[LLVM][AArch64]Add assembly/disassembly for compare-and-branch instructions (#112726)

This patch adds the assembly/disassembly for the following instructions:

CBB<cc>, CBH<cc>,
CB<cc>(immediate), CB<cc>(register)
CBBLE, CBBLO, CBBLS, CBBLT
CBHLE, CBHLO, CBHLS, CBHLT
CBGE, CBHS, CBLE, CBLS (immediate)
CBLE, CBLO, CBLS, CBLT(register)

According to [1]

[1]https://developer.arm.com/documentation/ddi0602

Co-authored-by: Momchil Velikov [email protected]
Co-authored-by: Spencer Abson [email protected]

Author: CarolineConcatto

llvm/lib/Target/AArch64/AArch64InstrFormats.td

@@ -388,6 +388,46 @@ def uimm16 : Operand<i16>, ImmLeaf<i16, [{return Imm >= 0 && Imm < 65536;}]>{
   let ParserMatchClass = AsmImmRange<0, 65535>;
 }
 
+def uimm6_64b : Operand<i64>, ImmLeaf<i64, [{ return Imm >= 0 && Imm < 64; }]> {
+    let ParserMatchClass = UImm6Operand;
+}
+
+def uimm6_32b : Operand<i32>, ImmLeaf<i32, [{ return Imm >= 0 && Imm < 64; }]> {
+   let ParserMatchClass = UImm6Operand;
+}
+
+def UImm6Plus1Operand : AsmOperandClass {
+  let Name = "UImm6P1";
+  let DiagnosticType = "InvalidImm1_64";
+  let RenderMethod = "addImmOperands";
+  let ParserMethod = "tryParseAdjImm0_63<-1>";
+  let PredicateMethod = "isImmInRange<0,63>";
+}
+
+def UImm6Minus1Operand : AsmOperandClass {
+  let Name = "UImm6M1";
+  let DiagnosticType = "InvalidImmM1_62";
+  let RenderMethod = "addImmOperands";
+  let ParserMethod = "tryParseAdjImm0_63<1>";
+  let PredicateMethod = "isImmInRange<0,63>";
+}
+
+def uimm6p1_32b : Operand<i32> {
+  let ParserMatchClass = UImm6Plus1Operand;
+}
+
+def uimm6p1_64b : Operand<i64> {
+  let ParserMatchClass = UImm6Plus1Operand;
+}
+
+def uimm6m1_32b : Operand<i32> {
+  let ParserMatchClass = UImm6Minus1Operand;
+}
+
+def uimm6m1_64b : Operand<i64> {
+  let ParserMatchClass = UImm6Minus1Operand;
+}
+
 def SImm9Operand : SImmOperand<9>;
 def simm9 : Operand<i64>, ImmLeaf<i64, [{ return Imm >= -256 && Imm < 256; }]> {
   let ParserMatchClass = SImm9Operand;
@@ -657,6 +697,7 @@ class PCRelLabel<int N> : BranchTarget<N> {
 def BranchTarget14Operand : BranchTarget<14>;
 def BranchTarget26Operand : BranchTarget<26>;
 def PCRelLabel19Operand   : PCRelLabel<19>;
+def PCRelLabel9Operand    : PCRelLabel<9>;
 
 def MovWSymbolG3AsmOperand : AsmOperandClass {
   let Name = "MovWSymbolG3";
@@ -2134,6 +2175,17 @@ def am_brcond : Operand<OtherVT> {
   let OperandType = "OPERAND_PCREL";
 }
 
+// Conditional branch target. 9-bit immediate. The low two bits of the target
+// offset are implied zero and so are not part of the immediate.
+def am_brcmpcond : Operand<OtherVT> {
+  let EncoderMethod = "getCondCompBranchTargetOpValue";
+  let DecoderMethod = "DecodePCRelLabel9";
+  let PrintMethod   = "printAlignedLabel";
+  let ParserMatchClass = PCRelLabel9Operand;
+  let OperandType = "OPERAND_PCREL";
+}
+
+
 class BranchCond<bit bit4, string mnemonic>
    : I<(outs), (ins ccode:$cond, am_brcond:$target),
        mnemonic, ".$cond\t$target", "",
@@ -12607,6 +12659,89 @@ class MulAccumCPA<bit isSub, string asm>
   let Inst{31} = 0b1;
 }
 
