[AMDGPU][NFC] Have helpers to deal with encoding fields. (#82772)

These are hoped to provide more convenient and less error prone
facilities to encode and decode fields than manually defined constants
and functions.

10 files changed, 74 insertions, 89 deletions

diff --git a/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp b/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
index 0d3b158a0df7..13d751072913 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
@@ -4824,9 +4824,8 @@ bool AMDGPULegalizerInfo::legalizeFDIV16(MachineInstr &MI,
   return true;
 }
 
-static const unsigned SPDenormModeBitField =
-    AMDGPU::Hwreg::ID_MODE | (4 << AMDGPU::Hwreg::OFFSET_SHIFT_) |
-    (1 << AMDGPU::Hwreg::WIDTH_M1_SHIFT_);
+static constexpr unsigned SPDenormModeBitField =
+    AMDGPU::Hwreg::HwregEncoding::encode(AMDGPU::Hwreg::ID_MODE, 4, 2);
 
 // Enable or disable FP32 denorm mode. When 'Enable' is true, emit instructions
 // to enable denorm mode. When 'Enable' is false, disable denorm mode.
diff --git a/llvm/lib/Target/AMDGPU/AsmParser/AMDGPUAsmParser.cpp b/llvm/lib/Target/AMDGPU/AsmParser/AMDGPUAsmParser.cpp
index 5b32b34079f4..b7b471d8dc7b 100644
--- a/llvm/lib/Target/AMDGPU/AsmParser/AMDGPUAsmParser.cpp
+++ b/llvm/lib/Target/AMDGPU/AsmParser/AMDGPUAsmParser.cpp
@@ -7272,11 +7272,11 @@ ParseStatus AMDGPUAsmParser::parseHwreg(OperandVector &Operands) {
 
   if (trySkipId("hwreg", AsmToken::LParen)) {
     OperandInfoTy HwReg(OPR_ID_UNKNOWN);
-    OperandInfoTy Offset(OFFSET_DEFAULT_);
-    OperandInfoTy Width(WIDTH_DEFAULT_);
+    OperandInfoTy Offset(HwregOffset::Default);
+    OperandInfoTy Width(HwregSize::Default);
     if (parseHwregBody(HwReg, Offset, Width) &&
         validateHwreg(HwReg, Offset, Width)) {
-      ImmVal = encodeHwreg(HwReg.Id, Offset.Id, Width.Id);
+      ImmVal = HwregEncoding::encode(HwReg.Id, Offset.Id, Width.Id);
     } else {
       return ParseStatus::Failure;
     }
diff --git a/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp b/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp
index a727134b53de..00fa93cc1923 100644
--- a/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp
@@ -177,7 +177,7 @@ static bool isLdsDma(const MachineInstr &MI) {
 static unsigned getHWReg(const SIInstrInfo *TII, const MachineInstr &RegInstr) {
   const MachineOperand *RegOp = TII->getNamedOperand(RegInstr,
                                                      AMDGPU::OpName::simm16);
-  return RegOp->getImm() & AMDGPU::Hwreg::ID_MASK_;
+  return std::get<0>(AMDGPU::Hwreg::HwregEncoding::decode(RegOp->getImm()));
 }
 
 ScheduleHazardRecognizer::HazardType
diff --git a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUInstPrinter.cpp b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUInstPrinter.cpp
index a45fea6701f3..a32be1e50a60 100644
--- a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUInstPrinter.cpp
+++ b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUInstPrinter.cpp
@@ -1778,13 +1778,9 @@ void AMDGPUInstPrinter::printSDelayALU(const MCInst *MI, unsigned OpNo,
 
 void AMDGPUInstPrinter::printHwreg(const MCInst *MI, unsigned OpNo,
                                    const MCSubtargetInfo &STI, raw_ostream &O) {
-  unsigned Id;
-  unsigned Offset;
-  unsigned Width;
-
   using namespace llvm::AMDGPU::Hwreg;
   unsigned Val = MI->getOperand(OpNo).getImm();
-  decodeHwreg(Val, Id, Offset, Width);
+  auto [Id, Offset, Width] = HwregEncoding::decode(Val);
   StringRef HwRegName = getHwreg(Id, STI);
 
