Gary Funck wrote:
While working with GCC's language hooks, we found that certain places in GCC test for a null value of lang_hooks.callgraph.expand_function, but cgraph_expand_function() calls the hook directly:
When cgraph was first added, it was optional, and could be disabled if -fno-unit-at-a-time was used, or if the language front-end did not support cgraph.
For a while, our intentions have been to make this mandatory, and eliminate the -fno-unit-at-a-time option. It appears that we have already reached the point where front end support for cgraph is mandatory, as the code no longer works when callgraph.expand_function is NULL. This means all of the checks for NULL are now obsolete and can be removed. The -fno-unit-at-a-time options still exists meanwhile, but will eventually be dropped.
It looks like gcc-3.4 supports a NULL callgraph.expand_function hook, and gcc-4.0 and later do not, so I'd guess this transition happened when tree-ssa got merged in. Or maybe it was enabled by the tree-ssa work.
-- Jim Wilson, GNU Tools Support, http://www.specifix.com
