Optimize codegen for VSETLNi{8,16,32} operating on Q registers. Degenerate to a VSETLN on D registers, instead of an (INSERT_SUBREG (VSETLN (EXTRACT_SUBREG ))) sequence to help the register coalescer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163298 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 51 insertions, 0 deletions

diff --git a/lib/Target/ARM/ARMExpandPseudoInsts.cpp b/lib/Target/ARM/ARMExpandPseudoInsts.cpp
index 15bb32eb14..8ed6b751f3 100644
--- a/lib/Target/ARM/ARMExpandPseudoInsts.cpp
+++ b/lib/Target/ARM/ARMExpandPseudoInsts.cpp
@@ -1208,6 +1208,57 @@ bool ARMExpandPseudo::ExpandMI(MachineBasicBlock &MBB,
       ExpandLaneOp(MBBI);
       return true;
 
+    case ARM::VSETLNi8Q:
+    case ARM::VSETLNi16Q: {
+      // Expand VSETLNs acting on a Q register to equivalent VSETLNs acting
+      // on the respective D register.
+
+      unsigned QReg  = MI.getOperand(1).getReg();
+      unsigned QLane = MI.getOperand(3).getImm();
+
+      unsigned NewOpcode, DLane, DSubReg;
+      switch (Opcode) {
+      default: llvm_unreachable("Invalid opcode!");
+      case ARM::VSETLNi8Q:
+        // 4 possible 8-bit lanes per DPR:
+        NewOpcode = ARM::VSETLNi8;
+        DLane = QLane % 8;
+        DSubReg  = (QLane / 8) ? ARM::dsub_1 : ARM::dsub_0;
+        break;
+      case ARM::VSETLNi16Q:
+        // 4 possible 16-bit lanes per DPR.
+        NewOpcode = ARM::VSETLNi16;
+        DLane = QLane % 4;
+        DSubReg  = (QLane / 4) ? ARM::dsub_1 : ARM::dsub_0;
+        break;
+      }
+
+      MachineInstrBuilder MIB =
+        BuildMI(MBB, MBBI, MI.getDebugLoc(), TII->get(NewOpcode));
+
+      unsigned DReg = TRI->getSubReg(QReg, DSubReg);
+
+      MIB.addReg(DReg, RegState::Define); // Output DPR
+      MIB.addReg(DReg);                   // Input DPR
+      MIB.addOperand(MI.getOperand(2));   // Input GPR
+      MIB.addImm(DLane);                  // Lane
+
+      // Add the predicate operands.
+      MIB.addOperand(MI.getOperand(4));
+      MIB.addOperand(MI.getOperand(5));
+
+      if (MI.getOperand(1).isKill()) // Add an implicit kill for the Q register.
+        MIB->addRegisterKilled(QReg, TRI, true);
+      // And an implicit def of the output register (which should always be the
+      // same as the input register).
+      MIB->addRegisterDefined(QReg, TRI);
+
+      TransferImpOps(MI, MIB, MIB);
+
+      MI.eraseFromParent();
+      return true;
+    }
+
     case ARM::VTBL3Pseudo: ExpandVTBL(MBBI, ARM::VTBL3, false); return true;
     case ARM::VTBL4Pseudo: ExpandVTBL(MBBI, ARM::VTBL4, false); return true;
     case ARM::VTBX3Pseudo: ExpandVTBL(MBBI, ARM::VTBX3, true); return true;