Makefile.in without Makefile.am in GCC?

Question

I'm reading GCC's source code and have some questions. It's obvious that GCC is build with autotools. But I couldn't find the Makefile.am files required by automake. Is GCC's Makefile.in files written by hand? And if they are written by hand, where can I find the documents describing the syntax of a Makefile.in?

A similar question: Makefile.in without Makefile.am in projects

Answer 1

Makefile.am is a later addition to Autotools family and not all projects use it. GCC in particular does not use it. The top-level Makefile.in is generated from Makefile.tpl using autogen (see here for details). Other Makefile.in 's are written by hand according to Autoconf rules .