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llvm-project/llvm/lib/ExecutionEngine/JIT/JITEmitter.cpp

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//===-- JITEmitter.cpp - Write machine code to executable memory ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file 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 the JIT to
// write machine code to memory and remember where relocatable values are.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "jit"
#include "JIT.h"
#include "JITDwarfEmitter.h"
#include "llvm/Constant.h"
#include "llvm/Module.h"
#include "llvm/Type.h"
#include "llvm/CodeGen/MachineCodeEmitter.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRelocation.h"
#include "llvm/ExecutionEngine/JITMemoryManager.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetJITInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MutexGuard.h"
#include "llvm/System/Disassembler.h"
#include "llvm/System/Memory.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/ADT/Statistic.h"
#include <algorithm>
using namespace llvm;
STATISTIC(NumBytes, "Number of bytes of machine code compiled");
STATISTIC(NumRelos, "Number of relocations applied");
static JIT *TheJIT = 0;
//===----------------------------------------------------------------------===//
// JIT lazy compilation code.
//
namespace {
class JITResolverState {
private:
/// FunctionToStubMap - Keep track of the stub created for a particular
/// function so that we can reuse them if necessary.
std::map<Function*, void*> FunctionToStubMap;
/// StubToFunctionMap - Keep track of the function that each stub
/// corresponds to.
std::map<void*, Function*> StubToFunctionMap;
/// GlobalToLazyPtrMap - Keep track of the lazy pointer created for a
/// particular GlobalVariable so that we can reuse them if necessary.
std::map<GlobalValue*, void*> GlobalToLazyPtrMap;
public:
std::map<Function*, void*>& getFunctionToStubMap(const MutexGuard& locked) {
assert(locked.holds(TheJIT->lock));
return FunctionToStubMap;
}
std::map<void*, Function*>& getStubToFunctionMap(const MutexGuard& locked) {
assert(locked.holds(TheJIT->lock));
return StubToFunctionMap;
}
std::map<GlobalValue*, void*>&
getGlobalToLazyPtrMap(const MutexGuard& locked) {
assert(locked.holds(TheJIT->lock));
return GlobalToLazyPtrMap;
}
};
/// JITResolver - Keep track of, and resolve, call sites for functions that
/// have not yet been compiled.
class JITResolver {
/// LazyResolverFn - The target lazy resolver function that we actually
/// rewrite instructions to use.
TargetJITInfo::LazyResolverFn LazyResolverFn;
JITResolverState state;
/// ExternalFnToStubMap - This is the equivalent of FunctionToStubMap for
/// external functions.
std::map<void*, void*> ExternalFnToStubMap;
//map addresses to indexes in the GOT
std::map<void*, unsigned> revGOTMap;
unsigned nextGOTIndex;
static JITResolver *TheJITResolver;
public:
explicit JITResolver(JIT &jit) : nextGOTIndex(0) {
TheJIT = &jit;
LazyResolverFn = jit.getJITInfo().getLazyResolverFunction(JITCompilerFn);
assert(TheJITResolver == 0 && "Multiple JIT resolvers?");
TheJITResolver = this;
}
~JITResolver() {
TheJITResolver = 0;
}
/// getFunctionStub - This returns a pointer to a function stub, creating
/// one on demand as needed.
void *getFunctionStub(Function *F);
/// getExternalFunctionStub - Return a stub for the function at the
/// specified address, created lazily on demand.
void *getExternalFunctionStub(void *FnAddr);
/// getGlobalValueLazyPtr - Return a lazy pointer containing the specified
/// GV address.
void *getGlobalValueLazyPtr(GlobalValue *V, void *GVAddress);
/// AddCallbackAtLocation - If the target is capable of rewriting an
/// instruction without the use of a stub, record the location of the use so
/// we know which function is being used at the location.
void *AddCallbackAtLocation(Function *F, void *Location) {
MutexGuard locked(TheJIT->lock);
/// Get the target-specific JIT resolver function.
state.getStubToFunctionMap(locked)[Location] = F;
return (void*)(intptr_t)LazyResolverFn;
}
/// getGOTIndexForAddress - Return a new or existing index in the GOT for
/// an address. This function only manages slots, it does not manage the
/// contents of the slots or the memory associated with the GOT.
unsigned getGOTIndexForAddr(void *addr);
/// JITCompilerFn - This function is called to resolve a stub to a compiled
/// address. If the LLVM Function corresponding to the stub has not yet
/// been compiled, this function compiles it first.
static void *JITCompilerFn(void *Stub);
};
}
JITResolver *JITResolver::TheJITResolver = 0;
/// getFunctionStub - This returns a pointer to a function stub, creating
/// one on demand as needed.
void *JITResolver::getFunctionStub(Function *F) {
MutexGuard locked(TheJIT->lock);
// If we already have a stub for this function, recycle it.
void *&Stub = state.getFunctionToStubMap(locked)[F];
if (Stub) return Stub;
// Call the lazy resolver function unless we already KNOW it is an external
// function, in which case we just skip the lazy resolution step.
void *Actual = (void*)(intptr_t)LazyResolverFn;
if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode())
Actual = TheJIT->getPointerToFunction(F);
// Otherwise, codegen a new stub. For now, the stub will call the lazy
// resolver function.
