On Tue, Sep 27, 2011 at 1:12 PM, Miles Bader <miles@xxxxxxx> wrote: > Miles Bader <miles@xxxxxxx> writes: >>> Hmm, actually testing with a recent gcc snapshot, it _is_ merging the >>> two if-blocks: >> ... >> >> and in fact, gcc 4.4.6, 4.5.3, and 4.6.1 seem to do the same thing! >> >> So I dunno... what's the complaint again...? > > I note that this optimization only takes place at -O2 or above; maybe > the original poster simply didn't use a high-enough optimization level? > > -miles > > -- > I'd rather be consing. > A case I ran into with gcc trunk after cprop1 pass: cc <- compare(r684, 0) if (cc != 0) goto .L1 r191 <- 0 goto .L2 .L1: r191 <- 0 ...other insns .L2: In my experiment, both following pre and cse passes do not hoist the r191<-0 to the beginning. I understand that it is actually not a redundant case, and not pre's job. So which pass in gcc might handle it? Thanks very much. Wondering is it a similar story to the original post? -- Best Regards.
