Use mimalloc allocator for Linux static build (#7378)

The new CMake flag MIMALLOC_STATIC controls this.

mimalloc fixes perf problems, especially on heavily multi-threaded
workloads (many functions, high core count machines) on the musl
allocator, see #5561.

Author: danleh

.github/workflows/ci.yml

@@ -250,7 +250,7 @@ jobs:
 
     - name: cmake
       run: |
-        ./alpine.sh cmake . -G Ninja -DCMAKE_INSTALL_PREFIX=out/install -DCMAKE_CXX_FLAGS="-static" -DCMAKE_C_FLAGS="-static" -DCMAKE_BUILD_TYPE=Release -DBUILD_STATIC_LIB=ON -DCMAKE_INSTALL_PREFIX=install
+        ./alpine.sh cmake . -G Ninja -DCMAKE_INSTALL_PREFIX=out/install -DCMAKE_CXX_FLAGS="-static" -DCMAKE_C_FLAGS="-static" -DCMAKE_BUILD_TYPE=Release -DBUILD_STATIC_LIB=ON -DMIMALLOC_STATIC=ON -DCMAKE_INSTALL_PREFIX=install
 
     - name: build
       run: |

.github/workflows/create_release.yml

@@ -140,7 +140,7 @@ jobs:
 
     - name: cmake
       run: |
-        ./alpine.sh cmake . -G Ninja -DCMAKE_CXX_FLAGS="-static" -DCMAKE_C_FLAGS="-static" -DCMAKE_BUILD_TYPE=Release -DBUILD_STATIC_LIB=ON -DCMAKE_INSTALL_PREFIX=install
+        ./alpine.sh cmake . -G Ninja -DCMAKE_CXX_FLAGS="-static" -DCMAKE_C_FLAGS="-static" -DCMAKE_BUILD_TYPE=Release -DBUILD_STATIC_LIB=ON -DMIMALLOC_STATIC=ON -DCMAKE_INSTALL_PREFIX=install
 
     - name: build
       run: |

.gitmodules

@@ -7,3 +7,6 @@
 [submodule "third_party/fuzztest"]
 	path = third_party/fuzztest
 	url = https://github.com/google/fuzztest
+[submodule "third_party/mimalloc"]
+	path = third_party/mimalloc
+	url = https://github.com/microsoft/mimalloc.git

CMakeLists.txt

@@ -49,14 +49,21 @@ endif()
 
 option(BUILD_STATIC_LIB "Build as a static library" OFF)
 if(MSVC)
-  # We don't have dllexport declarations set up for windows yet.
+  # We don't have dllexport declarations set up for Windows yet.
   set(BUILD_STATIC_LIB ON)
 endif()
 
-# Turn this off to install only tools and not static/dynamic libs
+# Advised to turn on when statically linking against musl libc (e.g., in the
+# Alpine Linux build we use for producing official Linux binaries), because
+# musl libc's allocator has very bad performance on heavily multi-threaded
+# workloads / high core count machines.
+# See https://github.com/WebAssembly/binaryen/issues/5561.
+option(MIMALLOC_STATIC "Build with statically linked mimalloc allocator" OFF)
+
+# Turn this off to install only tools and not static/dynamic libs.
 option(INSTALL_LIBS "Install libraries" ON)
 
-# Turn this on to build only the subset of tools needed for emscripten
+# Turn this on to build only the subset of tools needed for Emscripten.
 option(BUILD_EMSCRIPTEN_TOOLS_ONLY "Build only tools needed by emscripten" OFF)
 
 # Turn this on to build binaryen.js as ES5, with additional compatibility configuration for js_of_ocaml.
@@ -345,11 +352,11 @@ if(EMSCRIPTEN)
     # in opt builds, LTO helps so much (>20%) it's worth slow compile times
     add_nondebug_compile_flag("-flto")
   endif()
-    if(EMSCRIPTEN_ENABLE_WASM64)
-      add_compile_flag("-sMEMORY64 -Wno-experimental")
-      add_link_flag("-sMEMORY64")
-    endif()
+  if(EMSCRIPTEN_ENABLE_WASM64)
+    add_compile_flag("-sMEMORY64 -Wno-experimental")
+    add_link_flag("-sMEMORY64")
   endif()
+endif()
 
 # clang doesn't print colored diagnostics when invoked from Ninja
 if(UNIX AND CMAKE_GENERATOR STREQUAL "Ninja")
@@ -455,6 +462,14 @@ if(BUILD_LLVM_DWARF)
   target_link_libraries(binaryen llvm_dwarf)
 endif()
 
+if(MIMALLOC_STATIC)
+  if(NOT(LINUX AND BUILD_STATIC_LIB) OR EMSCRIPTEN)
+    message(FATAL_ERROR "Statically linking mimalloc is only supported when building as a native, statically linked library on Linux.")
+  endif()
+  message(STATUS "Building with statically linked mimalloc allocator.")
+  target_link_libraries(binaryen mimalloc-static)
+endif()
+
 add_subdirectory(src/ir)
 add_subdirectory(src/asmjs)
 add_subdirectory(src/cfg)

third_party/CMakeLists.txt

@@ -15,3 +15,18 @@ endif()
 if(BUILD_LLVM_DWARF)
   add_subdirectory(llvm-project)
 endif()
+
+if(MIMALLOC_STATIC)
+  # Using a C++ compiler avoids warnings about -fno-rtti with a C compiler.
+  set(MI_USE_CXX ON)
+  # We only need the static library, nothing else.
+  set(MI_BUILD_STATIC ON)
+  set(MI_BUILD_SHARED OFF)
+  set(MI_BUILD_OBJECT OFF)
+  set(MI_BUILD_TESTS OFF)
+  # Do not show debug and warning messages of the allocator by default.
+  # (They can still be enabled via MIMALLOC_VERBOSE=1 wasm-opt ...)
+  add_compile_definitions(MI_DEBUG=0)
+  
+  add_subdirectory(mimalloc)
+endif()