[AMDGPU] Define 1024 VGPRs on gfx1250 (llvm#156765)

This is a baseline support, it is not useable yet.

Author: rampitec

llvm/lib/Target/AMDGPU/AsmParser/AMDGPUAsmParser.cpp

@@ -564,6 +564,14 @@ class AMDGPUOperand : public MCParsedAsmOperand {
     return isRegOrInlineNoMods(AMDGPU::VS_32RegClassID, MVT::i32);
   }
 
+  bool isVCSrc_b32_Lo256() const {
+    return isRegOrInlineNoMods(AMDGPU::VS_32_Lo256RegClassID, MVT::i32);
+  }
+
+  bool isVCSrc_b64_Lo256() const {
+    return isRegOrInlineNoMods(AMDGPU::VS_64_Lo256RegClassID, MVT::i64);
+  }
+
   bool isVCSrc_b64() const {
     return isRegOrInlineNoMods(AMDGPU::VS_64RegClassID, MVT::i64);
   }
@@ -2986,7 +2994,12 @@ MCRegister AMDGPUAsmParser::getRegularReg(RegisterKind RegKind, unsigned RegNum,
 
   const MCRegisterInfo *TRI = getContext().getRegisterInfo();
   const MCRegisterClass RC = TRI->getRegClass(RCID);
-  if (RegIdx >= RC.getNumRegs()) {
+  if (RegIdx >= RC.getNumRegs() || (RegKind == IS_VGPR && RegIdx > 255)) {
+    Error(Loc, "register index is out of range");
+    return AMDGPU::NoRegister;
+  }
+
+  if (RegKind == IS_VGPR && !isGFX1250() && RegIdx + RegWidth / 32 > 256) {
     Error(Loc, "register index is out of range");
     return MCRegister();
   }

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

@@ -1223,6 +1223,26 @@ void AMDGPUDisassembler::convertVOP3DPPInst(MCInst &MI) const {
   }
 }
 
+// Given a wide tuple \p Reg check if it will overflow 256 registers.
+// \returns \p Reg on success or NoRegister otherwise.
+static unsigned CheckVGPROverflow(unsigned Reg, const MCRegisterClass &RC,
+                                  const MCRegisterInfo &MRI) {
+  unsigned NumRegs = RC.getSizeInBits() / 32;
+  MCRegister Sub0 = MRI.getSubReg(Reg, AMDGPU::sub0);
+  if (!Sub0)
+    return Reg;
+
+  MCRegister BaseReg;
+  if (MRI.getRegClass(AMDGPU::VGPR_32RegClassID).contains(Sub0))
+    BaseReg = AMDGPU::VGPR0;
+  else if (MRI.getRegClass(AMDGPU::AGPR_32RegClassID).contains(Sub0))
+    BaseReg = AMDGPU::AGPR0;
+
+  assert(BaseReg && "Only vector registers expected");
+
+  return (Sub0 - BaseReg + NumRegs <= 256) ? Reg : AMDGPU::NoRegister;
+}
+
 // Note that before gfx10, the MIMG encoding provided no information about
 // VADDR size. Consequently, decoded instructions always show address as if it
 // has 1 dword, which could be not really so.
@@ -1327,8 +1347,9 @@ void AMDGPUDisassembler::convertMIMGInst(MCInst &MI) const {
     MCRegister VdataSub0 = MRI.getSubReg(Vdata0, AMDGPU::sub0);
     Vdata0 = (VdataSub0 != 0)? VdataSub0 : Vdata0;
 
