[EH/SjLj] Support Wasm EH + Wasm SjLj (#16072)

Now that
llvm/llvm-project@eb675e9
has landed, we can use Wasm EH and Wasm SjLj together.

This PR
- enables Wasm EH + Wasm SjLj combination which was previously banned
- unifies `@with_both_exception_handling` and `@with_both_sjlj_handling`
  into `@with_both_eh_sjlj`. Given that we don't really have a
  plan to test Wasm EH + Emscripten SjLj combination going forward,
  which was meant to be only a temporary measure during the period we
  have only Wasm EH but not Wasm SjLj, I don't think it's worth the
  hassle of keeping three different decorators like
  `@with_both_exception_handling`, `@with_both_sjlj_handling`,
  `@with_both_eh_sjlj`.
- adds `@with_both_eh_sjlj` to several more tests that mix EH + SjLj
- adds one more test that mixes EH + SjLj
- duplicates `test_longjmp` into `test_longjmp_stadnalone`. I couldn't
  find a way to attach two decorators (`@with_both_eh_sjlj and
  `@also_with_standalone_wasm`) to a single test.
- adds `test_longjmp_with_and_without_exceptions` and
`test_exceptions_with_and_without_longjmp`.

Fixes #15404.

Author: aheejin

emcc.py

@@ -1413,8 +1413,6 @@ def default_setting(name, new_default):
       exit_with_error('SUPPORT_LONGJMP=wasm cannot be used with DISABLE_EXCEPTION_CATCHING=0')
     if not settings.DISABLE_EXCEPTION_THROWING:
       exit_with_error('SUPPORT_LONGJMP=wasm cannot be used with DISABLE_EXCEPTION_THROWING=0')
-    if settings.EXCEPTION_HANDLING:
-      exit_with_error('Wasm SjLj is not supported with Wasm exceptions yet')
 
   return (newargs, input_files)
 

tests/core/test_exceptions_longjmp4.cpp

@@ -0,0 +1,29 @@
+#include <stdio.h>
+#include <setjmp.h>
+
+static jmp_buf buf;
+
+void foo() {
+  throw 3;
+}
+
+int main() {
+  int jmpval = setjmp(buf);
+  if (jmpval != 0) {
+    // This is not reached, because foo() doesn't longjmp. This test checks
+    // compilation of a setjmp call with a nested try.
+    printf("setjmp returned for the second time\n");
+    return 0;
+  }
+  try {
+    foo();
+    try {
+      foo();
+    } catch (int n) {
+      printf("inner catch: caught %d\n", n);
+    }
+  } catch (int n) {
+    printf("outer catch: caught %d\n", n);
+  }
+  return 0;
+}

tests/core/test_exceptions_longjmp4.out

@@ -0,0 +1 @@
+outer catch: caught 3