[Wasm64] Fix EM_ASM for addresses >4GB addresses

This change use makeGetValue helper macros to avoid direct heap access.

This does come with a 11 byte code size cost (I measured the size of the
JS code generated for core3.test_em_asm going from 15091 to 15102) but
I think its useful enough to pay that price.

.circleci/config.yml

@@ -607,6 +607,7 @@ jobs:
           test_targets: "
             wasm64
             wasm64_4gb.test_hello_world
+            wasm64_4gb.test_em_asm
             wasm64l.test_bigswitch
             other.test_memory64_proxies
             other.test_failing_growth_wasm64"

src/library.js

@@ -2869,7 +2869,6 @@ mergeInto(LibraryManager.library, {
     var ch;
     // Most arguments are i32s, so shift the buffer pointer so it is a plain
     // index into HEAP32.
-    buf >>= 2;
     while (ch = HEAPU8[sigPtr++]) {
 #if ASSERTIONS
       var chr = String.fromCharCode(ch);
@@ -2885,24 +2884,24 @@ mergeInto(LibraryManager.library, {
 #endif
       assert(validChars.includes(chr), `Invalid character ${ch}("${chr}") in readEmAsmArgs! Use only [${validChars}], and do not specify "v" for void return argument.`);
 #endif
-      // Floats are always passed as doubles, and doubles and int64s take up 8
-      // bytes (two 32-bit slots) in memory, align reads to these:
-      buf += (ch != 105/*i*/) & buf;
+      // Floats are always passed as doubles, so all types except for 'i'
+      // are 8 bytes and require alignment.
+      buf += (ch != {{{ charCode('i') }}}) && buf % 8 ? 4 : 0;
+      readEmAsmArgsArray.push(
 #if MEMORY64
       // Special case for pointers under wasm64 which we read as int53 Numbers.
-      if (ch == 112/*p*/) {
-        readEmAsmArgsArray.push(readI53FromI64(buf++ << 2));
-      } else
+      (ch == {{{ charCode('p') }}}) ?
+        {{{ makeGetValue('buf', 0, '*') }}} :
 #endif
-      readEmAsmArgsArray.push(
-        ch == 105/*i*/ ? HEAP32[buf] :
 #if WASM_BIGINT
-       (ch == 106/*j*/ ? HEAP64 : HEAPF64)[buf++ >> 1]
-#else
-       HEAPF64[buf++ >> 1]
+      (ch == {{{ charCode('j') }}}) ?
+        {{{ makeGetValue('buf', 0, 'i64') }}} :
 #endif
+      (ch == {{{ charCode('i') }}}) ?
+        {{{ makeGetValue('buf', 0, 'i32') }}} :
+        {{{ makeGetValue('buf', 0, 'double') }}}
       );
-      ++buf;
+      buf += ch == {{{ charCode('i') }}} ? 4 : 8;
     }
     return readEmAsmArgsArray;
   },

test/runner.py

@@ -284,7 +284,7 @@ def load_test_suites(args, modules):
       for test in tests:
         suite.addTest(test)
       suites.append((m.__name__, suite))
-  if total_tests == 1:
+  if total_tests == 1 or parallel_testsuite.num_cores() == 1:
     common.EMTEST_SAVE_DIR = True
   return suites, unmatched_test_names
 

test/test_core.py

@@ -2144,6 +2144,7 @@ def test_inlinejs4(self):
 ''', 'false', assert_returncode=NON_ZERO)
 
   def test_em_asm(self):
+    self.maybe_closure()
     self.do_core_test('test_em_asm.cpp')
 
   def test_em_asm_c(self):