[llvm-commits] [llvm] r128782 - in /llvm/trunk: include/llvm/Transforms/Utils/Local.h lib/Transforms/Utils/Local.cpp test/Transforms/JumpThreading/2011-04-02-SimplifyDeadBlock.ll

[Eli Friedman]

On Sun, Apr 3, 2011 at 4:41 PM, Francois Pichet <pichet2000 at gmail.com> wrote:
> On Sat, Apr 2, 2011 at 6:45 PM, Eli Friedman <eli.friedman at gmail.com> wrote:
>> Author: efriedma
>> Date: Sat Apr  2 17:45:17 2011
>> New Revision: 128782
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=128782&view=rev
>> Log:
>> PR9446: RecursivelyDeleteTriviallyDeadInstructions can delete the instruction
>> after the given instruction; make sure to handle that case correctly.
>> (It's difficult to trigger; the included testcase involves a dead
>> block, but I don't think that's a requirement.)
>>
>> While I'm here, get rid of the unnecessary warning about
>> SimplifyInstructionsInBlock, since it should work correctly as far as I know.
>>
>>
>> Added:
>>    llvm/trunk/test/Transforms/JumpThreading/2011-04-02-SimplifyDeadBlock.ll
>> Modified:
>>    llvm/trunk/include/llvm/Transforms/Utils/Local.h
>>    llvm/trunk/lib/Transforms/Utils/Local.cpp
>>
>> Modified: llvm/trunk/include/llvm/Transforms/Utils/Local.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/Local.h?rev=128782&r1=128781&r2=128782&view=diff
>> ==============================================================================
>> --- llvm/trunk/include/llvm/Transforms/Utils/Local.h (original)
>> +++ llvm/trunk/include/llvm/Transforms/Utils/Local.h Sat Apr  2 17:45:17 2011
>> @@ -74,10 +74,6 @@
>>  ///
>>  /// This returns true if it changed the code, note that it can delete
>>  /// instructions in other blocks as well in this block.
>> -///
>> -/// WARNING: Do not use this function on unreachable blocks, as recursive
>> -/// simplification is not able to handle corner-case scenarios that can
>> -/// arise in them.
>>  bool SimplifyInstructionsInBlock(BasicBlock *BB, const TargetData *TD = 0);
>>
>>  //===----------------------------------------------------------------------===//
>>
>> Modified: llvm/trunk/lib/Transforms/Utils/Local.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/Local.cpp?rev=128782&r1=128781&r2=128782&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Utils/Local.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Utils/Local.cpp Sat Apr  2 17:45:17 2011
>> @@ -332,8 +332,11 @@
>>         BI = BB->begin();
>>       continue;
>>     }
>> -
>> +
>> +    WeakVH BIHandle(BI);
>
> Here BI can be equal to BB->end()
> Hence an end iterator is dereferenced causing the crash in WeakVH
> constructor on MSVC

Ah, of course; try r128802?

-Eli