On Fri, Jun 7, 2019 at 5:04 AM Martin Liška <mli...@suse.cz> wrote:
>
> On 6/7/19 10:57 AM, Richard Biener wrote:
> > On Mon, Jun 3, 2019 at 3:35 PM Martin Liška <mli...@suse.cz> wrote:
> >>
> >> On 6/1/19 12:06 AM, Jeff Law wrote:
> >>> On 5/22/19 3:13 AM, Martin Liška wrote:
> >>>> On 5/21/19 1:51 PM, Richard Biener wrote:
> >>>>> On Tue, May 21, 2019 at 1:02 PM Martin Liška <mli...@suse.cz> wrote:
> >>>>>>
> >>>>>> On 5/21/19 11:38 AM, Richard Biener wrote:
> >>>>>>> On Tue, May 21, 2019 at 12:07 AM Jeff Law <l...@redhat.com> wrote:
> >>>>>>>>
> >>>>>>>> On 5/13/19 1:41 AM, Martin Liška wrote:
> >>>>>>>>> On 11/8/18 9:56 AM, Martin Liška wrote:
> >>>>>>>>>> On 11/7/18 11:23 PM, Jeff Law wrote:
> >>>>>>>>>>> On 10/30/18 6:28 AM, Martin Liška wrote:
> >>>>>>>>>>>> On 10/30/18 11:03 AM, Jakub Jelinek wrote:
> >>>>>>>>>>>>> On Mon, Oct 29, 2018 at 04:14:21PM +0100, Martin Liška wrote:
> >>>>>>>>>>>>>> +hashtab_chk_error ()
> >>>>>>>>>>>>>> +{
> >>>>>>>>>>>>>> + fprintf (stderr, "hash table checking failed: "
> >>>>>>>>>>>>>> + "equal operator returns true for a pair "
> >>>>>>>>>>>>>> + "of values with a different hash value");
> >>>>>>>>>>>>> BTW, either use internal_error here, or at least if using
> >>>>>>>>>>>>> fprintf
> >>>>>>>>>>>>> terminate with \n, in your recent mail I saw:
> >>>>>>>>>>>>> ...different hash valueduring RTL pass: vartrack
> >>>>>>>>>>>>> ^^^^^^
> >>>>>>>>>>>> Sure, fixed in attached patch.
> >>>>>>>>>>>>
> >>>>>>>>>>>> Martin
> >>>>>>>>>>>>
> >>>>>>>>>>>>>> + gcc_unreachable ();
> >>>>>>>>>>>>>> +}
> >>>>>>>>>>>>> Jakub
> >>>>>>>>>>>>>
> >>>>>>>>>>>> 0001-Sanitize-equals-and-hash-functions-in-hash-tables.patch
> >>>>>>>>>>>>
> >>>>>>>>>>>> From 0d9c979c845580a98767b83c099053d36eb49bb9 Mon Sep 17
> >>>>>>>>>>>> 00:00:00 2001
> >>>>>>>>>>>> From: marxin <mli...@suse.cz>
> >>>>>>>>>>>> Date: Mon, 29 Oct 2018 09:38:21 +0100
> >>>>>>>>>>>> Subject: [PATCH] Sanitize equals and hash functions in
> >>>>>>>>>>>> hash-tables.
> >>>>>>>>>>>>
> >>>>>>>>>>>> ---
> >>>>>>>>>>>> gcc/hash-table.h | 40 +++++++++++++++++++++++++++++++++++++++-
> >>>>>>>>>>>> 1 file changed, 39 insertions(+), 1 deletion(-)
> >>>>>>>>>>>>
> >>>>>>>>>>>> diff --git a/gcc/hash-table.h b/gcc/hash-table.h
> >>>>>>>>>>>> index bd83345c7b8..694eedfc4be 100644
> >>>>>>>>>>>> --- a/gcc/hash-table.h
> >>>>>>>>>>>> +++ b/gcc/hash-table.h
> >>>>>>>>>>>> @@ -503,6 +503,7 @@ private:
> >>>>>>>>>>>>
> >>>>>>>>>>>> value_type *alloc_entries (size_t n CXX_MEM_STAT_INFO) const;
> >>>>>>>>>>>> value_type *find_empty_slot_for_expand (hashval_t);
> >>>>>>>>>>>> + void verify (const compare_type &comparable, hashval_t hash);
> >>>>>>>>>>>> bool too_empty_p (unsigned int);
> >>>>>>>>>>>> void expand ();
> >>>>>>>>>>>> static bool is_deleted (value_type &v)
> >>>>>>>>>>>> @@ -882,8 +883,12 @@ hash_table<Descriptor, Allocator>
> >>>>>>>>>>>> if (insert == INSERT && m_size * 3 <= m_n_elements * 4)
> >>>>>>>>>>>> expand ();
> >>>>>>>>>>>>
> >>>>>>>>>>>> - m_searches++;
> >>>>>>>>>>>> +#if ENABLE_EXTRA_CHECKING
> >>>>>>>>>>>> + if (insert == INSERT)
> >>>>>>>>>>>> + verify (comparable, hash);
> >>>>>>>>>>>> +#endif
> >>>>>>>>>>>>
> >>>>>>>>>>>> + m_searches++;
> >>>>>>>>>>>> value_type *first_deleted_slot = NULL;
> >>>>>>>>>>>> hashval_t index = hash_table_mod1 (hash, m_size_prime_index);
> >>>>>>>>>>>> hashval_t hash2 = hash_table_mod2 (hash, m_size_prime_index);
> >>>>>>>>>>>> @@ -930,6 +935,39 @@ hash_table<Descriptor, Allocator>
> >>>>>>>>>>>> return &m_entries[index];
> >>>>>>>>>>>> }
> >>>>>>>>>>>>
> >>>>>>>>>>>> +#if ENABLE_EXTRA_CHECKING
