Problem about `DerivedConstants.h` and `tmp.c` in `includes/dist-derivedconstants/header`, GHC 7.8.3

Hi everyone, I am having trouble porting some 6.8.2 GHC code to 7.8.3 GHC. The main trouble I met is that, in 6.8.2, there is a includes/mkDerivedConstants.c and some constants about RTS are declared here. While in 7.8.3, there is only a similar `includes/dist-derivedconstants/header` directory containing a bunch of code. Some seems generated like `DerivedConstants.h`, and it seems like `tmp.c` generated this. However, when I added some entries in `tmp.c` and compiled it, then it became the original version ... So I doubted that if there is another file which is equivalent to the includes/mkDerivedConstants.c in 6.8.2? Thank a lot! Zhen