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a9f40ad80a68f753e510aedf77b49983b8064ffe
llvm/lldb/source/Target/Memory.cpp
Greg Clayton a9f40ad80a For stepping performance I added the ability to outlaw all memory accesseses 
to the __PAGEZERO segment on darwin. The dynamic loader now correctly doesn't
slide __PAGEZERO and it also registers it as an invalid region of memory. This
allows us to not make any memory requests from the local or remote debug session
for any addresses in this region. Stepping performance can improve when uninitialized
local variables that point to locations in __PAGEZERO are attempted to be read 
from memory as we won't even make the memory read or write request.

llvm-svn: 151128
2012-02-22 04:37:26 +00:00

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//===-- Memory.cpp ----------------------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "lldb/Target/Memory.h"
// C Includes
// C++ Includes
// Other libraries and framework includes
// Project includes
#include "lldb/Core/DataBufferHeap.h"
#include "lldb/Core/State.h"
#include "lldb/Core/Log.h"
#include "lldb/Target/Process.h"
using namespace lldb;
using namespace lldb_private;
//----------------------------------------------------------------------
// MemoryCache constructor
//----------------------------------------------------------------------
MemoryCache::MemoryCache(Process &process) :
m_process (process),
m_cache_line_byte_size (512),
m_mutex (Mutex::eMutexTypeRecursive),
m_cache (),
m_invalid_ranges ()
{
}
//----------------------------------------------------------------------
// Destructor
//----------------------------------------------------------------------
MemoryCache::~MemoryCache()
{
}
void
MemoryCache::Clear()
{
Mutex::Locker locker (m_mutex);
m_cache.clear();
}
void
MemoryCache::Flush (addr_t addr, size_t size)
{
if (size == 0)
return;
const uint32_t cache_line_byte_size = m_cache_line_byte_size;
const addr_t end_addr = (addr + size - 1);
const addr_t flush_start_addr = addr - (addr % cache_line_byte_size);
const addr_t flush_end_addr = end_addr - (end_addr % cache_line_byte_size);
Mutex::Locker locker (m_mutex);
if (m_cache.empty())
return;
assert ((flush_start_addr % cache_line_byte_size) == 0);
for (addr_t curr_addr = flush_start_addr; curr_addr <= flush_end_addr; curr_addr += cache_line_byte_size)
{
BlockMap::iterator pos = m_cache.find (curr_addr);
if (pos != m_cache.end())
m_cache.erase(pos);
}
}
void
MemoryCache::AddInvalidRange (lldb::addr_t base_addr, lldb::addr_t byte_size)
{
if (byte_size > 0)
{
Mutex::Locker locker (m_mutex);
InvalidRanges::Entry range (base_addr, byte_size);
m_invalid_ranges.Append(range);
m_invalid_ranges.Sort();
}
}
bool
MemoryCache::RemoveInvalidRange (lldb::addr_t base_addr, lldb::addr_t byte_size)
{
if (byte_size > 0)
{
Mutex::Locker locker (m_mutex);
const uint32_t idx = m_invalid_ranges.FindEntryIndexThatContains(base_addr);
if (idx != UINT32_MAX)
{
const InvalidRanges::Entry *entry = m_invalid_ranges.GetEntryAtIndex (idx);
if (entry->GetRangeBase() == base_addr && entry->GetByteSize() == byte_size)
return m_invalid_ranges.RemoveEntrtAtIndex (idx);
}
}
return false;
}
size_t
MemoryCache::Read (addr_t addr,
void *dst,
size_t dst_len,
Error &error)
{
size_t bytes_left = dst_len;
if (dst && bytes_left > 0)
{
const uint32_t cache_line_byte_size = m_cache_line_byte_size;
uint8_t *dst_buf = (uint8_t *)dst;
addr_t curr_addr = addr - (addr % cache_line_byte_size);
addr_t cache_offset = addr - curr_addr;
Mutex::Locker locker (m_mutex);
while (bytes_left > 0)
{
if (m_invalid_ranges.FindEntryThatContains(curr_addr))
return dst_len - bytes_left;
BlockMap::const_iterator pos = m_cache.find (curr_addr);
BlockMap::const_iterator end = m_cache.end ();
if (pos != end)
{
size_t curr_read_size = cache_line_byte_size - cache_offset;
if (curr_read_size > bytes_left)
curr_read_size = bytes_left;
memcpy (dst_buf + dst_len - bytes_left, pos->second->GetBytes() + cache_offset, curr_read_size);
bytes_left -= curr_read_size;
curr_addr += curr_read_size + cache_offset;
cache_offset = 0;
if (bytes_left > 0)
{
// Get sequential cache page hits
for (++pos; (pos != end) && (bytes_left > 0); ++pos)
{
assert ((curr_addr % cache_line_byte_size) == 0);
if (pos->first != curr_addr)
break;
curr_read_size = pos->second->GetByteSize();
if (curr_read_size > bytes_left)
curr_read_size = bytes_left;
memcpy (dst_buf + dst_len - bytes_left, pos->second->GetBytes(), curr_read_size);
bytes_left -= curr_read_size;
curr_addr += curr_read_size;
// We have a cache page that succeeded to read some bytes
// but not an entire page. If this happens, we must cap
// off how much data we are able to read...
