Commit 5e3b0f52 authored by Eli Zaretskii's avatar Eli Zaretskii

Clean up memory allocation and unexec support on MS-Windows

* src/w32heap.c (report_temacs_memory_usage): Condition on
(init_heap): Accept an argument, which tells us what heap
allocation method to use.
(DUMPED_HEAP_SIZE) [CANNOT_DUMP]: Define to a small value, as
we don't use dumped_data[] in this case.
* src/w32heap.h (init_heap): Adjust prototype.
<using_dynamic_heap>: Remove declaration.
* src/emacs.c (main) [WINDOWSNT]: Determine heap allocation
method based on whether we are in temacs and whether unexec
will be used to dump Emacs.  Pass the heap allocation method
to init_heap, which is now called after parsing the
--temacs=METHOD option.
* src/unexw32.c (unexec): Don't fiddle with using_dynamic_heap.
<using_dynamic_heap>: Remove definition.
* src/w32proc.c (malloc_before_init, realloc_before_init)
(free_before_init): New functions, to catch memory allocation
before heap allocation method is set up.
parent f9434091
Pipeline #561 passed with stage
in 48 minutes and 23 seconds
......@@ -871,8 +871,25 @@ main (int argc, char **argv)
#if defined WINDOWSNT || defined HAVE_NTGUI
/* Grab our malloc arena space now, before anything important
happens. This relies on the static heap being needed only in
temacs and only if we are going to dump with unexec. */
bool use_dynamic_heap = false;
if (strstr (argv[0], "temacs") != NULL)
eassert (temacs);
/* Note that gflags are set at this point only if we have been
called with the --temacs=METHOD option. We assume here that
temacs is always called that way, otherwise the functions
that rely on gflags, like will_dump_with_pdumper_p below,
will not do their job. */
use_dynamic_heap = will_dump_with_pdumper_p ();
use_dynamic_heap = true;
init_heap (use_dynamic_heap);
/* Set global variables used to detect Windows version. Do this as
early as possible. (unexw32.c calls this function as well, but
early as possible. (w32proc.c calls this function as well, but
the additional call here is harmless.) */
cache_system_info ();
......@@ -45,9 +45,6 @@ extern char *my_begbss_static;
#include "w32heap.h"
/* Basically, our "initialized" flag. */
BOOL using_dynamic_heap = FALSE;
void get_section_info (file_data *p_file);
void copy_executable_and_dump_data (file_data *, file_data *);
void dump_bss_and_heap (file_data *p_infile, file_data *p_outfile);
......@@ -649,15 +646,8 @@ unexec (const char *new_name, const char *old_name)
exit (1);
/* Set the flag (before dumping). */
using_dynamic_heap = TRUE;
copy_executable_and_dump_data (&in_file, &out_file);
/* Unset it because it is plain wrong to keep it after dumping.
Malloc can still occur! */
using_dynamic_heap = FALSE;
/* Patch up header fields; profiler is picky about this. */
......@@ -28,7 +28,7 @@
Memory allocation scheme for w32/w64:
- Buffers are mmap'ed using a very simple emulation of mmap/munmap
- During the temacs phase:
- During the temacs phase, if unexec is to be used:
* we use a private heap declared to be stored into the `dumped_data'
* unfortunately, this heap cannot be made growable, so the size of
blocks it can allocate is limited to (0x80000 - pagesize)
......@@ -37,7 +37,7 @@
We use a very simple first-fit scheme to reuse those blocks.
* we check that the private heap does not cross the area used
by the bigger chunks.
- During the emacs phase:
- During the emacs phase, or always if pdumper is used:
* we create a private heap for new memory blocks
* we make sure that we never free a block that has been dumped.
Freeing a dumped block could work in principle, but may prove
......@@ -115,10 +115,16 @@ typedef struct _RTL_HEAP_PARAMETERS {
than half of the size stated below. It would be nice to find a way
to build only the first bootstrap-emacs.exe with the large size,
and reset that to a lower value afterwards. */
#if defined _WIN64 || defined WIDE_EMACS_INT
# define DUMPED_HEAP_SIZE (23*1024*1024)
/* We don't use dumped_data[] when CANNOT_DUMP, so define to a small
size that won't matter. */
# define DUMPED_HEAP_SIZE 10
# define DUMPED_HEAP_SIZE (13*1024*1024)
# if defined _WIN64 || defined WIDE_EMACS_INT
# define DUMPED_HEAP_SIZE (23*1024*1024)
# else
# define DUMPED_HEAP_SIZE (13*1024*1024)
# endif
static unsigned char dumped_data[DUMPED_HEAP_SIZE];
......@@ -173,8 +179,8 @@ static DWORD blocks_number = 0;
static unsigned char *bc_limit;
/* Handle for the private heap:
- inside the dumped_data[] array before dump,
- outside of it after dump.
