[compiler-rt] r183645 - tsan: fix old gcc warnings

[David Blaikie]

On Mon, Jun 10, 2013 at 4:15 AM, Dmitry Vyukov <dvyukov at google.com> wrote:
> On Mon, Jun 10, 2013 at 3:14 PM, Dmitry Vyukov <dvyukov at google.com> wrote:
>> It's gcc4.7 and it says:
>
> gcc gotsan.cc -S -o tmp.s -I../rtl -I../.. -I../../sanitizer_common
> -I../../../include -m64 -Wall -Werror -fno-exception
> s -fno-rtti -DTSAN_GO -DSANITIZER_GO -DTSAN_SHADOW_COUNT=4
> -Wno-error=attributes -Wno-attributes -DTSAN_DEBUG=0 -O3 -fom
> it-frame-pointer
> In file included from ../rtl/tsan_clock.h:17:0,
>                  from ../rtl/tsan_rtl.h:33,
>                  from gotsan.cc:14:
> ../rtl/tsan_vector.h: In function 'void
> __tsan::ReportRace(__tsan::ThreadState*)':
> ../rtl/tsan_vector.h:63:5: error: '*((void*)(&
> hash)+16).__tsan::MD5Hash::hash[1]' may be used uninitialized in this
> fun
> ction [-Werror=maybe-uninitialized]

We've disabled this warning in the LLVM/Clang builds (because of false
positives like this and adding explicit initialization removes the
ability for dynamic tools (such as msan, valgrind, etc) to detect an
actual failure to initialize (if the md5 hash function didn't write to
the whole value, etc)) - is there a reason it's not disabled in
compiler-rt?

> gotsan.cc:2709:14: note: '*((void*)(&
> hash)+16).__tsan::MD5Hash::hash[1]' was declared here
> In file included from ../rtl/tsan_clock.h:17:0,
>                  from ../rtl/tsan_rtl.h:33,
>                  from gotsan.cc:14:
> ../rtl/tsan_vector.h:63:5: error: '*((void*)(&
> hash)+16).__tsan::MD5Hash::hash[0]' may be used uninitialized in this
> fun
> ction [-Werror=maybe-uninitialized]
> gotsan.cc:2709:14: note: '*((void*)(&
> hash)+16).__tsan::MD5Hash::hash[0]' was declared here
> In file included from ../rtl/tsan_clock.h:17:0,
>                  from ../rtl/tsan_rtl.h:33,
>                  from gotsan.cc:14:
> ../rtl/tsan_vector.h:63:5: error: 'hash.__tsan::MD5Hash::hash[1]' may
> be used uninitialized in this function [-Werror=ma
> ybe-uninitialized]
> gotsan.cc:2709:14: note: 'hash.__tsan::MD5Hash::hash[1]' was declared here
> In file included from ../rtl/tsan_clock.h:17:0,
>                  from ../rtl/tsan_rtl.h:33,
>                  from gotsan.cc:14:
> ../rtl/tsan_vector.h:63:5: error: 'hash.__tsan::MD5Hash::hash[0]' may
> be used uninitialized in this function [-Werror=ma
> ybe-uninitialized]
> gotsan.cc:2709:14: note: 'hash.__tsan::MD5Hash::hash[0]' was declared here
> cc1plus.exe: all warnings being treated as errors
>
>
>
>> On Mon, Jun 10, 2013 at 2:38 PM, Alexey Samsonov <samsonov at google.com> wrote:
>>> I think this change will lead to warnings in the newer compilers. AFAIR
>>> we've dropped gcc 4.4 support in sanitizers. Is it needed for
>>> Go-ThreadSanitizer?
>>>
>>>
>>> On Mon, Jun 10, 2013 at 2:30 PM, Dmitry Vyukov <dvyukov at google.com> wrote:
>>>>
>>>> Author: dvyukov
>>>> Date: Mon Jun 10 05:30:19 2013
>>>> New Revision: 183645
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=183645&view=rev
>>>> Log:
>>>> tsan: fix old gcc warnings
>>>>
>>>> Modified:
>>>>     compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_report.cc
>>>>
>>>> Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_report.cc
>>>> URL:
>>>> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_report.cc?rev=183645&r1=183644&r2=183645&view=diff
>>>>
>>>> ==============================================================================
>>>> --- compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_report.cc (original)
>>>> +++ compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_report.cc Mon Jun 10 05:30:19
>>>> 2013
>>>> @@ -448,7 +448,7 @@ static bool HandleRacyStacks(ThreadState
>>>>      uptr addr_min, uptr addr_max) {
>>>>    Context *ctx = CTX();
>>>>    bool equal_stack = false;
>>>> -  RacyStacks hash;
>>>> +  RacyStacks hash = {};
>>>>    if (flags()->suppress_equal_stacks) {
>>>>      hash.hash[0] = md5_hash(traces[0].Begin(), traces[0].Size() *
>>>> sizeof(uptr));
>>>>      hash.hash[1] = md5_hash(traces[1].Begin(), traces[1].Size() *
>>>> sizeof(uptr));
>>>> @@ -488,7 +488,7 @@ static void AddRacyStacks(ThreadState *t
>>>>      uptr addr_min, uptr addr_max) {
>>>>    Context *ctx = CTX();
>>>>    if (flags()->suppress_equal_stacks) {
>>>> -    RacyStacks hash;
>>>> +    RacyStacks hash = {};
>>>>      hash.hash[0] = md5_hash(traces[0].Begin(), traces[0].Size() *
>>>> sizeof(uptr));
>>>>      hash.hash[1] = md5_hash(traces[1].Begin(), traces[1].Size() *
>>>> sizeof(uptr));
>>>>      ctx->racy_stacks.PushBack(hash);
>>>>
>>>>
>>>> _______________________________________________
>>>> llvm-commits mailing list
>>>> llvm-commits at cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>>
>>>
>>>
>>>
>>> --
>>> Alexey Samsonov, MSK
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