-    NewVdata = MRI.getMatchingSuperReg(Vdata0, AMDGPU::sub0,
-                                       &MRI.getRegClass(DataRCID));
+    const MCRegisterClass &NewRC = MRI.getRegClass(DataRCID);
+    NewVdata = MRI.getMatchingSuperReg(Vdata0, AMDGPU::sub0, &NewRC);
+    NewVdata = CheckVGPROverflow(NewVdata, NewRC, MRI);
     if (!NewVdata) {
       // It's possible to encode this such that the low register + enabled
       // components exceeds the register count.
@@ -1347,8 +1368,9 @@ void AMDGPUDisassembler::convertMIMGInst(MCInst &MI) const {
     VAddrSA = VAddrSubSA ? VAddrSubSA : VAddrSA;
 
     auto AddrRCID = MCII->get(NewOpcode).operands()[VAddrSAIdx].RegClass;
-    NewVAddrSA = MRI.getMatchingSuperReg(VAddrSA, AMDGPU::sub0,
-                                        &MRI.getRegClass(AddrRCID));
+    const MCRegisterClass &NewRC = MRI.getRegClass(AddrRCID);
+    NewVAddrSA = MRI.getMatchingSuperReg(VAddrSA, AMDGPU::sub0, &NewRC);
+    NewVAddrSA = CheckVGPROverflow(NewVAddrSA, NewRC, MRI);
     if (!NewVAddrSA)
       return;
   }

llvm/lib/Target/AMDGPU/GCNSubtarget.cpp

@@ -577,6 +577,7 @@ GCNSubtarget::getMaxNumVectorRegs(const Function &F) const {
 
   unsigned MaxNumVGPRs = MaxVectorRegs;
   unsigned MaxNumAGPRs = 0;
+  unsigned NumArchVGPRs = has1024AddressableVGPRs() ? 1024 : 256;
 
   // On GFX90A, the number of VGPRs and AGPRs need not be equal. Theoretically,
   // a wave may have up to 512 total vector registers combining together both
@@ -589,7 +590,6 @@ GCNSubtarget::getMaxNumVectorRegs(const Function &F) const {
   if (hasGFX90AInsts()) {
     unsigned MinNumAGPRs = 0;
     const unsigned TotalNumAGPRs = AMDGPU::AGPR_32RegClass.getNumRegs();
-    const unsigned TotalNumVGPRs = AMDGPU::VGPR_32RegClass.getNumRegs();
 
     const std::pair<unsigned, unsigned> DefaultNumAGPR = {~0u, ~0u};
 
@@ -614,11 +614,11 @@ GCNSubtarget::getMaxNumVectorRegs(const Function &F) const {
     MaxNumAGPRs = std::min(std::max(MinNumAGPRs, MaxNumAGPRs), MaxVectorRegs);
     MinNumAGPRs = std::min(std::min(MinNumAGPRs, TotalNumAGPRs), MaxNumAGPRs);
 
-    MaxNumVGPRs = std::min(MaxVectorRegs - MinNumAGPRs, TotalNumVGPRs);
+    MaxNumVGPRs = std::min(MaxVectorRegs - MinNumAGPRs, NumArchVGPRs);
     MaxNumAGPRs = std::min(MaxVectorRegs - MaxNumVGPRs, MaxNumAGPRs);
 
     assert(MaxNumVGPRs + MaxNumAGPRs <= MaxVectorRegs &&
-           MaxNumAGPRs <= TotalNumAGPRs && MaxNumVGPRs <= TotalNumVGPRs &&
+           MaxNumAGPRs <= TotalNumAGPRs && MaxNumVGPRs <= NumArchVGPRs &&
            "invalid register counts");
   } else if (hasMAIInsts()) {
     // On gfx908 the number of AGPRs always equals the number of VGPRs.

llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUMCCodeEmitter.cpp

@@ -402,7 +402,7 @@ void AMDGPUMCCodeEmitter::encodeInstruction(const MCInst &MI,
   if (AMDGPU::isGFX10Plus(STI) && isVCMPX64(Desc)) {
     assert((Encoding & 0xFF) == 0);
     Encoding |= MRI.getEncodingValue(AMDGPU::EXEC_LO) &
-                AMDGPU::HWEncoding::REG_IDX_MASK;
+                AMDGPU::HWEncoding::LO256_REG_IDX_MASK;
   }
 
   for (unsigned i = 0; i < bytes; i++) {
@@ -551,7 +551,7 @@ void AMDGPUMCCodeEmitter::getAVOperandEncoding(
     SmallVectorImpl<MCFixup> &Fixups, const MCSubtargetInfo &STI) const {
   MCRegister Reg = MI.getOperand(OpNo).getReg();
   unsigned Enc = MRI.getEncodingValue(Reg);
-  unsigned Idx = Enc & AMDGPU::HWEncoding::REG_IDX_MASK;
+  unsigned Idx = Enc & AMDGPU::HWEncoding::LO256_REG_IDX_MASK;
   bool IsVGPROrAGPR =
       Enc & (AMDGPU::HWEncoding::IS_VGPR | AMDGPU::HWEncoding::IS_AGPR);
 
