Re: [tree-ssa] Removal of gotos from cfg based ir

[law at redhat dot com]

In message <Pine.LNX.4.44.0311142046460.13268-100000@wotan.suse.de>, Michael Ma
tz writes:
 >Hi,
 >
 >On Fri, 14 Nov 2003 law@redhat.com wrote:
 >
 >> But more importantly in my mind is the design implications -- namely that
 >> the IL no longer represents the function.
 >
 >In case of EH and non-call exceptions the insn stream _already_ doesn't
 >represent the function fully.  Sure the are the REG_EH_REGION tags, but
 >those also need side lookups, and are more directly handled by looking at
 >the CFG.
Yes, that's true for RTL.  Hmmm, that may even be true now for tree-ssa
with Richard's lowering changes.  Hmmm.


 >> And for me at least, a fundamental design change needs to have large
 >> benefits, not minor ones.
 >
 >Easier way to RTL cgf-layout mode for instance.
Yes, but I don't see that as a major benefits.

 > No fiddling with consistency of CFG and insn stream.
Likewise.  Though it is clearly a benefit.

 > No difference of fallthrough but no goto, and other edges and goto.
True.  But there's other less fundamentally changing ways to deal with that.


LLVM's use of def-use  & use-def chains for preds/succs is actually a
very interesting concept.  I don't know if it's any better than Zdenek's
scheme or what we do now, but it's definitely interesting :-)

jeff