On Thu, Nov 16, 2017 at 4:08 AM, Martin Sebor <mse...@gmail.com> wrote: > On 11/15/2017 03:51 AM, Richard Biener wrote: >> >> On Tue, Nov 14, 2017 at 6:45 PM, Martin Sebor <mse...@gmail.com> wrote: >>> >>> On 11/14/2017 05:28 AM, Richard Biener wrote: >>>> >>>> >>>> On Mon, Nov 13, 2017 at 6:37 PM, Martin Sebor <mse...@gmail.com> wrote: >>>>> >>>>> >>>>> Richard, this thread may have been conflated with the one Re: >>>>> [PATCH] enhance -Warray-bounds to detect out-of-bounds offsets >>>>> (PR 82455) They are about different things. >>>>> >>>>> I'm still looking for approval of: >>>>> >>>>> https://gcc.gnu.org/ml/gcc-patches/2017-10/msg01208.html >>> >>> >>> >>> Sorry, I pointed to an outdated version. This is the latest >>> version: >>> >>> https://gcc.gnu.org/ml/gcc-patches/2017-10/msg01304.html >>> >>> My bad... >>> >>> >>>> >>>> + tree maxbound >>>> + = build_int_cst (sizetype, ~(1LLU << (TYPE_PRECISION (sizetype) - >>>> 1))); >>>> >>>> this looks possibly bogus. Can you instead use >>>> >>>> up_bound_p1 >>>> = wide_int_to_tree (sizetype, wi::div_trunc (wi::max_value >>>> (TYPE_PRECISION (sizetype), SIGNED), wi::to_wide (eltsize))); >>>> >>>> please? Note you are _not_ computing the proper upper bound here >>>> because >>>> that >>>> is what you compute plus low_bound. >>>> >>>> + up_bound_p1 = int_const_binop (TRUNC_DIV_EXPR, maxbound, >>>> eltsize); >>>> >>>> + >>>> + tree arg = TREE_OPERAND (ref, 0); >>>> + tree_code code = TREE_CODE (arg); >>>> + if (code == COMPONENT_REF) >>>> + { >>>> + HOST_WIDE_INT off; >>>> + if (tree base = get_addr_base_and_unit_offset (ref, &off)) >>>> + { >>>> + tree size = TYPE_SIZE_UNIT (TREE_TYPE (base)); >>>> + if (TREE_CODE (size) == INTEGER_CST) >>>> + up_bound_p1 = int_const_binop (MINUS_EXPR, up_bound_p1, size); >>>> >>>> I think I asked this multiple times now but given 'ref' is the >>>> variable array-ref >>>> a.b.c[i] when you call get_addr_base_and_unit_offset (ref, &off) you >>>> always >>>> get a NULL_TREE return value. >>>> >>>> So I asked you to pass it 'arg' instead ... which gets you the offset of >>>> a.b.c, which looks like what you intended to get anyway. >>>> >>>> I also wonder what you compute here - you are looking at the size of >>>> 'base' >>>> but that is the size of 'a'. You don't even use the computed offset! >>>> Which >>>> means you could have used get_base_address instead!? Also the type >>>> of 'base' may be completely off given MEM[&blk + 8].b.c[i] would return >>>> blk >>>> as base which might be an array of chars and not in any way related to >>>> the type of the innermost structure we access with COMPONENT_REFs. >>>> >>>> Why are you only looking at COMPONENT_REF args anyways? You >>>> don't want to handle a.b[3][i]? >>>> >>>> That is, I'd have expected you do >>>> >>>> if (get_addr_base_and_unit_offset (ref, &off)) >>>> up_bound_p1 = wide_int_to_tree (sizetype, wi::sub (wi::to_wide >>>> (up_bound_p1), off)); >> >> >> ^^^^^^^^^ > > > Please see the attached update.
Ok. Thanks, Richard. > Martin
