On 10/26/2017 05:05 AM, Aldy Hernandez wrote: > Howdy. > > In the backwards threader we attempt to thread paths that lead to a > basic block ending in either a GIMPLE_COND, GIMPLE_SWITCH, or a > GIMPLE_GOTO. The latter doesn't make much sense, since we only handle > constants. What does a goto to a constant mean? Does that ever happen? When we're able to thread a computed goto, we should be threading to an ADDR_EXPR or LABEL_EXPR. Threading to a constant just doesn't make sense.
However, we have to filter that case reasonably -- there's certainly a test in the testsuite where a computed jump can be threaded to a constant. THe DOM threader aborted/faulted on that in the past. So I wouldn't lose any sleep if we just didn't handle computed gotos in the backwards threader and left it to DOM to catch the rare cases were we can thread to a label/decl. Jeff
