Prefer calloc over of malloc+zeroMemory. NFC

IIUC, there are cases where the allocator can take advantage of the fact
that it knows the memory is fresh and avoid the memset completely.

Author: sbc100

src/library_dylink.js

@@ -363,7 +363,7 @@ var LibraryDylink = {
   // Allocate memory even if malloc isn't ready yet.  The allocated memory here
   // must be zero initialized since its used for all static data, including bss.
   $getMemory__noleakcheck: true,
-  $getMemory__deps: ['$GOT', '__heap_base', '$zeroMemory', '$alignMemory', 'malloc'],
+  $getMemory__deps: ['$GOT', '__heap_base', '$alignMemory', 'calloc'],
   $getMemory: (size) => {
     // After the runtime is initialized, we must only use sbrk() normally.
 #if DYLINK_DEBUG
@@ -373,7 +373,7 @@ var LibraryDylink = {
       // Currently we don't support freeing of static data when modules are
       // unloaded via dlclose.  This function is tagged as `noleakcheck` to
       // avoid having this reported as leak.
-      return zeroMemory(_malloc(size), size);
+      return _calloc(size, 1);
     }
     var ret = ___heap_base;
     // Keep __heap_base stack aligned.
@@ -597,7 +597,7 @@ var LibraryDylink = {
   $loadWebAssemblyModule__deps: [
     '$loadDynamicLibrary', '$getMemory',
     '$relocateExports', '$resolveGlobalSymbol', '$GOTHandler',
-    '$getDylinkMetadata', '$alignMemory', '$zeroMemory',
+    '$getDylinkMetadata', '$alignMemory',
     '$currentModuleWeakSymbols',
     '$updateTableMap',
     '$wasmTable',

src/library_pthread.js

@@ -36,7 +36,7 @@ var LibraryPThread = {
   $PThread__deps: ['_emscripten_thread_init',
                    '$killThread',
                    '$terminateWorker',
-                   '$cancelThread', '$cleanupThread', '$zeroMemory',
+                   '$cancelThread', '$cleanupThread',
 #if MAIN_MODULE
                    '$markAsFinished',
 #endif

src/library_sdl.js

@@ -1357,7 +1357,7 @@ var LibrarySDL = {
     return SDL.version;
   },
 
-  SDL_Init__deps: ['$zeroMemory', 'memcpy'],
+  SDL_Init__deps: ['calloc', 'memcpy'],
   SDL_Init__proxy: 'sync',
   SDL_Init__docs: '/** @param{number} initFlags */',
   SDL_Init: (initFlags) => {
@@ -1376,8 +1376,7 @@ var LibrarySDL = {
     }
 
     window.addEventListener("unload", SDL.receiveEvent);
-    SDL.keyboardState = _malloc(0x10000); // Our SDL needs 512, but 64K is safe for older SDLs
-    zeroMemory(SDL.keyboardState, 0x10000);
+    SDL.keyboardState = _calloc(0x10000, 1); // Our SDL needs 512, but 64K is safe for older SDLs
     // Initialize this structure carefully for closure
     SDL.DOMEventToSDLEvent['keydown']    = 0x300  /* SDL_KEYDOWN */;
     SDL.DOMEventToSDLEvent['keyup']      = 0x301  /* SDL_KEYUP */;
@@ -1413,11 +1412,10 @@ var LibrarySDL = {
     return 1;
   },
 
-  SDL_GetVideoInfo__deps: ['$zeroMemory'],
+  SDL_GetVideoInfo__deps: ['calloc'],
   SDL_GetVideoInfo__proxy: 'sync',
   SDL_GetVideoInfo: () => {
-    var ret = _malloc({{{ C_STRUCTS.SDL_VideoInfo.__size__ }}});
-    zeroMemory(ret, {{{ C_STRUCTS.SDL_version.__size__ }}});
+    var ret = _calloc({{{ C_STRUCTS.SDL_VideoInfo.__size__ }}}, 1);
     {{{ makeSetValue('ret', C_STRUCTS.SDL_VideoInfo.current_w, 'Module["canvas"].width', 'i32') }}};
     {{{ makeSetValue('ret', C_STRUCTS.SDL_VideoInfo.current_h, 'Module["canvas"].height', 'i32') }}};
     return ret;

test/other/codesize/test_codesize_hello_dylink.exports

@@ -2,8 +2,8 @@ __wasm_apply_data_relocs
 __wasm_call_ctors
 _emscripten_stack_alloc
 _emscripten_stack_restore
+calloc
 dynCall_jiji
 emscripten_stack_get_current
 main
-malloc
 setThrew

test/other/codesize/test_codesize_hello_dylink.funcs

@@ -8,7 +8,7 @@ $__wasm_apply_global_relocs
 $__wasm_call_ctors
 $_emscripten_stack_alloc
 $_emscripten_stack_restore
-$dlmalloc
+$dlcalloc
 $emscripten_stack_get_current
 $legalstub$dynCall_jiji
 $main

test/other/codesize/test_codesize_hello_dylink.gzsize

@@ -1 +1 @@
-6293
+6284

test/other/codesize/test_codesize_hello_dylink.jssize

@@ -1 +1 @@
-13851
+13838

test/other/codesize/test_codesize_hello_dylink.size

@@ -1 +1 @@
-9347
+9760

test/test_core.py

@@ -1943,9 +1943,7 @@ def test_em_asm_side_module(self):
   def test_em_js(self, args, force_c):
     if '-sMAIN_MODULE=2' in args:
       self.check_dylink()
-    else:
-      self.emcc_args += ['-sEXPORTED_FUNCTIONS=_main,_malloc']
-    self.emcc_args += args
+    self.emcc_args += ['-sEXPORTED_FUNCTIONS=_main,_malloc'] + args
     if '-pthread' in args:
       self.setup_node_pthreads()
 

test/test_other.py

@@ -2198,6 +2198,7 @@ def test_dylink_pthread_bigint_em_asm(self):
   def test_dylink_pthread_bigint_em_js(self):
     self.set_setting('MAIN_MODULE', 2)
     self.set_setting('WASM_BIGINT')
+    self.set_setting('EXPORTED_FUNCTIONS', '_malloc,_main')
     self.emcc_args += ['-Wno-experimental', '-pthread']
     self.do_runf('core/test_em_js.cpp')