[Bug middle-end/18938] Out of memory with many select case statements

["Thomas dot Koenig at online dot de" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From Thomas dot Koenig at online dot de  2004-12-12 10:42 -------
(In reply to comment #2)
> Speculations I'd put money on if the bookies would accept it: 
> 1) You can show this same problem with C/C++ if you have enough cases.

Yes.

$ time ./multi-case-c 150000 > multi-case.c
$ gcc multi-case.c

cc1: out of memory allocating 2815331376 bytes after a total of 10571776 bytes
$ gcc -v
Reading specs from /home/ig25/lib/gcc/i686-pc-linux-gnu/4.0.0/specs
Configured with: ../gcc/configure --prefix=/home/ig25 --enable-languages=c,c++,f95
Thread model: posix
gcc version 4.0.0 20041208 (experimental)
$ cat multi-case-c
#! /usr/bin/perl

$last = shift;

for ($i=1; $i<=$last; $i++) {
    push(@lines, sprintf("    case %d:\n         j = %d;\n    break;\n", $i,
$last-$i));
}
for ($i=0; $i<=$last; $i++) {
    $j = int(rand($last));
    $temp = $lines[$i];
    $lines[$i] = $lines[$j];
    $lines[$j] = $temp;
}
print <<EOF;
#include <stdio.h>
int main()
{
    int i,j;
    scanf("%d",&i);
    switch(i) {
EOF
print @lines;
print <<EOF;
    }
    printf("%d\\n",i);
    return 0;
}
EOF
$ ./multi-case-c 4
#include <stdio.h>
int main()
{
    int i,j;
    scanf("%d",&i);
    switch(i) {
    case 2:
         j = 2;
    break;
    case 4:
         j = 0;
    break;
    case 3:
         j = 1;
    break;
    case 1:
         j = 3;
    break;
    }
    printf("%d\n",i);
    return 0;

This isn't a regression, gcc 3.3 had the same problem:

$ /usr/bin/gcc multi-case.c

cc1: out of memory allocating 2815312608 bytes after a total of 18419712 bytes
$ /usr/bin/gcc -v
Reading specs from /usr/lib/gcc-lib/i486-linux/3.3.5/specs
Configured with: ../src/configure -v
--enable-languages=c,c++,java,f77,pascal,objc,ada,treelang --prefix=/usr
--mandir=/usr/share/man
--infodir=/usr/share/info--with-gxx-include-dir=/usr/include/c++/3.3
--enable-shared --with-system-zlib --enable-nls --without-included-gettext
--enable-__cxa_atexit --enable-clocale=gnu --enable-debug --enable-java-gc=boehm
--enable-java-awt=xlib --enable-objc-gci486-linux
Thread model: posix
gcc version 3.3.5 (Debian 1:3.3.5-3)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18938