- inside the dumped_data[] array before dump with unexec,
- outside of it after dump, or always if pdumper is used.
......@@ -188,8 +194,8 @@ free_fn the_free_fn; */
/* This is the function to commit memory when the heap allocator
claims for new memory. Before dumping, we allocate space
from the fixed size dumped_data[] array.
claims for new memory. Before dumping with unexec, we allocate
space from the fixed size dumped_data[] array.
dumped_data_commit (PVOID Base, PVOID *CommitAddress, PSIZE_T CommitSize)
......@@ -223,22 +229,14 @@ typedef enum _HEAP_INFORMATION_CLASS {
BOOL using_dynamic_heap = FALSE;
init_heap (void)
init_heap (bool use_dynamic_heap)
using_dynamic_heap = TRUE;
if (using_dynamic_heap)
/* FIXME: Remove the condition, the 'else' branch below, and all the
related definitions and code, including dumped_data[], when unexec
support is removed from Emacs. */
if (use_dynamic_heap)
#ifndef MINGW_W64
unsigned long enable_lfh = 2;
/* After dumping, use a new private heap. We explicitly enable
the low fragmentation heap (LFH) here, for the sake of pre
Vista versions. Note: this will harmlessly fail on Vista and
......@@ -255,6 +253,7 @@ init_heap (void)
heap = HeapCreate (0, 0, 0);
#ifndef MINGW_W64
unsigned long enable_lfh = 2;
/* Set the low-fragmentation heap for OS before Vista. */
HMODULE hm_kernel32dll = LoadLibrary ("kernel32.dll");
HeapSetInformation_Proc s_pfn_Heap_Set_Information =
......@@ -283,7 +282,7 @@ init_heap (void)
the_free_fn = free_after_dump;
else /* Before dumping with unexec: use static heap. */
/* Find the RtlCreateHeap function. Headers for this function
are provided with the w32 DDK, but the function is available
......@@ -362,6 +361,8 @@ malloc_after_dump (size_t size)
return p;
/* FIXME: The *_before_dump functions should be removed when pdumper
becomes the only dumping method. */
void *
malloc_before_dump (size_t size)
......@@ -596,7 +597,7 @@ free_after_dump_9x (void *ptr)
#if !defined (CANNOT_DUMP) && defined (ENABLE_CHECKING)
report_temacs_memory_usage (void)
......@@ -31,7 +31,6 @@ along with GNU Emacs. If not, see <>.
extern unsigned char *get_data_start (void);
extern unsigned char *get_data_end (void);
extern size_t reserved_heap_size;
extern BOOL using_dynamic_heap;
extern void *mmap_realloc (void **, size_t);
extern void mmap_free (void **);
......@@ -43,7 +42,7 @@ extern void report_temacs_memory_usage (void);
extern void *sbrk (ptrdiff_t size);
/* Initialize heap structures for sbrk on startup. */
extern void init_heap (void);
extern void init_heap (bool);
/* ----------------------------------------------------------------- */
/* Useful routines for manipulating memory-mapped files. */
......@@ -81,6 +81,36 @@ static sigset_t sig_mask;
static CRITICAL_SECTION crit_sig;
/* Catch memory allocation before the heap allocation scheme is set
up. These functions should never be called, unless code is added
early on in 'main' that runs before init_heap is called. */
_Noreturn void * malloc_before_init (size_t);
_Noreturn void * realloc_before_init (void *, size_t);
_Noreturn void free_before_init (void *);
_Noreturn void *
malloc_before_init (size_t size)
fprintf (stderr,
"error: 'malloc' called before setting up heap allocation; exiting.\n");
exit (-1);
_Noreturn void *
realloc_before_init (void *ptr, size_t size)
fprintf (stderr,
"error: 'realloc' called before setting up heap allocation; exiting.\n");
exit (-1);
_Noreturn void
free_before_init (void *ptr)
fprintf (stderr,
"error: 'free' called before setting up heap allocation; exiting.\n");
exit (-1);
extern BOOL ctrl_c_handler (unsigned long type);
......@@ -110,12 +140,13 @@ _start (void)
DebugBreak ();
the_malloc_fn = malloc_before_init;
the_realloc_fn = realloc_before_init;
the_free_fn = free_before_init;
/* Cache system info, e.g., the NT page size. */
cache_system_info ();
/* Grab our malloc arena space now, before CRT starts up. */
init_heap ();
/* This prevents ctrl-c's in shells running while we're suspended from
having us exit. */
SetConsoleCtrlHandler ((PHANDLER_ROUTINE) ctrl_c_handler, TRUE);
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