C++ code generation: any way of deflating large expressions?

Richard B. Kreckel kreckel at thep.physik.uni-mainz.de
Mon Jul 21 23:58:48 CEST 2003

Dear Hugo,

On Thu, 10 Jul 2003 hugo_lec at club-internet.fr wrote:
>        There's an algorithm to use the less temporary variables as possible (in order
> to help the compiler to optimize).

Could you please elaborate a little bit on that statement?

As it stands I find it slightly irritiating.  Is this assessment based on
real experience?  Given a compiler that transforms its parsed tree into
SSA form at some stage (as GCC 3.5 will), besides those phi-expressions
tons of temporaries are generated anyway in the IR.  More or less by
definition, later optimizations must cope with and reduce them.  So: is
there a point in trying to keep the number of temporaries low or is that
just fiction?

Maybe an example of the effect you are alluding at would be helpful.

Richard B. Kreckel
<Richard.Kreckel at GiNaC.DE>

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