Stub = TheJIT->getJITInfo().emitFunctionStub(F, Actual,
*TheJIT->getCodeEmitter());
if (Actual != (void*)(intptr_t)LazyResolverFn) {
// If we are getting the stub for an external function, we really want the
// address of the stub in the GlobalAddressMap for the JIT, not the address
// of the external function.
TheJIT->updateGlobalMapping(F, Stub);
}
DOUT << "JIT: Stub emitted at [" << Stub << "] for function '"
<< F->getName() << "'\n";
// Finally, keep track of the stub-to-Function mapping so that the
// JITCompilerFn knows which function to compile!
state.getStubToFunctionMap(locked)[Stub] = F;
return Stub;
}
/// getGlobalValueLazyPtr - Return a lazy pointer containing the specified
/// GV address.
void *JITResolver::getGlobalValueLazyPtr(GlobalValue *GV, void *GVAddress) {
MutexGuard locked(TheJIT->lock);
// If we already have a stub for this global variable, recycle it.
void *&LazyPtr = state.getGlobalToLazyPtrMap(locked)[GV];
if (LazyPtr) return LazyPtr;
// Otherwise, codegen a new lazy pointer.
LazyPtr = TheJIT->getJITInfo().emitGlobalValueLazyPtr(GV, GVAddress,
*TheJIT->getCodeEmitter());
DOUT << "JIT: Stub emitted at [" << LazyPtr << "] for GV '"
<< GV->getName() << "'\n";
return LazyPtr;
}
/// getExternalFunctionStub - Return a stub for the function at the
/// specified address, created lazily on demand.
void *JITResolver::getExternalFunctionStub(void *FnAddr) {
// If we already have a stub for this function, recycle it.
void *&Stub = ExternalFnToStubMap[FnAddr];
if (Stub) return Stub;
Stub = TheJIT->getJITInfo().emitFunctionStub(0, FnAddr,
*TheJIT->getCodeEmitter());
DOUT << "JIT: Stub emitted at [" << Stub
<< "] for external function at '" << FnAddr << "'\n";
return Stub;
}
unsigned JITResolver::getGOTIndexForAddr(void* addr) {
unsigned idx = revGOTMap[addr];
if (!idx) {
idx = ++nextGOTIndex;
revGOTMap[addr] = idx;
DOUT << "Adding GOT entry " << idx << " for addr " << addr << "\n";
}
return idx;
}
/// JITCompilerFn - This function is called when a lazy compilation stub has
/// been entered. It looks up which function this stub corresponds to, compiles
/// it if necessary, then returns the resultant function pointer.
void *JITResolver::JITCompilerFn(void *Stub) {
JITResolver &JR = *TheJITResolver;
MutexGuard locked(TheJIT->lock);
// The address given to us for the stub may not be exactly right, it might be
// a little bit after the stub. As such, use upper_bound to find it.
std::map<void*, Function*>::iterator I =
JR.state.getStubToFunctionMap(locked).upper_bound(Stub);
assert(I != JR.state.getStubToFunctionMap(locked).begin() &&
"This is not a known stub!");
Function *F = (--I)->second;
// If we have already code generated the function, just return the address.
void *Result = TheJIT->getPointerToGlobalIfAvailable(F);
if (!Result) {
// Otherwise we don't have it, do lazy compilation now.
// If lazy compilation is disabled, emit a useful error message and abort.
if (TheJIT->isLazyCompilationDisabled()) {
cerr << "LLVM JIT requested to do lazy compilation of function '"
<< F->getName() << "' when lazy compiles are disabled!\n";
abort();
}
// We might like to remove the stub from the StubToFunction map.
// We can't do that! Multiple threads could be stuck, waiting to acquire the
// lock above. As soon as the 1st function finishes compiling the function,
// the next one will be released, and needs to be able to find the function
// it needs to call.
