Bug 1717914 - wasm: Add feature flags for Memory64. r=lth

Differential Revision: https://phabricator.services.mozilla.com/D118644

js/moz.configure

@@ -872,6 +872,24 @@ def wasm_relaxed_simd(value, wasm_simd):
 set_config("ENABLE_WASM_RELAXED_SIMD", wasm_relaxed_simd)
 set_define("ENABLE_WASM_RELAXED_SIMD", wasm_relaxed_simd)
 
+# Support for WebAssembly Memory64.
+# ===========================
+
+option(
+    "--enable-wasm-memory64",
+    default=False,
+    help="{Enable|Disable} WebAssembly Memory64",
+)
+
+
+@depends("--enable-wasm-memory64")
+def wasm_memory64(value):
+    if value:
+        return True
+
+
+set_config("ENABLE_WASM_MEMORY64", wasm_memory64)
+set_define("ENABLE_WASM_MEMORY64", wasm_memory64)
 
 # Options for generating the shell as a script
 # ============================================

js/public/WasmFeatures.h

@@ -77,6 +77,11 @@
 #else
 #  define WASM_GC_ENABLED 0
 #endif
+#ifdef ENABLE_WASM_MEMORY64
+#  define WASM_MEMORY64_ENABLED 1
+#else
+#  define WASM_MEMORY64_ENABLED 0
+#endif
 
 // clang-format off
 #define JS_FOR_WASM_FEATURES(DEFAULT, EXPERIMENTAL)                           \
@@ -125,7 +130,15 @@
                /* flag predicate     */ !IsFuzzingCranelift(cx) &&            \
                js::jit::JitSupportsWasmSimd(),                                \
                /* shell flag         */ "relaxed-simd",                       \
-               /* preference name    */ "relaxed_simd")
+               /* preference name    */ "relaxed_simd")                       \
+  EXPERIMENTAL(/* capitalized name   */ Memory64,                             \
+               /* lower case name    */ memory64,                             \
+               /* compile predicate  */ WASM_MEMORY64_ENABLED,                \
+               /* compiler predicate */ BaselineAvailable(cx),                \
+               /* flag predicate     */ !IsFuzzingIon(cx) &&                  \
+                   !IsFuzzingCranelift(cx),                                   \
+               /* shell flag         */ "memory64",                           \
+               /* preference name    */ "memory64")
 
 // clang-format on
 

modules/libpref/init/StaticPrefList.yaml

@@ -6016,6 +6016,13 @@
     mirror: always
 #endif
 
+#if defined(ENABLE_WASM_MEMORY64)
+-   name: javascript.options.wasm_memory64
+    type: bool
+    value: true
+    mirror: always
+#endif  // defined(ENABLE_WASM_MEMORY64)
+
 # Support for ArrayBuffers larger than 2 GB on 64-bit systems
 - name: javascript.options.large_arraybuffers
   type: bool