wasm: add simd support

Emscripten only supports
SSE1, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, and 128-bit AVX instruction
sets at this time.
https://emscripten.org/docs/porting/simd.html

Browsers might need to enable simd support in the advanced
configurations
about: config or chrome:flags

Enable by configuring Qt with -sse2

Pick-to: 6.2
Fixes: QTBUG-63924
Change-Id: Ifeafae20e199dee0d19689802ad20fd0bd424ca7
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

cmake/QtCompilerOptimization.cmake

@@ -199,4 +199,7 @@ if(WASM)
     set(QT_CFLAGS_OPTIMIZE_FULL "-O3")
     set(QT_CFLAGS_OPTIMIZE_SIZE "-Os")
     set(QT_CFLAGS_OPTIMIZE_DEBUG "-g2")
+
+    set(QT_CFLAGS_SSE2 -O2 -msimd128 -msse -msse2)
+
 endif()

cmake/QtInternalTargets.cmake

@@ -177,6 +177,10 @@ if(UIKIT)
     qt_internal_apply_bitcode_flags(PlatformCommonInternal)
 endif()
 
+if(WASM AND QT_FEATURE_sse2)
+    target_compile_definitions(PlatformCommonInternal INTERFACE QT_COMPILER_SUPPORTS_SSE2)
+endif()
+
 # Taken from mkspecs/common/msvc-version.conf and mkspecs/common/msvc-desktop.conf
 if (MSVC)
     if (MSVC_VERSION GREATER_EQUAL 1799)

cmake/QtWasmHelpers.cmake

@@ -19,6 +19,11 @@ function (qt_internal_setup_wasm_target_properties wasmTarget)
 
     target_compile_options("${wasmTarget}" INTERFACE --bind)
 
+    #simd
+    if (QT_FEATURE_sse2)
+        target_compile_options("${wasmTarget}" INTERFACE -O2 -msimd128 -msse -msse2)
+    endif()
+
     # Hardcode wasm memory size. Emscripten does not currently support memory growth
     # (ALLOW_MEMORY_GROWTH) in pthreads mode, and requires specifying the memory size
     # at build time. Further, browsers limit the maximum initial memory size to 1GB.

config.tests/arch/CMakeLists.txt

@@ -4,3 +4,7 @@ project(arch LANGUAGES CXX)
 add_executable(architecture_test)
 set_property(TARGET architecture_test PROPERTY MACOSX_BUNDLE FALSE)
 target_sources(architecture_test PRIVATE arch.cpp)
+
+if(EMSCRIPTEN)
+    target_compile_options(architecture_test PRIVATE -O2 -msimd128 -msse -msse2)
+endif()

configure.cmake

@@ -659,7 +659,9 @@ qt_feature("signaling_nan" PUBLIC
 )
 qt_feature("sse2" PRIVATE
     LABEL "SSE2"
-    CONDITION ( ( ( TEST_architecture_arch STREQUAL i386 ) OR ( TEST_architecture_arch STREQUAL x86_64 ) ) AND TEST_subarch_sse2 ) OR QT_FORCE_FEATURE_sse2 # special case
+    CONDITION ( ( (  TEST_architecture_arch STREQUAL i386 )
+        OR ( TEST_architecture_arch STREQUAL x86_64 ) ) AND TEST_subarch_sse2 ) OR QT_FORCE_FEATURE_sse2 OR WASM
+    AUTODETECT NOT WASM
 )
 qt_feature_definition("sse2" "QT_COMPILER_SUPPORTS_SSE2" VALUE "1")
 qt_feature_config("sse2" QMAKE_PRIVATE_CONFIG)
@@ -1017,7 +1019,7 @@ qt_configure_add_summary_entry(
     TYPE "featureList"
     ARGS "sse2 sse3 ssse3 sse4_1 sse4_2"
     MESSAGE "SSE"
-    CONDITION ( ( TEST_architecture_arch STREQUAL i386 ) OR ( TEST_architecture_arch STREQUAL x86_64 ) )
+    CONDITION ( ( TEST_architecture_arch STREQUAL i386 ) OR ( TEST_architecture_arch STREQUAL x86_64 ) OR ( TEST_architecture_arch STREQUAL wasm ) )
 )
 qt_configure_add_summary_entry(
     TYPE "featureList"

mkspecs/features/wasm/wasm.prf

@@ -36,6 +36,14 @@ exists($$QMAKE_QT_CONFIG) {
             message("Setting INITIAL_MEMORY to" $$INITIAL_MEMORY)
             EMCC_THREAD_LFLAGS += -s INITIAL_MEMORY=$$INITIAL_MEMORY
     }
+
+    qtConfig(sse2) {
+        QMAKE_CFLAGS += -O2 -msimd128 -msse -msse2
+        QMAKE_CXXFLAGS += -O2 -msimd128 -msse -msse2
+        QMAKE_LFLAGS       += -msimd128 -msse -msse2
+        QMAKE_LFLAGS_DEBUG += -msimd128 -msse -msse2
+    }
+
     QMAKE_LFLAGS       += $$EMCC_THREAD_LFLAGS
     QMAKE_LFLAGS_DEBUG += $$EMCC_THREAD_LFLAGS
     QMAKE_CFLAGS += $$EMCC_THREAD_LFLAGS

src/corelib/global/qprocessordetection.h

@@ -340,6 +340,10 @@
 #  define Q_PROCESSOR_WASM
 #  define Q_BYTE_ORDER Q_LITTLE_ENDIAN
 #  define Q_PROCESSOR_WORDSIZE 8
+#ifdef QT_COMPILER_SUPPORTS_SSE2
+#  define Q_PROCESSOR_X86 6   // enables SIMD support
+#endif
+
 #endif
 
 /*

src/corelib/global/qsimd_p.h

@@ -190,10 +190,13 @@
 #    define __SSE__                         1
 #  endif
 
-#  if defined(Q_CC_GNU) && !defined(Q_CC_INTEL)
+#  if defined(Q_CC_GNU) && !defined(Q_CC_INTEL) && !defined(Q_OS_WASM)
 // GCC 4.4 and Clang 2.8 added a few more intrinsics there
 #    include <x86intrin.h>
 #  endif
+#ifdef Q_OS_WASM
+#   include <immintrin.h>
+# endif
 
 #  if defined(__SSE4_2__) && defined(QT_COMPILER_SUPPORTS_SIMD_ALWAYS) && (defined(Q_CC_INTEL) || defined(Q_CC_MSVC))
 // POPCNT instructions: