| //===-- MacOSJITEventListener.cpp - Save symbol table for OSX perf tools --===// |
| // |
| // 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 JITEventListener object that records JITted functions to |
| // a global __jitSymbolTable linked list. Apple's performance tools use this to |
| // 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". |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "macos-jit-event-listener" |
| #include "llvm/Function.h" |
| #include "llvm/ExecutionEngine/JITEventListener.h" |
| #include <stddef.h> |
| using namespace llvm; |
| |
| #ifdef __APPLE__ |
| #define ENABLE_JIT_SYMBOL_TABLE 0 |
| #endif |
| |
| #if ENABLE_JIT_SYMBOL_TABLE |
| |
| namespace { |
| |
| /// 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; |
| }; |
| |
| class MacOSJITEventListener : public JITEventListener { |
| public: |
| virtual void NotifyFunctionEmitted(const Function &F, |
| void *FnStart, size_t FnSize, |
| const EmittedFunctionDetails &Details); |
| virtual void NotifyFreeingMachineCode(const Function &F, void *OldPtr); |
| }; |
| |
| } // anonymous namespace. |
| |
| // This is a public symbol so the performance tools can find it. |
| JITSymbolTable *__jitSymbolTable; |
| |
| namespace llvm { |
| JITEventListener *createMacOSJITEventListener() { |
| return new MacOSJITEventListener; |
| } |
| } |
| |
| // Adds the just-emitted function to the symbol table. |
| void MacOSJITEventListener::NotifyFunctionEmitted( |
| const Function &F, void *FnStart, size_t FnSize, |
| const EmittedFunctionDetails &) { |
| const char *const FnName = F.getNameStart(); |
| assert(FnName != 0 && FnStart != 0 && "Bad symbol to add"); |
| JITSymbolTable **SymTabPtrPtr = 0; |
| SymTabPtrPtr = &__jitSymbolTable; |
| |
| // 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; |
| } |
| |
| // Removes the to-be-deleted function from the symbol table. |
| void MacOSJITEventListener::NotifyFreeingMachineCode( |
| const Function &, void *FnStart) { |
| assert(FnStart && "Invalid function pointer"); |
| JITSymbolTable **SymTabPtrPtr = 0; |
| SymTabPtrPtr = &__jitSymbolTable; |
| |
| 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; |
| } |
| |
| #else // !ENABLE_JIT_SYMBOL_TABLE |
| |
| namespace llvm { |
| // By defining this to return NULL, we can let clients call it unconditionally, |
| // even if they aren't on an Apple system. |
| JITEventListener *createMacOSJITEventListener() { |
| return NULL; |
| } |
| } // namespace llvm |
| |
| #endif // ENABLE_JIT_SYMBOL_TABLE |