Stack usage of g77-generated code: Worth a compiler option ?

Stack usage of g77-generated code: Worth a compiler option ?

[Toon Moene]

Craig and others on the egcs list,

Now that I am fully operational on my laptop (except for a modem  
connection and hence CVS'd snapshots), I decided to try to run our  
standard weather forecasting test suite.

Due to the fact that Modern Linux is ELF based (as opposed to my -  
loosely speaking - COFF based NEXTSTEP system) I didn't have to  
force all arrays (independent of size) to the stack.  [ For those  
who do not know this: NEXTSTEP's object format tends to fill all  
statically allocated arrays with zeros, which leads to huge object  
files and ditto .a libraries ]

However, my original (around '94) complaint about g77's default  
still has merit:  I compared the memory requirement of a run  
compiled with the standard "arrays of size above 32Kbytes are  
statically allocated" vs. "all arrays are allocated on the stack".

The first option led to an executable with 51 Mbyte of RSS, the  
second to one of 43 Mbyte.  This seems a significant difference to  
me.

The reason for this difference is that stack space gets reused,  
while statically allocated local arrays are there forever ;-)

Would it be possible to make the stack/nostack cutoff a compile  
time option ?  That sure beats rebuilding the compiler ...

Thanks in advance,
Toon.

Re: Stack usage of g77-generated code: Worth a compiler option ?

[Craig Burley]

>Would it be possible to make the stack/nostack cutoff a compile  
>time option ?  That sure beats rebuilding the compiler ...

I think it should be pretty straightforward.  It'd presumably work
like the -ffixed-line-length-N option, in case you (or someone else)
would like to try...I probably won't get to it *this* year myself!

        tq vm, (burley)