[llvm-commits] [llvm] r78318 - in /llvm/trunk: include/llvm/CodeGen/RegisterScavenging.h lib/CodeGen/RegisterScavenging.cpp

[Jakob Stoklund Olesen]

On 06/08/2009, at 18.32, John Mosby wrote:

> Author: jdm
> Date: Thu Aug  6 11:32:47 2009
> New Revision: 78318
>
> URL: http://llvm.org/viewvc/llvm-project?rev=78318&view=rev
> Log:
> Reg Scavenging generalization (Thumb support):
> - start support for new PEI w/reg alloc, allow running RS from  
> emit{Pro,Epi}logue() target hooks.
> - fix minor issue with recursion detection.

I was just about to remove RegScavenger::backward(). Will you be  
needing it?

> void RegScavenger::enterBasicBlock(MachineBasicBlock *mbb) {
>   MachineFunction &MF = *mbb->getParent();
>   const TargetMachine &TM = MF.getTarget();
> @@ -94,6 +117,7 @@
>   assert((NumPhysRegs == 0 || NumPhysRegs == TRI->getNumRegs()) &&
>          "Target changed?");
>
> +  // Self-initialize.
>   if (!MBB) {
>     NumPhysRegs = TRI->getNumRegs();
>     RegsAvailable.resize(NumPhysRegs);
> @@ -104,29 +128,23 @@
>     // Create callee-saved registers bitvector.
>     CalleeSavedRegs.resize(NumPhysRegs);
>     const unsigned *CSRegs = TRI->getCalleeSavedRegs();
> -    if (CSRegs != NULL)
> -      for (unsigned i = 0; CSRegs[i]; ++i)
> -        CalleeSavedRegs.set(CSRegs[i]);
> -  }

Perhaps CalleeSavedRegs could be renamed to UsedCalleeSavedRegs or  
something along those lines? Just so it is clear it doesn't correspond  
to TRI->getCalleeSavedRegs().

> -    assert(isUsed(Reg) && "Using an undefined register!");
> +    // Allow free CSRs to be processed as uses.
> +    assert((isUsed(Reg) || !CalleeSavedRegs[Reg]) &&
> +           "Using an undefined register!");

Please check the assert condition - it doesn't do what the comment says.

Have you considered simply marking the free CSRs as used in  
initRegState? Then you wouldn't have to disable check for these  
registers.