+
+//----------------------------------------------------------------------------
+// 2024 Armv9.6 Extensions
+//----------------------------------------------------------------------------
+
+//---
+// Compare-and-branch instructions.
+//---
+
+class BaseCmpBranchRegister<RegisterClass regtype, bit sf, bits<3> cc,
+                            bits<2>sz, string asm>
+    : I<(outs), (ins regtype:$Rt, regtype:$Rm, am_brcmpcond:$target),
+         asm, "\t$Rt, $Rm, $target", "",
+         []>,
+      Sched<[WriteBr]> {
+  let isBranch = 1;
+  let isTerminator = 1;
+
+  bits<5> Rm;
+  bits<5> Rt;
+  bits<9> target;
+  let Inst{31}    = sf;
+  let Inst{30-24} = 0b1110100;
+  let Inst{23-21} = cc;
+  let Inst{20-16} = Rm;
+  let Inst{15-14} = sz;
+  let Inst{13-5}  = target;
+  let Inst{4-0}   = Rt;
+}
+
+multiclass CmpBranchRegister<bits<3> cc, string asm> {
+  def Wrr : BaseCmpBranchRegister<GPR32, 0b0, cc, 0b00, asm>;
+  def Xrr : BaseCmpBranchRegister<GPR64, 0b1, cc, 0b00, asm>;
+}
+
+class BaseCmpBranchImmediate<RegisterClass regtype, bit sf, bits<3> cc,
+                             Operand imm_ty, string asm>
+    : I<(outs), (ins regtype:$Rt, imm_ty:$imm, am_brcmpcond:$target),
+         asm, "\t$Rt, $imm, $target", "",
+         []>,
+      Sched<[WriteBr]> {
+  let isBranch = 1;
+  let isTerminator = 1;
+
+  bits<5> Rt;
+  bits<6> imm;
+  bits<9> target;
+  let Inst{31}    = sf;
+  let Inst{30-24} = 0b1110101;
+  let Inst{23-21} = cc;
+  let Inst{20-15} = imm;
+  let Inst{14}    = 0b0;
+  let Inst{13-5}  = target;
+  let Inst{4-0}   = Rt;
+}
+
+multiclass CmpBranchImmediate<bits<3> cc, string imm_ty, string asm> {
+  def Wri : BaseCmpBranchImmediate<GPR32, 0b0, cc, !cast<Operand>(imm_ty # "_32b"), asm>;
+  def Xri : BaseCmpBranchImmediate<GPR64, 0b1, cc, !cast<Operand>(imm_ty # "_64b"), asm>;
+}
+
+multiclass CmpBranchImmediateAlias<string mnemonic, string insn, string imm_ty> {
+ def : InstAlias<mnemonic # "\t$Rt, $imm, $target",
+                 (!cast<Instruction>(insn # "Wri") GPR32:$Rt,
+                  !cast<Operand>(imm_ty # "_32b"):$imm,
+                  am_brcmpcond:$target), 0>;
+ def : InstAlias<mnemonic # "\t$Rt, $imm, $target",
+                 (!cast<Instruction>(insn # "Xri") GPR64:$Rt,
+                  !cast<Operand>(imm_ty # "_64b"):$imm,
+                  am_brcmpcond:$target), 0>;
+}
+
+multiclass CmpBranchWRegisterAlias<string mnemonic, string insn> {
+  def : InstAlias<mnemonic # "\t$Rt, $Rm, $target",
+                 (!cast<Instruction>(insn # "Wrr") GPR32:$Rm, GPR32:$Rt, am_brcmpcond:$target), 0>;
+}
+
+multiclass CmpBranchRegisterAlias<string mnemonic, string insn> {
+  defm : CmpBranchWRegisterAlias<mnemonic, insn>;
+
+  def : InstAlias<mnemonic # "\t$Rt, $Rm, $target",
+                 (!cast<Instruction>(insn # "Xrr") GPR64:$Rm, GPR64:$Rt, am_brcmpcond:$target), 0>;
+}
 //----------------------------------------------------------------------------
 // Allow the size specifier tokens to be upper case, not just lower.
 def : TokenAlias<".4B", ".4b">;  // Add dot product

llvm/lib/Target/AArch64/AArch64InstrInfo.td

@@ -10299,6 +10299,57 @@ defm : PromoteBinaryv8f16Tov4f32<any_fdiv, FDIVv4f32>;
 defm : PromoteBinaryv8f16Tov4f32<any_fmul, FMULv4f32>;
 defm : PromoteBinaryv8f16Tov4f32<any_fsub, FSUBv4f32>;
 
