Move get/setTemprRet0 from runtime to library JS code. NFC (#17554)

Most users won't see the benefits until we start setting
`LEGACY_RUNTIME` by default.

Author: sbc100

emcc.py

@@ -1903,8 +1903,8 @@ def phase_linker_setup(options, state, newargs, user_settings):
 
   if settings.MAIN_MODULE:
     settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += [
-        '$getDylinkMetadata',
-        '$mergeLibSymbols',
+      '$getDylinkMetadata',
+      '$mergeLibSymbols',
     ]
 
   if settings.USE_PTHREADS:
@@ -1914,11 +1914,11 @@ def phase_linker_setup(options, state, newargs, user_settings):
 
   if settings.RELOCATABLE:
     settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += [
-        '$reportUndefinedSymbols',
-        '$relocateExports',
-        '$GOTHandler',
-        '__heap_base',
-        '__stack_pointer',
+      '$reportUndefinedSymbols',
+      '$relocateExports',
+      '$GOTHandler',
+      '__heap_base',
+      '__stack_pointer',
     ]
 
     if settings.ASYNCIFY:
@@ -2373,6 +2373,12 @@ def check_memory_setting(setting):
     options.memory_init_file = True
     settings.MEM_INIT_IN_WASM = True
 
+  if settings.MAYBE_WASM2JS or settings.AUTODEBUG or settings.LINKABLE:
+    settings.DEFAULT_LIBRARY_FUNCS_TO_INCLUDE += [
+      '$getTempRet0',
+      '$setTempRet0',
+    ]
+
   # wasm side modules have suffix .wasm
   if settings.SIDE_MODULE and shared.suffix(target) == '.js':
     diagnostics.warning('emcc', 'output suffix .js requested, but wasm side modules are just wasm files; emitting only a .wasm, no .js')

src/library.js

@@ -28,16 +28,22 @@ mergeInto(LibraryManager.library, {
   // available to native code.
   // ==========================================================================
 
-  getTempRet0__sig: 'i',
-  getTempRet0: function() {
-    return getTempRet0();
+  $tempRet0: 0,
+  $getTempRet0__sig: 'i',
+  $getTempRet0__deps: ['$tempRet0'],
+  $getTempRet0: function() {
+    return tempRet0;
   },
 
-  setTempRet0__sig: 'vi',
-  setTempRet0: function(val) {
-    setTempRet0(val);
+  $setTempRet0__sig: 'vi',
+  $setTempRet0__deps: ['$tempRet0'],
+  $setTempRet0: function(val) {
+    tempRet0 = val;
   },
 
+  getTempRet0: '$getTempRet0',
+  setTempRet0: '$setTempRet0',
+
   $ptrToString: function(ptr) {
     return '0x' + ptr.toString(16).padStart(8, '0');
   },
@@ -3706,5 +3712,7 @@ DEFAULT_LIBRARY_FUNCS_TO_INCLUDE.push(
   '$ccall',
   '$cwrap',
   '$ExitStatus',
+  '$getTempRet0',
+  '$setTempRet0',
 );
 #endif

src/modules.js

@@ -358,8 +358,6 @@ function exportRuntime() {
     'getCompilerSetting',
     'print',
     'printErr',
-    'getTempRet0',
-    'setTempRet0',
     'callMain',
     'abort',
     'keepRuntimeAlive',

src/preamble_minimal.js

@@ -30,10 +30,6 @@ var tempDouble;
 var tempI64;
 #endif
 
-var tempRet0 = 0;
-var setTempRet0 = (value) => { tempRet0 = value };
-var getTempRet0 = () => tempRet0;
-
 #if WASM != 2 && MAYBE_WASM2JS
 #if !WASM2JS
 if (Module['doWasm2JS']) {

src/support.js

@@ -11,10 +11,6 @@ var POINTER_SIZE = {{{ MEMORY64 ? 8 : 4 }}};
 
 #include "runtime_debug.js"
 
-var tempRet0 = 0;
-var setTempRet0 = (value) => { tempRet0 = value; };
-var getTempRet0 = () => tempRet0;
-
 #if RETAIN_COMPILER_SETTINGS
 var compilerSettings = {{{ JSON.stringify(makeRetainedCompilerSettings()) }}} ;
 

test/other/metadce/test_metadce_cxx_except.jssize

@@ -1 +1 @@
-31504
+31508

test/other/metadce/test_metadce_cxx_mangle.jssize

@@ -1 +1 @@
-31604
+31608

test/other/metadce/test_metadce_hello_O0.jssize

@@ -1 +1 @@
-27514
+27523

test/other/metadce/test_metadce_minimal_O0.jssize

@@ -1 +1 @@
-22384
+22393

test/other/test_unoptimized_code_size.js.size

@@ -1 +1 @@
-84062
+84080