   O << "hwreg(";
@@ -1793,9 +1789,8 @@ void AMDGPUInstPrinter::printHwreg(const MCInst *MI, unsigned OpNo,
   } else {
     O << Id;
   }
-  if (Width != WIDTH_DEFAULT_ || Offset != OFFSET_DEFAULT_) {
+  if (Width != HwregSize::Default || Offset != HwregOffset::Default)
     O << ", " << Offset << ", " << Width;
-  }
   O << ')';
 }
 
diff --git a/llvm/lib/Target/AMDGPU/SIDefines.h b/llvm/lib/Target/AMDGPU/SIDefines.h
index 98310c3f70c4..0b516bfffb9b 100644
--- a/llvm/lib/Target/AMDGPU/SIDefines.h
+++ b/llvm/lib/Target/AMDGPU/SIDefines.h
@@ -549,33 +549,12 @@ enum Id { // HwRegCode, (6) [5:0]
   ID_SQ_PERF_SNAPSHOT_DATA1 = 22,
   ID_SQ_PERF_SNAPSHOT_PC_LO = 23,
   ID_SQ_PERF_SNAPSHOT_PC_HI = 24,
-
-  ID_SHIFT_ = 0,
-  ID_WIDTH_ = 6,
-  ID_MASK_ = (((1 << ID_WIDTH_) - 1) << ID_SHIFT_)
 };
 
 enum Offset : unsigned { // Offset, (5) [10:6]
-  OFFSET_DEFAULT_ = 0,
-  OFFSET_SHIFT_ = 6,
-  OFFSET_WIDTH_ = 5,
-  OFFSET_MASK_ = (((1 << OFFSET_WIDTH_) - 1) << OFFSET_SHIFT_),
-
   OFFSET_MEM_VIOL = 8,
 };
 
-enum WidthMinusOne : unsigned { // WidthMinusOne, (5) [15:11]
-  WIDTH_M1_DEFAULT_ = 31,
-  WIDTH_M1_SHIFT_ = 11,
-  WIDTH_M1_WIDTH_ = 5,
-  WIDTH_M1_MASK_ = (((1 << WIDTH_M1_WIDTH_) - 1) << WIDTH_M1_SHIFT_),
-};
-
-// Some values from WidthMinusOne mapped into Width domain.
-enum Width : unsigned {
-  WIDTH_DEFAULT_ = WIDTH_M1_DEFAULT_ + 1,
-};
-
 enum ModeRegisterMasks : uint32_t {
   FP_ROUND_MASK = 0xf << 0,  // Bits 0..3
   FP_DENORM_MASK = 0xf << 4, // Bits 4..7
diff --git a/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp b/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
index d02aee71870e..4f106bf0dfb1 100644
--- a/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
@@ -478,14 +478,13 @@ void SIFrameLowering::emitEntryFunctionFlatScratchInit(
         .addImm(0);
       Addc->getOperand(3).setIsDead(); // Mark SCC as dead.
 
-      BuildMI(MBB, I, DL, TII->get(AMDGPU::S_SETREG_B32)).
-        addReg(FlatScrInitLo).
-        addImm(int16_t(AMDGPU::Hwreg::ID_FLAT_SCR_LO |
-                       (31 << AMDGPU::Hwreg::WIDTH_M1_SHIFT_)));
-      BuildMI(MBB, I, DL, TII->get(AMDGPU::S_SETREG_B32)).
-        addReg(FlatScrInitHi).
-        addImm(int16_t(AMDGPU::Hwreg::ID_FLAT_SCR_HI |
-                       (31 << AMDGPU::Hwreg::WIDTH_M1_SHIFT_)));
+      using namespace AMDGPU::Hwreg;
+      BuildMI(MBB, I, DL, TII->get(AMDGPU::S_SETREG_B32))
+          .addReg(FlatScrInitLo)
+          .addImm(int16_t(HwregEncoding::encode(ID_FLAT_SCR_LO, 0, 32)));
+      BuildMI(MBB, I, DL, TII->get(AMDGPU::S_SETREG_B32))
+          .addReg(FlatScrInitHi)
+          .addImm(int16_t(HwregEncoding::encode(ID_FLAT_SCR_HI, 0, 32)));
       return;
     }
 
diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index 257dff6ef683..d8f528d86611 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -3960,7 +3960,7 @@ SDValue SITargetLowering::lowerGET_ROUNDING(SDValue Op,
   assert(Op.getValueType() == MVT::i32);
 
   uint32_t BothRoundHwReg =
-      AMDGPU::Hwreg::encodeHwreg(AMDGPU::Hwreg::ID_MODE, 0, 4);
+      AMDGPU::Hwreg::HwregEncoding::encode(AMDGPU::Hwreg::ID_MODE, 0, 4);
   SDValue GetRoundBothImm = DAG.getTargetConstant(BothRoundHwReg, SL, MVT::i32);
 
