFunction(F);
536 virtual void emitLabel(uint64_t LabelID) {
537 if (LabelLocations.size() <= LabelID)
538 LabelLocations.resize((LabelID+1)*2);
539 LabelLocations[LabelID] = getCurrentPCValue();
542 virtual intptr_t getLabelAddress(uint64_t LabelID) const {
543 assert(LabelLocations.size() > (unsigned)LabelID &&
544 LabelLocations[LabelID] && "Label not emitted!");
545 return LabelLocations[LabelID];
548 virtual void setModuleInfo(MachineModuleInfo* Info) {
550 if (ExceptionHandling) DE->setModuleInfo(Info);
554 void *getPointerToGlobal(GlobalValue *GV, void *Reference, bool NoNeedStub);
555 void *getPointerToGVLazyPtr(GlobalValue *V, void *Reference,
560 void *JITEmitter::getPointerToGlobal(GlobalValue *V, void *Reference,
561 bool DoesntNeedStub) {
562 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
563 /// FIXME: If we straightened things out, this could actually emit the
564 /// global immediately instead of queuing it for codegen later!
565 return TheJIT->getOrEmitGlobalVariable(GV);
568 // If we have already compiled the function, return a pointer to its body.
569 Function *F = cast<Function>(V);
570 void *ResultPtr = TheJIT->getPointerToGlobalIfAvailable(F);
571 if (ResultPtr) return ResultPtr;
573 if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode()) {
574 // If this is an external function pointer, we can force the JIT to
575 // 'compile' it, which really just adds it to the map.
577 return TheJIT->getPointerToFunction(F);
579 return Resolver.getFunctionStub(F);
582 // Okay, the function has not been compiled yet, if the target callback
583 // mechanism is capable of rewriting the instruction directly, prefer to do
584 // that instead of emitting a stub.
586 return Resolver.AddCallbackAtLocation(F, Reference);
588 // Otherwise, we have to emit a lazy resolving stub.
589 return Resolver.getFunctionStub(F);
592 void *JITEmitter::getPointerToGVLazyPtr(GlobalValue *V, void *Reference,
593 bool DoesntNeedStub) {
594 // Make sure GV is emitted first.
595 // FIXME: For now, if the GV is an external function we force the JIT to
596 // compile it so the lazy pointer will contain the fully resolved address.
597 void *GVAddress = getPointerToGlobal(V, Reference, true);
598 return Resolver.getGlobalValueLazyPtr(V, GVAddress);
601 static unsigned GetConstantPoolSizeInBytes(MachineConstantPool *MCP) {
602 const std::vector<MachineConstantPoolEntry> &Constants = MCP->getConstants();
603 if (Constants.empty()) return 0;
605 MachineConstantPoolEntry CPE = Constants.back();
606 unsigned Size = CPE.Offset;
607 const Type *Ty = CPE.isMachineConstantPoolEntry()
608 ? CPE.Val.MachineCPVal->getType() : CPE.Val.ConstVal->getType();
609 Size += TheJIT->getTargetData()->getABITypeSize(Ty);
613 static unsigned GetJumpTableSizeInBytes(MachineJumpTableInfo *MJTI) {
614 const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
615 if (JT.empty()) return 0;
617 unsigned NumEntries = 0;
618 for (unsigned i = 0, e = JT.size(); i != e; ++i)
619 NumEntries += JT[i].MBBs.size();
621 unsigned EntrySize = MJTI->getEntrySize();
623 return NumEntries * EntrySize;
626 static void AddAlignment(uintptr_t& Size, unsigned Alignment) {
627 if (Alignment == 0) Alignment = 1;
628 Size = (Size + Alignment - 1) & (Alignment - 1);
631 void JITEmitter::startFunction(MachineFunction &F) {
632 uintptr_t ActualSize = 0;
633 if (MemMgr->RequiresSize()) {
634 const TargetInstrInfo* TII = F.getTarget().getInstrInfo();
635 MachineJumpTableInfo *MJTI = F.getJumpTableInfo();
636 MachineConstantPool *MCP = F.getConstantPool();
638 // Ensure the constant pool/jump table info is at least 4-byte aligned.
639 AddAlignment(ActualSize, 16);
641 // Add the alignment of the constant pool
642 AddAlignment(ActualSize, 1 << MCP->getConstantPoolAlignment());
644 // Add the constant pool size
645 ActualSize += GetConstantPoolSizeInBytes(MCP);
647 // Add the aligment of the jump table info
648 AddAlignment(ActualSize, MJTI->getAlignment());
650 // Add the jump table size
651 ActualSize += GetJumpTableSizeInBytes(MJTI);
653 // Add the alignment for the function
654 AddAlignment(ActualSize, std::max(F.getFunction()->getAlignment(), 8U));
656 // Add the function size
657 ActualSize += TII->GetFunctionSizeInBytes(F);
660 BufferBegin = CurBufferPtr = MemMgr->startFunctionBody(F.getFunction(),
662 BufferEnd = BufferBegin+ActualSize;
664 // Ensure the constant pool/jump table info is at least 4-byte aligned.
