[llvm] [AMDGPU] fix up vop3p gisel errors (PR #136262)

Matt Arsenault via llvm-commits llvm-commits at lists.llvm.org
Mon Jun 16 07:01:14 PDT 2025


================
@@ -4318,60 +4318,586 @@ AMDGPUInstructionSelector::selectVOP3NoMods(MachineOperand &Root) const {
   }};
 }
 
-std::pair<Register, unsigned>
-AMDGPUInstructionSelector::selectVOP3PModsImpl(
-  Register Src, const MachineRegisterInfo &MRI, bool IsDOT) const {
+enum class SrcStatus {
+  IS_SAME,
+  IS_UPPER_HALF,
+  IS_LOWER_HALF,
+  IS_UPPER_HALF_NEG,
+  // This means current op = [op_upper, op_lower] and src = -op_lower.
+  IS_LOWER_HALF_NEG,
+  IS_HI_NEG,
+  // This means current op = [op_upper, op_lower] and src = [op_upper,
+  // -op_lower].
+  IS_LO_NEG,
+  IS_BOTH_NEG,
+  INVALID,
+  NEG_START = IS_UPPER_HALF_NEG,
+  NEG_END = IS_BOTH_NEG,
+  HALF_START = IS_UPPER_HALF,
+  HALF_END = IS_LOWER_HALF_NEG
+};
+// Test if the MI is truncating to half, such as `%reg0:n = G_TRUNC %reg1:2n`
+static bool isTruncHalf(const MachineInstr *MI,
+                        const MachineRegisterInfo &MRI) {
+  if (MI->getOpcode() != AMDGPU::G_TRUNC)
+    return false;
+
+  unsigned DstSize = MRI.getType(MI->getOperand(0).getReg()).getSizeInBits();
+  unsigned SrcSize = MRI.getType(MI->getOperand(1).getReg()).getSizeInBits();
+  return DstSize * 2 == SrcSize;
+}
+
+// Test if the MI is logic shift right with half bits,
+// such as `%reg0:2n =G_LSHR %reg1:2n, CONST(n)`
+static bool isLshrHalf(const MachineInstr *MI, const MachineRegisterInfo &MRI) {
+  if (MI->getOpcode() != AMDGPU::G_LSHR)
+    return false;
+
+  Register ShiftSrc;
+  std::optional<ValueAndVReg> ShiftAmt;
+  if (mi_match(MI->getOperand(0).getReg(), MRI,
+               m_GLShr(m_Reg(ShiftSrc), m_GCst(ShiftAmt)))) {
+    unsigned SrcSize = MRI.getType(MI->getOperand(1).getReg()).getSizeInBits();
+    unsigned Shift = ShiftAmt->Value.getZExtValue();
+    return Shift * 2 == SrcSize;
+  }
+  return false;
+}
+
+// Test if the MI is shift left with half bits,
+// such as `%reg0:2n =G_SHL %reg1:2n, CONST(n)`
+static bool isShlHalf(const MachineInstr *MI, const MachineRegisterInfo &MRI) {
+  if (MI->getOpcode() != AMDGPU::G_SHL)
+    return false;
+
+  Register ShiftSrc;
+  std::optional<ValueAndVReg> ShiftAmt;
+  if (mi_match(MI->getOperand(0).getReg(), MRI,
+               m_GShl(m_Reg(ShiftSrc), m_GCst(ShiftAmt)))) {
+    unsigned SrcSize = MRI.getType(MI->getOperand(1).getReg()).getSizeInBits();
+    unsigned Shift = ShiftAmt->Value.getZExtValue();
+    return Shift * 2 == SrcSize;
+  }
+  return false;
+}
+
+// Test function, if the MI is `%reg0:n, %reg1:n = G_UNMERGE_VALUES %reg2:2n`
+static bool isUnmergeHalf(const MachineInstr *MI,
+                          const MachineRegisterInfo &MRI) {
+  if (MI->getOpcode() != AMDGPU::G_UNMERGE_VALUES)
+    return false;
+  return MI->getNumOperands() == 3 && MI->getOperand(0).isDef() &&
+         MI->getOperand(1).isDef() && !MI->getOperand(2).isDef();
+}
+
+enum class TypeClass { VECTOR_OF_TWO, SCALAR, NONE_OF_LISTED };
+
+static TypeClass isVectorOfTwoOrScalar(Register Reg,
+                                       const MachineRegisterInfo &MRI) {
+  LLT OpTy = MRI.getType(Reg);
+  if (OpTy.isScalar())
+    return TypeClass::SCALAR;
+  if (OpTy.isVector() && OpTy.getNumElements() == 2)
+    return TypeClass::VECTOR_OF_TWO;
+  return TypeClass::NONE_OF_LISTED;
+}
+
+static SrcStatus getNegStatus(Register Reg, SrcStatus S,
+                              const MachineRegisterInfo &MRI) {
+  TypeClass NegType = isVectorOfTwoOrScalar(Reg, MRI);
+  if (NegType != TypeClass::VECTOR_OF_TWO && NegType != TypeClass::SCALAR)
+    return SrcStatus::INVALID;
+
+  switch (S) {
+  case SrcStatus::IS_SAME:
+    if (NegType == TypeClass::VECTOR_OF_TWO) {
+      // Vector of 2:
+      // [SrcHi, SrcLo]   = [CurrHi, CurrLo]
+      // [CurrHi, CurrLo] = neg [OpHi, OpLo](2 x Type)
+      // [CurrHi, CurrLo] = [-OpHi, -OpLo](2 x Type)
+      // [SrcHi, SrcLo]   = [-OpHi, -OpLo]
+      return SrcStatus::IS_BOTH_NEG;
+    }
+    if (NegType == TypeClass::SCALAR) {
+      // Scalar:
+      // [SrcHi, SrcLo]   = [CurrHi, CurrLo]
