Support build with mimalloc (#348)

* Support build with mimalloc

* Use latest stable tag

CMakeLists.txt

@@ -1,11 +1,30 @@
 cmake_minimum_required(VERSION 3.10)
 project(c3c)
+include(FetchContent)
 include(FeatureSummary)
 
 set(CMAKE_FIND_PACKAGE_SORT_ORDER NATURAL)
 set(CMAKE_FIND_PACKAGE_SORT_DIRECTION DEC)
 set(C3_LLVM_VERSION "auto" CACHE STRING "Use LLVM version [default: auto]")
+option(C3_USE_MIMALLOC "Use built-in mimalloc" ON)
+set(C3_MIMALLOC_TAG "v1.7.3" CACHE STRING "Used version of mimalloc")
 
+if(WIN32)
+    set(C3_USE_MIMALLOC OFF)
+endif()
+
+if(C3_USE_MIMALLOC)
+    option(MI_BUILD_TESTS OFF)
+    option(MI_BUILD_SHARED OFF)
+    option(MI_PADDING OFF)
+    option(MI_DEBUG_FULL OFF)
+    FetchContent_Declare(
+    mimalloc
+    GIT_REPOSITORY https://github.com/microsoft/mimalloc.git
+    GIT_TAG ${C3_MIMALLOC_TAG}
+    )
+    FetchContent_MakeAvailable(mimalloc)
+endif()
 
 if(NOT C3_LLVM_VERSION STREQUAL "auto")
     if(${C3_LLVM_VERSION} VERSION_LESS 12 OR ${C3_LLVM_VERSION} VERSION_GREATER 14)
@@ -192,6 +211,9 @@ if(UNIX)
     target_link_libraries(c3c_wrappers ${llvm_libs} ${lld_libs})
     target_link_libraries(c3c m ${llvm_libs} c3c_wrappers ${lld_libs})
 #    target_link_libraries(c3c m ${llvm_libs} c3c_wrappers ${TB_LIB} ${lld_libs})
+    if(C3_USE_MIMALLOC)
+        target_link_libraries(c3c m mimalloc-static)
+    endif()
 else()
     # todo: maybe get this from llvm-config somehow? it should be in LLVM_DIR\..\..\..\bin I think.
     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -LIBPATH:C:\\llvm\\llvm\\build\\Release\\lib") # needed for lldCommon.lib