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

[Evan Cheng]

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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