//JR.state.getStubToFunctionMap(locked).erase(I);
DOUT << "JIT: Lazily resolving function '" << F->getName()
<< "' In stub ptr = " << Stub << " actual ptr = "
<< I->first << "\n";
Result = TheJIT->getPointerToFunction(F);
}
// We don't need to reuse this stub in the future, as F is now compiled.
JR.state.getFunctionToStubMap(locked).erase(F);
// FIXME: We could rewrite all references to this stub if we knew them.
// What we will do is set the compiled function address to map to the
// same GOT entry as the stub so that later clients may update the GOT
// if they see it still using the stub address.
// Note: this is done so the Resolver doesn't have to manage GOT memory
// Do this without allocating map space if the target isn't using a GOT
if(JR.revGOTMap.find(Stub) != JR.revGOTMap.end())
JR.revGOTMap[Result] = JR.revGOTMap[Stub];
return Result;
}
//===----------------------------------------------------------------------===//
// Function Index Support
// On MacOS we generate an index of currently JIT'd functions so that
// performance tools can determine a symbol name and accurate code range for a
// PC value. Because performance tools are generally asynchronous, the code
// below is written with the hope that it could be interrupted at any time and
// have useful answers. However, we don't go crazy with atomic operations, we
// just do a "reasonable effort".
#ifdef __APPLE__
#define ENABLE_JIT_SYMBOL_TABLE 0
#endif
/// JitSymbolEntry - Each function that is JIT compiled results in one of these
/// being added to an array of symbols. This indicates the name of the function
/// as well as the address range it occupies. This allows the client to map
/// from a PC value to the name of the function.
struct JitSymbolEntry {
const char *FnName; // FnName - a strdup'd string.
void *FnStart;
intptr_t FnSize;
};
struct JitSymbolTable {
/// NextPtr - This forms a linked list of JitSymbolTable entries. This
/// pointer is not used right now, but might be used in the future. Consider
/// it reserved for future use.
JitSymbolTable *NextPtr;
/// Symbols - This is an array of JitSymbolEntry entries. Only the first
/// 'NumSymbols' symbols are valid.
JitSymbolEntry *Symbols;
/// NumSymbols - This indicates the number entries in the Symbols array that
/// are valid.
unsigned NumSymbols;
/// NumAllocated - This indicates the amount of space we have in the Symbols
/// array. This is a private field that should not be read by external tools.
unsigned NumAllocated;
};
#if ENABLE_JIT_SYMBOL_TABLE
JitSymbolTable *__jitSymbolTable;
#endif
static void AddFunctionToSymbolTable(const char *FnName,
void *FnStart, intptr_t FnSize) {
assert(FnName != 0 && FnStart != 0 && "Bad symbol to add");
JitSymbolTable **SymTabPtrPtr = 0;
#if !ENABLE_JIT_SYMBOL_TABLE
return;
#else
SymTabPtrPtr = &__jitSymbolTable;
#endif
// If this is the first entry in the symbol table, add the JitSymbolTable
// index.
if (*SymTabPtrPtr == 0) {
JitSymbolTable *New = new JitSymbolTable();
New->NextPtr = 0;
New->Symbols = 0;
New->NumSymbols = 0;
New->NumAllocated = 0;
*SymTabPtrPtr = New;
}
JitSymbolTable *SymTabPtr = *SymTabPtrPtr;
// If we have space in the table, reallocate the table.
if (SymTabPtr->NumSymbols >= SymTabPtr->NumAllocated) {
// If we don't have space, reallocate the table.
unsigned NewSize = std::max(64U, SymTabPtr->NumAllocated*2);
JitSymbolEntry *NewSymbols = new JitSymbolEntry[NewSize];
JitSymbolEntry *OldSymbols = SymTabPtr->Symbols;
// Copy the old entries over.
memcpy(NewSymbols, OldSymbols,
SymTabPtr->NumSymbols*sizeof(OldSymbols[0]));
// Swap the new symbols in, delete the old ones.
SymTabPtr->Symbols = NewSymbols;
SymTabPtr->NumAllocated = NewSize;
delete [] OldSymbols;
}
// Otherwise, we have enough space, just tack it onto the end of the array.
