/*
 *    Stack-less Just-In-Time compiler
 *
 *    Copyright Zoltan Herczeg (hzmester@freemail.hu). All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are
 * permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright notice, this list of
 *      conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright notice, this list
 *      of conditions and the following disclaimer in the documentation and/or other materials
 *      provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) AND CONTRIBUTORS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE COPYRIGHT HOLDER(S) OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* ------------------------------------------------------------------------ */
/*  Locks                                                                   */
/* ------------------------------------------------------------------------ */

/* Executable Allocator */

#if (defined SLJIT_EXECUTABLE_ALLOCATOR && SLJIT_EXECUTABLE_ALLOCATOR) \
	&& !(defined SLJIT_WX_EXECUTABLE_ALLOCATOR && SLJIT_WX_EXECUTABLE_ALLOCATOR)
#if (defined SLJIT_SINGLE_THREADED && SLJIT_SINGLE_THREADED)
#define SLJIT_ALLOCATOR_LOCK()
#define SLJIT_ALLOCATOR_UNLOCK()
#elif !(defined _WIN32)
#include <pthread.h>

static pthread_mutex_t allocator_lock = PTHREAD_MUTEX_INITIALIZER;

#define SLJIT_ALLOCATOR_LOCK() pthread_mutex_lock(&allocator_lock)
#define SLJIT_ALLOCATOR_UNLOCK() pthread_mutex_unlock(&allocator_lock)
#else /* windows */
static HANDLE allocator_lock;

static SLJIT_INLINE void allocator_grab_lock(void)
{
	HANDLE lock;
	if (SLJIT_UNLIKELY(!InterlockedCompareExchangePointer(&allocator_lock, NULL, NULL))) {
		lock = CreateMutex(NULL, FALSE, NULL);
		if (InterlockedCompareExchangePointer(&allocator_lock, lock, NULL))
			CloseHandle(lock);
	}
	WaitForSingleObject(allocator_lock, INFINITE);
}

#define SLJIT_ALLOCATOR_LOCK() allocator_grab_lock()
#define SLJIT_ALLOCATOR_UNLOCK() ReleaseMutex(allocator_lock)
#endif /* thread implementation */
#endif /* SLJIT_EXECUTABLE_ALLOCATOR && !SLJIT_WX_EXECUTABLE_ALLOCATOR */

/* ------------------------------------------------------------------------ */
/*  Stack                                                                   */
/* ------------------------------------------------------------------------ */

#if ((defined SLJIT_UTIL_STACK && SLJIT_UTIL_STACK) \
	&& !(defined SLJIT_UTIL_SIMPLE_STACK_ALLOCATION && SLJIT_UTIL_SIMPLE_STACK_ALLOCATION)) \
	|| ((defined SLJIT_EXECUTABLE_ALLOCATOR && SLJIT_EXECUTABLE_ALLOCATOR) \
	&& !((defined SLJIT_PROT_EXECUTABLE_ALLOCATOR && SLJIT_PROT_EXECUTABLE_ALLOCATOR) \
	|| (defined SLJIT_WX_EXECUTABLE_ALLOCATOR && SLJIT_WX_EXECUTABLE_ALLOCATOR)))

#ifndef _WIN32
/* Provides mmap function. */
#include <sys/types.h>
#include <sys/mman.h>

#ifndef MAP_ANON
#ifdef MAP_ANONYMOUS
#define MAP_ANON MAP_ANONYMOUS
#endif /* MAP_ANONYMOUS */
#endif /* !MAP_ANON */

#ifndef MAP_ANON

#include <fcntl.h>

#ifdef O_CLOEXEC
#define SLJIT_CLOEXEC	O_CLOEXEC
#else /* !O_CLOEXEC */
#define SLJIT_CLOEXEC	0
#endif /* O_CLOEXEC */

/* Some old systems do not have MAP_ANON. */
static int dev_zero = -1;