   SDValue IntrinID =
@@ -4195,8 +4195,8 @@ SITargetLowering::emitGWSMemViolTestLoop(MachineInstr &MI,
 
   MachineBasicBlock::iterator I = LoopBB->end();
 
-  const unsigned EncodedReg = AMDGPU::Hwreg::encodeHwreg(
-    AMDGPU::Hwreg::ID_TRAPSTS, AMDGPU::Hwreg::OFFSET_MEM_VIOL, 1);
+  const unsigned EncodedReg = AMDGPU::Hwreg::HwregEncoding::encode(
+      AMDGPU::Hwreg::ID_TRAPSTS, AMDGPU::Hwreg::OFFSET_MEM_VIOL, 1);
 
   // Clear TRAP_STS.MEM_VIOL
   BuildMI(*LoopBB, LoopBB->begin(), DL, TII->get(AMDGPU::S_SETREG_IMM32_B32))
@@ -4999,18 +4999,16 @@ MachineBasicBlock *SITargetLowering::EmitInstrWithCustomInserter(
     // Otherwise there was overflow and the result is hi2:0. In both cases the
     // result should represent the actual time at some point during the sequence
     // of three getregs.
+    using namespace AMDGPU::Hwreg;
     Register RegHi1 = MRI.createVirtualRegister(&AMDGPU::SReg_32RegClass);
     BuildMI(*BB, MI, DL, TII->get(AMDGPU::S_GETREG_B32), RegHi1)
-        .addImm(AMDGPU::Hwreg::encodeHwreg(AMDGPU::Hwreg::ID_SHADER_CYCLES_HI,
-                                           0, 32));
+        .addImm(HwregEncoding::encode(ID_SHADER_CYCLES_HI, 0, 32));
     Register RegLo1 = MRI.createVirtualRegister(&AMDGPU::SReg_32RegClass);
     BuildMI(*BB, MI, DL, TII->get(AMDGPU::S_GETREG_B32), RegLo1)
-        .addImm(
-            AMDGPU::Hwreg::encodeHwreg(AMDGPU::Hwreg::ID_SHADER_CYCLES, 0, 32));
+        .addImm(HwregEncoding::encode(ID_SHADER_CYCLES, 0, 32));
     Register RegHi2 = MRI.createVirtualRegister(&AMDGPU::SReg_32RegClass);
     BuildMI(*BB, MI, DL, TII->get(AMDGPU::S_GETREG_B32), RegHi2)
-        .addImm(AMDGPU::Hwreg::encodeHwreg(AMDGPU::Hwreg::ID_SHADER_CYCLES_HI,
-                                           0, 32));
+        .addImm(HwregEncoding::encode(ID_SHADER_CYCLES_HI, 0, 32));
     BuildMI(*BB, MI, DL, TII->get(AMDGPU::S_CMP_EQ_U32))
         .addReg(RegHi1)
         .addReg(RegHi2);
@@ -5207,8 +5205,8 @@ MachineBasicBlock *SITargetLowering::EmitInstrWithCustomInserter(
     // FIXME: This could be predicates on the immediate, but tablegen doesn't
     // allow you to have a no side effect instruction in the output of a
     // sideeffecting pattern.
-    unsigned ID, Offset, Width;
-    AMDGPU::Hwreg::decodeHwreg(MI.getOperand(1).getImm(), ID, Offset, Width);
+    auto [ID, Offset, Width] =
+        AMDGPU::Hwreg::HwregEncoding::decode(MI.getOperand(1).getImm());
     if (ID != AMDGPU::Hwreg::ID_MODE)
       return BB;
 
@@ -10495,9 +10493,8 @@ SDValue SITargetLowering::LowerFDIV32(SDValue Op, SelectionDAG &DAG) const {
   SDValue NegDivScale0 = DAG.getNode(ISD::FNEG, SL, MVT::f32,
                                      DenominatorScaled, Flags);
 
