[3.3 branch] IA64 bootstrap failure

[Zack Weinberg]

Hans-Peter Nilsson <hp@bitrange.com> writes:

> On Tue, 8 Jul 2003, H. J. Lu wrote:
>> On Tue, Jul 08, 2003 at 04:30:11PM -0700, Jim Wilson wrote:
>> > On Tue, 2003-07-08 at 15:56, S. Bosscher wrote:
>> > > Doesn't valgrind check for uninitialized/out-of-bounds memory refs?
>> > Ah, yes, I keep forgetting about valgrind.  Maybe I should try using it
>> > someday.
>> I tried valgrind with a cross compiler to ia64 from ix86. I didn't
>> find anything serious:
>>
>> http://gcc.gnu.org/ml/gcc/2003-07/msg00084.html
>
> It looks by "tried valgrind" you man running just plain valgrind
> instead of configure --enable-checking=valgrind. The latter
> would instrument the memory management inside GCC (and properly
> handle the mmap end+1 thingy), so without it you would miss that
> reused-pool-entries are actually uninitialized memory accesses.

For a bug like this, suggest also using --param ggc-min-expand=0
--param ggc-min-heapsize=0 on the file being miscompiled - this
forces a garbage collection run at every opportunity, which will
expose more uses of freed memory.  --enable-checking=gcac,valgrind
would have the same effect, but on everything, and the build would
probably run into August.

zw