if (pos->second->GetByteSize() != cache_line_byte_size)
return dst_len - bytes_left;
}
}
}
// We need to read from the process
if (bytes_left > 0)
{
assert ((curr_addr % cache_line_byte_size) == 0);
std::auto_ptr<DataBufferHeap> data_buffer_heap_ap(new DataBufferHeap (cache_line_byte_size, 0));
size_t process_bytes_read = m_process.ReadMemoryFromInferior (curr_addr,
data_buffer_heap_ap->GetBytes(),
data_buffer_heap_ap->GetByteSize(),
error);
if (process_bytes_read == 0)
return dst_len - bytes_left;
if (process_bytes_read != cache_line_byte_size)
data_buffer_heap_ap->SetByteSize (process_bytes_read);
m_cache[curr_addr] = DataBufferSP (data_buffer_heap_ap.release());
// We have read data and put it into the cache, continue through the
// loop again to get the data out of the cache...
}
}
}
return dst_len - bytes_left;
}
AllocatedBlock::AllocatedBlock (lldb::addr_t addr,
uint32_t byte_size,
uint32_t permissions,
uint32_t chunk_size) :
m_addr (addr),
m_byte_size (byte_size),
m_permissions (permissions),
m_chunk_size (chunk_size),
m_offset_to_chunk_size ()
// m_allocated (byte_size / chunk_size)
{
assert (byte_size > chunk_size);
}
AllocatedBlock::~AllocatedBlock ()
{
}
lldb::addr_t
AllocatedBlock::ReserveBlock (uint32_t size)
{
addr_t addr = LLDB_INVALID_ADDRESS;
if (size <= m_byte_size)
{
const uint32_t needed_chunks = CalculateChunksNeededForSize (size);
LogSP log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_PROCESS | LIBLLDB_LOG_VERBOSE));
if (m_offset_to_chunk_size.empty())
{
m_offset_to_chunk_size[0] = needed_chunks;
if (log)
log->Printf ("[1] AllocatedBlock::ReserveBlock (size = %u (0x%x)) => offset = 0x%x, %u %u bit chunks", size, size, 0, needed_chunks, m_chunk_size);
addr = m_addr;
}
else
{
uint32_t last_offset = 0;
OffsetToChunkSize::const_iterator pos = m_offset_to_chunk_size.begin();
OffsetToChunkSize::const_iterator end = m_offset_to_chunk_size.end();
while (pos != end)
{
if (pos->first > last_offset)
{
const uint32_t bytes_available = pos->first - last_offset;
const uint32_t num_chunks = CalculateChunksNeededForSize (bytes_available);
if (num_chunks >= needed_chunks)
{
m_offset_to_chunk_size[last_offset] = needed_chunks;
if (log)
log->Printf ("[2] AllocatedBlock::ReserveBlock (size = %u (0x%x)) => offset = 0x%x, %u %u bit chunks", size, size, last_offset, needed_chunks, m_chunk_size);
addr = m_addr + last_offset;
break;
}
}
last_offset = pos->first + pos->second * m_chunk_size;
if (++pos == end)
{
// Last entry...
const uint32_t chunks_left = CalculateChunksNeededForSize (m_byte_size - last_offset);
if (chunks_left >= needed_chunks)
{
m_offset_to_chunk_size[last_offset] = needed_chunks;
if (log)
log->Printf ("[3] AllocatedBlock::ReserveBlock (size = %u (0x%x)) => offset = 0x%x, %u %u bit chunks", size, size, last_offset, needed_chunks, m_chunk_size);
addr = m_addr + last_offset;
break;
}
}
}
}
// const uint32_t total_chunks = m_allocated.size ();
// uint32_t unallocated_idx = 0;
// uint32_t allocated_idx = m_allocated.find_first();
// uint32_t first_chunk_idx = UINT32_MAX;
// uint32_t num_chunks;
// while (1)
// {
// if (allocated_idx == UINT32_MAX)
// {
// // No more bits are set starting from unallocated_idx, so we
// // either have enough chunks for the request, or we don't.
// // Eiter way we break out of the while loop...
// num_chunks = total_chunks - unallocated_idx;
// if (needed_chunks <= num_chunks)
// first_chunk_idx = unallocated_idx;
// break;
// }
// else if (allocated_idx > unallocated_idx)
// {
// // We have some allocated chunks, check if there are enough
// // free chunks to satisfy the request?
// num_chunks = allocated_idx - unallocated_idx;
// if (needed_chunks <= num_chunks)
// {
// // Yep, we have enough!
