[llvm] r230141 - Calling memmove on a MachineOperand is totally safe.

[Pete Cooper]

Are you sure this is safe? I thought register operands had use lists which memmove isn't going to know to update?

Pete

Sent from my iPhone

> On Feb 21, 2015, at 8:22 AM, Benjamin Kramer <benny.kra at googlemail.com> wrote:
> 
> Author: d0k
> Date: Sat Feb 21 10:22:48 2015
> New Revision: 230141
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=230141&view=rev
> Log:
> Calling memmove on a MachineOperand is totally safe.
> 
> While it's not POD due to the user-defined constructor, it's still a trivially
> copyable type. No functional change.
> 
> Modified:
>    llvm/trunk/lib/CodeGen/MachineInstr.cpp
> 
> Modified: llvm/trunk/lib/CodeGen/MachineInstr.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineInstr.cpp?rev=230141&r1=230140&r2=230141&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/MachineInstr.cpp (original)
> +++ llvm/trunk/lib/CodeGen/MachineInstr.cpp Sat Feb 21 10:22:48 2015
> @@ -674,14 +674,8 @@ static void moveOperands(MachineOperand
>   if (MRI)
>     return MRI->moveOperands(Dst, Src, NumOps);
> 
> -  // Here it would be convenient to call memmove, so that isn't allowed because
> -  // MachineOperand has a constructor and so isn't a POD type.
> -  if (Dst < Src)
> -    for (unsigned i = 0; i != NumOps; ++i)
> -      new (Dst + i) MachineOperand(Src[i]);
> -  else
> -    for (unsigned i = NumOps; i ; --i)
> -      new (Dst + i - 1) MachineOperand(Src[i - 1]);
> +  // MachineOperand is a trivially copyable type so we can just use memmove.
> +  std::memmove(Dst, Src, NumOps * sizeof(MachineOperand));
> }
> 
> /// addOperand - Add the specified operand to the instruction.  If it is an
> 
> 
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