[mips][microMIPS] Implement microMIPS 16-bit instructions registers

[jkolek]

Summary

Implement microMIPS 16-bit instructions registers.

[sstankovic]

lib/Target/Mips/MipsRegisterInfo.td

294

I think that you don't need a template for a register class, since you instantiate it in only one place; you can directly define GPRMM16 as:

def GPRMM16 : RegisterClass<"Mips", [i32], 32, (add

// Return Values and Arguments
V0, V1, A0, A1, A2, A3,
// Callee save
S0, S1)>;

[jkolek]

Class GPRMM16Class removed , GPRMM16 is defined directly.

[sstankovic]

LGTM

Closed by commit rL220273 (authored by zjovanovic).

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

     return RegIdx.RegInfo->getRegClass(ClassID).getRegister(RegIdx.Index);
   }
 
+  /// Coerce the register to GPR32 and return the real register for the current
+  /// target.
+  unsigned getGPRMM16Reg() const {
+    assert(isRegIdx() && (RegIdx.Kind & RegKind_GPR) && "Invalid access!");
+    unsigned ClassID = Mips::GPR32RegClassID;
+    return RegIdx.RegInfo->getRegClass(ClassID).getRegister(RegIdx.Index);
+  }
+
   /// Coerce the register to GPR64 and return the real register for the current
   /// target.
   unsigned getGPR64Reg() const {

     Inst.addOperand(MCOperand::CreateReg(getGPR32Reg()));
   }
 
+  void addGPRMM16AsmRegOperands(MCInst &Inst, unsigned N) const {
+    assert(N == 1 && "Invalid number of operands!");
+    Inst.addOperand(MCOperand::CreateReg(getGPRMM16Reg()));
+  }
+
   /// Render the operand to an MCInst as a GPR64
   /// Asserts if the wrong number of operands are requested, or the operand
   /// is not a k_RegisterIndex compatible with RegKind_GPR

   bool isGPRAsmReg() const {
     return isRegIdx() && RegIdx.Kind & RegKind_GPR && RegIdx.Index <= 31;
   }
+  bool isMM16AsmReg() const {
+    if (!(isRegIdx() && RegIdx.Kind))
+      return false;
+    return ((RegIdx.Index >= 2 && RegIdx.Index <= 7)
+            || RegIdx.Index == 16 || RegIdx.Index == 17);
+  }
   bool isFGRAsmReg() const {
     // AFGR64 is $0-$15 but we handle this in getAFGR64()
     return isRegIdx() && RegIdx.Kind & RegKind_FGR && RegIdx.Index <= 31;

lib/Target/Mips/Disassembler/MipsDisassembler.cpp

                                                  uint64_t Address,
                                                  const void *Decoder);
 
+static DecodeStatus DecodeGPRMM16RegisterClass(MCInst &Inst,
+                                               unsigned RegNo,
+                                               uint64_t Address,
+                                               const void *Decoder);
+
 static DecodeStatus DecodeGPR32RegisterClass(MCInst &Inst,
                                              unsigned RegNo,
                                              uint64_t Address,

   return MCDisassembler::Success;
 }
 
+static DecodeStatus DecodeGPRMM16RegisterClass(MCInst &Inst,
+                                               unsigned RegNo,
+                                               uint64_t Address,
+                                               const void *Decoder) {
+  return MCDisassembler::Fail;
+}
+
 static DecodeStatus DecodeGPR32RegisterClass(MCInst &Inst,
                                              unsigned RegNo,
                                              uint64_t Address,

lib/Target/Mips/MipsRegisterInfo.td

 def GPR32 : GPR32Class<[i32]>;
 def DSPR  : GPR32Class<[v4i8, v2i16]>;
 
+class GPRMM16Class<list<ValueType> regTypes> :
+  RegisterClass<"Mips", regTypes, 32, (add
+  // Callee save
+  S0, S1,
+  // Return Values and Arguments
+  V0, V1, A0, A1, A2, A3)>;
+
+def GPRMM16 : GPRMM16Class<[i32]>;
+
 def GPR64 : RegisterClass<"Mips", [i64], 64, (add
 // Reserved
   ZERO_64, AT_64,

   let PredicateMethod = "isGPRAsmReg";
 }
 
+def GPRMM16AsmOperand : MipsAsmRegOperand {
+  let Name = "GPRMM16AsmReg";
+  let PredicateMethod = "isMM16AsmReg";
+}
+
 def ACC64DSPAsmOperand : MipsAsmRegOperand {
   let Name = "ACC64DSPAsmReg";
   let PredicateMethod = "isACCAsmReg";

   let ParserMatchClass = GPR32AsmOperand;
 }
 
+def GPRMM16Opnd : RegisterOperand<GPRMM16> {
+  let ParserMatchClass = GPRMM16AsmOperand;
+}
+
 def GPR64Opnd : RegisterOperand<GPR64> {
   let ParserMatchClass = GPR64AsmOperand;
 }