[m-dev.] for review: bug-avoidance in value numbering

[Fergus Henderson]

On 14-Mar-1998, Zoltan Somogyi <zs at cs.mu.OZ.AU> wrote:
> 
> > > value_number.m:
> > > 	Do not attempt to optimize code sequences that manipulate tickets.
> > > 	That code is buggy, and it is not worth fixing in this incarnation
> > > 	of the value numbering optimization.
> > 
> > The code in the diff also disables optimization of code sequences
> > that contain c_code, pragma_c, or block instructions.  Why?
> 
> There is already code that disables value numbering for entire procedures
> if they contain c_code or pragma_c instructions, so disabling them again
> for code fragments is double insurance. Block instructions are only introduced
> in the post-value number pass, which is run after all invocations of
> value numbering.
> 
> I will change the handling of all three to call error instead.

OK, that should be fine then.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>  |  of excellence is a lethal habit"
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