+      // [CurrHi, CurrLo] = neg [OpHi, OpLo](Type)
+      // [CurrHi, CurrLo] = [-OpHi, OpLo](Type)
+      // [SrcHi, SrcLo]   = [-OpHi, OpLo]
+      return SrcStatus::IS_HI_NEG;
+    }
+    break;
+  case SrcStatus::IS_HI_NEG:
+    if (NegType == TypeClass::VECTOR_OF_TWO) {
+      // Vector of 2:
+      // [SrcHi, SrcLo]   = [-CurrHi, CurrLo]
+      // [CurrHi, CurrLo] = neg [OpHi, OpLo](2 x Type)
+      // [CurrHi, CurrLo] = [-OpHi, -OpLo](2 x Type)
+      // [SrcHi, SrcLo]   = [-(-OpHi), -OpLo] = [OpHi, -OpLo]
+      return SrcStatus::IS_LO_NEG;
+    }
+    if (NegType == TypeClass::SCALAR) {
+      // Scalar:
+      // [SrcHi, SrcLo]   = [-CurrHi, CurrLo]
+      // [CurrHi, CurrLo] = neg [OpHi, OpLo](Type)
+      // [CurrHi, CurrLo] = [-OpHi, OpLo](Type)
+      // [SrcHi, SrcLo]   = [-(-OpHi), OpLo] = [OpHi, OpLo]
+      return SrcStatus::IS_SAME;
+    }
+    break;
+  case SrcStatus::IS_LO_NEG:
+    if (NegType == TypeClass::VECTOR_OF_TWO) {
+      // Vector of 2:
+      // [SrcHi, SrcLo]   = [CurrHi, -CurrLo]
+      // [CurrHi, CurrLo] = fneg [OpHi, OpLo](2 x Type)
+      // [CurrHi, CurrLo] = [-OpHi, -OpLo](2 x Type)
+      // [SrcHi, SrcLo]   = [-OpHi, -(-OpLo)] = [-OpHi, OpLo]
+      return SrcStatus::IS_HI_NEG;
+    }
+    if (NegType == TypeClass::SCALAR) {
+      // Scalar:
+      // [SrcHi, SrcLo]   = [CurrHi, -CurrLo]
+      // [CurrHi, CurrLo] = fneg [OpHi, OpLo](Type)
+      // [CurrHi, CurrLo] = [-OpHi, OpLo](Type)
+      // [SrcHi, SrcLo]   = [-OpHi, -OpLo]
+      return SrcStatus::IS_BOTH_NEG;
+    }
+    break;
+  case SrcStatus::IS_BOTH_NEG:
+    if (NegType == TypeClass::VECTOR_OF_TWO) {
+      // Vector of 2:
+      // [SrcHi, SrcLo]   = [-CurrHi, -CurrLo]
+      // [CurrHi, CurrLo] = fneg [OpHi, OpLo](2 x Type)
+      // [CurrHi, CurrLo] = [-OpHi, -OpLo](2 x Type)
+      // [SrcHi, SrcLo]   = [OpHi, OpLo]
+      return SrcStatus::IS_SAME;
+    }
+    if (NegType == TypeClass::SCALAR) {
+      // Scalar:
+      // [SrcHi, SrcLo]   = [-CurrHi, -CurrLo]
+      // [CurrHi, CurrLo] = fneg [OpHi, OpLo](Type)
+      // [CurrHi, CurrLo] = [-OpHi, OpLo](Type)
+      // [SrcHi, SrcLo]   = [OpHi, -OpLo]
+      return SrcStatus::IS_LO_NEG;
+    }
+    break;
+  case SrcStatus::IS_UPPER_HALF:
+    // Vector of 2:
+    // Src = CurrUpper
+    // Curr = [CurrUpper, CurrLower]
+    // [CurrUpper, CurrLower] = fneg [OpUpper, OpLower](2 x Type)
+    // [CurrUpper, CurrLower] = [-OpUpper, -OpLower](2 x Type)
+    // Src = -OpUpper
+    //
+    // Scalar:
+    // Src = CurrUpper
+    // Curr = [CurrUpper, CurrLower]
+    // [CurrUpper, CurrLower] = fneg [OpUpper, OpLower](Type)
+    // [CurrUpper, CurrLower] = [-OpUpper, OpLower](Type)
+    // Src = -OpUpper
+    return SrcStatus::IS_UPPER_HALF_NEG;
+  case SrcStatus::IS_LOWER_HALF:
+    if (NegType == TypeClass::VECTOR_OF_TWO) {
+      // Vector of 2:
+      // Src = CurrLower
+      // Curr = [CurrUpper, CurrLower]
+      // [CurrUpper, CurrLower] = fneg [OpUpper, OpLower](2 x Type)
+      // [CurrUpper, CurrLower] = [-OpUpper, -OpLower](2 x Type)
+      // Src = -OpLower
+      return SrcStatus::IS_LOWER_HALF_NEG;
+    }
+    if (NegType == TypeClass::SCALAR) {
+      // Scalar:
+      // Src = CurrLower
+      // Curr = [CurrUpper, CurrLower]
+      // [CurrUpper, CurrLower] = fneg [OpUpper, OpLower](Type)
+      // [CurrUpper, CurrLower] = [-OpUpper, OpLower](Type)
+      // Src = OpLower
+      return SrcStatus::IS_LOWER_HALF;
+    }
+    break;
+  case SrcStatus::IS_UPPER_HALF_NEG:
+    // Vector of 2:
+    // Src = -CurrUpper
+    // Curr = [CurrUpper, CurrLower]
+    // [CurrUpper, CurrLower] = fneg [OpUpper, OpLower](2 x Type)
+    // [CurrUpper, CurrLower] = [-OpUpper, -OpLower](2 x Type)
+    // Src = -(-OpUpper) = OpUpper
+    //
+    // Scalar:
+    // Src = -CurrUpper
+    // Curr = [CurrUpper, CurrLower]
+    // [CurrUpper, CurrLower] = fneg [OpUpper, OpLower](Type)
+    // [CurrUpper, CurrLower] = [-OpUpper, OpLower](Type)
+    // Src = -(-OpUpper) = OpUpper
+    return SrcStatus::IS_UPPER_HALF;
+  case SrcStatus::IS_LOWER_HALF_NEG:
+    if (NegType == TypeClass::VECTOR_OF_TWO) {
+      // Vector of 2:
+      // Src = -CurrLower
