[wasm backend] Add compiler-rt libs just like any others (#6880)

I'm not sure where these were being special cases really.
Previously there were being added by calculate() and then
assumed to exist.  But calculate() isn't called in all cases,
and in those cases these cache accesses would fail.

Author: sbc100

tools/shared.py

@@ -1916,13 +1916,6 @@ def llvm_backend_args():
 
   @staticmethod
   def link_lld(files, target, opts=[], lto_level=0):
-    def wasm_rt_fail(archive_file):
-      def wrapped():
-        raise FatalError('Expected {} to already be built'.format(archive_file))
-      return wrapped
-
-    libc_rt_lib = Cache.get('wasm_libc_rt.a', wasm_rt_fail('wasm_libc_rt.a'), 'a')
-    compiler_rt_lib = Cache.get('wasm_compiler_rt.a', wasm_rt_fail('wasm_compiler_rt.a'), 'a')
     cmd = [
         WASM_LD,
         '-z',
@@ -1937,7 +1930,7 @@ def wrapped():
         '--export',
         '__wasm_call_ctors',
         '--lto-O%d' % lto_level,
-    ] + files + [libc_rt_lib, compiler_rt_lib]
+    ] + files
 
     if Settings.WASM_MEM_MAX != -1:
       cmd.append('--max-memory=%d' % Settings.WASM_MEM_MAX)

tools/system_libs.py

@@ -614,11 +614,9 @@ def do_create():
       force = force.union(deps)
   ret.sort(key=lambda x: x.endswith('.a')) # make sure to put .a files at the end.
 
-  # Handle backend compiler_rt separately because it is not a bitcode system lib like the others.
-  # Here, just ensure that it's in the cache.
-  if shared.Settings.WASM and shared.Settings.WASM_BACKEND:
-    shared.Cache.get('wasm_compiler_rt.a', lambda: create_wasm_compiler_rt('wasm_compiler_rt.a'), extension='a')
-    shared.Cache.get('wasm_libc_rt.a', lambda: create_wasm_libc_rt('wasm_libc_rt.a'), extension='a')
+  if shared.Settings.WASM_BACKEND:
+    ret.append(shared.Cache.get('wasm_compiler_rt.a', lambda: create_wasm_compiler_rt('wasm_compiler_rt.a'), extension='a'))
+    ret.append(shared.Cache.get('wasm_libc_rt.a', lambda: create_wasm_libc_rt('wasm_libc_rt.a'), extension='a'))
 
   for actual in ret:
     if os.path.basename(actual) == 'libcxxabi.bc':