[Bug preprocessor/19821] New: Preprocessor oom with nested vector operations

["pochini at shiny dot it" <gcc-bugzilla at gcc dot gnu dot org>]

With 4 nested vec_add()'s gcc goes out of memory on my 512MB+1GBswap ppc box. 
With 3 adds it consumes about 150MB of memory and eventually succeeds. The 
preprocessor expands the y=... line into an exagerately huge expression. fftw3 
fails to compile because of this.
Tested on gcc 3.4.1 and 3.4.3, stable versions. They were configured with the 
following options:

./configure --prefix=/usr/ --enable-shared --enable-threads=posix --with-system-
zlib --enable-__cxa_atexit --disable-checking --enable-altivec --with-cpu=7450 -
-enable-languages=c,c++,objc



#include <altivec.h>

main() {
	vector float y, a, b;

	y = vec_add(a, vec_add(a, vec_add(a, vec_add(a, b))));
}

# gcc -maltivec c.c

-- 
           Summary: Preprocessor oom with nested vector operations
           Product: gcc
           Version: 3.4.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: preprocessor
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pochini at shiny dot it
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: powerpc-unknown-linux-gnu
  GCC host triplet: powerpc-unknown-linux-gnu
GCC target triplet: powerpc-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19821