mirror of
https://github.com/c64scene-ar/llvm-6502.git
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174 lines
5.8 KiB
C++
174 lines
5.8 KiB
C++
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//===-- MacOSJITEventListener.cpp - Save symbol table for OSX perf tools --===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines a JITEventListener object that records JITted functions to
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// a global __jitSymbolTable linked list. Apple's performance tools use this to
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// determine a symbol name and accurate code range for a PC value. Because
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// performance tools are generally asynchronous, the code below is written with
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// the hope that it could be interrupted at any time and have useful answers.
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// However, we don't go crazy with atomic operations, we just do a "reasonable
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// effort".
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "macos-jit-event-listener"
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#include "llvm/Function.h"
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#include "llvm/ExecutionEngine/JITEventListener.h"
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#include <stddef.h>
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using namespace llvm;
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#ifdef __APPLE__
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#define ENABLE_JIT_SYMBOL_TABLE 0
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#endif
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#if ENABLE_JIT_SYMBOL_TABLE
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namespace {
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/// JITSymbolEntry - Each function that is JIT compiled results in one of these
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/// being added to an array of symbols. This indicates the name of the function
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/// as well as the address range it occupies. This allows the client to map
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/// from a PC value to the name of the function.
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struct JITSymbolEntry {
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const char *FnName; // FnName - a strdup'd string.
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void *FnStart;
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intptr_t FnSize;
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};
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struct JITSymbolTable {
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/// NextPtr - This forms a linked list of JitSymbolTable entries. This
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/// pointer is not used right now, but might be used in the future. Consider
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/// it reserved for future use.
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JITSymbolTable *NextPtr;
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/// Symbols - This is an array of JitSymbolEntry entries. Only the first
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/// 'NumSymbols' symbols are valid.
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JITSymbolEntry *Symbols;
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/// NumSymbols - This indicates the number entries in the Symbols array that
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/// are valid.
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unsigned NumSymbols;
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/// NumAllocated - This indicates the amount of space we have in the Symbols
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/// array. This is a private field that should not be read by external tools.
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unsigned NumAllocated;
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};
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class MacOSJITEventListener : public JITEventListener {
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public:
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virtual void NotifyFunctionEmitted(const Function &F,
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void *FnStart, size_t FnSize,
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const EmittedFunctionDetails &Details);
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virtual void NotifyFreeingMachineCode(const Function &F, void *OldPtr);
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};
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} // anonymous namespace.
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// This is a public symbol so the performance tools can find it.
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JITSymbolTable *__jitSymbolTable;
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namespace llvm {
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JITEventListener *createMacOSJITEventListener() {
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return new MacOSJITEventListener;
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}
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}
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// Adds the just-emitted function to the symbol table.
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void MacOSJITEventListener::NotifyFunctionEmitted(
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const Function &F, void *FnStart, size_t FnSize,
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const EmittedFunctionDetails &) {
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const char *const FnName = F.getNameStart();
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assert(FnName != 0 && FnStart != 0 && "Bad symbol to add");
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JITSymbolTable **SymTabPtrPtr = 0;
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SymTabPtrPtr = &__jitSymbolTable;
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// If this is the first entry in the symbol table, add the JITSymbolTable
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// index.
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if (*SymTabPtrPtr == 0) {
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JITSymbolTable *New = new JITSymbolTable();
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New->NextPtr = 0;
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New->Symbols = 0;
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New->NumSymbols = 0;
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New->NumAllocated = 0;
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*SymTabPtrPtr = New;
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}
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JITSymbolTable *SymTabPtr = *SymTabPtrPtr;
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// If we have space in the table, reallocate the table.
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if (SymTabPtr->NumSymbols >= SymTabPtr->NumAllocated) {
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// If we don't have space, reallocate the table.
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unsigned NewSize = std::max(64U, SymTabPtr->NumAllocated*2);
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JITSymbolEntry *NewSymbols = new JITSymbolEntry[NewSize];
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JITSymbolEntry *OldSymbols = SymTabPtr->Symbols;
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// Copy the old entries over.
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memcpy(NewSymbols, OldSymbols, SymTabPtr->NumSymbols*sizeof(OldSymbols[0]));
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// Swap the new symbols in, delete the old ones.
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SymTabPtr->Symbols = NewSymbols;
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SymTabPtr->NumAllocated = NewSize;
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delete [] OldSymbols;
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}
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// Otherwise, we have enough space, just tack it onto the end of the array.
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JITSymbolEntry &Entry = SymTabPtr->Symbols[SymTabPtr->NumSymbols];
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Entry.FnName = strdup(FnName);
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Entry.FnStart = FnStart;
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Entry.FnSize = FnSize;
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++SymTabPtr->NumSymbols;
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}
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// Removes the to-be-deleted function from the symbol table.
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void MacOSJITEventListener::NotifyFreeingMachineCode(
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const Function &, void *FnStart) {
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assert(FnStart && "Invalid function pointer");
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JITSymbolTable **SymTabPtrPtr = 0;
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SymTabPtrPtr = &__jitSymbolTable;
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JITSymbolTable *SymTabPtr = *SymTabPtrPtr;
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JITSymbolEntry *Symbols = SymTabPtr->Symbols;
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// Scan the table to find its index. The table is not sorted, so do a linear
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// scan.
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unsigned Index;
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for (Index = 0; Symbols[Index].FnStart != FnStart; ++Index)
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assert(Index != SymTabPtr->NumSymbols && "Didn't find function!");
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// Once we have an index, we know to nuke this entry, overwrite it with the
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// entry at the end of the array, making the last entry redundant.
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const char *OldName = Symbols[Index].FnName;
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Symbols[Index] = Symbols[SymTabPtr->NumSymbols-1];
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free((void*)OldName);
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// Drop the number of symbols in the table.
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--SymTabPtr->NumSymbols;
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// Finally, if we deleted the final symbol, deallocate the table itself.
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if (SymTabPtr->NumSymbols != 0)
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return;
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*SymTabPtrPtr = 0;
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delete [] Symbols;
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delete SymTabPtr;
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}
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#else // !ENABLE_JIT_SYMBOL_TABLE
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namespace llvm {
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// By defining this to return NULL, we can let clients call it unconditionally,
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// even if they aren't on an Apple system.
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JITEventListener *createMacOSJITEventListener() {
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return NULL;
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}
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} // namespace llvm
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#endif // ENABLE_JIT_SYMBOL_TABLE
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