+      // Curr = [CurrUpper, CurrLower]
+      // [CurrUpper, CurrLower] = fneg [OpUpper, OpLower](2 x Type)
+      // [CurrUpper, CurrLower] = [-OpUpper, -OpLower](2 x Type)
+      // Src = -(-OpLower) = OpLower
+      return SrcStatus::IS_LOWER_HALF;
+    }
+    if (NegType == TypeClass::SCALAR) {
+      // Scalar:
+      // Src = -CurrLower
+      // Curr = [CurrUpper, CurrLower]
+      // [CurrUpper, CurrLower] = fneg [OpUpper, OpLower](Type)
+      // [CurrUpper, CurrLower] = [-OpUpper, OpLower](Type)
+      // Src = -OpLower
+      return SrcStatus::IS_LOWER_HALF_NEG;
+    }
+    break;
+  default:
+    llvm_unreachable("unexpected SrcStatus");
+  }
+}
+
+static std::optional<std::pair<Register, SrcStatus>>
+calcNextStatus(std::pair<Register, SrcStatus> Curr,
+               const MachineRegisterInfo &MRI) {
+  const MachineInstr *MI = MRI.getVRegDef(Curr.first);
+
+  unsigned Opc = MI->getOpcode();
+
+  // Handle general Opc cases.
+  switch (Opc) {
+  case AMDGPU::G_BITCAST:
+  case AMDGPU::COPY:
+    if (MI->getOperand(1).getReg().isPhysical())
+      return std::nullopt;
+    return std::optional<std::pair<Register, SrcStatus>>(
+        {MI->getOperand(1).getReg(), Curr.second});
+  case AMDGPU::G_FNEG: {
+    SrcStatus Stat = getNegStatus(Curr.first, Curr.second, MRI);
+    if (Stat == SrcStatus::INVALID)
+      return std::nullopt;
+    return std::optional<std::pair<Register, SrcStatus>>(
+        {MI->getOperand(1).getReg(), Stat});
+  }
+  default:
+    break;
+  }
+
+  // Calc next Stat from current Stat.
+  switch (Curr.second) {
+  case SrcStatus::IS_SAME:
+    if (isTruncHalf(MI, MRI))
+      return std::optional<std::pair<Register, SrcStatus>>(
+          {MI->getOperand(1).getReg(), SrcStatus::IS_LOWER_HALF});
+    else if (isUnmergeHalf(MI, MRI)) {
+      if (Curr.first == MI->getOperand(0).getReg())
+        return std::optional<std::pair<Register, SrcStatus>>(
+            {MI->getOperand(2).getReg(), SrcStatus::IS_LOWER_HALF});
+      return std::optional<std::pair<Register, SrcStatus>>(
+          {MI->getOperand(2).getReg(), SrcStatus::IS_UPPER_HALF});
+    }
+    break;
+  case SrcStatus::IS_HI_NEG:
+    if (isTruncHalf(MI, MRI)) {
+      // [SrcHi, SrcLo]   = [-CurrHi, CurrLo]
+      // [CurrHi, CurrLo] = trunc [OpUpper, OpLower] = OpLower
+      //                  = [OpLowerHi, OpLowerLo]
+      // Src = [SrcHi, SrcLo] = [-CurrHi, CurrLo]
+      //     = [-OpLowerHi, OpLowerLo]
+      //     = -OpLower
+      return std::optional<std::pair<Register, SrcStatus>>(
+          {MI->getOperand(1).getReg(), SrcStatus::IS_LOWER_HALF_NEG});
+    }
+    if (isUnmergeHalf(MI, MRI)) {
+      if (Curr.first == MI->getOperand(0).getReg())
+        return std::optional<std::pair<Register, SrcStatus>>(
+            {MI->getOperand(2).getReg(), SrcStatus::IS_LOWER_HALF_NEG});
+      return std::optional<std::pair<Register, SrcStatus>>(
+          {MI->getOperand(2).getReg(), SrcStatus::IS_UPPER_HALF_NEG});
+    }
+    break;
+  case SrcStatus::IS_UPPER_HALF:
+    if (isShlHalf(MI, MRI))
+      return std::optional<std::pair<Register, SrcStatus>>(
+          {MI->getOperand(1).getReg(), SrcStatus::IS_LOWER_HALF});
+    break;
+  case SrcStatus::IS_LOWER_HALF:
+    if (isLshrHalf(MI, MRI))
+      return std::optional<std::pair<Register, SrcStatus>>(
+          {MI->getOperand(1).getReg(), SrcStatus::IS_UPPER_HALF});
+    break;
+  case SrcStatus::IS_UPPER_HALF_NEG:
+    if (isShlHalf(MI, MRI))
+      return std::optional<std::pair<Register, SrcStatus>>(
+          {MI->getOperand(1).getReg(), SrcStatus::IS_LOWER_HALF_NEG});
+    break;
+  case SrcStatus::IS_LOWER_HALF_NEG:
+    if (isLshrHalf(MI, MRI))
+      return std::optional<std::pair<Register, SrcStatus>>(
+          {MI->getOperand(1).getReg(), SrcStatus::IS_UPPER_HALF_NEG});
+    break;
+  default:
+    break;
+  }
+  return std::nullopt;
+}
+
+class searchOptions {
+private:
+  bool HasNeg = false;
+  // Assume all complex pattern of VOP3P has opsel.
+  bool HasOpsel = true;
+
+public:
+  searchOptions(Register Reg, const MachineRegisterInfo &MRI) {
+    const MachineInstr *MI = MRI.getVRegDef(Reg);
