diff options
| -rw-r--r-- | lib/CodeGen/SelectionDAG/InstrEmitter.cpp | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp index 000a7dfcd6..b0239e13b2 100644 --- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp +++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp @@ -280,15 +280,17 @@ InstrEmitter::AddRegisterOperand(MachineInstr *MI, SDValue Op, MCID.OpInfo[IIOpNum].isOptionalDef(); // If the instruction requires a register in a different class, create - // a new virtual register and copy the value into it. + // a new virtual register and copy the value into it, but first attempt to + // shrink VReg's register class within reason. For example, if VReg == GR32 + // and II requires a GR32_NOSP, just constrain VReg to GR32_NOSP. + const unsigned MinRCSize = 4; if (II) { - const TargetRegisterClass *SrcRC = MRI->getRegClass(VReg); const TargetRegisterClass *DstRC = 0; if (IIOpNum < II->getNumOperands()) DstRC = TII->getRegClass(*II, IIOpNum, TRI); assert((DstRC || (MCID.isVariadic() && IIOpNum >= MCID.getNumOperands())) && "Don't have operand info for this instruction!"); - if (DstRC && !SrcRC->hasSuperClassEq(DstRC)) { + if (DstRC && !MRI->constrainRegClass(VReg, DstRC, MinRCSize)) { unsigned NewVReg = MRI->createVirtualRegister(DstRC); BuildMI(*MBB, InsertPos, Op.getNode()->getDebugLoc(), TII->get(TargetOpcode::COPY), NewVReg).addReg(VReg); |