[compiler-rt] r227230 - tsan: properly instrument unaligned accesses

[Dmitry Vyukov]

On Fri, Jan 30, 2015 at 4:48 PM, Yury Gribov <y.gribov at samsung.com> wrote:
> On 01/27/2015 11:19 PM, Dmitry Vyukov wrote:
>>
>> Author: dvyukov
>> Date: Tue Jan 27 14:19:12 2015
>> New Revision: 227230
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=227230&view=rev
>> Log:
>> tsan: properly instrument unaligned accesses
>>
>> If a memory access is unaligned, emit __tsan_unaligned_read/write
>> callbacks instead of __tsan_read/write.
>> Required to change semantics of __tsan_unaligned_read/write to not do the
>> user memory.
>> But since they were unused (other than through
>> __sanitizer_unaligned_load/store) this is fine.
>> Fixes long standing issue 17:
>> https://code.google.com/p/thread-sanitizer/issues/detail?id=17
>
>
> FYI I've been seeing TSan regressions on Ubuntu 14 lately:
>
> FAIL: ThreadSanitizer :: aligned_vs_unaligned_race.cc (21921 of 22245)
> ******************** TEST 'ThreadSanitizer :: aligned_vs_unaligned_race.cc'
> FAILED ********************
> Script:
> --
> /home/ygribov/build/llvm-master-gcc/./bin/clang --driver-mode=g++
> -fsanitize=thread -Wall -m64 -gline-tables-only -O1
> /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/aligned_vs_unaligned_race.cc
> -o
> /home/ygribov/build/llvm-master-gcc/projects/compiler-rt/test/tsan/Output/aligned_vs_unaligned_race.cc.tmp
> && /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/deflake.bash
> /home/ygribov/build/llvm-master-gcc/projects/compiler-rt/test/tsan/Output/aligned_vs_unaligned_race.cc.tmp
> | FileCheck
> /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/aligned_vs_unaligned_race.cc
> --
> Exit Code: 2
>
> Command Output (stderr):
> --
> FileCheck error: '-' is empty.


Hi Yuri,

Please provide exact reproduction instructions.



> ********************
> FAIL: ThreadSanitizer :: simple_stack.c (22051 of 22245)
> ******************** TEST 'ThreadSanitizer :: simple_stack.c' FAILED
> ********************
> Script:
> --
> /home/ygribov/build/llvm-master-gcc/./bin/clang -fsanitize=thread -Wall -m64
> -gline-tables-only -O1
> /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/simple_stack.c
> -o
> /home/ygribov/build/llvm-master-gcc/projects/compiler-rt/test/tsan/Output/simple_stack.c.tmp
> && /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/deflake.bash
> /home/ygribov/build/llvm-master-gcc/projects/compiler-rt/test/tsan/Output/simple_stack.c.tmp
> | FileCheck
> /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/simple_stack.c
> --
> Exit Code: 1
>
> Command Output (stderr):
> --
> /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/simple_stack.c:52:16:
> error: expected string not found in input
> // CHECK-NEXT: #0 foo1{{.*}} {{.*}}simple_stack.c:7{{(:10)?}} ({{.*}})
>                ^
> <stdin>:4:2: note: scanning from here
>  #0 foo1
> /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/simple_stack.c:7:3
> (simple_stack.c.tmp+0x0000004962a4)
>  ^
> <stdin>:5:80: note: possible intended match here
>  #1 bar1
> /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/simple_stack.c:12:3
> (simple_stack.c.tmp+0x0000004962f4)
>
>         ^

This seems to be an issue with symbolizer.
The race is on line 7 col 10, but symbolizer says line 7 col 3.


> ********************
> FAIL: ThreadSanitizer :: simple_stack2.cc (22053 of 22245)
> ******************** TEST 'ThreadSanitizer :: simple_stack2.cc' FAILED
> ********************
> Script:
> --
> /home/ygribov/build/llvm-master-gcc/./bin/clang --driver-mode=g++
> -fsanitize=thread -Wall -m64 -gline-tables-only -O1
> /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/simple_stack2.cc
> -o
> /home/ygribov/build/llvm-master-gcc/projects/compiler-rt/test/tsan/Output/simple_stack2.cc.exe
> && /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/deflake.bash
> /home/ygribov/build/llvm-master-gcc/projects/compiler-rt/test/tsan/Output/simple_stack2.cc.exe
> | FileCheck
> /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/simple_stack2.cc
> --
> Exit Code: 1
>
> Command Output (stderr):
> --
> /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/simple_stack2.cc:47:16:
> error: expected string not found in input
> // CHECK-NEXT: #0 foo1{{.*}} {{.*}}simple_stack2.cc:7{{(:10)?}}
> (simple_stack2.cc.exe+{{.*}})
>                ^
> <stdin>:4:2: note: scanning from here
>  #0 foo1()
> /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/simple_stack2.cc:7:3
> (simple_stack2.cc.exe+0x000000496374)
>  ^
> <stdin>:4:57: note: possible intended match here
>  #0 foo1()
> /home/ygribov/src/llvm-master/projects/compiler-rt/test/tsan/simple_stack2.cc:7:3
> (simple_stack2.cc.exe+0x000000496374)
>
>