diff --git a/include/llvm/CodeGen/MachineRegisterInfo.h b/include/llvm/CodeGen/MachineRegisterInfo.h index 0cf584fd71e..36427e90ca2 100644 --- a/include/llvm/CodeGen/MachineRegisterInfo.h +++ b/include/llvm/CodeGen/MachineRegisterInfo.h @@ -156,6 +156,9 @@ public: // Strictly for use by MachineInstr.cpp. void removeRegOperandFromUseList(MachineOperand *MO); + // Strictly for use by MachineInstr.cpp. + void moveOperands(MachineOperand *Dst, MachineOperand *Src, unsigned NumOps); + /// reg_begin/reg_end - Provide iteration support to walk over all definitions /// and uses of a register within the MachineFunction that corresponds to this /// MachineRegisterInfo object. diff --git a/lib/CodeGen/MachineRegisterInfo.cpp b/lib/CodeGen/MachineRegisterInfo.cpp index 95d7a7dd689..9858b4999e0 100644 --- a/lib/CodeGen/MachineRegisterInfo.cpp +++ b/lib/CodeGen/MachineRegisterInfo.cpp @@ -180,6 +180,55 @@ void MachineRegisterInfo::removeRegOperandFromUseList(MachineOperand *MO) { MO->Contents.Reg.Next = 0; } +/// Move NumOps operands from Src to Dst, updating use-def lists as needed. +/// +/// The Dst range is assumed to be uninitialized memory. (Or it may contain +/// operands that won't be destroyed, which is OK because the MO destructor is +/// trivial anyway). +/// +/// The Src and Dst ranges may overlap. +void MachineRegisterInfo::moveOperands(MachineOperand *Dst, + MachineOperand *Src, + unsigned NumOps) { + assert(Src != Dst && NumOps && "Noop moveOperands"); + + // Copy backwards if Dst is within the Src range. + int Stride = 1; + if (Dst >= Src && Dst < Src + NumOps) { + Stride = -1; + Dst += NumOps - 1; + Src += NumOps - 1; + } + + // Copy one operand at a time. + do { + new (Dst) MachineOperand(*Src); + + // Dst takes Src's place in the use-def chain. + if (Src->isReg()) { + MachineOperand *&Head = getRegUseDefListHead(Src->getReg()); + MachineOperand *Prev = Src->Contents.Reg.Prev; + MachineOperand *Next = Src->Contents.Reg.Next; + assert(Head && "List empty, but operand is chained"); + assert(Prev && "Operand was not on use-def list"); + + // Prev links are circular, next link is NULL instead of looping back to + // Head. + if (Src == Head) + Head = Dst; + else + Prev->Contents.Reg.Next = Dst; + + // Update Prev pointer. This also works when Src was pointing to itself + // in a 1-element list. In that case Head == Dst. + (Next ? Next : Head)->Contents.Reg.Prev = Dst; + } + + Dst += Stride; + Src += Stride; + } while (--NumOps); +} + /// replaceRegWith - Replace all instances of FromReg with ToReg in the /// machine function. This is like llvm-level X->replaceAllUsesWith(Y), /// except that it also changes any definitions of the register as well.