Don't run binaryen postprocessing for Emscripten EH/SjLj (#12399)

Now that we are renaming invoke wrappers and `emscripten_longjmp_jmpbuf`
in the wasm backend, using Emscripten EH or SjLj does not need
Binaryen's postprocessing. This makes Emscripten not enable Binaryen
postprocessing using wasm-emscripten-finalize when we are using them,
and deletes all special handling for `emscripten_longjmp_jmpbuf`, given
that Emscripten will not see it.

Addresses:
WebAssembly/binaryen#3043
WebAssembly/binaryen#3081

Companions:
https://reviews.llvm.org/D88697
WebAssembly/binaryen#3191

Author: aheejin

emscripten.py

@@ -484,10 +484,6 @@ def finalize_wasm(infile, memfile, DEBUG):
   # if we don't need to modify the wasm, don't tell finalize to emit a wasm file
   modify_wasm = False
 
-  # C++ exceptions and longjmp require invoke processing,
-  # https://github.com/WebAssembly/binaryen/issues/3081
-  if shared.Settings.SUPPORT_LONGJMP or shared.Settings.DISABLE_EXCEPTION_CATCHING != 1:
-    modify_wasm = True
   if shared.Settings.WASM2JS:
     # wasm2js requires full legalization (and will do extra wasm binary
     # later processing later anyhow)

src/deps_info.json

@@ -124,7 +124,6 @@
   "longjmp": ["setThrew", "realloc", "testSetjmp", "saveSetjmp"],
   "siglongjmp": ["setThrew", "realloc", "testSetjmp", "saveSetjmp"],
   "emscripten_longjmp": ["setThrew", "realloc", "testSetjmp", "saveSetjmp"],
-  "emscripten_longjmp_jmpbuf": ["setThrew", "realloc", "testSetjmp", "saveSetjmp"],
   "emscripten_websocket_new": ["malloc", "free"],
   "emscripten_websocket_set_onmessage_callback_on_thread": ["malloc", "free"],
   "emscripten_websocket_set_onclose_callback_on_thread": ["malloc", "free"],

src/library.js

@@ -1794,7 +1794,6 @@ LibraryManager.library = {
   // they each have a different signature - it is only at the wasm level that
   // they become identical).
   emscripten_longjmp: 'longjmp',
-  emscripten_longjmp_jmpbuf: 'longjmp',
 
   // ==========================================================================
   // sys/wait.h

tests/test_other.py

@@ -9000,9 +9000,8 @@ def ok(args, filename='hello_world.cpp', expected='hello, world!'):
       self.run_process([EMCC, path_from_root('tests', filename)] + args)
       self.assertContained(expected, self.run_js('a.out.js'))
 
-    # -O0 with BigInt support (to avoid the need for legalization) and without
-    # longjmp
-    required_flags = ['-sWASM_BIGINT', '-sSUPPORT_LONGJMP=0']
+    # -O0 with BigInt support (to avoid the need for legalization)
+    required_flags = ['-sWASM_BIGINT']
     ok(required_flags)
     # Same with DWARF
     ok(required_flags + ['-g'])
@@ -9021,16 +9020,11 @@ def fail(args, details):
 
     # plain -O0
     legalization_message = 'to disable int64 legalization (which requires changes after link) use -s WASM_BIGINT'
-    longjmp_message = 'to disable longjmp support (which requires changes after link) use -s SUPPORT_LONGJMP=0'
     fail([], legalization_message)
-    fail(['-sWASM_BIGINT'], longjmp_message)
-    fail(['-sSUPPORT_LONGJMP=0'], legalization_message)
     # optimized builds even without legalization
     optimization_message = '-O2+ optimizations always require changes, build with -O0 or -O1 instead'
     fail(required_flags + ['-O2'], optimization_message)
     fail(required_flags + ['-O3'], optimization_message)
-    # exceptions fails until invokes are fixed
-    fail(required_flags + ['-fexceptions'], 'C++ exceptions always require changes')
 
   def test_output_to_nowhere(self):
     self.run_process([EMCC, path_from_root('tests', 'hello_world.cpp'), '-o', os.devnull, '-c'])

tools/building.py

@@ -1574,16 +1574,12 @@ def run_binaryen_command(tool, infile, outfile=None, args=[], debug=False, stdou
       # emit some extra helpful text for common issues
       extra = ''
       # a plain -O0 build *almost* doesn't need post-link changes, except for
-      # legalization and longjmp. show a clear error for those (as the flags
-      # the user passed in are not enough to see what went wrong)
+      # legalization. show a clear error for those (as the flags the user passed
+      # in are not enough to see what went wrong)
       if shared.Settings.LEGALIZE_JS_FFI:
         extra += '\nnote: to disable int64 legalization (which requires changes after link) use -s WASM_BIGINT'
-      if shared.Settings.SUPPORT_LONGJMP:
-        extra += '\nnote: to disable longjmp support (which requires changes after link) use -s SUPPORT_LONGJMP=0'
       if shared.Settings.OPT_LEVEL > 0:
         extra += '\nnote: -O2+ optimizations always require changes, build with -O0 or -O1 instead'
-      if shared.Settings.DISABLE_EXCEPTION_CATCHING != 1:
-        extra += '\nnote: C++ exceptions always require changes'
       exit_with_error('changes to the wasm are required after link, but disallowed by ERROR_ON_WASM_CHANGES_AFTER_LINK: ' + str(cmd) + extra)
   if debug:
     cmd += ['-g'] # preserve the debug info

tools/wasm2c/base.c

@@ -131,10 +131,6 @@ IMPORT_IMPL(void, Z_envZ_emscripten_longjmpZ_vii, (u32 buf, u32 value), {
   longjmp(setjmp_stack[next_setjmp - 1], 1);
 });
 
-IMPORT_IMPL(void, Z_envZ_emscripten_longjmp_jmpbufZ_vii, (u32 buf, u32 value), {
-  return Z_envZ_emscripten_longjmpZ_vii(buf, value);
-});
-
 IMPORT_IMPL(void, Z_envZ_emscripten_notify_memory_growthZ_vi, (u32 size), {});
 
 static u32 tempRet0 = 0;