[llvm] 15f2d4f - [AIX] Fixed "comparison of unsigned expression >= 0 is always true" gcc warnings.

[David Blaikie via llvm-commits]

On Tue, Dec 15, 2020 at 9:24 AM Hubert Tong <
hubert.reinterpretcast at gmail.com> wrote:

> On Mon, Dec 14, 2020 at 8:36 PM David Blaikie via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Any idea if this is the most suitable fix? Is "Bits" representing
>> negative values? If not, perhaps it'd be more appropriate to remove the >=
>> 0 comparison, rather than to change the type?
>>
> For context, this aspect of the implementation will likely be replaced as
> further functionality (to implement the encoding form when vector
> parameters are present) is implemented. In terms of NFC evolution of this
> code, the reparsing loop is not ideal. If the code was not being changed
> anyway, it would make sense to store the "next position" alongside the
> encoded bitstring.
>
> As for the signedness of the type: I believe changing the type is
> appropriate in this case even if the comparison is modified to avoid the
> subtraction.
>

Appropriate in that you think it's a more suitable type for the value being
stored in it, even if it weren't for the warning?


> I do agree that changing the comparison should also be done; however, the
> change to the type was the easiest change to eyeball in the context of
> responding to the breakage.
>

Would be good to clean that up, then - could someone make that change (&
mention the commit hash here)? (otherwise it'll be hard to track down the
longer the code evolves - without the warning to point to it)


>
>
>>
>> On Mon, Dec 14, 2020 at 8:09 AM via llvm-commits <
>> llvm-commits at lists.llvm.org> wrote:
>>
>>>
>>> Author: diggerlin
>>> Date: 2020-12-14T11:08:40-05:00
>>> New Revision: 15f2d4f198380762e9fcf6b456d405078b87ae7a
>>>
>>> URL:
>>> https://github.com/llvm/llvm-project/commit/15f2d4f198380762e9fcf6b456d405078b87ae7a
>>> DIFF:
>>> https://github.com/llvm/llvm-project/commit/15f2d4f198380762e9fcf6b456d405078b87ae7a.diff
>>>
>>> LOG: [AIX] Fixed "comparison of unsigned expression >= 0 is always true"
>>> gcc warnings.
>>>
>>> Summary:
>>>
>>> fixed a  Fixed "comparison of unsigned expression >= 0 is always true"
>>> gcc warnings.
>>> http://lab.llvm.org:8011/#/builders/5/builds/2407/steps/2/logs/stdio
>>>
>>> the error caused by patch https://reviews.llvm.org/D92398
>>>
>>> Added:
>>>
>>>
>>> Modified:
>>>     llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.cpp
>>>
>>> Removed:
>>>
>>>
>>>
>>>
>>> ################################################################################
>>> diff  --git a/llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.cpp
>>> b/llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.cpp
>>> index 02a425044c75..d364eb9d3996 100644
>>> --- a/llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.cpp
>>> +++ b/llvm/lib/Target/PowerPC/PPCMachineFunctionInfo.cpp
>>> @@ -67,7 +67,7 @@ bool PPCFunctionInfo::isLiveInZExt(Register VReg)
>>> const {
>>>
>>>  void PPCFunctionInfo::appendParameterType(ParamType Type) {
>>>    uint32_t CopyParamType = ParameterType;
>>> -  unsigned Bits = 0;
>>> +  int Bits = 0;
>>>
>>>    // If it is fixed type, we only need to increase the FixedParamNum,
>>> for
>>>    // the bit encode of fixed type is bit of zero, we do not need to
>>> change the
>>>
>>>
>>>
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