Re: [Chicken-hackers] [PATCH] add a second lightweight flow-analysis pass

[Peter Bex]

On Fri, Oct 12, 2012 at 07:45:44PM +0200, Felix wrote:
> This patch adds another lightweight flow-analysis pass to remove some
> unnecessary type checks after normal optimization has taken place.
> 
> Even with specialization, inlining (in particular cross-module
> inlining) may result in type checks that are in many cases redundant.
> For example inlined record accessors compiled in safe mode, and
> inlining of code in general (which is done after the normal
> flow-analysis pass) will introduce type-checks that specialization
> would have (sometimes) removed.

I'm not sure I completely understand why the scrutinizer can't remove
this after inlining, but ok.

> This patch adds a new compiler pass (called "lfa2"), that does a
> simplified flow-analysis to identify redundant forms of the form
> '(##core#inline "C_i_check_..." ...)'. Type-information is obtained
> from constant forms and predicates like '(##core#inline
> "C_i_structurep" ...)'. In unsafe mode checks will be removed in
> general.

Looks good, as far as I can understand it!  I've pushed the patch.

Cheers,
Peter
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