Reduce default stack size from 5Mb to 1Mb

See ChangeLog.md for rationale.

Author: sbc100

ChangeLog.md

@@ -20,6 +20,13 @@ See docs/process.md for more on how version tagging works.
 
 2.0.21
 ------
+- 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 reduces from 2Mb to 1Mb to match primary stack.
 - The WebAssembly linker (`wasm-ld`) now performes string tail merging on any
   static string data in your program.   This has long been part of the native
   ELF linker and should not be observable in well-behaved programs.  This

src/settings.js

@@ -113,7 +113,7 @@ var MEM_INIT_METHOD = 0;
 // 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
@@ -1508,7 +1508,7 @@ var PTHREAD_POOL_DELAY_LOAD = 0;
 // 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]