667 emitConstantPool(F.getConstantPool());
668 initJumpTableInfo(F.getJumpTableInfo());
670 // About to start emitting the machine code for the function.
671 emitAlignment(std::max(F.getFunction()->getAlignment(), 8U));
672 TheJIT->updateGlobalMapping(F.getFunction(), CurBufferPtr);
674 MBBLocations.clear();
677 bool JITEmitter::finishFunction(MachineFunction &F) {
678 if (CurBufferPtr == BufferEnd) {
679 // FIXME: Allocate more space, then try again.
680 cerr << "JIT: Ran out of space for generated machine code!\n";
684 emitJumpTableInfo(F.getJumpTableInfo());
686 // FnStart is the start of the text, not the start of the constant pool and
687 // other per-function data.
688 unsigned char *FnStart =
689 (unsigned char *)TheJIT->getPointerToGlobalIfAvailable(F.getFunction());
690 unsigned char *FnEnd = CurBufferPtr;
692 MemMgr->endFunctionBody(F.getFunction(), BufferBegin, FnEnd);
693 NumBytes += FnEnd-FnStart;
695 if (!Relocations.empty()) {
696 NumRelos += Relocations.size();
698 // Resolve the relocations to concrete pointers.
699 for (unsigned i = 0, e = Relocations.size(); i != e; ++i) {
700 MachineRelocation &MR = Relocations[i];
703 ResultPtr = TheJIT->getPointerToNamedFunction(MR.getString());
705 // If the target REALLY wants a stub for this function, emit it now.
706 if (!MR.doesntNeedStub())
707 ResultPtr = Resolver.getExternalFunctionStub(ResultPtr);
708 } else if (MR.isGlobalValue()) {
709 ResultPtr = getPointerToGlobal(MR.getGlobalValue(),
710 BufferBegin+MR.getMachineCodeOffset(),
711 MR.doesntNeedStub());
712 } else if (MR.isGlobalValueLazyPtr()) {
713 ResultPtr = getPointerToGVLazyPtr(MR.getGlobalValue(),
714 BufferBegin+MR.getMachineCodeOffset(),
715 MR.doesntNeedStub());
716 } else if (MR.isBasicBlock()) {
717 ResultPtr = (void*)getMachineBasicBlockAddress(MR.getBasicBlock());
718 } else if (MR.isConstantPoolIndex()) {
719 ResultPtr=(void*)getConstantPoolEntryAddress(MR.getConstantPoolIndex());
721 assert(MR.isJumpTableIndex());
722 ResultPtr=(void*)getJumpTableEntryAddress(MR.getJumpTableIndex());
725 MR.setResultPointer(ResultPtr);
727 // if we are managing the GOT and the relocation wants an index,
729 if (MR.isGOTRelative() && MemMgr->isManagingGOT()) {
730 unsigned idx = Resolver.getGOTIndexForAddr(ResultPtr);
732 if (((void**)MemMgr->getGOTBase())[idx] != ResultPtr) {
733 DOUT << "GOT was out of date for " << ResultPtr
734 << " pointing at " << ((void**)MemMgr->getGOTBase())[idx]
736 ((void**)MemMgr->getGOTBase())[idx] = ResultPtr;
741 TheJIT->getJITInfo().relocate(BufferBegin, &Relocations[0],
742 Relocations.size(), MemMgr->getGOTBase());
745 // Update the GOT entry for F to point to the new code.
746 if (MemMgr->isManagingGOT()) {
747 unsigned idx = Resolver.getGOTIndexForAddr((void*)BufferBegin);
748 if (((void**)MemMgr->getGOTBase())[idx] != (void*)BufferBegin) {
749 DOUT << "GOT was out of date for " << (void*)BufferBegin
750 << " pointing at " << ((void**)MemMgr->getGOTBase())[idx] << "\n";
751 ((void**)MemMgr->getGOTBase())[idx] = (void*)BufferBegin;
755 // Invalidate the icache if necessary.
756 synchronizeICache(FnStart, FnEnd-FnStart);
758 // Add it to the JIT symbol table if the host wants it.