JitSymbolEntry &Entry = SymTabPtr->Symbols[SymTabPtr->NumSymbols];
Entry.FnName = strdup(FnName);
Entry.FnStart = FnStart;
Entry.FnSize = FnSize;
++SymTabPtr->NumSymbols;
}
static void RemoveFunctionFromSymbolTable(void *FnStart) {
assert(FnStart && "Invalid function pointer");
JitSymbolTable **SymTabPtrPtr = 0;
#if !ENABLE_JIT_SYMBOL_TABLE
return;
#else
SymTabPtrPtr = &__jitSymbolTable;
#endif
JitSymbolTable *SymTabPtr = *SymTabPtrPtr;
JitSymbolEntry *Symbols = SymTabPtr->Symbols;
// Scan the table to find its index. The table is not sorted, so do a linear
// scan.
unsigned Index;
for (Index = 0; Symbols[Index].FnStart != FnStart; ++Index)
assert(Index != SymTabPtr->NumSymbols && "Didn't find function!");
// Once we have an index, we know to nuke this entry, overwrite it with the
// entry at the end of the array, making the last entry redundant.
const char *OldName = Symbols[Index].FnName;
Symbols[Index] = Symbols[SymTabPtr->NumSymbols-1];
free((void*)OldName);
// Drop the number of symbols in the table.
--SymTabPtr->NumSymbols;
// Finally, if we deleted the final symbol, deallocate the table itself.
if (SymTabPtr->NumSymbols != 0)
return;
*SymTabPtrPtr = 0;
delete [] Symbols;
delete SymTabPtr;
}
//===----------------------------------------------------------------------===//
// JITEmitter code.
//
namespace {
/// JITEmitter - The JIT implementation of the MachineCodeEmitter, which is
/// used to output functions to memory for execution.
class JITEmitter : public MachineCodeEmitter {
JITMemoryManager *MemMgr;
// When outputting a function stub in the context of some other function, we
// save BufferBegin/BufferEnd/CurBufferPtr here.
unsigned char *SavedBufferBegin, *SavedBufferEnd, *SavedCurBufferPtr;
/// Relocations - These are the relocations that the function needs, as
/// emitted.
std::vector<MachineRelocation> Relocations;
/// MBBLocations - This vector is a mapping from MBB ID's to their address.
/// It is filled in by the StartMachineBasicBlock callback and queried by
/// the getMachineBasicBlockAddress callback.
std::vector<intptr_t> MBBLocations;
/// ConstantPool - The constant pool for the current function.
///
MachineConstantPool *ConstantPool;
/// ConstantPoolBase - A pointer to the first entry in the constant pool.
///
void *ConstantPoolBase;
/// JumpTable - The jump tables for the current function.
///
MachineJumpTableInfo *JumpTable;
/// JumpTableBase - A pointer to the first entry in the jump table.
///
void *JumpTableBase;
/// Resolver - This contains info about the currently resolved functions.
JITResolver Resolver;
/// DE - The dwarf emitter for the jit.
JITDwarfEmitter *DE;
/// LabelLocations - This vector is a mapping from Label ID's to their
/// address.
std::vector<intptr_t> LabelLocations;
/// MMI - Machine module info for exception informations
MachineModuleInfo* MMI;
public:
JITEmitter(JIT &jit, JITMemoryManager *JMM) : Resolver(jit) {
MemMgr = JMM ? JMM : JITMemoryManager::CreateDefaultMemManager();
if (jit.getJITInfo().needsGOT()) {
MemMgr->AllocateGOT();
DOUT << "JIT is managing a GOT\n";
}
if (ExceptionHandling) DE = new JITDwarfEmitter(jit);
}
~JITEmitter() {
delete MemMgr;
if (ExceptionHandling) delete DE;
}
JITResolver &getJITResolver() { return Resolver; }
virtual void startFunction(MachineFunction &F);
virtual bool finishFunction(MachineFunction &F);
void emitConstantPool(MachineConstantPool *MCP);
void initJumpTableInfo(MachineJumpTableInfo *MJTI);
void emitJumpTableInfo(MachineJumpTableInfo *MJTI);
virtual void startFunctionStub(const GlobalValue* F, unsigned StubSize,
unsigned Alignment = 1);
virtual void* finishFunctionStub(const GlobalValue *F);
virtual void addRelocation(const MachineRelocation &MR) {
Relocations.push_back(MR);
}
virtual void StartMachineBasicBlock(MachineBasicBlock *MBB) {
if (MBBLocations.size() <= (unsigned)MBB->getNumber())
MBBLocations.resize((MBB->getNumber()+1)*2);
MBBLocations[MBB->getNumber()] = getCurrentPCValue();
}
virtual intptr_t getConstantPoolEntryAddress(unsigned Entry) const;
virtual intptr_t getJumpTableEntryAddress(unsigned Entry) const;
virtual intptr_t getMachineBasicBlockAddress(MachineBasicBlock *MBB) const {
assert(MBBLocations.size() > (unsigned)MBB->getNumber() &&
MBBLocations[MBB->getNumber()] && "MBB not emitted!");
return MBBLocations[MBB->getNumber()];
}
/// deallocateMemForFunction - Deallocate all memory for the specified
/// function body.
