Improve DIMASSOC object #4666

Job	Run time
linux-cmake	5m 31s
macOS	7m 49s
mingw	12m 7s
mingw-cmake	7m 19s
linux (CFLAGS="-O1 -fno-omit-frame-pointer -fsanitize=address -fno-var-tracking" --disable-bindin...	9m 36s
mips32-big-endian	12m 16s
ppc64-big-endian	12m 20s
linux (CC="clang")	9m 17s
vs2019	5m 12s
vs2019-ninja	4m 53s
linux (--enable-release)	12m 17s
linux (--enable-gcov --disable-bindings --disable-docs CFLAGS="-O0 -g")	4m 51s
linux (--disable-write --disable-docs)	10m 32s
linux (CFLAGS="-O2 -m32" --disable-bindings --disable-docs)	7m 45s
linux (CFLAGS="-O2 -fno-omit-frame-pointer -fsanitize=undefined -fno-var-tracking" --disable-bind...	12m 18s
	2h 14m 3s

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