> -----Original Message----- > From: > avr-gcc-list-bounces+eric.weddington=atmel....@nongnu.org > [mailto:avr-gcc-list-bounces+eric.weddington=atmel....@nongnu. > org] On Behalf Of Sean D'Epagnier > Sent: Saturday, May 09, 2009 1:36 PM > To: avr-gcc-list@nongnu.org > Subject: [avr-gcc-list] mcall-prologues completely broken for >128k > > Hi, I originally thought my extensive used of the gcc extension > "Address labels" was the cause of my problems. After inspection of > the assembly I realized that they worked perfectly via the trampoline > mechanism.. so what was the problem? > > I found that prologue_saves calls eijmp at the end, which makes sense, > it gets back to the function it was in. However, the EIND register is > not set which means it jumps to the wrong section if the function was > in the upper section. > > I verified it by recompiling everything (including avr-libc) without > -mcall_prologues and the program seems to run.. (before there was no > luck) > > This issue is pretty easy to fix.. I can set EIND before jumping to > prologue_saves.. but this would break when the next eijmp or eicall > instruction is executed if I don't set EIND back to 0. > > The thing confusing me the most right now, is why gcc currently emits > eijmp or eicall at all. Since EIND is _never_ set, why did someone go > to all the trouble to make gcc emit eijmp and eicall? I want to > change gcc to use ijmp and icall always.. then in libgcc.S use eijmp, > and set EIND in prologue_saves and I won't have to bother restoring > it. > > If I'm confused about something, or there is a better explanation, let > me know. I'm going to modify gcc and have a patch for this soon.
Known issue. There is a bug report in the WinAVR bug database about it (EIND not being set correctly). I have recently changed avr-libc (in HEAD and 1.6 branch) to compile the libs without -mcall-prologues because I ran into this very problem. A patch to GCC to fix the EIND issue would be *very* welcome and I would include it in the next WinAVR release. _______________________________________________ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
