Re: alternatives to java byte-codes

> David Gay wrote:
> > My gut feeling is that trees
> > make some transfor- mations harder, especially if the tree is close to
> > the language's source code.


Niall Dalton wrote:
> Well, trees in general are common in compilers, for example expression
> trees as an internal representation for functional languages and you may
> generate locally optimal code using Sethi-Ullman numbers from an
> appropiate tree representation of a program.


Yes, but. What I have seen over the years is that the syntactically
supplied trees are not necessarily the ones that you want to use. For
instance, in the case of C, C++, and Java, the use of expression
operators and comma operators gunks up your syntax trees with ordering
constraints, and they may not even be the largest possible trees. It
is a relatively simple exercise (well, I thought it was simple) to
walk the instructions of a basic block and construct a
largest-possible true expression tree before doing your Sethi-Ullman
numbering.


David Chase
NaturalBridge LLC

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