[llvm] r182490 - Add the IncludeSelf parameter to the MCSubRegIterator and MCSuperRegIterator

[Chad Rosier]

On May 22, 2013, at 11:46 AM, Rafael Espíndola <rafael.espindola at gmail.com> wrote:

> On 22 May 2013 13:26, Chad Rosier <mcrosier at apple.com> wrote:
>> Author: mcrosier
>> Date: Wed May 22 12:26:26 2013
>> New Revision: 182490
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=182490&view=rev
>> Log:
>> Add the IncludeSelf parameter to the MCSubRegIterator and MCSuperRegIterator
>> constructors.  No functional change.
>> Part of rdar://12906217
> 
> Can you provide a bit more context on how this will be used?

This can simplify a few things.  For example, LiveVariables.cpp has a lot of code like this:

       Live.insert(SubReg);
       for (MCSubRegIterator SS(SubReg, TRI); SS.isValid(); ++SS)
         Live.insert(*SS);

An includeSelf argument would be useful here. I.e.,

       for (MCSubRegIterator SS(SubReg, TRI, /*IncludeSelf=*/true); SS.isValid(); ++SS)
         Live.insert(*SS);

My forthcoming patch uses it in a similar way.  Hope this helps.

 Chad

> 
>> Modified:
>>    llvm/trunk/include/llvm/MC/MCRegisterInfo.h
>> 
>> Modified: llvm/trunk/include/llvm/MC/MCRegisterInfo.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCRegisterInfo.h?rev=182490&r1=182489&r2=182490&view=diff
>> ==============================================================================
>> --- llvm/trunk/include/llvm/MC/MCRegisterInfo.h (original)
>> +++ llvm/trunk/include/llvm/MC/MCRegisterInfo.h Wed May 22 12:26:26 2013
>> @@ -421,20 +421,28 @@ public:
>> // aliasing registers. Use these iterator classes to traverse the lists.
>> 
>> /// MCSubRegIterator enumerates all sub-registers of Reg.
>> +/// If IncludeSelf is set, Reg itself is included in the list.
>> class MCSubRegIterator : public MCRegisterInfo::DiffListIterator {
>> public:
>> -  MCSubRegIterator(unsigned Reg, const MCRegisterInfo *MCRI) {
>> +  MCSubRegIterator(unsigned Reg, const MCRegisterInfo *MCRI,
>> +                     bool IncludeSelf = false) {
>>     init(Reg, MCRI->DiffLists + MCRI->get(Reg).SubRegs);
>> -    ++*this;
>> +    // Initially, the iterator points to Reg itself.
>> +    if (!IncludeSelf)
>> +      ++*this;
>>   }
>> };
>> 
>> /// MCSuperRegIterator enumerates all super-registers of Reg.
>> +/// If IncludeSelf is set, Reg itself is included in the list.
>> class MCSuperRegIterator : public MCRegisterInfo::DiffListIterator {
>> public:
>> -  MCSuperRegIterator(unsigned Reg, const MCRegisterInfo *MCRI) {
>> +  MCSuperRegIterator(unsigned Reg, const MCRegisterInfo *MCRI,
>> +                     bool IncludeSelf = false) {
>>     init(Reg, MCRI->DiffLists + MCRI->get(Reg).SuperRegs);
>> -    ++*this;
>> +    // Initially, the iterator points to Reg itself.
>> +    if (!IncludeSelf)
>> +      ++*this;
>>   }
>> };
>> 
>> @@ -443,7 +451,7 @@ public:
>> class MCRegAliasIterator : public MCRegisterInfo::DiffListIterator {
>> public:
>>   MCRegAliasIterator(unsigned Reg, const MCRegisterInfo *MCRI,
>> -                     bool IncludeSelf) {
>> +                     bool IncludeSelf = false) {
>>     init(Reg, MCRI->DiffLists + MCRI->get(Reg).Overlaps);
>>     // Initially, the iterator points to Reg itself.
>>     if (!IncludeSelf)
>> 
>> 
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