GCC: Warnings with syzygy

[mcostalba]

I have this warnings when building with gcc

syzygy/tbprobe.cpp: In function ‘int probe_ab(Position&, int, int, int_)’:
syzygy/tbprobe.cpp:204:14: warning: array subscript is above array bounds [-Warray-bounds]
p[i++] = pop_lsb(&bb) ^ mirror;
^
syzygy/tbprobe.cpp:204:14: warning: array subscript is above array bounds [-Warray-bounds]
syzygy/tbprobe.cpp: In function ‘int Tablebases::probe_dtz(Position&, int_)’:
syzygy/tbprobe.cpp:314:14: warning: array subscript is above array bounds [-Warray-bounds]
p[i++] = pop_lsb(&bb) ^ mirror;
^
syzygy/tbprobe.cpp:314:14: warning: array subscript is above array bounds [-Warray-bounds]

[glinscott]

Which compiler?

[matthewlai]

I also get that.

Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin14.0.0
Thread model: posix

[mcostalba]

gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1)

On Sat, Jan 10, 2015 at 7:05 PM, Gary Linscott notifications@github.com
wrote:

Which compiler?

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[joergoster]

I only get that when compiling with debug=yes.
gcc version 4.9.2 (Ubuntu 4.9.2-0ubuntu1~14.04)

[zamar]

gcc is known to suffer from false positives in this area... especially with -O3

[zamar]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56273

[mcostalba]

Thanks for the link. Sadly it seems they simply don't care (after a failed
first attempt) to fix it.

On Wed, Jan 14, 2015 at 9:09 AM, Joona Kiiski notifications@github.com
wrote:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56273

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[zamar]

Ignore for SF6.

syzygy implementation will be worked on during SF7 anyway.

[zamar]

Good news. They have fixed the bug in the gcc5 branch :)

[Kingdefender]

Hi all,

This just for the record, I have recently installed the latest MinGW and, as reported by Felix on FishCooking also, it seems the issue is not fixed/back again, at least with current Stockfish master, you get the same warning. My version of GCC:
C:>GCC --version
GCC (i686-posix-dwarf-rev0, Built by MinGW-W64 project) 5.3.0
Copyright (C) 2015 Free Software Foundation, Inc.

Eelco

[zamar]

Still unfixed gcc bug:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59124

[vondele]

this issue can now be closed.

What about making gcc's -Werror (all warnings are error) part of the makefile now ?

[lantonov]

With Marco's syzygy rewrite and gcc-6.1.0 I no longer get this warning

[mcostalba]

Fixed by c0bb0415394179e9c771

[mstembera]

I get these warnings under MSVC w/ the new C++ syzygy implementation.
tbprobe.cpp(536): warning C4267: 'initializing': conversion from 'size_t' to 'uint32_t', possible loss of data
tbprobe.cpp(547): warning C4267: 'initializing': conversion from 'size_t' to 'int', possible loss of data
tbprobe.cpp(582): warning C4244: '=': conversion from 'uint64_t' to '`anonymous-namespace'::Sym', possible loss of data
tbprobe.cpp(983): warning C4267: '=': conversion from 'size_t' to 'int', possible loss of data
tbprobe.cpp(1010): warning C4267: 'initializing': conversion from 'size_t' to 'int', possible loss of data

[mcostalba]

Thanks for reporting. I knew them also by looking at Travis ci output after
each commit.

I don't plan to fix them because they are wrong (gcc and clang don't report
them) and the fix if is a bunch of casts it is very ugly too.

If you are able to fix them without using casts then it's ok.

On Tuesday, November 8, 2016, mstembera notifications@github.com wrote:

I get these warnings under MSVC w/ the new C++ syzygy implementation.
tbprobe.cpp(536): warning C4267: 'initializing': conversion from 'size_t'
to 'uint32_t', possible loss of data
tbprobe.cpp(547): warning C4267: 'initializing': conversion from 'size_t'
to 'int', possible loss of data
tbprobe.cpp(582): warning C4244: '=': conversion from 'uint64_t' to
'`anonymous-namespace'::Sym', possible loss of data
tbprobe.cpp(983): warning C4267: '=': conversion from 'size_t' to 'int',
possible loss of data
tbprobe.cpp(1010): warning C4267: 'initializing': conversion from 'size_t'
to 'int', possible loss of data

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