Is there analog of Clang AST in GCC?
Sometimes it's usefull to see code as the compiler sees it.
Clang AST options -ast-view, -ast-tree and -ast-print are very helpful here.
I'm interested if there are such options for GCC or some tools to produce AST tree that work with GCC.
You can dump the (result of the) tree passes by means of -fdump-tree-all and the inter-procedural analysis passes by -fdump-ipa-all. For a compilation unit module.c, this will write dump files module.c.<num>t.<name> and module.c.<num>i.<name>, respectively. <num> indicated the order in which these passes are run, <name> indicates the pass name.
There are also 100s of options controlling dumping for specific passes only, see GCC Developer Options.
These dumps' syntax is mostly C-ish. After the tree passes there are the machine-dependent RTL passes. You can dump these with -fdump-rtl-all or -da. These dumps are LISP-ish and named module.c.<num>r.<name>.
You can also dump the final RTL with -fdump-final-insns.
In order to see which RTL is associated to which assembly instructions, you can -save-temps -dP and then inspect the assembly file module.s.
In the case you are using LTO (-flto) the assembly file will only contain lto1 gibberish. You can add the assembly code by means of -ffat-lto-objects. Notice however that with LTO, this is not the final code as produced by the lto run. To see that code, use -save-temps -flto -o program.exe and the dumps from the LTO run are named program.exe.ltrans<id>.<num>[tir].<name>.