+let Predicates = [HasCMPBR] in {
+ defm CBGT : CmpBranchRegister<0b000, "cbgt">;
+ defm CBGE : CmpBranchRegister<0b001, "cbge">;
+ defm CBHI : CmpBranchRegister<0b010, "cbhi">;
+ defm CBHS : CmpBranchRegister<0b011, "cbhs">;
+ defm CBEQ : CmpBranchRegister<0b110, "cbeq">;
+ defm CBNE : CmpBranchRegister<0b111, "cbne">;
+
+ def CBHGTWrr : BaseCmpBranchRegister<GPR32, 0b0, 0b000, 0b11, "cbhgt">;
+ def CBHGEWrr : BaseCmpBranchRegister<GPR32, 0b0, 0b001, 0b11, "cbhge">;
+ def CBHHIWrr : BaseCmpBranchRegister<GPR32, 0b0, 0b010, 0b11, "cbhhi">;
+ def CBHHSWrr : BaseCmpBranchRegister<GPR32, 0b0, 0b011, 0b11, "cbhhs">;
+ def CBHEQWrr : BaseCmpBranchRegister<GPR32, 0b0, 0b110, 0b11, "cbheq">;
+ def CBHNEWrr : BaseCmpBranchRegister<GPR32, 0b0, 0b111, 0b11, "cbhne">;
+
+ def CBBGTWrr : BaseCmpBranchRegister<GPR32, 0b0, 0b000, 0b10, "cbbgt">;
+ def CBBGEWrr : BaseCmpBranchRegister<GPR32, 0b0, 0b001, 0b10, "cbbge">;
+ def CBBHIWrr : BaseCmpBranchRegister<GPR32, 0b0, 0b010, 0b10, "cbbhi">;
+ def CBBHSWrr : BaseCmpBranchRegister<GPR32, 0b0, 0b011, 0b10, "cbbhs">;
+ def CBBEQWrr : BaseCmpBranchRegister<GPR32, 0b0, 0b110, 0b10, "cbbeq">;
+ def CBBNEWrr : BaseCmpBranchRegister<GPR32, 0b0, 0b111, 0b10, "cbbne">;
+
+ defm CBGT : CmpBranchImmediate<0b000, "uimm6", "cbgt">;
+ defm CBLT : CmpBranchImmediate<0b001, "uimm6", "cblt">;
+ defm CBHI : CmpBranchImmediate<0b010, "uimm6", "cbhi">;
+ defm CBLO : CmpBranchImmediate<0b011, "uimm6", "cblo">;
+ defm CBEQ : CmpBranchImmediate<0b110, "uimm6", "cbeq">;
+ defm CBNE : CmpBranchImmediate<0b111, "uimm6", "cbne">;
+
+ defm : CmpBranchImmediateAlias<"cbge", "CBGT", "uimm6p1">;
+ defm : CmpBranchImmediateAlias<"cbhs", "CBHI", "uimm6p1">;
+ defm : CmpBranchImmediateAlias<"cble", "CBLT", "uimm6m1">;
+ defm : CmpBranchImmediateAlias<"cbls", "CBLO", "uimm6m1">;
+
+ defm : CmpBranchRegisterAlias<"cble", "CBGE">;
+ defm : CmpBranchRegisterAlias<"cblo", "CBHI">;
+ defm : CmpBranchRegisterAlias<"cbls", "CBHS">;
+ defm : CmpBranchRegisterAlias<"cblt", "CBGT">;
+
+ defm : CmpBranchWRegisterAlias<"cbble", "CBBGE">;
+ defm : CmpBranchWRegisterAlias<"cbblo", "CBBHI">;
+ defm : CmpBranchWRegisterAlias<"cbbls", "CBBHS">;
+ defm : CmpBranchWRegisterAlias<"cbblt", "CBBGT">;
+
+ defm : CmpBranchWRegisterAlias<"cbhle", "CBHGE">;
+ defm : CmpBranchWRegisterAlias<"cbhlo", "CBHHI">;
+ defm : CmpBranchWRegisterAlias<"cbhls", "CBHHS">;
+ defm : CmpBranchWRegisterAlias<"cbhlt", "CBHGT">;
+} // HasCMPBR
+
+
 //===-----------------------------------------------------===//
 // Atomic floating-point in-memory instructions (FEAT_LSFE)
 //===-----------------------------------------------------===//

llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

@@ -286,6 +286,7 @@ class AArch64AsmParser : public MCTargetAsmParser {
   ParseStatus tryParseSVEVecLenSpecifier(OperandVector &Operands);
   ParseStatus tryParseGPR64x8(OperandVector &Operands);
   ParseStatus tryParseImmRange(OperandVector &Operands);
+  template <int> ParseStatus tryParseAdjImm0_63(OperandVector &Operands);
 
 public:
   enum AArch64MatchResultTy {
@@ -2070,6 +2071,20 @@ class AArch64Operand : public MCParsedAsmOperand {
     Inst.addOperand(MCOperand::createImm(MCE->getValue() >> 2));
   }
 
