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Re: [tree-ssa] Removal of gotos from cfg based ir
- From: Michael Matz <matz at suse dot de>
- To: law at redhat dot com
- Cc: Andrew MacLeod <amacleod at redhat dot com>,Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>,gcc-patches <gcc-patches at gcc dot gnu dot org>, <jh at suse dot cz>
- Date: Fri, 14 Nov 2003 20:56:33 +0100 (CET)
- Subject: Re: [tree-ssa] Removal of gotos from cfg based ir
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 the IL no longer represents the function.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.
> The function's representation is the IL + the CFG in Zdenek's scheme.
> That's a fundamental design change
I'm not sure about the attribute 'fundamental', really, but for sure it's
a change ;) I tried to give justification from an abstract pov in my mail
to Andrew.
> 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. No fiddling with
consistency of CFG and insn stream. No difference of fallthrough but no
goto, and other edges and goto. Honza gave more detailed benefits.
Ciao,
Michael.