Eric Blake wrote: > According to Eric Blake on 10/27/2008 8:18 AM: >> Not for this patch, but food for thought for a subsequent improvement. We >> are >> spending quite a few forks building two different test files; it should be >> possible to build a single test file that does: > >> if (sizeof ($[]2)) >> return 0; >> #ifdef AC_SECOND >> if (sizeof (($[]2))) >> return 0; >> #endif > >> then invoke the compiler with -DAC_SECOND added to CFLAGS on the second run, >> to >> reduce the overhead inherent in two full-blown AC_COMPILE_IFELSE. I don't >> think we can skip two separate compile runs, however, as I don't think we'll >> be >> lucky enough to accurately parse error messages to the point where we verify >> that the compiler only complained about the second statement. > > What do you think of this patch? It doesn't reduce the size of configure > much (now that a single shell function body is the only place where this > is expanded), but does remove two cat processes. On the other hand, it > adds an rm process, so I only see a net drop of one process per type > check. Maybe we can still figure out a slicker way to reduce the number > of rm processes.
I must say I don't like it much, unless it gives a net improvement of at least 2-3% on coreutils, say. But I disagree on the math: doesn't it save only one cat *but also* one rm? Paolo
