Laurent: We observed performance loss between jdk8 and jdk9 on Maskfill (c software loops). I provided the EllipseFill test (jmh) and you provided a patch to gcc compiler options:
CFLAGS := -fgcse-after-reload -ftree-vectorize $(CFLAGS_JDKLIB) $(LIBAWT_CFLAGS), \

See discussion:
http://mail.openjdk.java.net/pipermail/graphics-rasterizer-dev/2015-October/000332.html

I confirmed it improved performance ~10% on my machine i7-4800 (amd64 linux) that is comparable to jdk8 performance.