Reduce default stack size from 5Mb to 1Mb

See ChangeLog.md for rationale.

Author: sbc100

ChangeLog.md

@@ -601,6 +601,14 @@ See docs/process.md for more on how version tagging works.
 
 2.0.21: 05/18/2021
 ------------------
+------
+- Default shadow stack size used by emscripten reduced from 5Mb to 1Mb.  Anyone
+  running into issues can restore the old size using `-sTOTAL_STACK=5Mb`.  Since
+  windows has max stack of 1Mb and since WebAssembly stack usage should be less
+  than on native platforms (since its only used for address taken values) it
+  seems like 1Mb might still be on the high side here.  For reference, llvm
+  (`wasm-ld`) use 64kb as the default stack size.  `DEFAULT_PTHREAD_STACK_SIZE`
+  was also reduced from 2Mb to 1Mb to match primary stack.
 - Options such as EXPORTED_FUNCTIONS that can take a response file containing
   list of symbols can now use a simple one-symbol-per-line format.  This new
   format is much simpler and doesn't require commas between symbols, opening

src/settings.js

@@ -110,7 +110,7 @@ var MEM_INIT_METHOD = false;
 // assertions are on, we will assert on not exceeding this, otherwise,
 // it will fail silently.
 // [link]
-var TOTAL_STACK = 5*1024*1024;
+var TOTAL_STACK = 1*1024*1024;
 
 // What malloc()/free() to use, out of
 //  * dlmalloc - a powerful general-purpose malloc
@@ -1582,7 +1582,7 @@ var PTHREAD_POOL_DELAY_LOAD = false;
 // those that have their addresses taken, or ones that are too large to fit as
 // local vars in wasm code.
 // [link]
-var DEFAULT_PTHREAD_STACK_SIZE = 2*1024*1024;
+var DEFAULT_PTHREAD_STACK_SIZE = 1*1024*1024;
 
 // True when building with --threadprofiler
 // [link]

test/core/test_emmalloc_memory_statistics.cpp

@@ -2,30 +2,29 @@
 #include <emscripten/emmalloc.h>
 
 template<typename T>
-T round_to_4k(T val) {
-  return (T)(((size_t)val + 4095) & ~4095);
+T round_to_4k(T val){
+	return (T)(((size_t)val + 4095) & ~4095);
 }
 
-int main() {
-  void *ptr = malloc(32*1024*1024);
-  void *ptr2 = malloc(4*1024*1024);
-  void *ptr3 = malloc(64*1024*1024);
-  void *ptr4 = malloc(16*1024);
-  void *ptr5 = malloc(2*1024*1024);
-  printf("%ld\n", (long)(ptr && ptr2 && ptr3 && ptr4 && ptr5));
-  free(ptr2);
-  free(ptr4);
-  printf("validate_memory_regions: %d\n", emmalloc_validate_memory_regions());
-  printf("dynamic_heap_size: %zu\n", emmalloc_dynamic_heap_size());
-  printf("free_dynamic_memory: %zu\n", emmalloc_free_dynamic_memory());
-  size_t numFreeMemoryRegions = 0;
-  size_t freeMemorySizeMap[32];
-  numFreeMemoryRegions = emmalloc_compute_free_dynamic_memory_fragmentation_map(freeMemorySizeMap);
-  printf("numFreeMemoryRegions: %zu\n", numFreeMemoryRegions);
-  for (int i = 0; i < 32; ++i) {
-    printf("%zu ", freeMemorySizeMap[i]);
-  }
-  printf("\n");
-  printf("unclaimed_heap_memory: %zu\n", round_to_4k(emmalloc_unclaimed_heap_memory()));
-  return 0;
+int main()
+{
+	void *ptr = malloc(32*1024*1024);
+	void *ptr2 = malloc(4*1024*1024);
+	void *ptr3 = malloc(64*1024*1024);
+	void *ptr4 = malloc(16*1024);
+	void *ptr5 = malloc(2*1024*1024);
+	printf("valid allocs: %d\n", (int)(ptr && ptr2 && ptr3 && ptr4 && ptr5));
+	free(ptr2);
+	free(ptr4);
+	printf("emmalloc_validate_memory_regions: %d\n", emmalloc_validate_memory_regions());
+	printf("emmalloc_dynamic_heap_size      : %zu\n", emmalloc_dynamic_heap_size());
+	printf("emmalloc_free_dynamic_memory    : %zu\n", emmalloc_free_dynamic_memory());
+	size_t numFreeMemoryRegions = 0;
+	size_t freeMemorySizeMap[32];
+	numFreeMemoryRegions = emmalloc_compute_free_dynamic_memory_fragmentation_map(freeMemorySizeMap);
+	printf("numFreeMemoryRegions: %zu\n", numFreeMemoryRegions);
+	for(int i = 0; i < 32; ++i)
+		printf("%zu ", freeMemorySizeMap[i]);
+	printf("\n");
+	printf("emmalloc_unclaimed_heap_memory  : %zu\n", round_to_4k(emmalloc_unclaimed_heap_memory()));
 }

