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compiled C function for postgresql fails (64-bit only)

I have a function that I've used since early postgres-7.x days.  Now migrating to a 64-bit
(i7) machine - running 2.6.30/'squeeze' with postgresql-8.4.1-1.  This function is a simple
one that takes a string representation of a number as its sole argument (engineering
notation), and returns the number.  The floating point value that it returns is the same
value {6.94822224692498e-310} with every call, even when the string changes.
	The same function works perfectly on a separate 2.6.30/'squeeze' system, PG-8.4.1-1,
that is a 32-bit system - just like it has on previous postgres versions.
	If I enable a diagnostic mid-functon dump-to-a-file, I can see that the function
is receiving its input and computing the output properly - it's "just" a matter of
getting the output translated into sql-land.  This is with the "Version 0" calling
conventions, with a return type of float8* .  Attempting "Version 1" calling conventions
on the 64-bit system has not yet been successful - I haven't yet been able to avoid a client
segfault, whether I use a stack variable for the float8 result, or use palloc().

	In case it would help, the key parts of the function are:

float8 *sick_fct(const char *strng)
   float8 	*result;
   char		stack_string_buffer[BIG_STRING_SPACE];

	// string copy operation : strng -> stack_string_buffer

	result= (float8*)palloc(sizeof(float8));
	*result= inner_conversion_function(stack_string_buffer);
	// printing this *result to a file shows that the conversion is correct
	// the mysteriously wrong part seems to be:
	return result;

I'm compiling it as:
	g++-4.3 -c -I/usr/include -I/usr/lib/gcc/x86_64-linux-gnu/4.3/include -Wall -Wshadow -Wpointer-arith -Wcast-align -I/usr/include/postgresql -I(yet more includes) -fPIC -x c  sick_fct.c -o sick_fct.o

and building the library as:
	g++-4.3 -shared -Wl,-soname,lib_sickfct.so.1 -o lib_sickfct.so.1.0 *.o

and "creating" the function within PG as:
  AS '/lib-path/lib_sickfct', 'sick_fct' LANGUAGE C STRICT;

Note that changing the "float" on the last line to "double precision" changes nothing.

	Odds are that I'm doing something stupid, but so far I haven't figured out
what it is.  Thanks for any insights you might have!


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