-  const unsigned Denorm32Reg = AMDGPU::Hwreg::ID_MODE |
-                               (4 << AMDGPU::Hwreg::OFFSET_SHIFT_) |
-                               (1 << AMDGPU::Hwreg::WIDTH_M1_SHIFT_);
+  using namespace AMDGPU::Hwreg;
+  const unsigned Denorm32Reg = HwregEncoding::encode(ID_MODE, 4, 2);
   const SDValue BitField = DAG.getTargetConstant(Denorm32Reg, SL, MVT::i32);
 
   const MachineFunction &MF = DAG.getMachineFunction();
diff --git a/llvm/lib/Target/AMDGPU/SIModeRegister.cpp b/llvm/lib/Target/AMDGPU/SIModeRegister.cpp
index e62ad026dc5c..c01b1266a553 100644
--- a/llvm/lib/Target/AMDGPU/SIModeRegister.cpp
+++ b/llvm/lib/Target/AMDGPU/SIModeRegister.cpp
@@ -225,11 +225,10 @@ void SIModeRegister::insertSetreg(MachineBasicBlock &MBB, MachineInstr *MI,
     unsigned Offset = llvm::countr_zero<unsigned>(InstrMode.Mask);
     unsigned Width = llvm::countr_one<unsigned>(InstrMode.Mask >> Offset);
     unsigned Value = (InstrMode.Mode >> Offset) & ((1 << Width) - 1);
+    using namespace AMDGPU::Hwreg;
     BuildMI(MBB, MI, nullptr, TII->get(AMDGPU::S_SETREG_IMM32_B32))
         .addImm(Value)
-        .addImm(((Width - 1) << AMDGPU::Hwreg::WIDTH_M1_SHIFT_) |
-                (Offset << AMDGPU::Hwreg::OFFSET_SHIFT_) |
-                (AMDGPU::Hwreg::ID_MODE << AMDGPU::Hwreg::ID_SHIFT_));
+        .addImm(HwregEncoding::encode(ID_MODE, Offset, Width));
     ++NumSetregInserted;
     Changed = true;
     InstrMode.Mask &= ~(((1 << Width) - 1) << Offset);
@@ -276,15 +275,11 @@ void SIModeRegister::processBlockPhase1(MachineBasicBlock &MBB,
       // as we assume it has been inserted by a higher authority (this is
       // likely to be a very rare occurrence).
       unsigned Dst = TII->getNamedOperand(MI, AMDGPU::OpName::simm16)->getImm();
-      if (((Dst & AMDGPU::Hwreg::ID_MASK_) >> AMDGPU::Hwreg::ID_SHIFT_) !=
-          AMDGPU::Hwreg::ID_MODE)
+      using namespace AMDGPU::Hwreg;
+      auto [Id, Offset, Width] = HwregEncoding::decode(Dst);
+      if (Id != ID_MODE)
         continue;
 
-      unsigned Width = ((Dst & AMDGPU::Hwreg::WIDTH_M1_MASK_) >>
-                        AMDGPU::Hwreg::WIDTH_M1_SHIFT_) +
-                       1;
-      unsigned Offset =
-          (Dst & AMDGPU::Hwreg::OFFSET_MASK_) >> AMDGPU::Hwreg::OFFSET_SHIFT_;
       unsigned Mask = maskTrailingOnes<unsigned>(Width) << Offset;
 
       // If an InsertionPoint is set we will insert a setreg there.
diff --git a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp
index dacdf7b5cd9a..ce91e05e5cc8 100644
--- a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp
@@ -1698,22 +1698,14 @@ int64_t getHwregId(const StringRef Name, const MCSubtargetInfo &STI) {
   return (Idx < 0) ? Idx : Opr[Idx].Encoding;
 }
 
