Remove dep between __cxa_rethrow_primary_exception and __cxa_rethrow (NFC) (#26518)

Currently `__cxa_rethrow_primary_exception` calls `__cxa_rethrow`, and
`__cxa_rethrow` is unnecessarily complicated to split logic when it is
called from `__cxa_rethrow_primary_exception` and when it is not.

This just decouples the two and duplicates the necessary logic in
`__cxa_rethrow_primary_exception`. This makes `__cxa_rethrow` simple and
easy to follow.

Author: aheejin

src/lib/libexceptions.js

@@ -125,22 +125,18 @@ var LibraryExceptions = {
 #endif
   ],
   __cxa_rethrow: () => {
-    var info = exceptionCaught.pop();
-    if (!info) {
+    if (!exceptionCaught.length) {
       abort('no exception to throw');
     }
+    var info = exceptionCaught.at(-1);
     var ptr = info.excPtr;
-    if (!info.get_rethrown()) {
-      // Only pop if the corresponding push was through rethrow_primary_exception
-      exceptionCaught.push(info);
-      info.set_rethrown(true);
-      info.set_caught(false);
-      uncaughtExceptionCount++;
-    }
+    info.set_rethrown(true);
+    info.set_caught(false);
+    uncaughtExceptionCount++;
 #if !DISABLE_EXCEPTION_CATCHING
     ___cxa_increment_exception_refcount(ptr);
 #if EXCEPTION_DEBUG
-    dbg('__cxa_rethrow, popped ' +
+    dbg('__cxa_rethrow: ' +
       [ptrToString(ptr), exceptionLast, 'stack', exceptionCaught]);
 #endif
     exceptionLast = new CppException(ptr);
@@ -216,13 +212,25 @@ var LibraryExceptions = {
     return info.get_type();
   },
 
-  __cxa_rethrow_primary_exception__deps: ['$ExceptionInfo', '$exceptionCaught', '__cxa_rethrow'],
+  __cxa_rethrow_primary_exception__deps: ['$ExceptionInfo', '$uncaughtExceptionCount',
+#if !DISABLE_EXCEPTION_CATCHING
+    '$exceptionLast',
+    '__cxa_increment_exception_refcount',
+#endif
+  ],
   __cxa_rethrow_primary_exception: (ptr) => {
     if (!ptr) return;
+#if EXCEPTION_DEBUG
+    dbg('__cxa_rethrow_primary_exception: ' + ptrToString(ptr));
+#endif
     var info = new ExceptionInfo(ptr);
-    exceptionCaught.push(info);
     info.set_rethrown(true);
-    ___cxa_rethrow();
+    info.set_caught(false);
+#if !DISABLE_EXCEPTION_CATCHING
+    ___cxa_increment_exception_refcount(ptr);
+    exceptionLast = new CppException(ptr);
+#endif
+    {{{ makeThrow('exceptionLast') }}}
   },
 
   // Finds a suitable catch clause for when an exception is thrown.

test/codesize/test_codesize_cxx_except.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 23195,
-  "a.out.js.gz": 8968,
+  "a.out.js": 23173,
+  "a.out.js.gz": 8962,
   "a.out.nodebug.wasm": 172516,
   "a.out.nodebug.wasm.gz": 57438,
-  "total": 195711,
-  "total_gz": 66406,
+  "total": 195689,
+  "total_gz": 66400,
   "sent": [
     "__cxa_begin_catch",
     "__cxa_end_catch",

test/codesize/test_codesize_cxx_mangle.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 23245,
-  "a.out.js.gz": 8990,
+  "a.out.js": 23223,
+  "a.out.js.gz": 8984,
   "a.out.nodebug.wasm": 238957,
   "a.out.nodebug.wasm.gz": 79847,
-  "total": 262202,
-  "total_gz": 88837,
+  "total": 262180,
+  "total_gz": 88831,
   "sent": [
     "__cxa_begin_catch",
     "__cxa_end_catch",