The fastcgi value is the name of my upstream.
The idea is: once the location /somedir/file1.php is reached, everything in @cache should execute.
In this way, I don't repeat several times the same code. This works:

location /somedir/file1.php {
try_files $uri =404;
fastcgi_split_path_info ^(.+\.php)(/.+)$;
fastcgi_pass fastcgi;
fastcgi_param PATH_INFO $fastcgi_path_info;
fastcgi_param PATH_TRANSLATED $document_root$fastcgi_script_name;
include fastcgi.conf;
}

This does not:
location = /somedir/file1.php {
try_files @cache =404;
}