Re: gcc2.95, libttf2, xfree86, and Alpha

["Christopher C. Chimelis" <chris@debian.org>]

With any luck, we should be using a newer gcc soon, so this should go away
then.  I don't know a time schedule yet, but we'll be going to gcc 3.2,
fyi.

C

On Mon, 12 Aug 2002, Doug Larrick wrote:

> Due to what appears to be a code generation issue, libttf2 
> 1.4pre.20011029-1 and XFree86 4.2 segfault on Alpha when attempting to 
> render some TrueType fonts.
> 
> I have not fully traced this code gen error to the source that triggers it 
> in libttf2, but it appears to be similar to the one in gtk+ where adjacent 
> 'short' fields in a struct get corrupted when writing into one or the 
> other.  You can reproduce it by building the source for libttf2 and 
> running the example programs (I used 'ftview 12 Arial.ttf').
> 
> Compiling libttf2 without -O2 (without any -O flag) on Alpha works around 
> this problem, as does compiling with gcc-3.0.  I would recommend to the 
> libttf2 maintainer to follow one of these courses of action to close this 
> bug. (I'll forward this message to the bug).
> 
> The situation in XFree86 is more difficult.  This bug is pretty major for 
> X because any attempt to use an affected TrueType font causes the server 
> to exit.  This bug has been present for a long time (certainly since 
> XFree86 4.1) and is still present in 4.2.  X uses the freetype sources 
> (major version 1, now renamed libttf2 by Debian) directly, building pieces 
> of the library into the libfreetype.a extension module, rather than 
> relying on the library from the package.  I can see four ways around the 
> bug for X:
> 
> * Modify this extension's build procedure, on Alpha, to not use 
> optimization.  We certainly don't want to compile the entire X server 
> without optimization.
> * Build X with gcc-3.0.  I have built the latest experimental XFree86 4.2 
> packages with gcc-3.0 and they do fix this problem, and seem to work OK.
> * Get X to switch to freetype 2 (libfreetype6 on Debian).  This is a 
> non-trivial change, as the API was completely rewritten.  Freetype 2 also 
> has problems on Alpha (e.g. misrendered glyphs) but I have not yet looked 
> into them.
> * Find the code that triggers this code gen bug and modify it to make the 
> compiler happy.  This approach turned out to be unworkable for gtk+ on 
> Alpha because there were other similar failures.
> 
> Comments?
> 
> -Doug
> 
> 
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