[llvm-commits] [llvm] r82834 - in /llvm/trunk/lib/CodeGen: MachineLICM.cpp MachineSink.cpp

[Dan Gohman]

I don't understand what you're asking here.  What do you mean, and
what problem would it fix?

Dan

On Sep 26, 2009, at 10:17 PM, Evan Cheng wrote:

> Why not just add the phys register uses to the destination's livein  
> set?
>
> Evan
>
> On Sep 25, 2009, at 7:34 PM, Dan Gohman wrote:
>
>> Author: djg
>> Date: Fri Sep 25 21:34:00 2009
>> New Revision: 82834
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=82834&view=rev
>> Log:
>> Don't hoist or sink instructions with physreg uses if the physreg is
>> allocatable. Even if it doesn't appear to have any defs, it may  
>> latter
>> on after register allocation.
>>
>> Modified:
>>   llvm/trunk/lib/CodeGen/MachineLICM.cpp
>>   llvm/trunk/lib/CodeGen/MachineSink.cpp
>>
>> Modified: llvm/trunk/lib/CodeGen/MachineLICM.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineLICM.cpp?rev=82834&r1=82833&r2=82834&view=diff
>>
>> =
>> =
>> =
>> =
>> =
>> =
>> =
>> =
>> = 
>> =====================================================================
>> --- llvm/trunk/lib/CodeGen/MachineLICM.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/MachineLICM.cpp Fri Sep 25 21:34:00 2009
>> @@ -44,6 +44,7 @@
>>    const TargetMachine   *TM;
>>    const TargetInstrInfo *TII;
>>    const TargetRegisterInfo *TRI;
>> +    BitVector AllocatableSet;
>>
>>    // Various analyses that we use...
>>    MachineLoopInfo      *LI;      // Current MachineLoopInfo
>> @@ -138,6 +139,7 @@
>>  TII = TM->getInstrInfo();
>>  TRI = TM->getRegisterInfo();
>>  RegInfo = &MF.getRegInfo();
>> +  AllocatableSet = TRI->getAllocatableSet(MF);
>>
>>  // Get our Loop information...
>>  LI = &getAnalysis<MachineLoopInfo>();
>> @@ -261,13 +263,20 @@
>>      // we can move it, but only if the def is dead.
>>      if (MO.isUse()) {
>>        // If the physreg has no defs anywhere, it's just an ambient  
>> register
>> -        // and we can freely move its uses.
>> +        // and we can freely move its uses. Alternatively, if it's  
>> allocatable,
>> +        // it could get allocated to something with a def during  
>> allocation.
>>        if (!RegInfo->def_empty(Reg))
>>          return false;
>> +        if (AllocatableSet.test(Reg))
>> +          return false;
>>        // Check for a def among the register's aliases too.
>> -        for (const unsigned *Alias = TRI->getAliasSet(Reg);  
>> *Alias; ++Alias)
>> -          if (!RegInfo->def_empty(*Alias))
>> +        for (const unsigned *Alias = TRI->getAliasSet(Reg);  
>> *Alias; ++Alias) {
>> +          unsigned AliasReg = *Alias;
>> +          if (!RegInfo->def_empty(AliasReg))
>> +            return false;
>> +          if (AllocatableSet.test(AliasReg))
>>            return false;
>> +        }
>>        // Otherwise it's safe to move.
>>        continue;
>>      } else if (!MO.isDead()) {
>>
>> Modified: llvm/trunk/lib/CodeGen/MachineSink.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineSink.cpp?rev=82834&r1=82833&r2=82834&view=diff
>>
>> = 
>> = 
>> = 
>> = 
>> = 
>> = 
>> = 
>> = 
>> = 
>> =====================================================================
>> --- llvm/trunk/lib/CodeGen/MachineSink.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/MachineSink.cpp Fri Sep 25 21:34:00 2009
>> @@ -39,6 +39,7 @@
>>    MachineFunction       *CurMF; // Current MachineFunction
>>    MachineRegisterInfo  *RegInfo; // Machine register information
>>    MachineDominatorTree *DT;   // Machine dominator tree
>> +    BitVector AllocatableSet;   // Which physregs are allocatable?
>>
>>  public:
>>    static char ID; // Pass identification
>> @@ -99,6 +100,7 @@
>>  TRI = TM->getRegisterInfo();
>>  RegInfo = &CurMF->getRegInfo();
>>  DT = &getAnalysis<MachineDominatorTree>();
>> +  AllocatableSet = TRI->getAllocatableSet(*CurMF);
>>
>>  bool EverMadeChange = false;
>>
>> @@ -180,13 +182,20 @@
>>      // we can move it, but only if the def is dead.
>>      if (MO.isUse()) {
>>        // If the physreg has no defs anywhere, it's just an ambient  
>> register
>> -        // and we can freely move its uses.
>> +        // and we can freely move its uses. Alternatively, if it's  
>> allocatable,
>> +        // it could get allocated to something with a def during  
>> allocation.
>>        if (!RegInfo->def_empty(Reg))
>>          return false;
>> +        if (AllocatableSet.test(Reg))
>> +          return false;
>>        // Check for a def among the register's aliases too.
>> -        for (const unsigned *Alias = TRI->getAliasSet(Reg);  
>> *Alias; ++Alias)
>> -          if (!RegInfo->def_empty(*Alias))
>> +        for (const unsigned *Alias = TRI->getAliasSet(Reg);  
>> *Alias; ++Alias) {
>> +          unsigned AliasReg = *Alias;
>> +          if (!RegInfo->def_empty(AliasReg))
>> +            return false;
>> +          if (AllocatableSet.test(AliasReg))
>>            return false;
>> +        }
>>      } else if (!MO.isDead()) {
>>        // A def that isn't dead. We can't move it.
>>        return false;
>>
>>
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