-bool isValidHwreg(int64_t Id) {
-  return 0 <= Id && isUInt<ID_WIDTH_>(Id);
-}
+bool isValidHwreg(int64_t Id) { return 0 <= Id && isUInt<HwregId::Width>(Id); }
 
 bool isValidHwregOffset(int64_t Offset) {
-  return 0 <= Offset && isUInt<OFFSET_WIDTH_>(Offset);
+  return 0 <= Offset && isUInt<HwregOffset::Width>(Offset);
 }
 
 bool isValidHwregWidth(int64_t Width) {
-  return 0 <= (Width - 1) && isUInt<WIDTH_M1_WIDTH_>(Width - 1);
-}
-
-uint64_t encodeHwreg(uint64_t Id, uint64_t Offset, uint64_t Width) {
-  return (Id << ID_SHIFT_) |
-         (Offset << OFFSET_SHIFT_) |
-         ((Width - 1) << WIDTH_M1_SHIFT_);
+  return 0 <= (Width - 1) && isUInt<HwregSize::Width>(Width - 1);
 }
 
 StringRef getHwreg(unsigned Id, const MCSubtargetInfo &STI) {
@@ -1721,12 +1713,6 @@ StringRef getHwreg(unsigned Id, const MCSubtargetInfo &STI) {
   return (Idx < 0) ? "" : Opr[Idx].Name;
 }
 
-void decodeHwreg(unsigned Val, unsigned &Id, unsigned &Offset, unsigned &Width) {
-  Id = (Val & ID_MASK_) >> ID_SHIFT_;
-  Offset = (Val & OFFSET_MASK_) >> OFFSET_SHIFT_;
-  Width = ((Val & WIDTH_M1_MASK_) >> WIDTH_M1_SHIFT_) + 1;
-}
-
 } // namespace Hwreg
 
 //===----------------------------------------------------------------------===//
diff --git a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h
index b38016a58160..6826cd273195 100644
--- a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h
+++ b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h
@@ -322,6 +322,35 @@ getNumVGPRBlocks(const MCSubtargetInfo *STI, unsigned NumSGPRs,
 
 } // end namespace IsaInfo
 
+// Represents a field in an encoded value.
+template <unsigned HighBit, unsigned LowBit, unsigned D = 0>
+struct EncodingField {
+  static_assert(HighBit >= LowBit, "Invalid bit range!");
+  static constexpr unsigned Offset = LowBit;
+  static constexpr unsigned Width = HighBit - LowBit + 1;
+
+  using ValueType = unsigned;
+  static constexpr ValueType Default = D;
+
+  ValueType Value;
+  constexpr EncodingField(ValueType Value) : Value(Value) {}
+
+  constexpr uint64_t encode() const { return Value; }
+  static ValueType decode(uint64_t Encoded) { return Encoded; }
+};
+
+// A helper for encoding and decoding multiple fields.
+template <typename... Fields> struct EncodingFields {
+  static constexpr uint64_t encode(Fields... Values) {
+    return ((Values.encode() << Values.Offset) | ...);
+  }
+
+  static std::tuple<typename Fields::ValueType...> decode(uint64_t Encoded) {
+    return {Fields::decode((Encoded >> Fields::Offset) &
+                           maxUIntN(Fields::Width))...};
+  }
+};
+
 LLVM_READONLY
 int16_t getNamedOperandIdx(uint16_t Opcode, uint16_t NamedIdx);
 
@@ -1021,6 +1050,17 @@ unsigned encodeStorecntDscnt(const IsaVersion &Version, const Waitcnt &Decoded);
 
 namespace Hwreg {
 
+using HwregId = EncodingField<5, 0>;
+using HwregOffset = EncodingField<10, 6>;
+
+struct HwregSize : EncodingField<15, 11, 32> {
+  using EncodingField::EncodingField;
+  constexpr uint64_t encode() const { return Value - 1; }
+  static ValueType decode(uint64_t Encoded) { return Encoded + 1; }
+};
+
+using HwregEncoding = EncodingFields<HwregId, HwregOffset, HwregSize>;
+
 LLVM_READONLY
 int64_t getHwregId(const StringRef Name, const MCSubtargetInfo &STI);
 
@@ -1034,13 +1074,8 @@ LLVM_READNONE
 bool isValidHwregWidth(int64_t Width);
 
 LLVM_READNONE
-uint64_t encodeHwreg(uint64_t Id, uint64_t Offset, uint64_t Width);
-
-LLVM_READNONE
 StringRef getHwreg(unsigned Id, const MCSubtargetInfo &STI);
 
-void decodeHwreg(unsigned Val, unsigned &Id, unsigned &Offset, unsigned &Width);
-
 } // namespace Hwreg
 
 namespace DepCtr {