[chbot] GCC and recursion

[Mark Atherton]

Didn't pursue it, found a simpler solution.

Just investigating Shunting yard algorithm for Algebraic to RPN 
conversion; can't see how can avoid recursion to process complex 
expressions :)

Hair-loss to follow...

-Mark


On 4/13/2024 6:42 PM, Charles Manning wrote:
> I am curious Mark: did you get the recursion working?
> 
> 
> On Sat, Mar 30, 2024 at 1:25 PM Mark Atherton <markaren1 at xtra.co.nz 
> <mailto:markaren1 at xtra.co.nz>> wrote:
> 
>     All,
> 
>     The cross assembler is x86 based, has a deterministic exit condition,
>     and debug code showing return values. It only exits once, hence
>     checking
>     compiler constraints before looking closer look for stupidity on my
>     part.
> 
>     Thanks for all the comments.
> 
>     Mark
> 
>     On 3/30/2024 12:15 PM, Volker Kuhlmann wrote:
>      >> I am building an RPN expression evaluator for the uCPU
>     assembler; I can't
>      >> see any other way to go other than to use recursion to do the nested
>      >> processing that I wish.
>      >
>      > I agree that that should have nothing to do with gcc, although it is
>      > possible that gcc has quite a few bugs affecting correct code
>     generation
>      > for some µC cores. Those are gcc version dependent too.
>      >
>      > What architecture are you generating code for? Is your assembler
>     running
>      > on x86? It's safe to assume for that that crashes are caused by your
>      > code, not gcc.
>      >
>      > Recursive programming relies on having a reliable exit condition,
>     taken
>      > before resources like stack run out. An easy way to check is to write
>      > out the parameters for each call on a single line, one line per call,
>      > and any unrestrained criteria show up at the bottom of the screen.
>      >
>      >> It could be that the compiler is not generating re-entrant code.
>      >
>      > Not for x86. More likely a variable which changes with each call
>     is not
>      > local. A compiler bug, if it's for esoteric cores, would still be
>     down
>      > on my list.
>      >
>      > Why don't you just compile for x86 and test in a high-resource
>      > environment first?
>      >
>      > Volker
>      >
> 
> 
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