[AMDGPU][True16] Don't use the VGPR_LO/HI16 register classes. (#76440)

Removing the classes requires updating tests and so is planned to be
done with a separate change.

Author: kosarev

llvm/lib/Target/AMDGPU/AMDGPURegisterBanks.td

@@ -11,7 +11,7 @@ def SGPRRegBank : RegisterBank<"SGPR",
 >;
 
 def VGPRRegBank : RegisterBank<"VGPR",
-  [VGPR_LO16, VGPR_HI16, VGPR_32, VReg_64, VReg_96, VReg_128, VReg_160, VReg_192, VReg_224, VReg_256, VReg_288, VReg_320, VReg_352, VReg_384, VReg_512, VReg_1024]
+  [VGPR_32, VReg_64, VReg_96, VReg_128, VReg_160, VReg_192, VReg_224, VReg_256, VReg_288, VReg_320, VReg_352, VReg_384, VReg_512, VReg_1024]
 >;
 
 // It is helpful to distinguish conditions from ordinary SGPRs.

llvm/lib/Target/AMDGPU/AMDGPUResourceUsageAnalysis.cpp

@@ -346,8 +346,7 @@ AMDGPUResourceUsageAnalysis::analyzeResourceUsage(
           IsSGPR = true;
           Width = 1;
         } else if (AMDGPU::VGPR_32RegClass.contains(Reg) ||
-                   AMDGPU::VGPR_LO16RegClass.contains(Reg) ||
-                   AMDGPU::VGPR_HI16RegClass.contains(Reg)) {
+                   AMDGPU::VGPR_16RegClass.contains(Reg)) {
           IsSGPR = false;
           Width = 1;
         } else if (AMDGPU::AGPR_32RegClass.contains(Reg) ||

llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp

@@ -1284,9 +1284,8 @@ MCOperand AMDGPUDisassembler::createSRegOperand(unsigned SRegClassID,
 
 MCOperand AMDGPUDisassembler::createVGPR16Operand(unsigned RegIdx,
                                                   bool IsHi) const {
-  unsigned RCID =
-      IsHi ? AMDGPU::VGPR_HI16RegClassID : AMDGPU::VGPR_LO16RegClassID;
-  return createRegOperand(RCID, RegIdx);
+  unsigned RegIdxInVGPR16 = RegIdx * 2 + (IsHi ? 1 : 0);
+  return createRegOperand(AMDGPU::VGPR_16RegClassID, RegIdxInVGPR16);
 }
 
 // Decode Literals for insts which always have a literal in the encoding

llvm/lib/Target/AMDGPU/SIInstrInfo.cpp

@@ -955,12 +955,8 @@ void SIInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
     bool IsSGPRSrc = AMDGPU::SReg_LO16RegClass.contains(SrcReg);
     bool IsAGPRDst = AMDGPU::AGPR_LO16RegClass.contains(DestReg);
     bool IsAGPRSrc = AMDGPU::AGPR_LO16RegClass.contains(SrcReg);
-    bool DstLow = AMDGPU::VGPR_LO16RegClass.contains(DestReg) ||
-                  AMDGPU::SReg_LO16RegClass.contains(DestReg) ||
-                  AMDGPU::AGPR_LO16RegClass.contains(DestReg);
-    bool SrcLow = AMDGPU::VGPR_LO16RegClass.contains(SrcReg) ||
-                  AMDGPU::SReg_LO16RegClass.contains(SrcReg) ||
-                  AMDGPU::AGPR_LO16RegClass.contains(SrcReg);
+    bool DstLow = !AMDGPU::isHi(DestReg, RI);
+    bool SrcLow = !AMDGPU::isHi(SrcReg, RI);
     MCRegister NewDestReg = RI.get32BitRegister(DestReg);
     MCRegister NewSrcReg = RI.get32BitRegister(SrcReg);
 

llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp

@@ -330,8 +330,10 @@ SIRegisterInfo::SIRegisterInfo(const GCNSubtarget &ST)
 
   RegPressureIgnoredUnits.resize(getNumRegUnits());
   RegPressureIgnoredUnits.set(*regunits(MCRegister::from(AMDGPU::M0)).begin());
-  for (auto Reg : AMDGPU::VGPR_HI16RegClass)
-    RegPressureIgnoredUnits.set(*regunits(Reg).begin());
+  for (auto Reg : AMDGPU::VGPR_16RegClass) {
+    if (AMDGPU::isHi(Reg, *this))
+      RegPressureIgnoredUnits.set(*regunits(Reg).begin());
+  }
 
   // HACK: Until this is fully tablegen'd.
   static llvm::once_flag InitializeRegSplitPartsFlag;
@@ -2808,8 +2810,6 @@ getAlignedVectorSuperClassForBitWidth(unsigned BitWidth) {
 
 const TargetRegisterClass *
 SIRegisterInfo::getVectorSuperClassForBitWidth(unsigned BitWidth) const {
-  if (BitWidth == 16)
-    return &AMDGPU::VGPR_LO16RegClass;
   if (BitWidth == 32)
     return &AMDGPU::AV_32RegClass;
   return ST.needsAlignedVGPRs()
@@ -3041,8 +3041,6 @@ unsigned SIRegisterInfo::getRegPressureLimit(const TargetRegisterClass *RC,
   default:
     return AMDGPUGenRegisterInfo::getRegPressureLimit(RC, MF);
   case AMDGPU::VGPR_32RegClassID:
-  case AMDGPU::VGPR_LO16RegClassID:
-  case AMDGPU::VGPR_HI16RegClassID:
     return std::min(ST.getMaxNumVGPRs(Occupancy), ST.getMaxNumVGPRs(MF));
   case AMDGPU::SGPR_32RegClassID:
   case AMDGPU::SGPR_LO16RegClassID:

llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp

@@ -2296,8 +2296,6 @@ bool isSISrcInlinableOperand(const MCInstrDesc &Desc, unsigned OpNo) {
 // (move from MC* level to Target* level). Return size in bits.
 unsigned getRegBitWidth(unsigned RCID) {
   switch (RCID) {
-  case AMDGPU::VGPR_LO16RegClassID:
-  case AMDGPU::VGPR_HI16RegClassID:
   case AMDGPU::SGPR_LO16RegClassID:
   case AMDGPU::AGPR_LO16RegClassID:
     return 16;