[U-Boot-Users] [PATCH] Squash warnings from pointer aliasing in dlmalloc

Wolfgang Denk wd at denx.de
Sun Jul 6 00:32:02 CEST 2008


In message <Pine.LNX.4.64.0806042337200.650 at blarg.am.freescale.net> you wrote:
> When we building with gcc-4.3.x on a ppc host we get the following warnings:
> 
> dlmalloc.c: In function 'malloc_extend_top':
> dlmalloc.c:1971: warning: dereferencing type-punned pointer will break strict-aliasing rules
> dlmalloc.c:1999: warning: dereferencing type-punned pointer will break strict-aliasing rules
...
> This is due to pointer aliasing that the dlmalloc code does and depends on.

Can you please explain why the dlmalloc code depends on this?

In my experience so far it has always been possible to avoid such
warnings by trivial changes to the code (the tricky part was usually
to understand what the exact problem was and what changes were
necessary).

> Instead of trying trying to work around the warnings, we use the per file
> CFLAGs to disable the warnings via -fno-strict-aliasing.

I tend to reject this patch. I would much rather have the problem
fixed in the sources. Hushing up compiler warnings has never been a
good idea.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
Our business is run on trust.  We trust you will pay in advance.




More information about the U-Boot mailing list