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Re: egcs-19980508 powerpc-ibm-aix4.1.4.0 results (failures with -p/-pg)


>>>>> "Kaveh R Ghazi" writes:

Kaveh> Thanks for the info David.  I agree that spending time on a bug
Kaveh> in a gcc C language extension which occurs only when using -p/-pg on AIX
Kaveh> seems like a waste of time.  However, I wonder if this bug impacts other
Kaveh> front ends which make use of this feature. 

Kaveh> Eg, don't Fortran and Pascal make use of gcc's nested function
Kaveh> support?  If so, would this bug mean that standards conforming Fortran or
Kaveh> Pascal code couldn't be profiled using g77 or gpc?  I can't say, but I
Kaveh> thought I'd bring it up in case you could clear it up. 

	Yes, this might affect combining profiling with those other
languages.  I stepped through one of the failures generating a SIGKILL and
it occurred on the last iteration of the loop when it was storing an
updated stack value.  The memory address was valid (in fact the program
read from the address a few instructions before).

	AIX profiling routines touch the stack.  The *way* that GCC
implements nested functions simply may not be compatible with AIX
assumptions during profiling.  I haven't had time to explore this further
to understand exactly what is causing the store to blowup.  Again, this is
not a SEGV, the kernel is destroying the entire program context when this
occurs, not just handing the program an unmaskable signal.

David


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