diff options
Diffstat (limited to 'lib/CodeGen/LowerSubregs.cpp')
| -rw-r--r-- | lib/CodeGen/LowerSubregs.cpp | 35 |
1 files changed, 22 insertions, 13 deletions
diff --git a/lib/CodeGen/LowerSubregs.cpp b/lib/CodeGen/LowerSubregs.cpp index 0710a35300..296e6d45c3 100644 --- a/lib/CodeGen/LowerSubregs.cpp +++ b/lib/CodeGen/LowerSubregs.cpp @@ -108,15 +108,20 @@ bool LowerSubregsInstructionPass::LowerSubregToReg(MachineInstr *MI) { DOUT << "subreg: CONVERTING: " << *MI; - // Insert sub-register copy - const TargetRegisterClass *TRC0 = TRI.getPhysicalRegisterRegClass(DstSubReg); - const TargetRegisterClass *TRC1 = TRI.getPhysicalRegisterRegClass(InsReg); - TII.copyRegToReg(*MBB, MI, DstSubReg, InsReg, TRC0, TRC1); + if (DstSubReg == InsReg) { + // No need to insert an identify copy instruction. + DOUT << "subreg: eliminated!"; + } else { + // Insert sub-register copy + const TargetRegisterClass *TRC0= TRI.getPhysicalRegisterRegClass(DstSubReg); + const TargetRegisterClass *TRC1= TRI.getPhysicalRegisterRegClass(InsReg); + TII.copyRegToReg(*MBB, MI, DstSubReg, InsReg, TRC0, TRC1); #ifndef NDEBUG - MachineBasicBlock::iterator dMI = MI; - DOUT << "subreg: " << *(--dMI); + MachineBasicBlock::iterator dMI = MI; + DOUT << "subreg: " << *(--dMI); #endif + } DOUT << "\n"; MBB->remove(MI); @@ -149,15 +154,19 @@ bool LowerSubregsInstructionPass::LowerInsert(MachineInstr *MI) { DOUT << "subreg: CONVERTING: " << *MI; - // Insert sub-register copy - const TargetRegisterClass *TRC0 = TRI.getPhysicalRegisterRegClass(DstSubReg); - const TargetRegisterClass *TRC1 = TRI.getPhysicalRegisterRegClass(InsReg); - TII.copyRegToReg(*MBB, MI, DstSubReg, InsReg, TRC0, TRC1); - + if (DstSubReg == InsReg) { + // No need to insert an identify copy instruction. + DOUT << "subreg: eliminated!"; + } else { + // Insert sub-register copy + const TargetRegisterClass *TRC0= TRI.getPhysicalRegisterRegClass(DstSubReg); + const TargetRegisterClass *TRC1= TRI.getPhysicalRegisterRegClass(InsReg); + TII.copyRegToReg(*MBB, MI, DstSubReg, InsReg, TRC0, TRC1); #ifndef NDEBUG - MachineBasicBlock::iterator dMI = MI; - DOUT << "subreg: " << *(--dMI); + MachineBasicBlock::iterator dMI = MI; + DOUT << "subreg: " << *(--dMI); #endif + } DOUT << "\n"; MBB->remove(MI); |