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#ifndef __nanojit_CodeAlloc__
#define __nanojit_CodeAlloc__
namespace nanojit
{
/** return true if ptr is in the range [start, end] */
inline bool containsPtr(const NIns* start, const NIns* end, const NIns* ptr) {
return ptr >= start && ptr <= end;
}
/**
* CodeList is a linked list of non-contigous blocks of code. Clients use CodeList*
* to point to a list, and each CodeList instance tracks a single contiguous
* block of code.
*/
class CodeList
{
friend class CodeAlloc;
/** for making singly linked lists of blocks in any order */
CodeList* next;
/** adjacent block at lower address. This field plus higher
form a doubly linked list of blocks in address order, used
for splitting and coalescing blocks. */
CodeList* lower;
/** true if block is free, false otherwise */
bool isFree;
union {
// this union is used in leu of pointer punning in code
// the end of this block is always the address of the next higher block
CodeList* higher; // adjacent block at higher address
NIns* end; // points just past the end
};
/** code holds this block's payload of binary code, from
here to this->end */
NIns code[1]; // more follows
/** return the starting address for this block only */
NIns* start() { return &code[0]; }
/** return just the usable size of this block */
size_t size() const { return uintptr_t(end) - uintptr_t(&code[0]); }
/** return the whole size of this block including overhead */
size_t blockSize() const { return uintptr_t(end) - uintptr_t(this); }
/** return true if just this block contains p */
bool contains(NIns* p) const { return containsPtr(&code[0], end, p); }
};
/**
* Code memory allocator.
* Long lived manager for many code blocks,
* manages interaction with an underlying code memory allocator,
* setting page permissions, api's for allocating and freeing
* individual blocks of code memory (for methods, stubs, or compiled
* traces), and also static functions for managing lists of allocated
* code.
*/
class CodeAlloc
{
static const size_t sizeofMinBlock = offsetof(CodeList, code);
static const size_t minAllocSize = LARGEST_UNDERRUN_PROT;
/** Terminator blocks. All active and free allocations
are reachable by traversing this chain and each
element's lower chain. */
CodeList* heapblocks;
/** Reusable blocks. */
CodeList* availblocks;
size_t totalAllocated;
/** remove one block from a list */
static CodeList* removeBlock(CodeList* &list);
/** add one block to a list */
static void addBlock(CodeList* &blocks, CodeList* b);
/** compute the CodeList pointer from a [start, end) range */
static CodeList* getBlock(NIns* start, NIns* end);
/** add raw memory to the free list */
CodeList* addMem(void* mem, size_t bytes);
/** make sure all the higher/lower pointers are correct for every block */
void sanity_check();
/** find the beginning of the heapblock terminated by term */
static CodeList* firstBlock(CodeList* term);
//
// CodeAlloc's SPI. Implementations must be defined by nanojit embedder.
// allocation failures should cause an exception or longjmp; nanojit
// intentionally does not check for null.
//
/** allocate nbytes of memory to hold code. Never return null! */
void* allocCodeChunk(size_t nbytes);
/** free a block previously allocated by allocCodeMem. nbytes will
* match the previous allocCodeMem, but is provided here as well
* to mirror the mmap()/munmap() api. */
void freeCodeChunk(void* addr, size_t nbytes);
public:
CodeAlloc();
~CodeAlloc();
/** return all the memory allocated through this allocator to the gcheap. */
void reset();
/** allocate some memory for code, return pointers to the region. */
void alloc(NIns* &start, NIns* &end);
/** free a block of memory previously returned by alloc() */
void free(NIns* start, NIns* end);
/** free several blocks */
void freeAll(CodeList* &code);
/** flush the icache for all code in the list, before executing */
static void flushICache(CodeList* &blocks);
/** flush the icache for a specific extent */
static void flushICache(void *start, size_t len);
/** add the ranges [start, holeStart) and [holeEnd, end) to code, and
free [holeStart, holeEnd) if the hole is >= minsize */
void addRemainder(CodeList* &code, NIns* start, NIns* end, NIns* holeStart, NIns* holeEnd);
/** add a block previously returned by alloc(), to code */
static void add(CodeList* &code, NIns* start, NIns* end);
/** move all the code in list "from" to list "to", and leave from empty. */
static void moveAll(CodeList* &to, CodeList* &from);
/** return true if any block in list "code" contains the code pointer p */
static bool contains(const CodeList* code, NIns* p);
/** return the number of bytes in all the code blocks in "code", including block overhead */
static size_t size(const CodeList* code);
/** return the total number of bytes held by this CodeAlloc. */
size_t size();
/** print out stats about heap usage */
void logStats();
enum CodePointerKind {
kUnknown, kFree, kUsed
};
/** determine whether the given address is not code, or is allocated or free */
CodePointerKind classifyPtr(NIns *p);
/** return any completely empty pages */
void sweep();
};
}
#endif // __nanojit_CodeAlloc__