+    unsigned Opc = MI->getOpcode();
+
+    if (Opc < TargetOpcode::GENERIC_OP_END) {
+      // Keep same for generic op.
+      HasNeg = true;
+    } else if (Opc == TargetOpcode::G_INTRINSIC) {
+      Intrinsic::ID IntrinsicID = cast<GIntrinsic>(*MI).getIntrinsicID();
+      // Only float point intrinsic has neg & neg_hi bits.
+      if (IntrinsicID == Intrinsic::amdgcn_fdot2)
+        HasNeg = true;
+    }
+  }
+  bool checkOptions(SrcStatus Stat) const {
+    if (!HasNeg &&
+        (Stat >= SrcStatus::NEG_START && Stat <= SrcStatus::NEG_END)) {
+      return false;
+    }
+    if (!HasOpsel &&
+        (Stat >= SrcStatus::HALF_START && Stat <= SrcStatus::HALF_END)) {
+      return false;
+    }
+    return true;
+  }
+};
+
+static SmallVector<std::pair<Register, SrcStatus>>
+getSrcStats(Register Reg, const MachineRegisterInfo &MRI,
+            searchOptions SearchOptions, int MaxDepth = 6) {
+  int Depth = 0;
+  auto Curr = calcNextStatus({Reg, SrcStatus::IS_SAME}, MRI);
+  SmallVector<std::pair<Register, SrcStatus>> Statlist;
+
+  while (Depth <= MaxDepth && Curr.has_value()) {
+    Depth++;
+    if (SearchOptions.checkOptions(Curr.value().second))
+      Statlist.push_back(Curr.value());
+    Curr = calcNextStatus(Curr.value(), MRI);
+  }
+
+  return Statlist;
+}
+
+static std::pair<Register, SrcStatus>
+getLastSameOrNeg(Register Reg, const MachineRegisterInfo &MRI,
+                 searchOptions SearchOptions, int MaxDepth = 6) {
+  int Depth = 0;
+  std::pair<Register, SrcStatus> LastSameOrNeg = {Reg, SrcStatus::IS_SAME};
+  auto Curr = calcNextStatus(LastSameOrNeg, MRI);
+
+  while (Depth <= MaxDepth && Curr.has_value()) {
+    Depth++;
+    if (SearchOptions.checkOptions(Curr.value().second)) {
+      if (Curr.value().second == SrcStatus::IS_SAME ||
+          Curr.value().second == SrcStatus::IS_HI_NEG ||
+          Curr.value().second == SrcStatus::IS_LO_NEG ||
+          Curr.value().second == SrcStatus::IS_BOTH_NEG)
+        LastSameOrNeg = Curr.value();
+    }
+    Curr = calcNextStatus(Curr.value(), MRI);
+  }
+
+  return LastSameOrNeg;
+}
+
+static bool isSameBitWidth(Register Reg1, Register Reg2,
+                           const MachineRegisterInfo &MRI) {
+  unsigned Width1 = MRI.getType(Reg1).getSizeInBits();
+  unsigned Width2 = MRI.getType(Reg2).getSizeInBits();
+  return Width1 == Width2;
+}
+
+static unsigned updateMods(SrcStatus HiStat, SrcStatus LoStat, unsigned Mods) {
+  // SrcStatus::IS_LOWER_HALF remain 0.
+  if (HiStat == SrcStatus::IS_UPPER_HALF_NEG) {
+    Mods ^= SISrcMods::NEG_HI;
+    Mods |= SISrcMods::OP_SEL_1;
+  } else if (HiStat == SrcStatus::IS_UPPER_HALF)
+    Mods |= SISrcMods::OP_SEL_1;
+  else if (HiStat == SrcStatus::IS_LOWER_HALF_NEG)
+    Mods ^= SISrcMods::NEG_HI;
+  else if (HiStat == SrcStatus::IS_HI_NEG)
+    Mods ^= SISrcMods::NEG_HI;
+
+  if (LoStat == SrcStatus::IS_UPPER_HALF_NEG) {
+    Mods ^= SISrcMods::NEG;
+    Mods |= SISrcMods::OP_SEL_0;
+  } else if (LoStat == SrcStatus::IS_UPPER_HALF)
+    Mods |= SISrcMods::OP_SEL_0;
+  else if (LoStat == SrcStatus::IS_LOWER_HALF_NEG)
+    Mods |= SISrcMods::NEG;
+  else if (LoStat == SrcStatus::IS_HI_NEG)
+    Mods ^= SISrcMods::NEG;
+
+  return Mods;
+}
+
+static bool isValidToPack(SrcStatus HiStat, SrcStatus LoStat, Register NewReg,
+                          Register RootReg, const SIInstrInfo &TII,
+                          const MachineRegisterInfo &MRI) {
+  auto IsHalfState = [](SrcStatus S) {
+    return S == SrcStatus::IS_UPPER_HALF || S == SrcStatus::IS_UPPER_HALF_NEG ||
+           S == SrcStatus::IS_LOWER_HALF || S == SrcStatus::IS_LOWER_HALF_NEG;
+  };
+  return isSameBitWidth(NewReg, RootReg, MRI) && IsHalfState(LoStat) &&
+         IsHalfState(HiStat);
+}
+
+std::pair<Register, unsigned> AMDGPUInstructionSelector::selectVOP3PModsImpl(
+    Register RootReg, const MachineRegisterInfo &MRI, bool IsDOT) const {
   unsigned Mods = 0;
-  MachineInstr *MI = MRI.getVRegDef(Src);
+  // No modification if Root type is not form of <2 x Type>.
+  if (isVectorOfTwoOrScalar(RootReg, MRI) != TypeClass::VECTOR_OF_TWO) {
+    Mods |= SISrcMods::OP_SEL_1;
+    return {RootReg, Mods};
+  }
 
