R600/SI: Update instruction conversions for VI

There are 3 changes:
- Convert 32-bit S_LSHL/LSHR/ASHR to their V_*REV variants for VI
- Lower RSQ_CLAMP for VI
- Don't generate MIN/MAX_LEGACY on VI

llvm-svn: 223604

llvm/lib/Target/R600/AMDGPUISelLowering.cpp

@@ -892,7 +892,19 @@ SDValue AMDGPUTargetLowering::LowerINTRINSIC_WO_CHAIN(SDValue Op,
       return DAG.getNode(AMDGPUISD::RSQ_LEGACY, DL, VT, Op.getOperand(1));
 
     case Intrinsic::AMDGPU_rsq_clamped:
-      return DAG.getNode(AMDGPUISD::RSQ_CLAMPED, DL, VT, Op.getOperand(1));
+      if (Subtarget->getGeneration() >= AMDGPUSubtarget::VOLCANIC_ISLANDS) {
+        Type *Type = VT.getTypeForEVT(*DAG.getContext());
+        APFloat Max = APFloat::getLargest(Type->getFltSemantics());
+        APFloat Min = APFloat::getLargest(Type->getFltSemantics(), true);
+
+        SDValue Rsq = DAG.getNode(AMDGPUISD::RSQ, DL, VT, Op.getOperand(1));
+        SDValue Tmp = DAG.getNode(ISD::FMINNUM, DL, VT, Rsq,
+                                  DAG.getConstantFP(Max, VT));
+        return DAG.getNode(ISD::FMAXNUM, DL, VT, Tmp,
+                           DAG.getConstantFP(Min, VT));
+      } else {
+        return DAG.getNode(AMDGPUISD::RSQ_CLAMPED, DL, VT, Op.getOperand(1));
+      }
 
     case Intrinsic::AMDGPU_ldexp:
       return DAG.getNode(AMDGPUISD::LDEXP, DL, VT, Op.getOperand(1),
@@ -1035,6 +1047,9 @@ SDValue AMDGPUTargetLowering::CombineFMinMax(SDLoc DL,
   case ISD::SETOLT:
   case ISD::SETLE:
   case ISD::SETLT: {
+    if (Subtarget->getGeneration() >= AMDGPUSubtarget::VOLCANIC_ISLANDS)
+      break;
+
     // We need to permute the operands to get the correct NaN behavior. The
     // selected operand is the second one based on the failing compare with NaN,
     // so permute it based on the compare type the hardware uses.
@@ -1048,6 +1063,9 @@ SDValue AMDGPUTargetLowering::CombineFMinMax(SDLoc DL,
   case ISD::SETOGE:
   case ISD::SETUGT:
   case ISD::SETOGT: {
+    if (Subtarget->getGeneration() >= AMDGPUSubtarget::VOLCANIC_ISLANDS)
+      break;
+
     if (LHS == True)
       return DAG.getNode(AMDGPUISD::FMAX_LEGACY, DL, VT, RHS, LHS);
     return DAG.getNode(AMDGPUISD::FMIN_LEGACY, DL, VT, LHS, RHS);

llvm/lib/Target/R600/SIInstrInfo.cpp

@@ -1356,6 +1356,14 @@ unsigned SIInstrInfo::split64BitImm(SmallVectorImpl<MachineInstr *> &Worklist,
   return Dst;
 }
 
+// Change the order of operands from (0, 1, 2) to (0, 2, 1)
+void SIInstrInfo::swapOperands(MachineBasicBlock::iterator Inst) const {
+  assert(Inst->getNumExplicitOperands() == 3);
+  MachineOperand Op1 = Inst->getOperand(1);
+  Inst->RemoveOperand(1);
+  Inst->addOperand(Op1);
+}
+
 bool SIInstrInfo::isOperandLegal(const MachineInstr *MI, unsigned OpIdx,
                                  const MachineOperand *MO) const {
   const MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
@@ -1931,6 +1939,25 @@ void SIInstrInfo::moveToVALU(MachineInstr &TopInst) const {
       continue;
     }
 
+    case AMDGPU::S_LSHL_B32:
+      if (ST.getGeneration() >= AMDGPUSubtarget::VOLCANIC_ISLANDS) {
+        NewOpcode = AMDGPU::V_LSHLREV_B32_e64;
+        swapOperands(Inst);
+      }
+      break;
+    case AMDGPU::S_ASHR_I32:
+      if (ST.getGeneration() >= AMDGPUSubtarget::VOLCANIC_ISLANDS) {
+        NewOpcode = AMDGPU::V_ASHRREV_I32_e64;
+        swapOperands(Inst);
+      }
+      break;
+    case AMDGPU::S_LSHR_B32:
+      if (ST.getGeneration() >= AMDGPUSubtarget::VOLCANIC_ISLANDS) {
+        NewOpcode = AMDGPU::V_LSHRREV_B32_e64;
+        swapOperands(Inst);
+      }
+      break;
+
     case AMDGPU::S_BFE_U64:
     case AMDGPU::S_BFM_B64:
       llvm_unreachable("Moving this op to VALU not implemented");

llvm/lib/Target/R600/SIInstrInfo.h

@@ -45,6 +45,8 @@ private:
                          const TargetRegisterClass *RC,
                          const MachineOperand &Op) const;
 
+  void swapOperands(MachineBasicBlock::iterator Inst) const;
+
   void splitScalar64BitUnaryOp(SmallVectorImpl<MachineInstr *> &Worklist,
                                MachineInstr *Inst, unsigned Opcode) const;