On Tue, Nov 19, 2013 at 6:27 PM, Jeff Law wrote: > I don't remember the history here, but that may have been to better support > divmod and similar insns.
Yes. In the GCC3 days it was important for sincos on i386, and on mk68 it used to be important for some of the funnier patterns. Not sure if it's still useful today, though. Might be worth looking into, just to avoid the confusion in the future. There's been confusion about this before, where people assumed single_set really means "just one SET in this pattern". (ISTR fixing gcse.c's hash_scan_rtx for this at some point...?). But that's not the semantics of single_set. The proper test for "just one SET" is (!multiple_sets && single_set). At least, that's how I've always coded it... Ciao! Steven
