wamrc: Support cross building and linking LLVM shared libs (#1578)

1. Support cross building wamrc and installing it
2. Remove PIE flag for Windows to fix compilation error when compiled by clang
3. Support linking LLVM shared libs to help build with system default or custom
   LLVM installation and reduce binary size.

core/shared/platform/windows/platform_internal.h

@@ -26,8 +26,8 @@
 #include <malloc.h>
 #include <process.h>
 #include <winsock2.h>
-#include <Windows.h>
-#include <BaseTsd.h>
+#include <windows.h>
+#include <basetsd.h>
 
 #ifdef __cplusplus
 extern "C" {

wamr-compiler/CMakeLists.txt

@@ -3,7 +3,13 @@
 
 cmake_minimum_required (VERSION 2.9)
 
-string (TOLOWER ${CMAKE_HOST_SYSTEM_NAME} WAMR_BUILD_PLATFORM)
+if (NOT DEFINED WAMR_BUILD_PLATFORM)
+  if (CMAKE_SYSTEM_NAME)
+    string(TOLOWER ${CMAKE_SYSTEM_NAME} WAMR_BUILD_PLATFORM)
+  else()
+    string(TOLOWER ${CMAKE_HOST_SYSTEM_NAME} WAMR_BUILD_PLATFORM)
+  endif()
+endif()
 
 if (NOT WAMR_BUILD_PLATFORM STREQUAL "windows")
   project (aot-compiler)
@@ -224,24 +230,20 @@ endif ()
 if (NOT MSVC)
   set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fstack-protector-strong --param ssp-buffer-size=4")
 endif()
-if (NOT (MSVC OR CMAKE_C_COMPILER MATCHES ".*clang.*" OR CMAKE_C_COMPILER_ID MATCHES ".*Clang"))
-  set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wl,-z,noexecstack,-z,relro,-z,now")
-  set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wl,-z,noexecstack,-z,relro,-z,now")
-endif()
 
 # We disable these flags by default to stay the same with wasm runtime
 # set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -mindirect-branch=thunk -mfunction-return=thunk")
 
 if (NOT MSVC)
-  if (NOT (CMAKE_C_COMPILER MATCHES ".*clang.*" OR CMAKE_C_COMPILER_ID MATCHES ".*Clang"))
-    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -pie -fPIE -ftrapv -D_FORTIFY_SOURCE=2")
-  else()
-    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIE -ftrapv -D_FORTIFY_SOURCE=2")
+  add_definitions(-D_FORTIFY_SOURCE=2)
+  set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -ftrapv")
+  if (NOT WIN32)
+    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -pie -fPIE")
   endif()
 endif()
 
-if (MSVC)
-  set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D_WINSOCK_DEPRECATED_NO_WARNINGS")
+if (WIN32)
+  add_definitions(-D_WINSOCK_DEPRECATED_NO_WARNINGS)
 endif()
 
 # message ("-- CMAKE_C_FLAGS: ${CMAKE_C_FLAGS}")
@@ -263,15 +265,23 @@ add_library (aotclib ${IWASM_COMPL_SOURCE})
 
 add_executable (wamrc main.c)
 
+if (LLVM_LINK_LLVM_DYLIB)
+  set(WAMRC_LINK_LLVM_LIBS LLVM)
+else()
+  set(WAMRC_LINK_LLVM_LIBS ${LLVM_AVAILABLE_LIBS})
+endif()
+
 if (NOT MSVC)
-  target_link_libraries (wamrc aotclib vmlib LLVMDemangle ${LLVM_AVAILABLE_LIBS} ${lib_ubsan}
+  target_link_libraries (wamrc aotclib vmlib ${WAMRC_LINK_LLVM_LIBS} ${lib_ubsan}
                          -lm -lpthread ${lib_lldb} ${UV_A_LIBS})
   if (MINGW)
-      target_link_libraries (wamrc -lssp -lWs2_32)
+      target_link_libraries (wamrc ssp.a ws2_32)
   else()
       target_link_libraries (wamrc -ldl)
   endif()
 else()
-  target_link_libraries (wamrc aotclib vmlib  ${lib_lldb} ${LLVM_AVAILABLE_LIBS} ${lib_ubsan}
+  target_link_libraries (wamrc aotclib vmlib  ${lib_lldb} ${WAMRC_LINK_LLVM_LIBS} ${lib_ubsan}
                          ${UV_A_LIBS})
 endif()
+
+install (TARGETS wamrc DESTINATION bin)