> >>>>>>>>>>>> +
> >>>>>>>>>>>> +/* Report a hash table checking error. */
> >>>>>>>>>>>> +
> >>>>>>>>>>>> +ATTRIBUTE_NORETURN ATTRIBUTE_COLD
> >>>>>>>>>>>> +static void
> >>>>>>>>>>>> +hashtab_chk_error ()
> >>>>>>>>>>>> +{
> >>>>>>>>>>>> + fprintf (stderr, "hash table checking failed: "
> >>>>>>>>>>>> + "equal operator returns true for a pair "
> >>>>>>>>>>>> + "of values with a different hash value\n");
> >>>>>>>>>>>> + gcc_unreachable ();
> >>>>>>>>>>>> +}
> >>>>>>>>>>> I think an internal_error here is probably still better than a
> >>>>>>>>>>> simple
> >>>>>>>>>>> fprintf, even if the fprintf is terminated with a \n :-)
> >>>>>>>>>> Fully agree with that, but I see a lot of build errors when using
> >>>>>>>>>> internal_error.
> >>>>>>>>>>
> >>>>>>>>>>> The question then becomes can we bootstrap with this stuff
> >>>>>>>>>>> enabled and
> >>>>>>>>>>> if not, are we likely to soon? It'd be a shame to put it into
> >>>>>>>>>>> EXTRA_CHECKING, but then not be able to really use EXTRA_CHECKING
> >>>>>>>>>>> because we've got too many bugs to fix.
> >>>>>>>>>> Unfortunately it's blocked with these 2 PRs:
> >>>>>>>>>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87845
> >>>>>>>>>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87847
> >>>>>>>>> Hi.
> >>>>>>>>>
> >>>>>>>>> I've just added one more PR:
> >>>>>>>>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90450
> >>>>>>>>>
> >>>>>>>>> I'm sending updated version of the patch that provides a
> >>>>>>>>> disablement for the 3 PRs
> >>>>>>>>> with a new function disable_sanitize_eq_and_hash.
> >>>>>>>>>
> >>>>>>>>> With that I can bootstrap and finish tests. However, I've done that
> >>>>>>>>> with a patch
> >>>>>>>>> limits maximal number of checks:
> >>>>>>>> So rather than call the disable_sanitize_eq_and_hash, can you have
> >>>>>>>> its
> >>>>>>>> state set up when you instantiate the object? It's not a huge deal,
> >>>>>>>> just thinking about loud.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> So how do we want to go forward, particularly the EXTRA_EXTRA
> >>>>>>>> checking
> >>>>>>>> issue :-)
> >>>>>>>
> >>>>>>> There is at least one PR where we have a table where elements _in_ the
> >>>>>>> table are never compared against each other but always against another
> >>>>>>> object (I guess that's usual even), but the setup is in a way that the
> >>>>>>> comparison function only works with those. With the patch we verify
> >>>>>>> hashing/comparison for something that is never used.
> >>>>>>>
> >>>>>>> So - wouldn't it be more "correct" to only verify comparison/hashing
> >>>>>>> at lookup time, using the object from the lookup and verify that
> >>>>>>> against
> >>>>>>> all other elements?
> >>>>>>
> >>>>>> I don't a have problem with that. Apparently this changes fixes
> >>>>>> PR90450 and PR87847.
> >>>>>>
> >>>>>> Changes from previous version:
> >>>>>> - verification happens only when an element is searched (not inserted)
> >>>>>> - new argument 'sanitize_eq_and_hash' added for hash_table::hash_table
> >>>>>> - new param has been introduced hash-table-verification-limit in order
> >>>>>> to limit number of elements that are compared within a table
> >>>>>> - verification happens only with flag_checking >= 2
> >>>>>>
> >>>>>> I've been bootstrapping and testing the patch right now.
> >>>>>
> >>>>> Looks like I misremembered the original patch. The issue isn't
> >>>>> comparing random two elements in the table.
> >>>>>
> >>>>> That it fixes PR90450 is because LIM never calls find_slot_with_hash
> >>>>> without INSERTing.
