[mips][microMIPS] Implement BREAK16 and SDBBP16 instructions

[sstankovic]

LGTM

[jkolek]

Closed by commit rL222900 (authored by @jkolek).

lib/Target/Mips/MicroMipsInstrFormats.td

class MFHILO_FM_MM16<bits<5> funct> {
 
   bits<16> Inst;
 
   let Inst{15-10} = 0x11;
   let Inst{9-5}   = funct;
   let Inst{4-0}   = rd;
 }
 
+class BRKSDBBP16_FM_MM<bits<6> op> {
+  bits<4> code_;
+  bits<16> Inst;
+
+  let Inst{15-10} = 0x11;
+  let Inst{9-4}   = op;
+  let Inst{3-0}   = code_;
+}
+
 //===----------------------------------------------------------------------===//
 // MicroMIPS 32-bit Instruction Formats
 //===----------------------------------------------------------------------===//
 
 class MMArch {
   string Arch = "micromips";
   list<dag> Pattern = [];
 }

lib/Target/Mips/MicroMipsInstrInfo.td

 class JumpLinkRegMM16<string opstr, RegisterOperand RO> :
   MicroMipsInst16<(outs), (ins RO:$rs), !strconcat(opstr, "\t$rs"),
            [(MipsJmpLink RO:$rs)], IIBranch, FrmR> {
   let isCall = 1;
   let hasDelaySlot = 1;
   let Defs = [RA];
 }
 
+// Break16 and Sdbbp16
+class BrkSdbbp16MM<string opstr> :
+  MicroMipsInst16<(outs), (ins uimm4:$code_),
+                  !strconcat(opstr, "\t$code_"),
+                  [], NoItinerary, FrmOther>;
+
 def MFHI16_MM : MoveFromHILOMM<"mfhi", GPR32Opnd, AC0>, MFHILO_FM_MM16<0x10>;
 def MFLO16_MM : MoveFromHILOMM<"mflo", GPR32Opnd, AC0>, MFHILO_FM_MM16<0x12>;
 def MOVE16_MM : MoveMM16<"move", GPR32Opnd>, MOVE_FM_MM16<0x03>;
 def JALR16_MM : JumpLinkRegMM16<"jalr", GPR32Opnd>, JALR_FM_MM16<0x0e>;
 
 class WaitMM<string opstr> :
   InstSE<(outs), (ins uimm10:$code_), !strconcat(opstr, "\t$code_"), [],
          NoItinerary, FrmOther, opstr>;
let DecoderNamespace = "MicroMips", Predicates = [InMicroMips] in {
   def TGEIU_MM : MMRel, TEQI_FT<"tgeiu", GPR32Opnd>, TEQI_FM_MM<0x0b>;
   def TLTI_MM  : MMRel, TEQI_FT<"tlti", GPR32Opnd>, TEQI_FM_MM<0x08>;
   def TLTIU_MM : MMRel, TEQI_FT<"tltiu", GPR32Opnd>, TEQI_FM_MM<0x0a>;
   def TNEI_MM  : MMRel, TEQI_FT<"tnei", GPR32Opnd>, TEQI_FM_MM<0x0c>;
 
   /// Load-linked, Store-conditional
   def LL_MM : LLBaseMM<"ll", GPR32Opnd>, LL_FM_MM<0x3>;
   def SC_MM : SCBaseMM<"sc", GPR32Opnd>, LL_FM_MM<0xb>;
+
+  def BREAK16_MM : BrkSdbbp16MM<"break16">, BRKSDBBP16_FM_MM<0x28>;
+  def SDBBP16_MM : BrkSdbbp16MM<"sdbbp16">, BRKSDBBP16_FM_MM<0x2C>;
 }
 
 //===----------------------------------------------------------------------===//
 // MicroMips instruction aliases
 //===----------------------------------------------------------------------===//
 
 let Predicates = [InMicroMips] in {
   def : MipsInstAlias<"wait", (WAIT_MM 0x0), 1>;
 }

test/MC/Mips/micromips-16-bit-instructions.s

 # RUN: llvm-mc %s -triple=mipsel -show-encoding -mattr=micromips | \
 # RUN: FileCheck -check-prefix=CHECK-EL %s
 # RUN: llvm-mc %s -triple=mips -show-encoding -mattr=micromips | \
 # RUN: FileCheck -check-prefix=CHECK-EB %s
 # Check that the assembler can handle the documented syntax
 # for arithmetic and logical instructions.
 #------------------------------------------------------------------------------
 # MicroMIPS 16-bit Instructions
 #------------------------------------------------------------------------------
 # Little endian
 #------------------------------------------------------------------------------
+# CHECK-EL: break16 8               # encoding: [0x88,0x46]
+# CHECK-EL: sdbbp16 14              # encoding: [0xce,0x46]
 # CHECK-EL: mfhi    $9              # encoding: [0x09,0x46]
 # CHECK-EL: mflo    $9              # encoding: [0x49,0x46]
 # CHECK-EL: move    $25, $1         # encoding: [0x21,0x0f]
 # CHECK-EL: jalr    $9              # encoding: [0xc9,0x45]
 #------------------------------------------------------------------------------
 # Big endian
 #------------------------------------------------------------------------------
+# CHECK-EB: break16 8               # encoding: [0x46,0x88]
+# CHECK-EB: sdbbp16 14              # encoding: [0x46,0xce]
 # CHECK-EB: mfhi    $9              # encoding: [0x46,0x09]
 # CHECK-EB: mflo    $9              # encoding: [0x46,0x49]
 # CHECK-EB: move    $25, $1         # encoding: [0x0f,0x21]
 # CHECK-EB: jalr    $9              # encoding: [0x45,0xc9]
 
+    break16 8
+    sdbbp16 14
     mfhi    $9
     mflo    $9
     move    $25, $1
     jalr    $9