[JSC] Enable Wasm SIMD on x64

https://bugs.webkit.org/show_bug.cgi?id=249850
rdar://103674073

Reviewed by Justin Michaud.

Enable Wasm SIMD by default for x64 if AVX is available.

* Source/JavaScriptCore/runtime/Options.cpp:
(JSC::Options::notifyOptionsChanged):
* Source/JavaScriptCore/runtime/OptionsList.h:

Canonical link: https://commits.webkit.org/258309@main

Source/JavaScriptCore/runtime/Options.cpp

@@ -30,6 +30,7 @@
 #include "CPU.h"
 #include "JITOperationValidation.h"
 #include "LLIntCommon.h"
+#include "MacroAssembler.h"
 #include "MinimumReservedZoneSize.h"
 #include <algorithm>
 #include <limits>
@@ -577,6 +578,7 @@ void Options::notifyOptionsChanged()
 #if !CPU(X86_64) && !CPU(ARM64)
     Options::useConcurrentGC() = false;
     Options::forceUnlinkedDFG() = false;
+    Options::useWebAssemblySIMD() = false;
 #endif
 
     if (!Options::allowDoubleShape())
@@ -662,6 +664,11 @@ void Options::notifyOptionsChanged()
         if (!Options::useBBQJIT() && Options::useOMGJIT())
             Options::wasmLLIntTiersUpToBBQ() = false;
 
+#if CPU(X86_64)
+        if (!MacroAssembler::supportsAVX())
+            Options::useWebAssemblySIMD() = false;
+#endif
+
         if (Options::forceAllFunctionsToUseSIMD() && !Options::useWebAssemblySIMD())
             Options::forceAllFunctionsToUseSIMD() = false;
 

Source/JavaScriptCore/runtime/OptionsList.h

@@ -559,7 +559,7 @@ bool canUseWebAssemblyFastMemory();
     v(Bool, useWebAssemblyTypedFunctionReferences, false, Normal, "Allow function types from the wasm typed function references spec.") \
     v(Bool, useWebAssemblyGC, false, Normal, "Allow gc types from the wasm gc proposal.") \
     v(Bool, forceAllFunctionsToUseSIMD, false, Normal, "Force all functions to act conservatively w.r.t fp/vector registers for testing.") \
-    v(Bool, useWebAssemblySIMD, isARM64(), Normal, "Allow the new simd instructions and types from the wasm simd spec.") \
+    v(Bool, useWebAssemblySIMD, true, Normal, "Allow the new simd instructions and types from the wasm simd spec.") \
     v(Bool, useWebAssemblyTailCalls, true, Normal, "Allow the new instructions from the wasm tail calls spec.") \