#if (defined SLJIT_SINGLE_THREADED && SLJIT_SINGLE_THREADED)

static SLJIT_INLINE int open_dev_zero(void)
{
	dev_zero = open("/dev/zero", O_RDWR | SLJIT_CLOEXEC);

	return dev_zero < 0;
}

#else /* !SLJIT_SINGLE_THREADED */

#include <pthread.h>

static pthread_mutex_t dev_zero_mutex = PTHREAD_MUTEX_INITIALIZER;

static SLJIT_INLINE int open_dev_zero(void)
{
	pthread_mutex_lock(&dev_zero_mutex);
	if (SLJIT_UNLIKELY(dev_zero < 0))
		dev_zero = open("/dev/zero", O_RDWR | SLJIT_CLOEXEC);

	pthread_mutex_unlock(&dev_zero_mutex);
	return dev_zero < 0;
}

#endif /* SLJIT_SINGLE_THREADED */
#undef SLJIT_CLOEXEC
#endif /* !MAP_ANON */
#endif /* !_WIN32 */
#endif /* open_dev_zero */

#if (defined SLJIT_UTIL_STACK && SLJIT_UTIL_STACK) \
	|| (defined SLJIT_EXECUTABLE_ALLOCATOR && SLJIT_EXECUTABLE_ALLOCATOR)

#ifdef _WIN32

static SLJIT_INLINE sljit_sw get_page_alignment(void) {
	SYSTEM_INFO si;
	static sljit_sw sljit_page_align;
	if (!sljit_page_align) {
		GetSystemInfo(&si);
		sljit_page_align = si.dwPageSize - 1;
	}
	return sljit_page_align;
}

#else

#include <unistd.h>

static SLJIT_INLINE sljit_sw get_page_alignment(void) {
	static sljit_sw sljit_page_align = -1;
	if (sljit_page_align < 0) {
#ifdef _SC_PAGESIZE
		sljit_page_align = sysconf(_SC_PAGESIZE);
#else
		sljit_page_align = getpagesize();
#endif
		/* Should never happen. */
		if (sljit_page_align < 0)
			sljit_page_align = 4096;
		sljit_page_align--;
	}
	return sljit_page_align;
}

#endif /* _WIN32 */

#endif /* get_page_alignment() */

#if (defined SLJIT_UTIL_STACK && SLJIT_UTIL_STACK)

#if (defined SLJIT_UTIL_SIMPLE_STACK_ALLOCATION && SLJIT_UTIL_SIMPLE_STACK_ALLOCATION)

SLJIT_API_FUNC_ATTRIBUTE struct sljit_stack* SLJIT_FUNC sljit_allocate_stack(sljit_uw start_size, sljit_uw max_size, void *allocator_data)
{
	struct sljit_stack *stack;
	void *ptr;

	SLJIT_UNUSED_ARG(allocator_data);

	if (start_size > max_size || start_size < 1)
		return NULL;

	stack = (struct sljit_stack*)SLJIT_MALLOC(sizeof(struct sljit_stack), allocator_data);
	if (stack == NULL)
		return NULL;

	ptr = SLJIT_MALLOC(max_size, allocator_data);
	if (ptr == NULL) {
		SLJIT_FREE(stack, allocator_data);
		return NULL;
	}

	stack->min_start = (sljit_u8 *)ptr;
 	stack->end = stack->min_start + max_size;
 	stack->start = stack->end - start_size;
	stack->top = stack->end;
	return stack;
}

SLJIT_API_FUNC_ATTRIBUTE void SLJIT_FUNC sljit_free_stack(struct sljit_stack *stack, void *allocator_data)
{
	SLJIT_UNUSED_ARG(allocator_data);
	SLJIT_FREE((void*)stack->min_start, allocator_data);
	SLJIT_FREE(stack, allocator_data);
}

SLJIT_API_FUNC_ATTRIBUTE sljit_u8 *SLJIT_FUNC sljit_stack_resize(struct sljit_stack *stack, sljit_u8 *new_start)
{
	if ((new_start < stack->min_start) || (new_start >= stack->end))
		return NULL;
	stack->start = new_start;
	return new_start;
}

#else /* !SLJIT_UTIL_SIMPLE_STACK_ALLOCATION */

#ifdef _WIN32

SLJIT_API_FUNC_ATTRIBUTE void SLJIT_FUNC sljit_free_stack(struct sljit_stack *stack, void *allocator_data)
{
	SLJIT_UNUSED_ARG(allocator_data);
	VirtualFree((void*)stack->min_start, 0, MEM_RELEASE);
	SLJIT_FREE(stack, allocator_data);
}

