[llvm] r224114 - Silence gcc 4.9.1 warning 'xyz' is used uninitialized in this function.

[Yaron Keren]

As far as I can see, the error is first caught in in RPCChannel.inc,
reported to errs() and then return true for success.

The local ReadBytes and WriteBytes transforms the boolean error code into
the number of bytes read or written and this number result was asserted on.

Instead of moving back and forth between bool error code and the number of
bytes I simply streamed the bool error code all the way until the caller,
acting on every error.

I don't know if this code is tested at all, but surely not on windows as
Windows\RPCChannel.inc is do nothing = allways fail.

Who is lli code owner? not found anyone in CODE_OWNERS.TXT.





2014-12-12 21:24 GMT+02:00 David Blaikie <dblaikie at gmail.com>:
>
> Honestly this isn't really my area - was just throwing the question out
> there for you/others who might own/care about this code to see if this was
> the right direction.
>
> Not sure what these error paths actually represent (are these the failure
> cases one would hit if one simply truncated a bitcode file? If so, we could
> actually have test coverage for that easily enough)? Or are there other
> checks that catch that earlier?


On Fri, Dec 12, 2014 at 11:15 AM, Yaron Keren <yaron.keren at gmail.com> wrote:
>
> I have propagated the error codes into ChildTarget.cpp.
> What do you think of the attached patch?
>
>
>
>
> 2014-12-12 19:56 GMT+02:00 David Blaikie <dblaikie at gmail.com>:
>>
>>
>>
>> On Fri, Dec 12, 2014 at 3:07 AM, Yaron Keren <yaron.keren at gmail.com>
>> wrote:
>>
>>> Author: yrnkrn
>>> Date: Fri Dec 12 05:07:51 2014
>>> New Revision: 224114
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=224114&view=rev
>>> Log:
>>> Silence gcc 4.9.1 warning 'xyz' is used uninitialized in this function.
>>>
>>> In release builds this is actually possible as without asserts there is
>>> no testing of the actual read bytes and the variables could be partially
>>> uninitialized.
>>>
>>
>> Should we instead be actually testing the number of bytes read in a
>> non-asserts build?
>>
>>
>>>
>>>
>>> Modified:
>>>     llvm/trunk/tools/lli/ChildTarget/ChildTarget.cpp
>>>
>>> Modified: llvm/trunk/tools/lli/ChildTarget/ChildTarget.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/lli/ChildTarget/ChildTarget.cpp?rev=224114&r1=224113&r2=224114&view=diff
>>>
>>> ==============================================================================
>>> --- llvm/trunk/tools/lli/ChildTarget/ChildTarget.cpp (original)
>>> +++ llvm/trunk/tools/lli/ChildTarget/ChildTarget.cpp Fri Dec 12 05:07:51
>>> 2014
>>> @@ -97,15 +97,15 @@ void LLIChildTarget::handleMessage(LLIMe
>>>  // Incoming message handlers
>>>  void LLIChildTarget::handleAllocateSpace() {
>>>    // Read and verify the message data size.
>>> -  uint32_t DataSize;
>>> +  uint32_t DataSize = 0;
>>>    int rc = ReadBytes(&DataSize, 4);
>>>    (void)rc;
>>>    assert(rc == 4);
>>>    assert(DataSize == 8);
>>>
>>>    // Read the message arguments.
>>> -  uint32_t Alignment;
>>> -  uint32_t AllocSize;
>>> +  uint32_t Alignment = 0;
>>> +  uint32_t AllocSize = 0;
>>>    rc = ReadBytes(&Alignment, 4);
>>>    assert(rc == 4);
>>>    rc = ReadBytes(&AllocSize, 4);
>>> @@ -121,13 +121,13 @@ void LLIChildTarget::handleAllocateSpace
>>>
>>>  void LLIChildTarget::handleLoadSection(bool IsCode) {
>>>    // Read the message data size.
>>> -  uint32_t DataSize;
>>> +  uint32_t DataSize = 0;
>>>    int rc = ReadBytes(&DataSize, 4);
>>>    (void)rc;
>>>    assert(rc == 4);
>>>
>>>    // Read the target load address.
>>> -  uint64_t Addr;
>>> +  uint64_t Addr = 0;
>>>    rc = ReadBytes(&Addr, 8);
>>>    assert(rc == 8);
>>>    size_t BufferSize = DataSize - 8;
>>> @@ -150,14 +150,14 @@ void LLIChildTarget::handleLoadSection(b
>>>
>>>  void LLIChildTarget::handleExecute() {
>>>    // Read the message data size.
>>> -  uint32_t DataSize;
>>> +  uint32_t DataSize = 0;
>>>    int rc = ReadBytes(&DataSize, 4);
>>>    (void)rc;
>>>    assert(rc == 4);
>>>    assert(DataSize == 8);
>>>
>>>    // Read the target address.
>>> -  uint64_t Addr;
>>> +  uint64_t Addr = 0;
>>>    rc = ReadBytes(&Addr, 8);
>>>    assert(rc == 8);
>>>
>>>
>>>
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>>> llvm-commits at cs.uiuc.edu
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>>>
>>
>>
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