Re: [PATCH] newlib: libc: Improved the readability of strcspn with minor optimization

[Brian Inglis <Brian.Inglis@SystematicSW.ab.ca>]

On 2023-12-21 01:00, Stefan Tauner wrote:
> On Wed, 20 Dec 2023 15:24:10 -0700 Brian Inglis wrote:
>> Using gotos throw away potential optimizations in modern compilers
> {{citation needed}}

Please note that is a simplification to make the point.
No gotos means reducible flow graphs which allow easier analysis and optimization.
The main problem is the creation of irreducible flow graphs using gotos.
Compilers may be able to convert irreducible flow graphs to reducible flow 
graphs, eliminating the gotos by restructuring.
This may then allow the code to meet preconditions allowing further loop or 
block optimizations designed for structured reducible flow graphs.

See:
https://groups.seas.harvard.edu/courses/cs153/2019fa/lectures/Lec23-Loop-optimization.pdf

	https://escholarship.mcgill.ca/concern/theses/x633f2516

-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer     but when there is no more to cut
                                 -- Antoine de Saint-Exupéry

[I was stunned into more structured approaches early on by having to work on a 
large monolithic uncommented Fortran program that used *only* assigned gotos 
with meaningless random numeric labels and dozens of human named label variables 
e.g.
...
813	ASSIGN 105 to FRED
	GOTO JIM
534	IF (I.GT.0) GO TO JOHN
	GOTO JACK
105	ASSIGN 534 to ANDY
	GOTO MIKE
...
interspersed with some matrix calculations. Aaaargh!]