update_path in gcc/prefix.h?

[Basile STARYNKEVITCH]

Hello all,


What is the exact intent of the update_path in gcc/prefix.[hc]?

I would guess it is related to the -B option to gcc driver executable. 
But I'm not sure how exactly. I don't exactly understand what it means 
to pass "GCC" (or "BINUTILS") as the key (2nd) argument to update_path.



in the MELT branch http://gcc.gnu.org/wiki/MiddleEndLispTranslator
I would like to reference from within the cc1 executable some 
directories like e.g. $(libexecsubdir)/melt-private-include/ in 
gcc/Makefile.in parlance.

I got the vague impression that a call to 
update_path("melt-private-include/', "GCC") would return it, but I am 
really not sure.

For motivations on why I'm asking, see the wiki page, the MELT branch 
itself, and previous related threads like
http://gcc.gnu.org/ml/gcc/2008-03/msg00524.html
http://gcc.gnu.org/ml/gcc/2008-03/msg00549.html
http://gcc.gnu.org/ml/gcc/2008-03/msg00151.html
http://gcc.gnu.org/ml/gcc/2008-02/msg00679.html
http://gcc.gnu.org/ml/gcc/2008-02/msg00632.html


More generally, any advices and how and where should I read files inside 
some middle-end code are welcome. I'm pretty sure other peoples got into 
similar issues, but I don't know where and how....

Regards
Regards.
-- 
Basile STARYNKEVITCH         http://starynkevitch.net/Basile/
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