Merge pull request #12917 from fwcd/sse-wasm-fixes

SSE: Check `!defined(__EMSCRIPTEN__)` where intrinsics are unavailable on WASM
mixxxdj · Apr 7, 2024 · 0416ba6 · 0416ba6
2 parents 6dcdb35 + 8c62564
commit 0416ba6
Show file tree

Hide file tree

Showing 3 changed files with 18 additions and 3 deletions.
diff --git a/src/soundio/sounddevicenetwork.cpp b/src/soundio/sounddevicenetwork.cpp
@@ -442,10 +442,18 @@ void SoundDeviceNetwork::callbackProcessClkRef() {
 
     if (!m_denormals) {
         m_denormals = true;
+
         // This disables the denormals calculations, to avoid a
         // performance penalty of ~20
         // https://github.com/mixxxdj/mixxx/issues/7747
-#ifdef __SSE__
+
+        // On Emscripten (WebAssembly) denormals-as-zero/flush-as-zero are
+        // neither supported nor configurable. This may lead to degraded
+        // performance compared to other platforms and may be addressed in the
+        // future if/when WebAssembly adds support for DAZ/FTZ. For further
+        // discussion and links see https://github.com/mixxxdj/mixxx/pull/12917
+
+#if defined(__SSE__) && !defined(__EMSCRIPTEN__)
         if (!_MM_GET_DENORMALS_ZERO_MODE()) {
             qDebug() << "SSE: Enabling denormals to zero mode";
             _MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_ON);

diff --git a/src/soundio/sounddeviceportaudio.cpp b/src/soundio/sounddeviceportaudio.cpp
@@ -906,10 +906,17 @@ int SoundDevicePortAudio::callbackProcessClkRef(
 #endif
         m_bSetThreadPriority = true;
 
-#ifdef __SSE__
         // This disables the denormals calculations, to avoid a
         // performance penalty of ~20
         // https://github.com/mixxxdj/mixxx/issues/7747
+
+        // On Emscripten (WebAssembly) denormals-as-zero/flush-as-zero are
+        // neither supported nor configurable. This may lead to degraded
+        // performance compared to other platforms and may be addressed in the
+        // future if/when WebAssembly adds support for DAZ/FTZ. For further
+        // discussion and links see https://github.com/mixxxdj/mixxx/pull/12917
+
+#if defined(__SSE__) && !defined(__EMSCRIPTEN__)
         if (!_MM_GET_DENORMALS_ZERO_MODE()) {
             qDebug() << "SSE: Enabling denormals to zero mode";
             _MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_ON);

diff --git a/src/util/denormalsarezero.h b/src/util/denormalsarezero.h
@@ -20,7 +20,7 @@
 #define _MM_DENORMALS_ZERO_OFF      0x0000
 #endif
 
-#ifdef __SSE__
+#if defined(__SSE__) && !defined(__EMSCRIPTEN__)
 
 #include <xmmintrin.h>