759 AddFunctionToSymbolTable(F.getFunction()->getNameStart(),
760 FnStart, FnEnd-FnStart);
762 DOUT << "JIT: Finished CodeGen of [" << (void*)FnStart
763 << "] Function: " << F.getFunction()->getName()
764 << ": " << (FnEnd-FnStart) << " bytes of text, "
765 << Relocations.size() << " relocations\n";
769 if (sys::hasDisassembler())
770 DOUT << "Disassembled code:\n"
771 << sys::disassembleBuffer(FnStart, FnEnd-FnStart, (uintptr_t)FnStart);
773 if (ExceptionHandling) {
774 uintptr_t ActualSize = 0;
775 SavedBufferBegin = BufferBegin;
776 SavedBufferEnd = BufferEnd;
777 SavedCurBufferPtr = CurBufferPtr;
779 if (MemMgr->RequiresSize()) {
780 ActualSize = DE->GetDwarfTableSize(F, *this, FnStart, FnEnd);
783 BufferBegin = CurBufferPtr = MemMgr->startExceptionTable(F.getFunction(),
785 BufferEnd = BufferBegin+ActualSize;
786 unsigned char* FrameRegister = DE->EmitDwarfTable(F, *this, FnStart, FnEnd);
787 MemMgr->endExceptionTable(F.getFunction(), BufferBegin, CurBufferPtr,
789 BufferBegin = SavedBufferBegin;
790 BufferEnd = SavedBufferEnd;
791 CurBufferPtr = SavedCurBufferPtr;
793 TheJIT->RegisterTable(FrameRegister);
800 void JITEmitter::emitConstantPool(MachineConstantPool *MCP) {
801 const std::vector<MachineConstantPoolEntry> &Constants = MCP->getConstants();
802 if (Constants.empty()) return;
804 MachineConstantPoolEntry CPE = Constants.back();
805 unsigned Size = CPE.Offset;
806 const Type *Ty = CPE.isMachineConstantPoolEntry()
807 ? CPE.Val.MachineCPVal->getType() : CPE.Val.ConstVal->getType();
808 Size += TheJIT->getTargetData()->getABITypeSize(Ty);
810 unsigned Align = 1 << MCP->getConstantPoolAlignment();
811 ConstantPoolBase = allocateSpace(Size, Align);
814 if (ConstantPoolBase == 0) return; // Buffer overflow.
816 DOUT << "JIT: Emitted constant pool at [" << ConstantPoolBase
817 << "] (size: " << Size << ", alignment: " << Align << ")\n";
819 // Initialize the memory for all of the constant pool entries.
820 for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
821 void *CAddr = (char*)ConstantPoolBase+Constants[i].Offset;
822 if (Constants[i].isMachineConstantPoolEntry()) {
823 // FIXME: add support to lower machine constant pool values into bytes!
824 cerr << "Initialize memory with machine specific constant pool entry"
825 << " has not been implemented!\n";
828 TheJIT->InitializeMemory(Constants[i].Val.ConstVal, CAddr);
829 DOUT << "JIT: CP" << i << " at [" << CAddr << "]\n";
833 void JITEmitter::initJumpTableInfo(MachineJumpTableInfo *MJTI) {
834 const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
835 if (JT.empty()) return;
837 unsigned NumEntries = 0;
838 for (unsigned i = 0, e = JT.size(); i != e; ++i)
839 NumEntries += JT[i].MBBs.size();
841 unsigned EntrySize = MJTI->getEntrySize();
843 // Just allocate space for all the jump tables now. We will fix up the actual
844 // MBB entries in the tables after we emit the code for each block, since then
845 // we will know the final locations of the MBBs in memory.
847 JumpTableBase = allocateSpace(NumEntries * EntrySize, MJTI->getAlignment());
850 void JITEmitter::emitJumpTableInfo(MachineJumpTableInfo *MJTI) {
851 const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
852 if (JT.empty() || JumpTableBase == 0) return;
854 if (TargetMachine::getRelocationModel() == Reloc::PIC_) {
855 assert(MJTI->getEntrySize() == 4 && "Cross JIT'ing?");
856 // For each jump table, place the offset from the beginning of the table
857 // to the target address.
858 int *SlotPtr = (int*)JumpTableBase;
860 for (unsigned i = 0, e = JT.size(); i != e; ++i) {
861 const std::vector<MachineBasicBlock*> &MBBs = JT[i].MBBs;
862 // Store the offset of the basic block for this jump table slot in the
863 // memory we allocated for the jump table in 'initJumpTableInfo'
864 intptr_t Base = (intptr_t)SlotPtr;
865 for (unsigned mi = 0, me = MBBs.size(); mi != me; ++mi) {
866 intptr_t MBBAddr = getMachineBasicBlockAddress(MBBs[mi]);
867 *SlotPtr++ = TheJIT->getJITInfo().getPICJumpTableEntry(MBBAddr, Base);
871 assert(MJTI->getEntrySize() == sizeof(void*) && "Cross JIT'ing?");
873 // For each jump table, map each target in the jump table to the address of
874 // an emitted MachineBasicBlock.