@@ -593,7 +593,7 @@ void AMDGPUMCCodeEmitter::getMachineOpValue(const MCInst &MI,
                                             const MCSubtargetInfo &STI) const {
   if (MO.isReg()){
     unsigned Enc = MRI.getEncodingValue(MO.getReg());
-    unsigned Idx = Enc & AMDGPU::HWEncoding::REG_IDX_MASK;
+    unsigned Idx = Enc & AMDGPU::HWEncoding::LO256_REG_IDX_MASK;
     bool IsVGPROrAGPR =
         Enc & (AMDGPU::HWEncoding::IS_VGPR | AMDGPU::HWEncoding::IS_AGPR);
     Op = Idx | (IsVGPROrAGPR << 8);
@@ -656,7 +656,7 @@ void AMDGPUMCCodeEmitter::getMachineOpValueT16Lo128(
   const MCOperand &MO = MI.getOperand(OpNo);
   if (MO.isReg()) {
     uint16_t Encoding = MRI.getEncodingValue(MO.getReg());
-    unsigned RegIdx = Encoding & AMDGPU::HWEncoding::REG_IDX_MASK;
+    unsigned RegIdx = Encoding & AMDGPU::HWEncoding::LO256_REG_IDX_MASK;
     bool IsHi = Encoding & AMDGPU::HWEncoding::IS_HI16;
     bool IsVGPR = Encoding & AMDGPU::HWEncoding::IS_VGPR;
     assert((!IsVGPR || isUInt<7>(RegIdx)) && "VGPR0-VGPR127 expected!");

llvm/lib/Target/AMDGPU/SIDefines.h

@@ -354,10 +354,11 @@ enum : unsigned {
 // Register codes as defined in the TableGen's HWEncoding field.
 namespace HWEncoding {
 enum : unsigned {
-  REG_IDX_MASK = 0xff,
-  IS_VGPR = 1 << 8,
-  IS_AGPR = 1 << 9,
-  IS_HI16 = 1 << 10,
+  REG_IDX_MASK = 0x3ff,
+  LO256_REG_IDX_MASK = 0xff,
+  IS_VGPR = 1 << 10,
+  IS_AGPR = 1 << 11,
+  IS_HI16 = 1 << 12,
 };
 } // namespace HWEncoding
 

llvm/lib/Target/AMDGPU/SIFrameLowering.cpp

@@ -1728,7 +1728,9 @@ void SIFrameLowering::determineCalleeSaves(MachineFunction &MF,
            "Whole wave functions can use the reg mapped for their i1 argument");
 
     // FIXME: Be more efficient!
-    for (MCRegister Reg : AMDGPU::VGPR_32RegClass)
+    unsigned NumArchVGPRs = ST.has1024AddressableVGPRs() ? 1024 : 256;
+    for (MCRegister Reg :
+         AMDGPU::VGPR_32RegClass.getRegisters().take_front(NumArchVGPRs))
       if (MF.getRegInfo().isPhysRegModified(Reg)) {
         MFI->reserveWWMRegister(Reg);
         MF.begin()->addLiveIn(Reg);