-  if (MI->getOpcode() == AMDGPU::G_FNEG &&
-      // It's possible to see an f32 fneg here, but unlikely.
-      // TODO: Treat f32 fneg as only high bit.
-      MRI.getType(Src) == LLT::fixed_vector(2, 16)) {
+  searchOptions SearchOptions(RootReg, MRI);
+
+  std::pair<Register, SrcStatus> Stat =
+      getLastSameOrNeg(RootReg, MRI, SearchOptions);
+
+  if (Stat.second == SrcStatus::IS_BOTH_NEG)
     Mods ^= (SISrcMods::NEG | SISrcMods::NEG_HI);
-    Src = MI->getOperand(1).getReg();
-    MI = MRI.getVRegDef(Src);
+  else if (Stat.second == SrcStatus::IS_HI_NEG)
+    Mods ^= SISrcMods::NEG_HI;
+  else if (Stat.second == SrcStatus::IS_LO_NEG)
+    Mods ^= SISrcMods::NEG;
+
+  MachineInstr *MI = MRI.getVRegDef(Stat.first);
+
+  if (MI->getOpcode() != AMDGPU::G_BUILD_VECTOR || MI->getNumOperands() != 3 ||
+      (IsDOT && Subtarget->hasDOTOpSelHazard())) {
+    Mods |= SISrcMods::OP_SEL_1;
+    return {Stat.first, Mods};
   }
 
-  // TODO: Handle G_FSUB 0 as fneg
+  SmallVector<std::pair<Register, SrcStatus>> StatlistHi =
+      getSrcStats(MI->getOperand(2).getReg(), MRI, SearchOptions);
+
+  if (StatlistHi.empty()) {
+    Mods |= SISrcMods::OP_SEL_1;
+    return {Stat.first, Mods};
+  }
 
-  // TODO: Match op_sel through g_build_vector_trunc and g_shuffle_vector.
-  (void)IsDOT; // DOTs do not use OPSEL on gfx942+, check ST.hasDOTOpSelHazard()
+  SmallVector<std::pair<Register, SrcStatus>> StatlistLo =
+      getSrcStats(MI->getOperand(1).getReg(), MRI, SearchOptions);
 
+  if (StatlistLo.empty()) {
+    Mods |= SISrcMods::OP_SEL_1;
+    return {Stat.first, Mods};
+  }
+
+  for (int I = StatlistHi.size() - 1; I >= 0; I--) {
+    for (int J = StatlistLo.size() - 1; J >= 0; J--) {
+      if (StatlistHi[I].first == StatlistLo[J].first &&
+          isValidToPack(StatlistHi[I].second, StatlistLo[J].second,
+                        StatlistHi[I].first, RootReg, TII, MRI))
+        return {StatlistHi[I].first,
+                updateMods(StatlistHi[I].second, StatlistLo[J].second, Mods)};
+    }
+  }
   // Packed instructions do not have abs modifiers.
   Mods |= SISrcMods::OP_SEL_1;
 
