[llvm-commits] [llvm] r122596 - /llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp

[Bob Wilson]

On Dec 28, 2010, at 2:49 AM, Cameron Zwarich wrote:

> Author: zwarich
> Date: Tue Dec 28 04:49:33 2010
> New Revision: 122596
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=122596&view=rev
> Log:
> Avoid iterating every operand of an instruction in StrongPHIElimination, since
> we are only interested in the defs when discovering interferences.
> 
> This is a 28% speedup running StrongPHIElimination on 403.gcc.
> 
> Modified:
>    llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp
> 
> Modified: llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp?rev=122596&r1=122595&r2=122596&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp (original)
> +++ llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp Tue Dec 28 04:49:33 2010
> @@ -471,10 +471,9 @@
>     DenseMap<unsigned, unsigned>& ImmediateDominatingParent) {
>   for (MachineBasicBlock::iterator BBI = MBB.begin(), BBE = MBB.end();
>   BBI != BBE; ++BBI) {
> -    for (unsigned i = 0, e = BBI->getNumOperands(); i != e; ++i) {
> -      MachineOperand& MO = BBI->getOperand(i);
> -      if (!MO.isReg() || !MO.isDef())
> -        continue;
> +    for (MachineInstr::const_mop_iterator I = BBI->operands_begin(),
> +         E = BBI->operands_end(); I != E && I->isReg() && I->isDef(); ++I) {
> +      const MachineOperand& MO = *I;

This is relying on the register def operands being first.  I'm not sure that's always true.  OptionalDefOperands, like cc_out for ARM, may come later in the operand list.

> 
>       unsigned DestReg = MO.getReg();
>       if (!DestReg || !TargetRegisterInfo::isVirtualRegister(DestReg))
> 
> 
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits