wasm: remove compiler and linker warnings

INITIAL_MEMORY and PTHREAD_POOL_SIZE are linker flags only
USE_PTHREADS is both linker and compiler arguments.

Also increase default INITIAL_MEMORY

Change-Id: Id1998efbf1d6de901f404db7e988f6cafd547a39
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
(cherry picked from commit d10b910e39c1d018c3d78f7f9c1ef31b37e4a132)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 31 insertions, 23 deletions

diff --git a/mkspecs/features/wasm/wasm.prf b/mkspecs/features/wasm/wasm.prf
index b80a565a2b..1ccda7a6e8 100644
--- a/mkspecs/features/wasm/wasm.prf
+++ b/mkspecs/features/wasm/wasm.prf
@@ -9,8 +9,8 @@ exists($$QMAKE_QT_CONFIG) {
 
     qtConfig(thread) {
 
-        EMCC_THREAD_LFLAGS += -pthread
-        EMCC_THREAD_CFLAGS += -pthread
+        EMCC_LFLAGS += -pthread
+        EMCC_CFLAGS += -pthread
 
         # Create worker threads at startup. This is supposed to be an optimization,
         # however exceeding the pool size has been obesverved to hang the application.
@@ -20,24 +20,30 @@ exists($$QMAKE_QT_CONFIG) {
         }
 
         message("Setting PTHREAD_POOL_SIZE to" $$POOL_SIZE)
-        EMCC_THREAD_LFLAGS += -s PTHREAD_POOL_SIZE=$$POOL_SIZE
+        EMCC_LFLAGS += -s PTHREAD_POOL_SIZE=$$POOL_SIZE
     } else {
-        EMCC_THREAD_LFLAGS += -s ALLOW_MEMORY_GROWTH=1
+        EMCC_LFLAGS += -s ALLOW_MEMORY_GROWTH=1
     }
 
-     qtConfig(thread) | !isEmpty(QT_WASM_INITIAL_MEMORY) {
+    isEmpty(QT_WASM_INITIAL_MEMORY) {
+        # Hardcode wasm memory size.
 
-            # 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.
-            # QT_WASM_INITIAL_MEMORY must be a multiple of 64KB
+        qtConfig(thread) {
+        # Pthreads and ALLOW_MEMORY_GROWTH can cause javascript wasm memory access to
+        # be slow. Instead, we specify the memory size
+        # at build time. Further, browsers limit the maximum initial memory size to 1GB.
+        # https://github.com/WebAssembly/design/issues/1271
             INITIAL_MEMORY = 1GB
-            !isEmpty(QT_WASM_INITIAL_MEMORY) {
-                INITIAL_MEMORY = $$QT_WASM_INITIAL_MEMORY
-            }
-            message("Setting INITIAL_MEMORY to" $$INITIAL_MEMORY)
-            EMCC_THREAD_LFLAGS += -s INITIAL_MEMORY=$$INITIAL_MEMORY
+        } else {
+            INITIAL_MEMORY = 50MB # emscripten default is 16MB, we need slightly more
+        }
+    } else {
+        # QT_WASM_INITIAL_MEMORY must be a multiple of 64KB (i.e. 65536)
+        INITIAL_MEMORY = $$QT_WASM_INITIAL_MEMORY
+        message("Setting INITIAL_MEMORY to" $$INITIAL_MEMORY)
     }
+    EMCC_LFLAGS += -s INITIAL_MEMORY=$$INITIAL_MEMORY
+    message("Setting INITIAL_MEMORY to" $$INITIAL_MEMORY)
 
     qtConfig(sse2) {
         QMAKE_CFLAGS += -O2 -msimd128 -msse -msse2
@@ -46,10 +52,10 @@ exists($$QMAKE_QT_CONFIG) {
         QMAKE_LFLAGS_DEBUG += -msimd128 -msse -msse2
     }
 
-    QMAKE_LFLAGS       += $$EMCC_THREAD_LFLAGS
-    QMAKE_LFLAGS_DEBUG += $$EMCC_THREAD_LFLAGS
-    QMAKE_CFLAGS += $$EMCC_THREAD_CFLAGS
-    QMAKE_CXXFLAGS += $$EMCC_THREAD_CFLAGS
+    QMAKE_LFLAGS       += $$EMCC_LFLAGS
+    QMAKE_LFLAGS_DEBUG += $$EMCC_LFLAGS
+    QMAKE_CFLAGS += $$EMCC_CFLAGS
+    QMAKE_CXXFLAGS += $$EMCC_CFLAGS
 }
 
 # Create js and wasm files for applications
diff --git a/src/corelib/Qt6WasmMacros.cmake b/src/corelib/Qt6WasmMacros.cmake
index 86044d7e02..8f9720653b 100644
--- a/src/corelib/Qt6WasmMacros.cmake
+++ b/src/corelib/Qt6WasmMacros.cmake
@@ -30,23 +30,25 @@ function(_qt_internal_wasm_add_target_helpers target)
             message(DEBUG "Setting PTHREAD_POOL_SIZE to ${POOL_SIZE} for ${target}")
         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.
-        # QT_WASM_INITIAL_MEMORY must be a multiple of 64KB (i.e. 65536)
+        # Hardcode wasm memory size.
         get_target_property(_tmp_initialMemory "${target}" QT_WASM_INITIAL_MEMORY)
         if(_tmp_initialMemory)
             set(QT_WASM_INITIAL_MEMORY "${_tmp_initialMemory}")
         elseif(NOT DEFINED QT_WASM_INITIAL_MEMORY)
             if(QT_FEATURE_thread)
+                # Pthreads and ALLOW_MEMORY_GROWTH can cause javascript wasm memory access to
+                # be slow and having to update HEAP* views. Instead, we specify the memory size
+                # at build time. Further, browsers limit the maximum initial memory size to 1GB.
+                # https://github.com/WebAssembly/design/issues/1271
                 set(QT_WASM_INITIAL_MEMORY "1GB")
             else()
                 # emscripten default is 16MB, we need slightly more sometimes
-                set(QT_WASM_INITIAL_MEMORY "20MB")
+                set(QT_WASM_INITIAL_MEMORY "50MB")
             endif()
         endif()
 
         if(DEFINED QT_WASM_INITIAL_MEMORY)
+            # QT_WASM_INITIAL_MEMORY must be a multiple of 65536
             target_link_options("${target}"
                 PRIVATE "SHELL:-s INITIAL_MEMORY=${QT_WASM_INITIAL_MEMORY}")
             message(DEBUG "-- Setting INITIAL_MEMORY to ${QT_WASM_INITIAL_MEMORY} for ${target}")