-  return std::pair(Src, Mods);
+  return {Stat.first, Mods};
 }
 
-InstructionSelector::ComplexRendererFns
-AMDGPUInstructionSelector::selectVOP3PMods(MachineOperand &Root) const {
-  MachineRegisterInfo &MRI
-    = Root.getParent()->getParent()->getParent()->getRegInfo();
+int64_t getAllKindImm(const MachineOperand *Op) {
+  switch (Op->getType()) {
+  case MachineOperand::MachineOperandType::MO_Immediate:
+    return Op->getImm();
+  case MachineOperand::MachineOperandType::MO_CImmediate:
+    return Op->getCImm()->getSExtValue();
+  case MachineOperand::MachineOperandType::MO_FPImmediate:
+    return Op->getFPImm()->getValueAPF().bitcastToAPInt().getSExtValue();
+  default:
+    llvm_unreachable("not an imm type");
+  }
+}
 
-  Register Src;
+static bool checkRB(Register Reg, unsigned int RBNo,
+                    const AMDGPURegisterBankInfo &RBI,
+                    const MachineRegisterInfo &MRI,
+                    const TargetRegisterInfo &TRI) {
+  const RegisterBank *RB = RBI.getRegBank(Reg, MRI, TRI);
+  return RB->getID() == RBNo;
+}
+
+// This function is used to get the correct register bank for returned reg.
+// Assume:
+// 1. VOP3P is always legal for VGPR.
+// 2. RootOp's regbank is legal.
+// Thus
+// 1. If RootOp is SGPR, then NewOp can be SGPR or VGPR.
+// 2. If RootOp is VGPR, then NewOp must be VGPR.
+static Register getLegalRegBank(Register NewReg, Register RootReg,
+                                const AMDGPURegisterBankInfo &RBI,
+                                MachineRegisterInfo &MRI,
+                                const TargetRegisterInfo &TRI,
+                                const SIInstrInfo &TII) {
+  // RootOp can only be VGPR or SGPR (some hand written cases such as.
+  // inst-select-ashr.v2s16.mir::ashr_v2s16_vs).
+  if (checkRB(RootReg, AMDGPU::SGPRRegBankID, RBI, MRI, TRI) ||
+      checkRB(NewReg, AMDGPU::VGPRRegBankID, RBI, MRI, TRI))
+    return NewReg;
+
+  MachineInstr *MI = MRI.getVRegDef(RootReg);
+  if (MI->getOpcode() == AMDGPU::COPY && NewReg == MI->getOperand(1).getReg()) {
+    // RootOp is VGPR, NewOp is not VGPR, but RootOp = COPY NewOp.
+    return RootReg;
+  }
+
+  MachineBasicBlock *BB = MI->getParent();
+  Register DstReg = MRI.cloneVirtualRegister(RootReg);
+
+  MachineInstrBuilder MIB =
+      BuildMI(*BB, MI, MI->getDebugLoc(), TII.get(AMDGPU::COPY), DstReg)
+          .addReg(NewReg);
+
+  // only accept VGPR.
----------------
arsenm wrote:

Capitalize 

https://github.com/llvm/llvm-project/pull/136262


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