void deallocateMemForFunction(Function *F) {
MemMgr->deallocateMemForFunction(F);
}
virtual void emitLabel(uint64_t LabelID) {
if (LabelLocations.size() <= LabelID)
LabelLocations.resize((LabelID+1)*2);
LabelLocations[LabelID] = getCurrentPCValue();
}
virtual intptr_t getLabelAddress(uint64_t LabelID) const {
assert(LabelLocations.size() > (unsigned)LabelID &&
LabelLocations[LabelID] && "Label not emitted!");
return LabelLocations[LabelID];
}
virtual void setModuleInfo(MachineModuleInfo* Info) {
MMI = Info;
if (ExceptionHandling) DE->setModuleInfo(Info);
}
private:
void *getPointerToGlobal(GlobalValue *GV, void *Reference, bool NoNeedStub);
void *getPointerToGVLazyPtr(GlobalValue *V, void *Reference,
bool NoNeedStub);
};
}
void *JITEmitter::getPointerToGlobal(GlobalValue *V, void *Reference,
bool DoesntNeedStub) {
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
/// FIXME: If we straightened things out, this could actually emit the
/// global immediately instead of queuing it for codegen later!
return TheJIT->getOrEmitGlobalVariable(GV);
}
if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
return TheJIT->getPointerToGlobal(GA->resolveAliasedGlobal());
// If we have already compiled the function, return a pointer to its body.
Function *F = cast<Function>(V);
void *ResultPtr = TheJIT->getPointerToGlobalIfAvailable(F);
if (ResultPtr) return ResultPtr;
if (F->isDeclaration() && !F->hasNotBeenReadFromBitcode()) {
// If this is an external function pointer, we can force the JIT to
// 'compile' it, which really just adds it to the map.
if (DoesntNeedStub)
return TheJIT->getPointerToFunction(F);
return Resolver.getFunctionStub(F);
}
// Okay, the function has not been compiled yet, if the target callback
// mechanism is capable of rewriting the instruction directly, prefer to do
// that instead of emitting a stub.
if (DoesntNeedStub)
return Resolver.AddCallbackAtLocation(F, Reference);
// Otherwise, we have to emit a lazy resolving stub.
return Resolver.getFunctionStub(F);
}
void *JITEmitter::getPointerToGVLazyPtr(GlobalValue *V, void *Reference,
bool DoesntNeedStub) {
// Make sure GV is emitted first.
// FIXME: For now, if the GV is an external function we force the JIT to
// compile it so the lazy pointer will contain the fully resolved address.
void *GVAddress = getPointerToGlobal(V, Reference, true);
return Resolver.getGlobalValueLazyPtr(V, GVAddress);
}
static unsigned GetConstantPoolSizeInBytes(MachineConstantPool *MCP) {
const std::vector<MachineConstantPoolEntry> &Constants = MCP->getConstants();
if (Constants.empty()) return 0;
MachineConstantPoolEntry CPE = Constants.back();
unsigned Size = CPE.Offset;
const Type *Ty = CPE.isMachineConstantPoolEntry()
? CPE.Val.MachineCPVal->getType() : CPE.Val.ConstVal->getType();
Size += TheJIT->getTargetData()->getABITypeSize(Ty);
return Size;
}
static unsigned GetJumpTableSizeInBytes(MachineJumpTableInfo *MJTI) {
const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
if (JT.empty()) return 0;
unsigned NumEntries = 0;
for (unsigned i = 0, e = JT.size(); i != e; ++i)
NumEntries += JT[i].MBBs.size();
unsigned EntrySize = MJTI->getEntrySize();
return NumEntries * EntrySize;
}
static uintptr_t RoundUpToAlign(uintptr_t Size, unsigned Alignment) {
if (Alignment == 0) Alignment = 1;
// Since we do not know where the buffer will be allocated, be pessimistic.
return Size + Alignment;
}
void JITEmitter::startFunction(MachineFunction &F) {
uintptr_t ActualSize = 0;
if (MemMgr->NeedsExactSize()) {
const TargetInstrInfo* TII = F.getTarget().getInstrInfo();
MachineJumpTableInfo *MJTI = F.getJumpTableInfo();
MachineConstantPool *MCP = F.getConstantPool();
// Ensure the constant pool/jump table info is at least 4-byte aligned.
ActualSize = RoundUpToAlign(ActualSize, 16);
// Add the alignment of the constant pool
ActualSize = RoundUpToAlign(ActualSize,
1 << MCP->getConstantPoolAlignment());
// Add the constant pool size
ActualSize += GetConstantPoolSizeInBytes(MCP);
// Add the aligment of the jump table info
ActualSize = RoundUpToAlign(ActualSize, MJTI->getAlignment());
// Add the jump table size
ActualSize += GetJumpTableSizeInBytes(MJTI);
// Add the alignment for the function
ActualSize = RoundUpToAlign(ActualSize,
std::max(F.getFunction()->getAlignment(), 8U));
// Add the function size
ActualSize += TII->GetFunctionSizeInBytes(F);
}
BufferBegin = CurBufferPtr = MemMgr->startFunctionBody(F.getFunction(),
ActualSize);
BufferEnd = BufferBegin+ActualSize;
// Ensure the constant pool/jump table info is at least 4-byte aligned.
emitAlignment(16);
emitConstantPool(F.getConstantPool());
initJumpTableInfo(F.getJumpTableInfo());
// About to start emitting the machine code for the function.
emitAlignment(std::max(F.getFunction()->getAlignment(), 8U));
TheJIT->updateGlobalMapping(F.getFunction(), CurBufferPtr);
MBBLocations.clear();
}
bool JITEmitter::finishFunction(MachineFunction &F) {
if (CurBufferPtr == BufferEnd) {
// FIXME: Allocate more space, then try again.
cerr << "JIT: Ran out of space for generated machine code!\n";
abort();
}
emitJumpTableInfo(F.getJumpTableInfo());
// FnStart is the start of the text, not the start of the constant pool and
// other per-function data.
unsigned char *FnStart =
(unsigned char *)TheJIT->getPointerToGlobalIfAvailable(F.getFunction());
unsigned char *FnEnd = CurBufferPtr;
MemMgr->endFunctionBody(F.getFunction(), BufferBegin, FnEnd);
NumBytes += FnEnd-FnStart;
if (!Relocations.empty()) {
NumRelos += Relocations.size();
// Resolve the relocations to concrete pointers.
for (unsigned i = 0, e = Relocations.size(); i != e; ++i) {
MachineRelocation &MR = Relocations[i];
void *ResultPtr;
if (MR.isString()) {
ResultPtr = TheJIT->getPointerToNamedFunction(MR.getString());
// If the target REALLY wants a stub for this function, emit it now.
if (!MR.doesntNeedStub())
ResultPtr = Resolver.getExternalFunctionStub(ResultPtr);
} else if (MR.isGlobalValue()) {
ResultPtr = getPointerToGlobal(MR.getGlobalValue(),
BufferBegin+MR.getMachineCodeOffset(),
MR.doesntNeedStub());
} else if (MR.isGlobalValueLazyPtr()) {
ResultPtr = getPointerToGVLazyPtr(MR.getGlobalValue(),
BufferBegin+MR.getMachineCodeOffset(),
MR.doesntNeedStub());
} else if (MR.isBasicBlock()) {
ResultPtr = (void*)getMachineBasicBlockAddress(MR.getBasicBlock());
} else if (MR.isConstantPoolIndex()) {
ResultPtr=(void*)getConstantPoolEntryAddress(MR.getConstantPoolIndex());
} else {
assert(MR.isJumpTableIndex());
ResultPtr=(void*)getJumpTableEntryAddress(MR.getJumpTableIndex());
}
MR.setResultPointer(ResultPtr);
// if we are managing the GOT and the relocation wants an index,
// give it one
if (MR.isGOTRelative() && MemMgr->isManagingGOT()) {
unsigned idx = Resolver.getGOTIndexForAddr(ResultPtr);
MR.setGOTIndex(idx);
if (((void**)MemMgr->getGOTBase())[idx] != ResultPtr) {
DOUT << "GOT was out of date for " << ResultPtr
<< " pointing at " << ((void**)MemMgr->getGOTBase())[idx]
<< "\n";
((void**)MemMgr->getGOTBase())[idx] = ResultPtr;
}
}
}
TheJIT->getJITInfo().relocate(BufferBegin, &Relocations[0],
Relocations.size(), MemMgr->getGOTBase());
}
// Update the GOT entry for F to point to the new code.
if (MemMgr->isManagingGOT()) {
unsigned idx = Resolver.getGOTIndexForAddr((void*)BufferBegin);
if (((void**)MemMgr->getGOTBase())[idx] != (void*)BufferBegin) {
DOUT << "GOT was out of date for " << (void*)BufferBegin
<< " pointing at " << ((void**)MemMgr->getGOTBase())[idx] << "\n";
((void**)MemMgr->getGOTBase())[idx] = (void*)BufferBegin;
}
}
// Invalidate the icache if necessary.
sys::Memory::InvalidateInstructionCache(FnStart, FnEnd-FnStart);
// Add it to the JIT symbol table if the host wants it.
AddFunctionToSymbolTable(F.getFunction()->getNameStart(),
FnStart, FnEnd-FnStart);
DOUT << "JIT: Finished CodeGen of [" << (void*)FnStart
<< "] Function: " << F.getFunction()->getName()
<< ": " << (FnEnd-FnStart) << " bytes of text, "
<< Relocations.size() << " relocations\n";
Relocations.clear();
#ifndef NDEBUG
if (sys::hasDisassembler())
DOUT << "Disassembled code:\n"
<< sys::disassembleBuffer(FnStart, FnEnd-FnStart, (uintptr_t)FnStart);
#endif
if (ExceptionHandling) {
uintptr_t ActualSize = 0;
SavedBufferBegin = BufferBegin;
SavedBufferEnd = BufferEnd;
SavedCurBufferPtr = CurBufferPtr;
if (MemMgr->NeedsExactSize()) {
ActualSize = DE->GetDwarfTableSizeInBytes(F, *this, FnStart, FnEnd);
}
BufferBegin = CurBufferPtr = MemMgr->startExceptionTable(F.getFunction(),
ActualSize);
BufferEnd = BufferBegin+ActualSize;
unsigned char* FrameRegister = DE->EmitDwarfTable(F, *this, FnStart, FnEnd);
MemMgr->endExceptionTable(F.getFunction(), BufferBegin, CurBufferPtr,
FrameRegister);
BufferBegin = SavedBufferBegin;
BufferEnd = SavedBufferEnd;
CurBufferPtr = SavedCurBufferPtr;
TheJIT->RegisterTable(FrameRegister);
}
MMI->EndFunction();
return false;
}
void JITEmitter::emitConstantPool(MachineConstantPool *MCP) {
const std::vector<MachineConstantPoolEntry> &Constants = MCP->getConstants();
if (Constants.empty()) return;
MachineConstantPoolEntry CPE = Constants.back();
unsigned Size = CPE.Offset;
const Type *Ty = CPE.isMachineConstantPoolEntry()
? CPE.Val.MachineCPVal->getType() : CPE.Val.ConstVal->getType();
Size += TheJIT->getTargetData()->getABITypeSize(Ty);
unsigned Align = 1 << MCP->getConstantPoolAlignment();
ConstantPoolBase = allocateSpace(Size, Align);
ConstantPool = MCP;
if (ConstantPoolBase == 0) return; // Buffer overflow.
DOUT << "JIT: Emitted constant pool at [" << ConstantPoolBase
<< "] (size: " << Size << ", alignment: " << Align << ")\n";
// Initialize the memory for all of the constant pool entries.
for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
void *CAddr = (char*)ConstantPoolBase+Constants[i].Offset;
if (Constants[i].isMachineConstantPoolEntry()) {
// FIXME: add support to lower machine constant pool values into bytes!
cerr << "Initialize memory with machine specific constant pool entry"
<< " has not been implemented!\n";
abort();
}
TheJIT->InitializeMemory(Constants[i].Val.ConstVal, CAddr);
DOUT << "JIT: CP" << i << " at [" << CAddr << "]\n";
}
}
void JITEmitter::initJumpTableInfo(MachineJumpTableInfo *MJTI) {
const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
if (JT.empty()) return;
unsigned NumEntries = 0;
for (unsigned i = 0, e = JT.size(); i != e; ++i)
NumEntries += JT[i].MBBs.size();
unsigned EntrySize = MJTI->getEntrySize();
// Just allocate space for all the jump tables now. We will fix up the actual
// MBB entries in the tables after we emit the code for each block, since then
// we will know the final locations of the MBBs in memory.
JumpTable = MJTI;
JumpTableBase = allocateSpace(NumEntries * EntrySize, MJTI->getAlignment());
}
void JITEmitter::emitJumpTableInfo(MachineJumpTableInfo *MJTI) {
const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
if (JT.empty() || JumpTableBase == 0) return;
if (TargetMachine::getRelocationModel() == Reloc::PIC_) {
assert(MJTI->getEntrySize() == 4 && "Cross JIT'ing?");
// For each jump table, place the offset from the beginning of the table
// to the target address.
int *SlotPtr = (int*)JumpTableBase;
for (unsigned i = 0, e = JT.size(); i != e; ++i) {
const std::vector<MachineBasicBlock*> &MBBs = JT[i].MBBs;
// Store the offset of the basic block for this jump table slot in the
// memory we allocated for the jump table in 'initJumpTableInfo'
intptr_t Base = (intptr_t)SlotPtr;
for (unsigned mi = 0, me = MBBs.size(); mi != me; ++mi) {
intptr_t MBBAddr = getMachineBasicBlockAddress(MBBs[mi]);
*SlotPtr++ = TheJIT->getJITInfo().getPICJumpTableEntry(MBBAddr, Base);
}
}
} else {
assert(MJTI->getEntrySize() == sizeof(void*) && "Cross JIT'ing?");
// For each jump table, map each target in the jump table to the address of
// an emitted MachineBasicBlock.
