Messages in this thread | | | Date | Tue, 27 Oct 2009 14:50:25 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] perf tools: Kill off -Wcast-align |
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* David Miller <davem@davemloft.net> wrote:
> From: Paul Mundt <lethal@linux-sh.org> > Date: Mon, 26 Oct 2009 18:47:30 +0900 > > > On Mon, Oct 26, 2009 at 07:25:20AM +0100, Ingo Molnar wrote: > >> > >> * Paul Mundt <lethal@linux-sh.org> wrote: > >> > >> > The present use of -Wcast-align causes the build to blow up on SH due to > >> > generating a "cast increases required alignment of target type" error on > >> > each invocation of list_for_each_entry(). > >> > > >> > It seems that this was previously reported and killed off in the ia64 > >> > support patch, but nothing seems to have happened with that. Presumably > >> > the same problem still remains there, too. > >> > > >> > Signed-off-by: Paul Mundt <lethal@linux-sh.org> > >> > >> Is this a GCC bug producing false positive warnings? The GCC manpage > >> says: > >> > >> -Wcast-align > >> Warn whenever a pointer is cast such that the required alignment of the > >> target is increased. For example, warn if a "char *" is cast to an > >> "int *" on machines where integers can only be accessed at two- or > >> four-byte boundaries. > >> > >> Which looks moderately useful - if it works. > >> > > Well, both ia64 and sh have hit this in the current compilers, and it > > doesn't seem to pose any code generation issues. In the areas where it is > > generated it seems to relate to 64-bit data types in the data structures, > > which in itself doesn't seem inherently problematic. > > sparc64 hits this too when building 32-bit perf binary, the first > thing I do after a pull is remove this warning option from the > Makefile :-)
Generally if you run into such issues in Sparc let us know so we can fix it :-)
Paul's fix is queued up for Linus.
Ingo
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