On 5/21/19 1:51 PM, Richard Biener wrote: > On Tue, May 21, 2019 at 1:02 PM Martin Liška wrote: >> >> On 5/21/19 11:38 AM, Richard Biener wrote: >>> On Tue, May 21, 2019 at 12:07 AM Jeff Law 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 >>>>>>>> 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 >>>>>>>> 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 >>>>>>>> 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::verify(ao_ref* const&, unsigned int) /home/marxin/Programming/gcc/gcc/hash-table.h:1040 0xe504ea hash_table::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 ? Thanks, Martin > I guess PR90450 is "real" indeed... > > Richard. > >> Martin >> >>> >>> Richard. >>> >>>> >>>> Jeff >>