+  void addPCRelLabel9Operands(MCInst &Inst, unsigned N) const {
+    // Branch operands don't encode the low bits, so shift them off
+    // here. If it's a label, however, just put it on directly as there's
+    // not enough information now to do anything.
+    assert(N == 1 && "Invalid number of operands!");
+    const MCConstantExpr *MCE = dyn_cast<MCConstantExpr>(getImm());
+    if (!MCE) {
+      addExpr(Inst, getImm());
+      return;
+    }
+    assert(MCE && "Invalid constant immediate operand!");
+    Inst.addOperand(MCOperand::createImm(MCE->getValue() >> 2));
+  }
+
   void addBranchTarget14Operands(MCInst &Inst, unsigned N) const {
     // Branch operands don't encode the low bits, so shift them off
     // here. If it's a label, however, just put it on directly as there's
@@ -5926,6 +5941,8 @@ bool AArch64AsmParser::showMatchError(SMLoc Loc, unsigned ErrCode,
     return Error(Loc, "immediate must be an integer in range [1, 32].");
   case Match_InvalidImm1_64:
     return Error(Loc, "immediate must be an integer in range [1, 64].");
+  case Match_InvalidImmM1_62:
+    return Error(Loc, "immediate must be an integer in range [-1, 62].");
   case Match_InvalidMemoryIndexedRange2UImm0:
     return Error(Loc, "vector select offset must be the immediate range 0:1.");
   case Match_InvalidMemoryIndexedRange2UImm1:
@@ -6696,6 +6713,7 @@ bool AArch64AsmParser::matchAndEmitInstruction(SMLoc IDLoc, unsigned &Opcode,
   case Match_InvalidImm1_16:
   case Match_InvalidImm1_32:
   case Match_InvalidImm1_64:
+  case Match_InvalidImmM1_62:
   case Match_InvalidMemoryIndexedRange2UImm0:
   case Match_InvalidMemoryIndexedRange2UImm1:
   case Match_InvalidMemoryIndexedRange2UImm2:
@@ -8163,3 +8181,37 @@ ParseStatus AArch64AsmParser::tryParseImmRange(OperandVector &Operands) {
       AArch64Operand::CreateImmRange(ImmFVal, ImmLVal, S, E, getContext()));
   return ParseStatus::Success;
 }
+
+template <int Adj>
+ParseStatus AArch64AsmParser::tryParseAdjImm0_63(OperandVector &Operands) {
+  SMLoc S = getLoc();
+
+  parseOptionalToken(AsmToken::Hash);
+  bool IsNegative = parseOptionalToken(AsmToken::Minus);
+
+  if (getTok().isNot(AsmToken::Integer))
+    return ParseStatus::NoMatch;
+
+  const MCExpr *Ex;
+  if (getParser().parseExpression(Ex))
+    return ParseStatus::NoMatch;
+
+  int64_t Imm = dyn_cast<MCConstantExpr>(Ex)->getValue();
+  if (IsNegative)
+    Imm = -Imm;
+
+  // We want an adjusted immediate in the range [0, 63]. If we don't have one,
+  // return a value, which is certain to trigger a error message about invalid
+  // immediate range instead of a non-descriptive invalid operand error.
+  static_assert(Adj == 1 || Adj == -1, "Unsafe immediate adjustment");
+  if (Imm == INT64_MIN || Imm == INT64_MAX || Imm + Adj < 0 || Imm + Adj > 63)
+    Imm = -2;
+  else
+    Imm += Adj;
+
+  SMLoc E = SMLoc::getFromPointer(getLoc().getPointer() - 1);
+  Operands.push_back(AArch64Operand::CreateImm(
+      MCConstantExpr::create(Imm, getContext()), S, E, getContext()));
+
+  return ParseStatus::Success;
+}

llvm/lib/Target/AArch64/Disassembler/AArch64Disassembler.cpp

@@ -80,6 +80,9 @@ static DecodeStatus DecodePCRelLabel16(MCInst &Inst, unsigned Imm,
 static DecodeStatus DecodePCRelLabel19(MCInst &Inst, unsigned Imm,
                                        uint64_t Address,
                                        const MCDisassembler *Decoder);
+static DecodeStatus DecodePCRelLabel9(MCInst &Inst, unsigned Imm,
+                                      uint64_t Address,
+                                      const MCDisassembler *Decoder);
 static DecodeStatus DecodeMemExtend(MCInst &Inst, unsigned Imm,
                                     uint64_t Address,
                                     const MCDisassembler *Decoder);
@@ -488,6 +491,20 @@ static DecodeStatus DecodePCRelLabel19(MCInst &Inst, unsigned Imm,
   return Success;
 }
 
