A question about integer promotion in GCC

[Nathan Sidwell]

Joseph S. Myers wrote:

> There is a mood towards doing less such optimisations at parse time (and 
> generally reducing the front end / middle end overlap), in particular 
> reducing parse-time folding to constant folding only and causing the 
> remaining optimisations fold() does to be done later on GIMPLE.  This is 
> however a substantial task to do while being sure that each change is an 
> incremental improvement that does not cause regressions, as every useful 
> transformation fold() does would need implementing at a later stage, and 
> the result would need careful checking to be sure that all such 
> transformations had been properly implemented, before any can be removed 
> from fold().

IMO when to tackle this is after the next release branches, and the
way to do is implement fe-fold-constant-expr (tree, flags) first, and then
make a fold-const optimizer pass from the remnants.

nathan

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