intptr_t *SlotPtr = (intptr_t*)JumpTableBase;
for (unsigned i = 0, e = JT.size(); i != e; ++i) {
const std::vector<MachineBasicBlock*> &MBBs = JT[i].MBBs;
// Store the address of the basic block for this jump table slot in the
// memory we allocated for the jump table in 'initJumpTableInfo'
for (unsigned mi = 0, me = MBBs.size(); mi != me; ++mi)
*SlotPtr++ = getMachineBasicBlockAddress(MBBs[mi]);
}
}
}
void JITEmitter::startFunctionStub(const GlobalValue* F, unsigned StubSize,
unsigned Alignment) {
SavedBufferBegin = BufferBegin;
SavedBufferEnd = BufferEnd;
SavedCurBufferPtr = CurBufferPtr;
BufferBegin = CurBufferPtr = MemMgr->allocateStub(F, StubSize, Alignment);
BufferEnd = BufferBegin+StubSize+1;
}
void *JITEmitter::finishFunctionStub(const GlobalValue* F) {
NumBytes += getCurrentPCOffset();
std::swap(SavedBufferBegin, BufferBegin);
BufferEnd = SavedBufferEnd;
CurBufferPtr = SavedCurBufferPtr;
return SavedBufferBegin;
}
// getConstantPoolEntryAddress - Return the address of the 'ConstantNum' entry
// in the constant pool that was last emitted with the 'emitConstantPool'
// method.
//
intptr_t JITEmitter::getConstantPoolEntryAddress(unsigned ConstantNum) const {
assert(ConstantNum < ConstantPool->getConstants().size() &&
"Invalid ConstantPoolIndex!");
return (intptr_t)ConstantPoolBase +
ConstantPool->getConstants()[ConstantNum].Offset;
}
// getJumpTableEntryAddress - Return the address of the JumpTable with index
// 'Index' in the jumpp table that was last initialized with 'initJumpTableInfo'
//
intptr_t JITEmitter::getJumpTableEntryAddress(unsigned Index) const {
const std::vector<MachineJumpTableEntry> &JT = JumpTable->getJumpTables();
assert(Index < JT.size() && "Invalid jump table index!");
unsigned Offset = 0;
unsigned EntrySize = JumpTable->getEntrySize();
for (unsigned i = 0; i < Index; ++i)
Offset += JT[i].MBBs.size();
Offset *= EntrySize;
return (intptr_t)((char *)JumpTableBase + Offset);
}
//===----------------------------------------------------------------------===//
// Public interface to this file
//===----------------------------------------------------------------------===//
MachineCodeEmitter *JIT::createEmitter(JIT &jit, JITMemoryManager *JMM) {
return new JITEmitter(jit, JMM);
}
// getPointerToNamedFunction - This function is used as a global wrapper to
// JIT::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) {
if (Function *F = TheJIT->FindFunctionNamed(Name))
return TheJIT->getPointerToFunction(F);
return TheJIT->getPointerToNamedFunction(Name);
}
}
// getPointerToFunctionOrStub - If the specified function has been
// code-gen'd, return a pointer to the function. If not, compile it, or use
// a stub to implement lazy compilation if available.
//
void *JIT::getPointerToFunctionOrStub(Function *F) {
// If we have already code generated the function, just return the address.
if (void *Addr = getPointerToGlobalIfAvailable(F))
return Addr;
// Get a stub if the target supports it.
assert(dynamic_cast<JITEmitter*>(MCE) && "Unexpected MCE?");
JITEmitter *JE = static_cast<JITEmitter*>(getCodeEmitter());
return JE->getJITResolver().getFunctionStub(F);
}
/// freeMachineCodeForFunction - release machine code memory for given Function.
///
void JIT::freeMachineCodeForFunction(Function *F) {
// Delete translation for this from the ExecutionEngine, so it will get
// retranslated next time it is used.
void *OldPtr = updateGlobalMapping(F, 0);
if (OldPtr)
RemoveFunctionFromSymbolTable(OldPtr);
// Free the actual memory for the function body and related stuff.
assert(dynamic_cast<JITEmitter*>(MCE) && "Unexpected MCE?");
static_cast<JITEmitter*>(MCE)->deallocateMemForFunction(F);
}
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