875 intptr_t *SlotPtr = (intptr_t*)JumpTableBase;
877 for (unsigned i = 0, e = JT.size(); i != e; ++i) {
878 const std::vector<MachineBasicBlock*> &MBBs = JT[i].MBBs;
879 // Store the address of the basic block for this jump table slot in the
880 // memory we allocated for the jump table in 'initJumpTableInfo'
881 for (unsigned mi = 0, me = MBBs.size(); mi != me; ++mi)
882 *SlotPtr++ = getMachineBasicBlockAddress(MBBs[mi]);
887 void JITEmitter::startFunctionStub(const GlobalValue* F, unsigned StubSize,
888 unsigned Alignment) {
889 SavedBufferBegin = BufferBegin;
890 SavedBufferEnd = BufferEnd;
891 SavedCurBufferPtr = CurBufferPtr;
893 BufferBegin = CurBufferPtr = MemMgr->allocateStub(F, StubSize, Alignment);
894 BufferEnd = BufferBegin+StubSize+1;
897 void *JITEmitter::finishFunctionStub(const GlobalValue* F) {
898 NumBytes += getCurrentPCOffset();
899 std::swap(SavedBufferBegin, BufferBegin);
900 BufferEnd = SavedBufferEnd;
901 CurBufferPtr = SavedCurBufferPtr;
902 return SavedBufferBegin;
905 // getConstantPoolEntryAddress - Return the address of the 'ConstantNum' entry
906 // in the constant pool that was last emitted with the 'emitConstantPool'
909 intptr_t JITEmitter::getConstantPoolEntryAddress(unsigned ConstantNum) const {
910 assert(ConstantNum < ConstantPool->getConstants().size() &&
911 "Invalid ConstantPoolIndex!");
912 return (intptr_t)ConstantPoolBase +
913 ConstantPool->getConstants()[ConstantNum].Offset;
916 // getJumpTableEntryAddress - Return the address of the JumpTable with index
917 // 'Index' in the jumpp table that was last initialized with 'initJumpTableInfo'
919 intptr_t JITEmitter::getJumpTableEntryAddress(unsigned Index) const {
920 const std::vector<MachineJumpTableEntry> &JT = JumpTable->getJumpTables();
921 assert(Index < JT.size() && "Invalid jump table index!");
924 unsigned EntrySize = JumpTable->getEntrySize();
926 for (unsigned i = 0; i < Index; ++i)
927 Offset += JT[i].MBBs.size();
931 return (intptr_t)((char *)JumpTableBase + Offset);
934 //===----------------------------------------------------------------------===//
935 // Public interface to this file
936 //===----------------------------------------------------------------------===//
938 MachineCodeEmitter *JIT::createEmitter(JIT &jit, JITMemoryManager *JMM) {
939 return new JITEmitter(jit, JMM);
942 // getPointerToNamedFunction - This function is used as a global wrapper to
943 // JIT::getPointerToNamedFunction for the purpose of resolving symbols when
944 // bugpoint is debugging the JIT. In that scenario, we are loading an .so and
945 // need to resolve function(s) that are being mis-codegenerated, so we need to
946 // resolve their addresses at runtime, and this is the way to do it.
948 void *getPointerToNamedFunction(const char *Name) {
949 if (Function *F = TheJIT->FindFunctionNamed(Name))
950 return TheJIT->getPointerToFunction(F);
951 return TheJIT->getPointerToNamedFunction(Name);
955 // getPointerToFunctionOrStub - If the specified function has been
956 // code-gen'd, return a pointer to the function. If not, compile it, or use
957 // a stub to implement lazy compilation if available.
959 void *JIT::getPointerToFunctionOrStub(Function *F) {
960 // If we have already code generated the function, just return the address.
961 if (void *Addr = getPointerToGlobalIfAvailable(F))
964 // Get a stub if the target supports it.
965 assert(dynamic_cast<JITEmitter*>(MCE) && "Unexpected MCE?");
966 JITEmitter *JE = static_cast<JITEmitter*>(getCodeEmitter());
967 return JE->getJITResolver().getFunctionStub(F);
970 /// freeMachineCodeForFunction - release machine code memory for given Function.
972 void JIT::freeMachineCodeForFunction(Function *F) {
974 // Delete translation for this from the ExecutionEngine, so it will get
975 // retranslated next time it is used.
976 void *OldPtr = updateGlobalMapping(F, 0);
979 RemoveFunctionFromSymbolTable(OldPtr);
981 // Free the actual memory for the function body and related stuff.
982 assert(dynamic_cast<JITEmitter*>(MCE) && "Unexpected MCE?");
983 static_cast<JITEmitter*>(MCE)->deallocateMemForFunction(F);