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Re: [PATCH] Fix bitmap_bit_in_range_p (PR tree-optimization/82493).
On 10/13/2017 04:59 PM, Jeff Law wrote:
> On 10/13/2017 07:02 AM, Martin Liška wrote:
>> On 10/12/2017 11:54 PM, Jeff Law wrote:
>>> On 10/11/2017 12:13 AM, Martin Liška wrote:
>>>> 2017-10-10 Martin Liska <mliska@suse.cz>
>>>>
>>>> PR tree-optimization/82493
>>>> * sbitmap.c (bitmap_bit_in_range_p): Fix the implementation.
>>>> (test_range_functions): New function.
>>>> (sbitmap_c_tests): Likewise.
>>>> * selftest-run-tests.c (selftest::run_tests): Run new tests.
>>>> * selftest.h (sbitmap_c_tests): New function.
>>> I went ahead and committed this along with a patch to fix the off-by-one
>>> error in live_bytes_read. Bootstrapped and regression tested on x86.
>>>
>>> Actual patch attached for archival purposes.
>>>
>>> Jeff
>>>
>>
>> Hello.
>>
>> I wrote a patch that adds various gcc_checking_asserts and I hit following:
>>
>> ./xgcc -B. /home/marxin/Programming/gcc/gcc/testsuite/gfortran.dg/char_result_12.f90 -c -O2
>> during GIMPLE pass: dse
>> /home/marxin/Programming/gcc/gcc/testsuite/gfortran.dg/char_result_12.f90:7:0:
>>
>> program testat
>>
>> internal compiler error: in bitmap_check_index, at sbitmap.h:105
>> 0x1c014c1 bitmap_check_index
>> ../../gcc/sbitmap.h:105
>> 0x1c01fa7 bitmap_bit_in_range_p(simple_bitmap_def const*, unsigned int, unsigned int)
>> ../../gcc/sbitmap.c:335
>> 0x1179002 live_bytes_read
>> ../../gcc/tree-ssa-dse.c:497
>> 0x117935a dse_classify_store
>> ../../gcc/tree-ssa-dse.c:595
>> 0x1179947 dse_dom_walker::dse_optimize_stmt(gimple_stmt_iterator*)
>> ../../gcc/tree-ssa-dse.c:786
>> 0x1179b6e dse_dom_walker::before_dom_children(basic_block_def*)
>> ../../gcc/tree-ssa-dse.c:853
>> 0x1a6f659 dom_walker::walk(basic_block_def*)
>> ../../gcc/domwalk.c:308
>> 0x1179cb9 execute
>> ../../gcc/tree-ssa-dse.c:907
>>
>> Where we call:
>> Breakpoint 1, bitmap_bit_in_range_p (bmap=0x29d6cd0, start=0, end=515) at ../../gcc/sbitmap.c:335
>> 335 bitmap_check_index (bmap, end);
>> (gdb) p *bmap
>> $1 = {n_bits = 256, size = 4, elms = {255}}
>>
>> Is it a valid call or should caller check indices?
> It doesn't look valid to me. I'll dig into it.
>
> In general the sbitmap interface requires callers to DTRT -- failure can
> easily lead to an out of bounds read or write. It's one of the things I
> really dislike about the sbitmap implementation.
>
> So it's safe to assume that I'm fully supportive of adding more testing
> to catch this kind thing.
>
> Jeff
>
Good.
Should I prepare fix for the ICE I mentioned or have you been working on that?
Thanks,
Martin