Use passive segments instead of mem files

.circleci/config.yml

@@ -478,4 +478,3 @@ workflows:
       - test-upstream-browser-firefox:
           requires:
             - build-upstream
-

ChangeLog.md

@@ -19,6 +19,9 @@ See docs/process.md for how version tagging works.
 Current Trunk
 -------------
 
+ - LLVM backend pthread builds no longer use external memory initialization
+   files, replacing them with passive data segments.
+
 v1.38.39: 07/16/2019
 --------------------
  - Add support for [address sanitizer](https://clang.llvm.org/docs/AddressSanitizer.html). (#8884)

emcc.py

@@ -1438,16 +1438,17 @@ def check(input_file):
       if any(s.startswith('MEM_INIT_METHOD=') for s in settings_changes):
         exit_with_error('MEM_INIT_METHOD is not supported in wasm. Memory will be embedded in the wasm binary if threads are not used, and included in a separate file if threads are used.')
       if shared.Settings.WASM2JS:
-        # in wasm2js, keep the mem init in the wasm itself if we can (no pthreads), and if the options
-        # wouldn't tell a js build to use a separate mem init file
-        shared.Settings.MEM_INIT_IN_WASM = not shared.Settings.USE_PTHREADS and not options.memory_init_file
+        # wasm2js does not support passive segments or atomics
+        if shared.Settings.USE_PTHREADS:
+          exit_with_error('WASM2JS does not yet support pthreads')
+        # in wasm2js, keep the mem init in the wasm itself if we can and if the
+        # options wouldn't tell a js build to use a separate mem init file
+        shared.Settings.MEM_INIT_IN_WASM = not options.memory_init_file
       else:
-        # wasm normally includes the mem init in the wasm binary. exceptions are pthreads, where we need
-        # to split it out until we have full bulk memory support, and wasm2js, which behaves more like js.
+        # wasm includes the mem init in the wasm binary. The exception is
+        # wasm2js, which behaves more like js.
         options.memory_init_file = True
-        # we will include the mem init data in the wasm, when we don't need the
-        # mem init file to be loadable by itself
-        shared.Settings.MEM_INIT_IN_WASM = not shared.Settings.USE_PTHREADS
+        shared.Settings.MEM_INIT_IN_WASM = True if shared.Settings.WASM_BACKEND else not shared.Settings.USE_PTHREADS
 
       # WASM_ASYNC_COMPILATION and SWAPPABLE_ASM_MODULE do not have a meaning in MINIMAL_RUNTIME (always async)
       if not shared.Settings.MINIMAL_RUNTIME:

tools/shared.py

@@ -1848,6 +1848,7 @@ def link_lld(args, target, opts=[], lto_level=0):
 
     if Settings.USE_PTHREADS:
       cmd.append('--shared-memory')
+      cmd.append('--passive-segments')
 
     for a in Building.llvm_backend_args():
       cmd += ['-mllvm', a]