test/core/test_emmalloc_memory_statistics.out

@@ -1,7 +1,7 @@
-1
-validate_memory_regions: 0
-dynamic_heap_size: 106971424
-free_dynamic_memory: 4210892
+valid allocs: 1
+emmalloc_validate_memory_regions: 0
+emmalloc_dynamic_heap_size      : 106971424
+emmalloc_free_dynamic_memory    : 4210892
 numFreeMemoryRegions: 3
 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 
-unclaimed_heap_memory: 21999616
+emmalloc_unclaimed_heap_memory  : 26193920

test/core/test_emmalloc_trim.out

@@ -1,35 +1,35 @@
 heap size: 134217728
 dynamic heap 0: 4096
 free dynamic memory 0: 4096
-unclaimed heap memory 0: 2142171136
-sbrk 0: 0x502000
+unclaimed heap memory 0: 2146365440
+sbrk 0: 0x102000
 1
 dynamic heap 1: 37752832
 free dynamic memory 1: 4096
-unclaimed heap memory 1: 2104422400
-sbrk 1: 0x2902000
+unclaimed heap memory 1: 2108616704
+sbrk 1: 0x2502000
 1st trim: 1
 dynamic heap 1: 37752832
 free dynamic memory 1: 0
-unclaimed heap memory 1: 2104422400
-sbrk 1: 0x2902000
+unclaimed heap memory 1: 2108616704
+sbrk 1: 0x2502000
 2nd trim: 0
 dynamic heap 2: 37752832
 free dynamic memory 2: 0
-unclaimed heap memory 2: 2104422400
-sbrk 2: 0x2902000
+unclaimed heap memory 2: 2108616704
+sbrk 2: 0x2502000
 3rd trim: 1
 dynamic heap 3: 33656832
 free dynamic memory 3: 102400
-unclaimed heap memory 3: 2104422400
-sbrk 3: 0x2902000
+unclaimed heap memory 3: 2108616704
+sbrk 3: 0x2502000
 4th trim: 0
 dynamic heap 4: 33656832
 free dynamic memory 4: 102400
-unclaimed heap memory 4: 2104422400
-sbrk 4: 0x2902000
+unclaimed heap memory 4: 2108616704
+sbrk 4: 0x2502000
 5th trim: 1
 dynamic heap 5: 33558528
 free dynamic memory 5: 0
-unclaimed heap memory 5: 2104422400
-sbrk 5: 0x2902000
+unclaimed heap memory 5: 2108616704
+sbrk 5: 0x2502000

test/core/test_memorygrowth_geometric_step.out

@@ -1,2 +1,2 @@
 Heap size before allocation: 16777216
-Ptr: 1, value: 16843009, Heap size now: 101777408 (increase: 85000192 bytes)
+Ptr: 1, value: 16843009, Heap size now: 97583104 (increase: 80805888 bytes)

test/test_other.py

@@ -2605,6 +2605,8 @@ def test_embind(self, extra_args):
          '--pre-js', test_file('embind/test.pre.js'),
          '--post-js', test_file('embind/test.post.js'),
          '-sWASM_ASYNC_COMPILATION=0',
+         # For some reason the default of 1Mb is not enough for these tests.
+         '-sTOTAL_STACK=2Mb',
          '-sIN_TEST_HARNESS'] + args)
 
       if '-sDYNAMIC_EXECUTION=0' in args:
@@ -5748,7 +5750,7 @@ def test_massive_alloc(self, wasm):
     # just care about message regarding allocating over 1GB of memory
     output = self.run_js('a.out.js')
     if not wasm:
-      self.assertContained('Warning: Enlarging memory arrays, this is not fast! 16777216,1473314816\n', output)
+      self.assertContained('Warning: Enlarging memory arrays, this is not fast! 16777216,1469120512\n', output)
 
   def test_failing_alloc(self):
     for pre_fail, post_fail, opts in [