+static DecodeStatus DecodePCRelLabel9(MCInst &Inst, unsigned Imm, uint64_t Addr,
+                                      const MCDisassembler *Decoder) {
+  int64_t ImmVal = Imm;
+
+  // Sign-extend 9-bit immediate.
+  if (ImmVal & (1 << (9 - 1)))
+    ImmVal |= ~((1LL << 9) - 1);
+
+  if (!Decoder->tryAddingSymbolicOperand(Inst, (ImmVal << 2), Addr,
+                                         /*IsBranch=*/true, 0, 0, 4))
+    Inst.addOperand(MCOperand::createImm(ImmVal));
+  return Success;
+}
+
 static DecodeStatus DecodeMemExtend(MCInst &Inst, unsigned Imm,
                                     uint64_t Address,
                                     const MCDisassembler *Decoder) {

llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp

@@ -66,6 +66,7 @@ class AArch64AsmBackend : public MCAsmBackend {
         {"fixup_aarch64_ldst_imm12_scale16", 10, 12, 0},
         {"fixup_aarch64_ldr_pcrel_imm19", 5, 19, PCRelFlagVal},
         {"fixup_aarch64_movw", 5, 16, 0},
+        {"fixup_aarch64_pcrel_branch9", 5, 9,  PCRelFlagVal},
         {"fixup_aarch64_pcrel_branch14", 5, 14, PCRelFlagVal},
         {"fixup_aarch64_pcrel_branch16", 5, 16, PCRelFlagVal},
         {"fixup_aarch64_pcrel_branch19", 5, 19, PCRelFlagVal},
@@ -120,6 +121,7 @@ static unsigned getFixupKindNumBytes(unsigned Kind) {
     return 2;
 
   case AArch64::fixup_aarch64_movw:
+  case AArch64::fixup_aarch64_pcrel_branch9:
   case AArch64::fixup_aarch64_pcrel_branch14:
   case AArch64::fixup_aarch64_pcrel_branch16:
   case AArch64::fixup_aarch64_add_imm12:
@@ -307,6 +309,14 @@ static uint64_t adjustFixupValue(const MCFixup &Fixup, const MCValue &Target,
     }
     return Value;
   }
+  case AArch64::fixup_aarch64_pcrel_branch9:
+    // Signed 11-bit(9bits + 2 shifts) label
+    if (!isInt<11>(SignedValue))
+      Ctx.reportError(Fixup.getLoc(), "fixup value out of range");
+    // Low two bits are not encoded (4-byte alignment assumed).
+    if (Value & 0b11)
+      Ctx.reportError(Fixup.getLoc(), "fixup not sufficiently aligned");
+    return (Value >> 2) & 0x1ff;
   case AArch64::fixup_aarch64_pcrel_branch14:
     // Signed 16-bit immediate
     if (!isInt<16>(SignedValue))
@@ -391,6 +401,7 @@ unsigned AArch64AsmBackend::getFixupKindContainereSizeInBytes(unsigned Kind) con
     return 8;
 
   case AArch64::fixup_aarch64_movw:
+  case AArch64::fixup_aarch64_pcrel_branch9:
   case AArch64::fixup_aarch64_pcrel_branch14:
   case AArch64::fixup_aarch64_pcrel_branch16:
   case AArch64::fixup_aarch64_add_imm12:

llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp

@@ -190,6 +190,11 @@ unsigned AArch64ELFObjectWriter::getRelocType(MCContext &Ctx,
       Ctx.reportError(Fixup.getLoc(),
                       "relocation of PAC/AUT instructions is not supported");
       return ELF::R_AARCH64_NONE;
+    case AArch64::fixup_aarch64_pcrel_branch9:
+      Ctx.reportError(
+          Fixup.getLoc(),
+          "relocation of compare-and-branch instructions not supported");
+      return ELF::R_AARCH64_NONE;
     case AArch64::fixup_aarch64_pcrel_branch19:
       return R_CLS(CONDBR19);
     default:

llvm/lib/Target/AArch64/MCTargetDesc/AArch64FixupKinds.h

@@ -40,6 +40,9 @@ enum Fixups {
   // FIXME: comment
   fixup_aarch64_movw,
 
+  // The high 9 bits of a 11-bit pc-relative immediate.
+  fixup_aarch64_pcrel_branch9,
+
   // The high 14 bits of a 21-bit pc-relative immediate.
   fixup_aarch64_pcrel_branch14,