Switch off assembler CRC32 on Windows by default.

CMakeLists.txt

@@ -227,14 +227,22 @@ else()
 endif()
 
 # Allow to prohibit assembler optimization code explicitly
+if(MSVC)
+  SET(ASM_OPTIMIZATIONS_DEFAULT OFF)
+else(MSVC)
+  SET(ASM_OPTIMIZATIONS_DEFAULT ON)
+endif(MSVC)
+
 option(ASM_OPTIMIZATIONS "whether hand-optimized assembler code should be used"
-  ON)
+  ${ASM_OPTIMIZATIONS_DEFAULT})
+
 if (ASM_OPTIMIZATIONS)
   add_definitions("-DASM_OPTIMIZATIONS=1")
 else (ASM_OPTIMIZATIONS)
   add_definitions("-DASM_OPTIMIZATIONS=0")
 endif(ASM_OPTIMIZATIONS)
 
+
 # Maintainer mode (Assertions) -------------------------------------------------
 option(USE_MAINTAINER_MODE
   "whether we want to have assertions and other development features" OFF)

lib/Basics/hashes.cpp

@@ -463,6 +463,10 @@ static bool HasSSE42() {
   }
 }
 
+// The following is currently not used, it is a fallback for the case
+// that the pure assembler source cannot be assembled or linked for
+// some reason.
+
 extern "C" uint32_t TRI_BlockCrc32_intrinsics(uint32_t value,
                                               char const* data,
                                               size_t length) {