> >>>>>
> >>>>
> >>>> There's updated version of the patch where I check all find operations
> >>>> (both w/ and w/o insertion).
> >>>>
> >>>> Patch can bootstrap on x86_64-linux-gnu and survives regression tests
> >>>> except for:
> >>>>
> >>>> $ ./xgcc -B.
> >>>> /home/marxin/Programming/gcc/gcc/testsuite/gcc.dg/torture/pr63941.c -O2
> >>>> -c
> >>>> hash table checking failed: equal operator returns true for a pair of
> >>>> values with a different hash value
> >>>> during GIMPLE pass: lim
> >>>> /home/marxin/Programming/gcc/gcc/testsuite/gcc.dg/torture/pr63941.c: In
> >>>> function ‘fn1’:
> >>>> /home/marxin/Programming/gcc/gcc/testsuite/gcc.dg/torture/pr63941.c:6:1:
> >>>> internal compiler error: in hashtab_chk_error, at hash-table.h:1019
> >>>> 6 | fn1 ()
> >>>> | ^~~
> >>>> 0x6c5725 hashtab_chk_error
> >>>> /home/marxin/Programming/gcc/gcc/hash-table.h:1019
> >>>> 0xe504ea hash_table<mem_ref_hasher, false, xcallocator>::verify(ao_ref*
> >>>> const&, unsigned int)
> >>>> /home/marxin/Programming/gcc/gcc/hash-table.h:1040
> >>>> 0xe504ea hash_table<mem_ref_hasher, false,
> >>>> xcallocator>::find_slot_with_hash(ao_ref* const&, unsigned int,
> >>>> insert_option)
> >>>> /home/marxin/Programming/gcc/gcc/hash-table.h:960
> >>>> 0xe504ea gather_mem_refs_stmt
> >>>> /home/marxin/Programming/gcc/gcc/tree-ssa-loop-im.c:1501
> >>>> 0xe504ea analyze_memory_references
> >>>> /home/marxin/Programming/gcc/gcc/tree-ssa-loop-im.c:1625
> >>>> 0xe504ea tree_ssa_lim
> >>>> /home/marxin/Programming/gcc/gcc/tree-ssa-loop-im.c:2646
> >>>> 0xe504ea execute
> >>>> /home/marxin/Programming/gcc/gcc/tree-ssa-loop-im.c:2708
> >>>>
> >>>> Richi: it's after your recent patch.
> >>>>
> >>>> For some reason I don't see PR87847 issue any longer.
> >>>>
> >>>>
> >>>> May I install the patch with disabled sanitization in tree-ssa-loop-im.c
> >>>> ?
> >>> Don't we still need to deal with the naked fprintf when there's a
> >>> failure. ie, shouldn't we be raising it with a gcc_assert or somesuch?
> >>
> >> Good point, I've just adjusted that.
> >>
> >> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> >>
> >> Ready to be installed?
> >
> > Ugh, the cselib one is really bad. But I don't hold my breath for anyone
> > fixing it ...
>
> Yes :D It's been some time and there's no interest in the PR.
>
> >
> > One question - there's unconditional
> >
> > + if (m_sanitize_eq_and_hash)
> > + verify (comparable, hash);
> >
> > which will read a global variable and have (possibly not inline) call
> > to verify on a common path even with checking disabled. So I think
> > we want to compile this checking feature out for !CHECKING_P
> > or at least make the if __builtin_expect (..., 0), ::verify not
> > inlined and marked pure () (thus, !CHECKING_P is simplest ;)).
>
> Fixed. May I install the patch? The cselib issue can be solved later..
After this patch, when I do a configure with --disable-bootstrap, and
build with "gcc (Debian 7.3.0-18) 7.3.0", I get a lot of warnings of
the form
In file included from ../../gccgo3/gcc/coretypes.h:440:0,
from ../../gccgo3/gcc/go/go-system.h:137,
from ../../gccgo3/gcc/go/gofrontend/go.cc:7:
../../gccgo3/gcc/hash-table.h:1017:1: warning: ‘void
hashtab_chk_error()’ defined but not used [-Wunused-function]
hashtab_chk_error ()
^~~~~~~~~~~~~~~~~
These are just warnings, since I am using --disable-bootstrap, but
they are distracting.
This patch fixes it. OK for trunk?
Ian
2019-06-23 Ian Lance Taylor <i...@golang.org>
* hash-table.h (hashtab_chk_error): Add ATTRIBUTE_UNUSED.
Index: hash-table.h
===================================================================
--- hash-table.h (revision 272609)
+++ hash-table.h (working copy)
@@ -1012,7 +1012,7 @@ hash_table<Descriptor, Lazy, Allocator>
/* Report a hash table checking error. */
-ATTRIBUTE_NORETURN ATTRIBUTE_COLD
+ATTRIBUTE_NORETURN ATTRIBUTE_COLD ATTRIBUTE_UNUSED
static void
hashtab_chk_error ()
{
