diff options
author | Howard Hinnant <hhinnant@apple.com> | 2012-01-24 21:02:21 +0000 |
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committer | Howard Hinnant <hhinnant@apple.com> | 2012-01-24 21:02:21 +0000 |
commit | c2dfdeb45185892867d765a75668760285dbfbf0 (patch) | |
tree | 6578a169dffe888737325d9a7ff6a069a6417831 /src/fallback_malloc.cpp | |
parent | 73fd45bc7dbe3f3874a69783cc8d5419201c4f1f (diff) |
Got fooled by fallback_malloc.cpp source file: it is really a private header. I've manually included it into the only place it is used: cxa_exception.cpp.
git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@148854 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'src/fallback_malloc.cpp')
-rw-r--r-- | src/fallback_malloc.cpp | 177 |
1 files changed, 0 insertions, 177 deletions
diff --git a/src/fallback_malloc.cpp b/src/fallback_malloc.cpp deleted file mode 100644 index b83cb8f..0000000 --- a/src/fallback_malloc.cpp +++ /dev/null @@ -1,177 +0,0 @@ -//===------------------------ fallback_malloc.cpp -------------------------===// -// -// The LLVM Compiler Infrastructure -// -// This file is dual licensed under the MIT and the University of Illinois Open -// Source Licenses. See LICENSE.TXT for details. -// -// -// This file implements the a small heap for allocation of exception -// in the situation where malloc fails. -// http://www.codesourcery.com/public/cxx-abi/abi-eh.html (section 2.4.2) -// -//===----------------------------------------------------------------------===// - -// A small, simple heap manager based (loosely) on -// the startup heap manager from FreeBSD, optimized for space. -// -// Manages a fixed-size memory pool, supports malloc and free only. -// No support for realloc. -// -// Allocates chunks in multiples of four bytes, with a four byte header -// for each chunk. The overhead of each chunk is kept low by keeping pointers -// as two byte offsets within the heap, rather than (4 or 8 byte) pointers. - -#include <pthread.h> - -namespace { - -static pthread_mutex_t heap_mutex = PTHREAD_MUTEX_INITIALIZER; - -class mutexor { -public: - mutexor ( pthread_mutex_t *m ) : mtx_(m) { pthread_mutex_lock ( mtx_ ); } - ~mutexor () { pthread_mutex_unlock ( mtx_ ); } -private: - mutexor ( const mutexor &rhs ); - mutexor & operator = ( const mutexor &rhs ); - pthread_mutex_t *mtx_; - }; - - -#define HEAP_SIZE 512 -char heap [ HEAP_SIZE ]; - -typedef unsigned short heap_offset; -typedef unsigned short heap_size; - -struct heap_node { - heap_offset next_node; // offset into heap - heap_size len; // size in units of "sizeof(heap_node)" -}; - -static const heap_node *list_end = (heap_node *) ( &heap [ HEAP_SIZE ] ); // one past the end of the heap -static heap_node *freelist = NULL; - -heap_node *node_from_offset ( const heap_offset offset ) throw() - { return (heap_node *) ( heap + ( offset * sizeof (heap_node))); } - -heap_offset offset_from_node ( const heap_node *ptr ) throw() - { return (((char *) ptr ) - heap) / sizeof (heap_node); } - -void init_heap () throw() { - freelist = (heap_node *) heap; - freelist->next_node = offset_from_node ( list_end ); - freelist->len = HEAP_SIZE / sizeof (heap_node); - } - -// How big a chunk we allocate -size_t alloc_size (size_t len) throw() - { return (len + sizeof(heap_node) - 1) / sizeof(heap_node) + 1; } - -bool is_fallback_ptr ( void *ptr ) throw() - { return ptr >= heap && ptr < ( heap + HEAP_SIZE ); } - -void *fallback_malloc(size_t len) throw() { - heap_node *p, *prev; - const size_t nelems = alloc_size ( len ); - mutexor mtx ( &heap_mutex ); - - if ( NULL == freelist ) - init_heap (); - -// Walk the free list, looking for a "big enough" chunk - for (p = freelist, prev = 0; - p && p != list_end; prev = p, p = node_from_offset ( p->next_node)) { - - if (p->len > nelems) { // chunk is larger, shorten, and return the tail - heap_node *q; - - p->len -= nelems; - q = p + p->len; - q->next_node = 0; - q->len = nelems; - return (void *) (q + 1); - } - - if (p->len == nelems) { // exact size match - if (prev == 0) - freelist = node_from_offset(p->next_node); - else - prev->next_node = p->next_node; - p->next_node = 0; - return (void *) (p + 1); - } - } - return NULL; // couldn't find a spot big enough -} - -// Return the start of the next block -heap_node *after ( struct heap_node *p ) throw() { return p + p->len; } - -void fallback_free (void *ptr) throw() { - struct heap_node *cp = ((struct heap_node *) ptr) - 1; // retrieve the chunk - struct heap_node *p, *prev; - - mutexor mtx ( &heap_mutex ); - -#ifdef DEBUG_FALLBACK_MALLOC - std::cout << "Freeing item at " << offset_from_node ( cp ) << " of size " << cp->len << std::endl; -#endif - - for (p = freelist, prev = 0; - p && p != list_end; prev = p, p = node_from_offset (p->next_node)) { -#ifdef DEBUG_FALLBACK_MALLOC - std::cout << " p, cp, after (p), after(cp) " - << offset_from_node ( p ) << ' ' - << offset_from_node ( cp ) << ' ' - << offset_from_node ( after ( p )) << ' ' - << offset_from_node ( after ( cp )) << std::endl; -#endif - if ( after ( p ) == cp ) { -#ifdef DEBUG_FALLBACK_MALLOC - std::cout << " Appending onto chunk at " << offset_from_node ( p ) << std::endl; -#endif - p->len += cp->len; // make the free heap_node larger - return; - } - else if ( after ( cp ) == p ) { // there's a free heap_node right after -#ifdef DEBUG_FALLBACK_MALLOC - std::cout << " Appending free chunk at " << offset_from_node ( p ) << std::endl; -#endif - cp->len += p->len; - if ( prev == 0 ) { - freelist = cp; - cp->next_node = p->next_node; - } - else - prev->next_node = offset_from_node(cp); - return; - } - } -// Nothing to merge with, add it to the start of the free list -#ifdef DEBUG_FALLBACK_MALLOC - std::cout << " Making new free list entry " << offset_from_node ( cp ) << std::endl; -#endif - cp->next_node = offset_from_node ( freelist ); - freelist = cp; -} - -#ifdef INSTRUMENT_FALLBACK_MALLOC -size_t print_free_list () { - struct heap_node *p, *prev; - heap_size total_free = 0; - if ( NULL == freelist ) - init_heap (); - - for (p = freelist, prev = 0; - p && p != list_end; prev = p, p = node_from_offset (p->next_node)) { - std::cout << ( prev == 0 ? "" : " ") << "Offset: " << offset_from_node ( p ) - << "\tsize: " << p->len << " Next: " << p->next_node << std::endl; - total_free += p->len; - } - std::cout << "Total Free space: " << total_free << std::endl; - return total_free; - } -#endif -} |