Make fails compiling GCC

The fact that with optimization level of -O1 or lower, 64-bit Ubuntu manages to compile the project, means that the problem lies with the optimization phase of gcc.

I would guess that some source-file in your project happens upon a bug or inefficiency in the gcc optimizer introduced in version 4.7.2. which causes the use of an unreasonable amount of memory.

So what I would suggest is :

1. A 32-bit version of gcc can only access 2-3 GB of memory (whatever size is the swap).
2. Enlarge the swap space, but keep on reading if this doesn't help. In any case, for a 32-bit gcc there will be a limit to the amount of memory that it can use.
3. By compiling the source files one-by-one, find the one that is responsible for the problem. If this is all of them, then the problem is with some include file(s).
4. If the problem is not with an include file, further break up the problematic source file into several parts, until you either stop getting the error or you locate the very function that causes it.
5. As a temporary workaround, modify the make file so as to compile that function with -O1. The problem is in this case with gcc itself, and you can submit that function in a bug report (together with all your include files).
6. You can of course also opt to compile the entire project with -O1 which should be sufficient for a PHP extension, or stay with gcc 4.6.3 for the moment.
7. Keep on trying out new updates to gcc, since the bug could be fixed (or the inefficiency removed) unrelatedly to your bug report.

This was fixed by installing libcrypt-devel.

Then everything worked just fine... So problem solved!

This explains it better: Re: Difficult compiling Package::Stash::XS