Bug 1673285 - Enable SIMD for Wasm sandboxed SoundTouch. r=glandium

This patch enables SIMD in Wasm sandboxed SoundTouch by using
simd-everywhere to map SSE intrinsics to WASMSIMD intrinsics and
compiling with -msimd128 flag.

Differential Revision: https://phabricator.services.mozilla.com/D183629

security/rlbox/moz.build

@@ -104,9 +104,18 @@ if CONFIG["MOZ_WASM_SANDBOXING_SOUNDTOUCH"]:
     include("/media/libsoundtouch/src/sources.mozbuild")
     WASM_SOURCES += ["/media/libsoundtouch/src/" + s for s in soundtouch_sources]
 
+    # Only enable SIMD if Float32 is supported
     if CONFIG["MOZ_SAMPLE_TYPE_FLOAT32"]:
         WASM_DEFINES["MOZ_SAMPLE_TYPE_FLOAT32"] = 1
 
+        # Enable SoundTouch SSE optimized intrinsics
+        WASM_SOURCES += ["/media/libsoundtouch/src/sse_optimized.cpp"]
+        WASM_DEFINES["SOUNDTOUCH_ALLOW_SSE"] = 1
+
+        # Enables SIMD-everywhere to map SSE intrinsics to WASMSIMD intrinsics
+        WASM_DEFINES["SOUNDTOUCH_WASM_SIMD"] = 1
+        WASM_DEFINES["SIMDE_ENABLE_NATIVE_ALIASES"] = 1
+
     for k, v in soundtouch_defines:
         WASM_DEFINES[k] = v