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

@@ -16916,7 +16916,7 @@ SITargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI_,
       switch (BitWidth) {
       case 16:
         RC = Subtarget->useRealTrue16Insts() ? &AMDGPU::VGPR_16RegClass
-                                             : &AMDGPU::VGPR_32RegClass;
+                                             : &AMDGPU::VGPR_32_Lo256RegClass;
         break;
       default:
         RC = TRI->getVGPRClassForBitWidth(BitWidth);
@@ -16963,7 +16963,7 @@ SITargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI_,
   auto [Kind, Idx, NumRegs] = AMDGPU::parseAsmConstraintPhysReg(Constraint);
   if (Kind != '\0') {
     if (Kind == 'v') {
-      RC = &AMDGPU::VGPR_32RegClass;
+      RC = &AMDGPU::VGPR_32_Lo256RegClass;
     } else if (Kind == 's') {
       RC = &AMDGPU::SGPR_32RegClass;
     } else if (Kind == 'a') {
@@ -17005,6 +17005,7 @@ SITargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI_,
         return std::pair(0U, nullptr);
       if (Idx < RC->getNumRegs())
         return std::pair(RC->getRegister(Idx), RC);
+      return std::pair(0U, nullptr);
     }
   }
 

llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp

@@ -152,7 +152,7 @@ static constexpr StringLiteral WaitEventTypeName[] = {
 // We reserve a fixed number of VGPR slots in the scoring tables for
 // special tokens like SCMEM_LDS (needed for buffer load to LDS).
 enum RegisterMapping {
-  SQ_MAX_PGM_VGPRS = 1024, // Maximum programmable VGPRs across all targets.
+  SQ_MAX_PGM_VGPRS = 2048, // Maximum programmable VGPRs across all targets.
   AGPR_OFFSET = 512,       // Maximum programmable ArchVGPRs across all targets.
   SQ_MAX_PGM_SGPRS = 128,  // Maximum programmable SGPRs across all targets.
   // Artificial register slots to track LDS writes into specific LDS locations
@@ -831,15 +831,14 @@ RegInterval WaitcntBrackets::getRegInterval(const MachineInstr *MI,
 
   MCRegister MCReg = AMDGPU::getMCReg(Op.getReg(), *Context->ST);
   unsigned RegIdx = TRI->getHWRegIndex(MCReg);
-  assert(isUInt<8>(RegIdx));
 
   const TargetRegisterClass *RC = TRI->getPhysRegBaseClass(Op.getReg());
   unsigned Size = TRI->getRegSizeInBits(*RC);
 
   // AGPRs/VGPRs are tracked every 16 bits, SGPRs by 32 bits
   if (TRI->isVectorRegister(*MRI, Op.getReg())) {
     unsigned Reg = RegIdx << 1 | (AMDGPU::isHi16Reg(MCReg, *TRI) ? 1 : 0);
-    assert(Reg < AGPR_OFFSET);
+    assert(!Context->ST->hasMAIInsts() || Reg < AGPR_OFFSET);
     Result.first = Reg;
     if (TRI->isAGPR(*MRI, Op.getReg()))
       Result.first += AGPR_OFFSET;

llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp

@@ -3273,6 +3273,10 @@ StringRef SIRegisterInfo::getRegAsmName(MCRegister Reg) const {
   return AMDGPUInstPrinter::getRegisterName(Reg);
 }
 
+unsigned SIRegisterInfo::getHWRegIndex(MCRegister Reg) const {
+  return getEncodingValue(Reg) & AMDGPU::HWEncoding::REG_IDX_MASK;
+}
+
 unsigned AMDGPU::getRegBitWidth(const TargetRegisterClass &RC) {
   return getRegBitWidth(RC.getID());
 }
@@ -3353,6 +3357,40 @@ SIRegisterInfo::getVGPRClassForBitWidth(unsigned BitWidth) const {
                                 : getAnyVGPRClassForBitWidth(BitWidth);
 }
 
