[chbot] Chchrobotics Digest, Vol 198, Issue 10 GCC and recursion

[Bevin Brett]

The alternative to recursion is either a linked list, a fixed size array, or a growing array

In RPN evaluation, the code often looks like this, because you don't need the full power and cost of recursion

ops : array of operators
stack : stack of operands
top = 0
for op in instructionStream do
    caseOf nOperands(op.code)
        alt add:
            stack[top - 1] += stack[top]
            top = top - 1
        alt int:
            top = top+1
            stack[top] = op.int
        ...

Don't forget to check for malformed expressions, which could result in h/w stack corruption due to indexing outside 'stack'

/Bevin

________________________________

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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.

Currently using "gcc version 12.2.0 (MinGW-W64 x86_64-ucrt-posix-seh,
built by Brecht Sanders)"

The first call of the recursed function worked fine, but crashes upon exit.

It could be that the compiler is not generating re-entrant code. The
only switch I have used is -O0 to disable compiler optimization.

Are there any other switches for GCC that I need to use/be aware of ?

Thanks, Mark

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