// first_chunk_idx = unallocated_idx;
// break;
// }
// }
//
// while (unallocated_idx < total_chunks)
// {
// if (m_allocated[unallocated_idx])
// ++unallocated_idx;
// else
// break;
// }
//
// if (unallocated_idx >= total_chunks)
// break;
//
// allocated_idx = m_allocated.find_next(unallocated_idx);
// }
//
// if (first_chunk_idx != UINT32_MAX)
// {
// const uint32_t end_bit_idx = unallocated_idx + needed_chunks;
// for (uint32_t idx = first_chunk_idx; idx < end_bit_idx; ++idx)
// m_allocated.set(idx);
// return m_addr + m_chunk_size * first_chunk_idx;
// }
}
LogSP log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_PROCESS | LIBLLDB_LOG_VERBOSE));
if (log)
log->Printf ("AllocatedBlock::ReserveBlock (size = %u (0x%x)) => 0x%16.16llx", size, size, (uint64_t)addr);
return addr;
}
bool
AllocatedBlock::FreeBlock (addr_t addr)
{
uint32_t offset = addr - m_addr;
OffsetToChunkSize::iterator pos = m_offset_to_chunk_size.find (offset);
bool success = false;
if (pos != m_offset_to_chunk_size.end())
{
m_offset_to_chunk_size.erase (pos);
success = true;
}
LogSP log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_PROCESS | LIBLLDB_LOG_VERBOSE));
if (log)
log->Printf ("AllocatedBlock::FreeBlock (addr = 0x%16.16llx) => %i", (uint64_t)addr, success);
return success;
}
AllocatedMemoryCache::AllocatedMemoryCache (Process &process) :
m_process (process),
m_mutex (Mutex::eMutexTypeRecursive),
m_memory_map()
{
}
AllocatedMemoryCache::~AllocatedMemoryCache ()
{
}
void
AllocatedMemoryCache::Clear()
{
Mutex::Locker locker (m_mutex);
if (m_process.IsAlive())
{
PermissionsToBlockMap::iterator pos, end = m_memory_map.end();
for (pos = m_memory_map.begin(); pos != end; ++pos)
m_process.DoDeallocateMemory(pos->second->GetBaseAddress());
}
m_memory_map.clear();
}
AllocatedMemoryCache::AllocatedBlockSP
AllocatedMemoryCache::AllocatePage (uint32_t byte_size,
uint32_t permissions,
uint32_t chunk_size,
Error &error)
{
AllocatedBlockSP block_sp;
const size_t page_size = 4096;
const size_t num_pages = (byte_size + page_size - 1) / page_size;
const size_t page_byte_size = num_pages * page_size;
addr_t addr = m_process.DoAllocateMemory(page_byte_size, permissions, error);
LogSP log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_PROCESS));
if (log)
{
log->Printf ("Process::DoAllocateMemory (byte_size = 0x%8.8zx, permissions = %s) => 0x%16.16llx",
page_byte_size,
GetPermissionsAsCString(permissions),
(uint64_t)addr);
}
if (addr != LLDB_INVALID_ADDRESS)
{
block_sp.reset (new AllocatedBlock (addr, page_byte_size, permissions, chunk_size));
m_memory_map.insert (std::make_pair (permissions, block_sp));
}
return block_sp;
}
lldb::addr_t
AllocatedMemoryCache::AllocateMemory (size_t byte_size,
uint32_t permissions,
Error &error)
{
Mutex::Locker locker (m_mutex);
addr_t addr = LLDB_INVALID_ADDRESS;
std::pair<PermissionsToBlockMap::iterator, PermissionsToBlockMap::iterator> range = m_memory_map.equal_range (permissions);
for (PermissionsToBlockMap::iterator pos = range.first; pos != range.second; ++pos)
{
addr = (*pos).second->ReserveBlock (byte_size);
}
if (addr == LLDB_INVALID_ADDRESS)
{
AllocatedBlockSP block_sp (AllocatePage (byte_size, permissions, 16, error));
if (block_sp)
addr = block_sp->ReserveBlock (byte_size);
}
LogSP log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_PROCESS));
if (log)
log->Printf ("AllocatedMemoryCache::AllocateMemory (byte_size = 0x%8.8zx, permissions = %s) => 0x%16.16llx", byte_size, GetPermissionsAsCString(permissions), (uint64_t)addr);
return addr;
}
bool
AllocatedMemoryCache::DeallocateMemory (lldb::addr_t addr)
{
Mutex::Locker locker (m_mutex);
PermissionsToBlockMap::iterator pos, end = m_memory_map.end();
bool success = false;
for (pos = m_memory_map.begin(); pos != end; ++pos)
{
if (pos->second->Contains (addr))
{
success = pos->second->FreeBlock (addr);
break;
}
}
LogSP log (GetLogIfAllCategoriesSet (LIBLLDB_LOG_PROCESS));
if (log)
log->Printf("AllocatedMemoryCache::DeallocateMemory (addr = 0x%16.16llx) => %i", (uint64_t)addr, success);
return success;
}
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