+const TargetRegisterClass *
+SIRegisterInfo::getAlignedLo256VGPRClassForBitWidth(unsigned BitWidth) const {
+  if (BitWidth <= 32)
+    return &AMDGPU::VGPR_32_Lo256RegClass;
+  if (BitWidth <= 64)
+    return &AMDGPU::VReg_64_Lo256_Align2RegClass;
+  if (BitWidth <= 96)
+    return &AMDGPU::VReg_96_Lo256_Align2RegClass;
+  if (BitWidth <= 128)
+    return &AMDGPU::VReg_128_Lo256_Align2RegClass;
+  if (BitWidth <= 160)
+    return &AMDGPU::VReg_160_Lo256_Align2RegClass;
+  if (BitWidth <= 192)
+    return &AMDGPU::VReg_192_Lo256_Align2RegClass;
+  if (BitWidth <= 224)
+    return &AMDGPU::VReg_224_Lo256_Align2RegClass;
+  if (BitWidth <= 256)
+    return &AMDGPU::VReg_256_Lo256_Align2RegClass;
+  if (BitWidth <= 288)
+    return &AMDGPU::VReg_288_Lo256_Align2RegClass;
+  if (BitWidth <= 320)
+    return &AMDGPU::VReg_320_Lo256_Align2RegClass;
+  if (BitWidth <= 352)
+    return &AMDGPU::VReg_352_Lo256_Align2RegClass;
+  if (BitWidth <= 384)
+    return &AMDGPU::VReg_384_Lo256_Align2RegClass;
+  if (BitWidth <= 512)
+    return &AMDGPU::VReg_512_Lo256_Align2RegClass;
+  if (BitWidth <= 1024)
+    return &AMDGPU::VReg_1024_Lo256_Align2RegClass;
+
+  return nullptr;
+}
+
 static const TargetRegisterClass *
 getAnyAGPRClassForBitWidth(unsigned BitWidth) {
   if (BitWidth == 64)
@@ -3547,7 +3585,17 @@ bool SIRegisterInfo::isSGPRReg(const MachineRegisterInfo &MRI,
 const TargetRegisterClass *
 SIRegisterInfo::getEquivalentVGPRClass(const TargetRegisterClass *SRC) const {
   unsigned Size = getRegSizeInBits(*SRC);
-  const TargetRegisterClass *VRC = getVGPRClassForBitWidth(Size);
+
+  switch (SRC->getID()) {
+  default:
+    break;
+  case AMDGPU::VS_32_Lo256RegClassID:
+  case AMDGPU::VS_64_Lo256RegClassID:
+    return getAllocatableClass(getAlignedLo256VGPRClassForBitWidth(Size));
+  }
+
+  const TargetRegisterClass *VRC =
+      getAllocatableClass(getVGPRClassForBitWidth(Size));
   assert(VRC && "Invalid register class size");
   return VRC;
 }
@@ -4005,7 +4053,12 @@ SIRegisterInfo::getSubRegAlignmentNumBits(const TargetRegisterClass *RC,
 unsigned SIRegisterInfo::getNumUsedPhysRegs(const MachineRegisterInfo &MRI,
                                             const TargetRegisterClass &RC,
                                             bool IncludeCalls) const {
-  for (MCPhysReg Reg : reverse(RC.getRegisters()))
+  unsigned NumArchVGPRs = ST.has1024AddressableVGPRs() ? 1024 : 256;
+  ArrayRef<MCPhysReg> Registers =
+      (RC.getID() == AMDGPU::VGPR_32RegClassID)
+          ? RC.getRegisters().take_front(NumArchVGPRs)
+          : RC.getRegisters();
+  for (MCPhysReg Reg : reverse(Registers))
     if (MRI.isPhysRegUsed(Reg, /*SkipRegMaskTest=*/!IncludeCalls))
       return getHWRegIndex(Reg) + 1;
   return 0;

llvm/lib/Target/AMDGPU/SIRegisterInfo.h

@@ -200,13 +200,14 @@ class SIRegisterInfo final : public AMDGPUGenRegisterInfo {
   StringRef getRegAsmName(MCRegister Reg) const override;
 
   // Pseudo regs are not allowed
-  unsigned getHWRegIndex(MCRegister Reg) const {
-    return getEncodingValue(Reg) & 0xff;
-  }
+  unsigned getHWRegIndex(MCRegister Reg) const;
 
   LLVM_READONLY
   const TargetRegisterClass *getVGPRClassForBitWidth(unsigned BitWidth) const;
 
+  LLVM_READONLY const TargetRegisterClass *
+  getAlignedLo256VGPRClassForBitWidth(unsigned BitWidth) const;
+
   LLVM_READONLY
   const TargetRegisterClass *getAGPRClassForBitWidth(unsigned BitWidth) const;