On 04 March 2005 17:32, Kurt Roeckx wrote:
I have no idea what ghc has too do with gcc,
A bit of background: GHC uses gcc as a backend compiler. GHC generates C code that is compiled using gcc (we also have a native code generator for some platforms; but not for x86_64 yet).
or what the problem exactly is.
The problem is that gcc generates incorrect code for C code that uses global register variables. You won't have noticed this, because most programs don't use global register variables. GHC uses global register variables to speed up the generated code.
We have very little problems with gcc for the debian amd64 port. Our default compiler is still 3.3. This builds almost everything without problems, however we build a few mozilla packages with gcc-3.4.
All I can tell is that ghc6 seems to be working on debian amd64. It can build itself and things like that.
That build of ghc6 is what we call "unregisterised": it doesn't make use of register variables to speed up the generated code. IOW, it generates plain ANSI C code, which gcc compiles fine.
Can someone please give a test case (and show what to do) to see what is wrong?
Ok, here's a really simple example: $ cat bug.c register void * R1 __asm__("%r13"); extern void g(void); static void f(void) { R1 = g; goto *R1; } $ gcc -S -O bug.c $ And take a look at the generated assembly for the function f: f: .LFB2: movl $g, %eax jmp *%rax Note that the assignment to the global variable R1 has been lost. It works fine on x86 though: change the register variable to %esi and try it.
Out current default compiler in debian is: gcc version 3.3.5 (Debian 1:3.3.5-8)
The gcc 3.4 version is: gcc version 3.4.4 20050203 (prerelease) (Debian 3.4.3-9)
And ghc6 is at version 6.2.2-3.
I'm going to try with different versions of gcc. I've just submitted this bug report to the gcc guys. Cheers, Simon