Re: [RFTesting] New POINTER_DIFF_EXPR

[Christophe Lyon <christophe dot lyon at linaro dot org>]

On 22 November 2017 at 09:29, Marc Glisse <marc.glisse@inria.fr> wrote:
> On Wed, 22 Nov 2017, Marc Glisse wrote:
>
>> On Wed, 22 Nov 2017, Christophe Lyon wrote:
>>
>>> Since you committed this patch (r255021), my cross-builds of GCC for
>>> aarch64-linux-gnu fail while building glibc:
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/tools/bin/aarch64-none-linux-gnu-gcc
>>> fetch-value.c -c -std=gnu99 -fgnu89-inline  -O2 -Wall -Winline -Wundef
>>> -Wwrite-string
>>> s -fmerge-all-constants -frounding-math -g -Wstrict-prototypes   -fPIC
>>>       -I../include
>>>
>>>
>>> -I/tmp/6857183_6.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-aarch64-none-linux-gnu/gl
>>> ibc-1/nptl_db
>>> -I/tmp/6857183_6.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-aarch64-none-linux-gnu/glibc-1
>>> -I../sysdeps/unix/sysv/linux/aarch64/nptl  -I../sysdeps/unix/sysv/lin
>>> ux/aarch64  -I../sysdeps/unix/sysv/linux/generic
>>> -I../sysdeps/unix/sysv/linux/wordsize-64
>>> -I../nptl/sysdeps/unix/sysv/linux  -I../nptl/sysdeps/pthread
>>> -I../sysdeps/pthread  -I
>>> ../sysdeps/unix/sysv/linux  -I../sysdeps/gnu  -I../sysdeps/unix/inet
>>> -I../nptl/sysdeps/unix/sysv  -I../sysdeps/unix/sysv
>>> -I../nptl/sysdeps/unix  -I../sysdeps/unix  -I../sysdeps
>>> /posix  -I../sysdeps/aarch64/fpu  -I../sysdeps/aarch64/nptl
>>> -I../sysdeps/aarch64  -I../sysdeps/wordsize-64
>>> -I../sysdeps/ieee754/ldbl-128  -I../sysdeps/ieee754/dbl-64/wordsize-6
>>> 4  -I../sysdeps/ieee754/dbl-64  -I../sysdeps/ieee754/flt-32
>>> -I../sysdeps/aarch64/soft-fp  -I../sysdeps/ieee754
>>> -I../sysdeps/generic  -I../nptl  -I.. -I../libio -I. -nostdinc -i
>>> system
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/tools/lib/gcc/aarch64-none-linux-gnu/8.0.0/include
>>> -isystem /tmp/6857183_6.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc
>>> /tools/lib/gcc/aarch64-none-linux-gnu/8.0.0/include-fixed -isystem
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/sysroot-aarch64-none-linux-gnu/usr/include
>>> -D_LIBC_REE
>>> NTRANT -include ../include/libc-symbols.h  -DPIC -DSHARED
>>> -DNOT_IN_libc=1 -DIS_IN_libthread_db=1 -DIN_LIB=libthread_db    -o
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccs
>>> rc/obj-aarch64-none-linux-gnu/glibc-1/nptl_db/fetch-value.os -MD -MP
>>> -MF
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-aarch64-none-linux-gnu/glibc-1/nptl_db/fetch-
>>> value.os.dt -MT
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/builds/gcc-fsf-gccsrc/obj-aarch64-none-linux-gnu/glibc-1/nptl_db/fetch-value.os
>>> during GIMPLE pass: vrp
>>> fetch-value.c: In function '_td_locate_field':
>>> fetch-value.c:44:1: internal compiler error: Segmentation fault
>>> _td_locate_field (td_thragent_t *ta,
>>> ^~~~~~~~~~~~~~~~
>>> 0xb87c75 crash_signal
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/toplev.c:325
>>> 0x5b1934 contains_struct_check
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/tree.h:3459
>>> 0x5b1934 wi::to_wide(tree_node const*)
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/tree.h:5247
>>> 0xf05557 vr_values::two_valued_val_range_p(tree_node*, tree_node**,
>>> tree_node**)
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/vr-values.c:4051
>>> 0xf0ee48 vr_values::simplify_stmt_using_ranges(gimple_stmt_iterator*)
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/vr-values.c:4115
>>> 0xd7068f
>>> substitute_and_fold_dom_walker::before_dom_children(basic_block_def*)
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/tree-ssa-propagate.c:1073
>>> 0x1204860 dom_walker::walk(basic_block_def*)
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/domwalk.c:308
>>> 0xd6e805 substitute_and_fold_engine::substitute_and_fold()
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/tree-ssa-propagate.c:1173
>>> 0xe71b0b vrp_prop::vrp_finalize(bool)
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/tree-vrp.c:6788
>>> 0xe81667 execute_vrp
>>>
>>> /tmp/6857183_6.tmpdir/aci-gcc-fsf/sources/gcc-fsf/gccsrc/gcc/tree-vrp.c:6864
>>> Please submit a full bug report,
>>
>>
>> Looks like PR 83104.
>>
>> (I am a bit curious what the code looks like, since the testcase in the PR
>> is rather on the undefined side of things, though ok for something embedded)
>
>
>   if (idx != 0 && DB_DESC_NELEM (desc) != 0
>       && idx - (psaddr_t) 0 > DB_DESC_NELEM (desc))
>
> "idx - (psaddr_t) 0": glibc should probably avoid doing pointer arithmetic
> with a null pointer, "(ptrdiff_t) idx" looks equivalent.
>

The patch you attached in PR83104 works for me (at least the build
completes, I haven't run the tests)

Thanks,

Christophe

> --
> Marc Glisse