llvm dev - Feb 2010 - [LLVMdev] RegisterScavenging on targets without subregisters

There's an assert at line 192, lib/CodeGen/RegisterScavenging.cpp that
appears to get tripped on targets that don't have subregisters defined:

        bool SubUsed = false;
        for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
             unsigned SubReg = *SubRegs; ++SubRegs)
          if (isUsed(SubReg)) {
            SubUsed = true;
            break;
          }
        assert(SubUsed && "Using an undefined register!");

CellSPU does not define any subregisters; consequently, SubUsed will always
be false and trip the assert. What's the intended behavior (before I submit
a bug report)?


-scooter
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Ugh. Management lobotomy kicked in. Need to RTFC better.

On Thu, Feb 25, 2010 at 6:18 PM, Scott Michel <scooter.phd at gmail.com>
wrote:
> There's an assert at line 192, lib/CodeGen/RegisterScavenging.cpp that
> appears to get tripped on targets that don't have subregisters defined:
>
>         bool SubUsed = false;
>         for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
>              unsigned SubReg = *SubRegs; ++SubRegs)
>           if (isUsed(SubReg)) {
>             SubUsed = true;
>             break;
>           }
>         assert(SubUsed && "Using an undefined
register!");
>
> CellSPU does not define any subregisters; consequently, SubUsed will always
> be false and trip the assert. What's the intended behavior (before I
submit
> a bug report)?
>
>
> -scooter
>
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No, I wasn't having a management lobotomy moment. If the target's
registers
have no subregisters, SubUsed is false and the assert gets tripped.

Ok, back to the original question: What was the original intent in this code
(lines 186-193 in lib/CodeGen/RegisterScavenging.cpp)?


-scooter

On Thu, Feb 25, 2010 at 7:00 PM, Scott Michel <scooter.phd at gmail.com>
wrote:
> Ugh. Management lobotomy kicked in. Need to RTFC better.
>
>
> On Thu, Feb 25, 2010 at 6:18 PM, Scott Michel <scooter.phd at
gmail.com>wrote:
>
>> There's an assert at line 192, lib/CodeGen/RegisterScavenging.cpp
that
>> appears to get tripped on targets that don't have subregisters
defined:
>>
>>         bool SubUsed = false;
>>         for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
>>              unsigned SubReg = *SubRegs; ++SubRegs)
>>           if (isUsed(SubReg)) {
>>             SubUsed = true;
>>             break;
>>           }
>>         assert(SubUsed && "Using an undefined
register!");
>>
>> CellSPU does not define any subregisters; consequently, SubUsed will
>> always be false and trip the assert. What's the intended behavior
(before I
>> submit a bug report)?
>>
>>
>> -scooter
>>
>
>
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