On 8/12/07, Dave Korn <[EMAIL PROTECTED]> wrote: > On 11 August 2007 08:42, Emmanuel Fleury wrote: > > Sunzir Deepur wrote: > >> so why are those class 3 edges created at all ? > > I didn't see any 3-edges blocks at all in your example. > Not 3-edge blocks; class 3 edges = the green lines. > > They appear to be showing where the fall-through path /would have/ gone in > those BBs which end with an unconditional jump if there had been no jump. > > Edge class in the vcg output is determined by the 'class' arg passed by > print_rtl_graph_with_bb to the draw_edge routine in graph.c. The only place > that generates class 3 edges is the catch-all if (!edge_printed) clause at the > end of the for (tmp_rtx) loop. The FOR_EACH_EDGE loop above will output all > the 'real' edges that represent possible code flow paths, so it looks to me > like gcc is using class 3 as a catch-all for things like EDGE_FAKE, > EDGE_CROSSING, and any other of the kinds of edges (basic-block.h) that the > compiler maintains for structural reasons that aren't real edges. > > You'd have to ask someone other than me for the details of what kinds of > things other than real edges the compiler stores edge structs for, but that's > what ends up being drawn as class 3.
so do you think it's a safe bet to say that all class 3 edges do not represent a possible flow of code ? thank you sunzir
