I'm using below gcc tool chain. gcc version 5.4.1 20160919 (release) [ARM/embedded-5-branch revision 240496] (GNU Tools for ARM Embedded Processors)
I could create .h.gch file but could not get .h.gch used while buidling .c files. I used -H and -Winvalid-pch options to check the reasons but compiler didn't give any information. Just like .h.gch doesn't exist and always search .h file.