#else /* !_WIN32 */

SLJIT_API_FUNC_ATTRIBUTE void SLJIT_FUNC sljit_free_stack(struct sljit_stack *stack, void *allocator_data)
{
	SLJIT_UNUSED_ARG(allocator_data);
	munmap((void*)stack->min_start, stack->end - stack->min_start);
	SLJIT_FREE(stack, allocator_data);
}

#endif /* _WIN32 */

SLJIT_API_FUNC_ATTRIBUTE struct sljit_stack* SLJIT_FUNC sljit_allocate_stack(sljit_uw start_size, sljit_uw max_size, void *allocator_data)
{
	struct sljit_stack *stack;
	void *ptr;
	sljit_sw page_align;

	SLJIT_UNUSED_ARG(allocator_data);

	if (start_size > max_size || start_size < 1)
		return NULL;

	stack = (struct sljit_stack*)SLJIT_MALLOC(sizeof(struct sljit_stack), allocator_data);
	if (stack == NULL)
		return NULL;

	/* Align max_size. */
	page_align = get_page_alignment();
	max_size = (max_size + page_align) & ~page_align;

#ifdef _WIN32
	ptr = VirtualAlloc(NULL, max_size, MEM_RESERVE, PAGE_READWRITE);
	if (!ptr) {
		SLJIT_FREE(stack, allocator_data);
		return NULL;
	}

	stack->min_start = (sljit_u8 *)ptr;
	stack->end = stack->min_start + max_size;
	stack->start = stack->end;

	if (sljit_stack_resize(stack, stack->end - start_size) == NULL) {
		sljit_free_stack(stack, allocator_data);
		return NULL;
	}
#else /* !_WIN32 */
#ifdef MAP_ANON
	ptr = mmap(NULL, max_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
#else /* !MAP_ANON */
	if (SLJIT_UNLIKELY((dev_zero < 0) && open_dev_zero())) {
		SLJIT_FREE(stack, allocator_data);
		return NULL;
	}
	ptr = mmap(NULL, max_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, dev_zero, 0);
#endif /* MAP_ANON */
	if (ptr == MAP_FAILED) {
		SLJIT_FREE(stack, allocator_data);
		return NULL;
	}
	stack->min_start = (sljit_u8 *)ptr;
	stack->end = stack->min_start + max_size;
	stack->start = stack->end - start_size;
#endif /* _WIN32 */

	stack->top = stack->end;
	return stack;
}

SLJIT_API_FUNC_ATTRIBUTE sljit_u8 *SLJIT_FUNC sljit_stack_resize(struct sljit_stack *stack, sljit_u8 *new_start)
{
#if defined _WIN32 || defined(POSIX_MADV_DONTNEED)
	sljit_uw aligned_old_start;
	sljit_uw aligned_new_start;
	sljit_sw page_align;
#endif

	if ((new_start < stack->min_start) || (new_start >= stack->end))
		return NULL;

#ifdef _WIN32
	page_align = get_page_alignment();

	aligned_new_start = (sljit_uw)new_start & ~page_align;
	aligned_old_start = ((sljit_uw)stack->start) & ~page_align;
	if (aligned_new_start != aligned_old_start) {
		if (aligned_new_start < aligned_old_start) {
			if (!VirtualAlloc((void*)aligned_new_start, aligned_old_start - aligned_new_start, MEM_COMMIT, PAGE_READWRITE))
				return NULL;
		}
		else {
			if (!VirtualFree((void*)aligned_old_start, aligned_new_start - aligned_old_start, MEM_DECOMMIT))
				return NULL;
		}
	}
#elif defined(POSIX_MADV_DONTNEED)
	if (stack->start < new_start) {
		page_align = get_page_alignment();

		aligned_new_start = (sljit_uw)new_start & ~page_align;
		aligned_old_start = ((sljit_uw)stack->start) & ~page_align;

		if (aligned_new_start > aligned_old_start) {
			posix_madvise((void*)aligned_old_start, aligned_new_start - aligned_old_start, POSIX_MADV_DONTNEED);
#ifdef MADV_FREE
			madvise((void*)aligned_old_start, aligned_new_start - aligned_old_start, MADV_FREE);
#endif /* MADV_FREE */
		}
	}
#endif /* _WIN32 */

	stack->start = new_start;
	return new_start;
}

#endif /* SLJIT_UTIL_SIMPLE_STACK_ALLOCATION */

#endif /* SLJIT_UTIL_STACK */
