You have to remember that integers are four bytes long, so you're actually trying to allocate an array of 4 * 2^29 bytes = 2,147,483,648 bytes. Note that this is one more than the theoretical maximum of 2^31 - 1 = 2,147,483,647. So, this does not appear to be a bug in the compiler, but probably expected behavior on a 32 bit machine. Thanks, Lyle -----Original Message----- From: gcc-help-owner@xxxxxxxxxxx [mailto:gcc-help-owner@xxxxxxxxxxx] On Behalf Of fdeng Sent: Wednesday, June 16, 2004 5:47 PM To: gcc-help@xxxxxxxxxxx Cc: fdeng@xxxxxxxxxxx Subject: gcc array size limitation problem Hi all, I used malloc() to create a large array. When array size m=2^28, no problem, but when m=2^29, it failed and malloc() returned NULL. My code is as follows: B = (unsigned int *)malloc(m*sizeof(unsigned int)); I used gcc 3.2.2 and then tried gcc 3.4.0, all failed. I searched the archive and found a similar problem of g77 and its answer. However, it seems not for gcc. Any ideas? Thanks a lot, Fan The similar mail I found is attached below: /********************************************** ignat wrote: > Using g77 (GNU project Fortran Compiler, v0.5.24) I have encountered a > problem of array size limitation. > I found out that size of an array is limited to 2^27 -1 = 134 217 728, > while integer itself can be 2^31 -1 = 2 147 483 647. > I actually need an array with 600 000 000 numbers. What can I do? I fixed this for the 3.1 release, basically by removing a check that I proved unnecessarily strict. So you could try out a recent snapshot of gcc/g77 (see our home page at http://gcc.gnu.org, entry "Snapshots" in the left column). However, one shouldn't use snapshot compilers for production work. Another option is to apply the following patch to a recent release (see entry "Releases" in the left column) and build that compiler. Hope this helps, -- Toon Moene - mailto:toon@xxxxxxxxxxxxxxxxxxxx - phoneto: +31 346 214290 Saturnushof 14, 3738 XG Maartensdijk, The Netherlands Maintainer, GNU Fortran 77: http://gcc.gnu.org/onlinedocs/g77_news.html Join GNU Fortran 95: http://g95.sourceforge.net/ (under construction) 2001-10-22 Toon Moene <toon@xxxxxxxxxxxxxxxxxxxx> * com.c (ffecom_check_size_overflow_): Only check for TREE_OVERFLOW. *** com.c.orig Fri Oct 19 14:59:44 2001 --- com.c Sun Oct 21 14:17:15 2001 *************** ffecom_check_size_overflow_ (ffesymbol s *** 2267,2272 **** if ((tree_int_cst_sgn (TYPE_SIZE (type)) < 0) ! || (!dummy && (((TREE_INT_CST_HIGH (TYPE_SIZE (type)) != 0)) ! || TREE_OVERFLOW (TYPE_SIZE (type))))) { ffebad_start (FFEBAD_ARRAY_LARGE); --- 2267,2271 ---- if ((tree_int_cst_sgn (TYPE_SIZE (type)) < 0) ! || (!dummy && TREE_OVERFLOW (TYPE_SIZE (type)))) { ffebad_start (FFEBAD_ARRAY_LARGE);
