[mips][microMIPS] Implement JRADDIUSP instruction

[jkolek]

Summary

Implement 16-bit microMIPS jump and adjust stack pointer instruction - JRADDIUSP.

[dsanders]

LGTM with a couple naming changes for consistency with similar existing code.

lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.cpp

354

The other similar functions assert that the bits shifted out are zero.

lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.h

79

'Shr2' is inconsistent with the other shifted immediates. I think it should be called 'getUImm5Lsl2Encoding' as per getSimm19Lsl2Encoding() and similar.

lib/Target/Mips/MicroMipsInstrInfo.td

7–9

Similar to above: Should be uimm5_lsl2 for consistency with simm19_lsl2 and similar.

[jkolek]

Names fixed.

[vmedic]

LGTM with a nit.

lib/Target/Mips/MicroMipsInstrInfo.td

114

Allignment

[jkolek]

Alignment fixed.

Closed by commit rL217681 (authored by zjovanovic).

lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.h

                                   SmallVectorImpl<MCFixup> &Fixups,
                                   const MCSubtargetInfo &STI) const;
 
+  // getUImm5Lsl2Encoding - Return binary encoding of the microMIPS jump
+  // target operand.
+  unsigned getUImm5Lsl2Encoding(const MCInst &MI, unsigned OpNo,
+                                SmallVectorImpl<MCFixup> &Fixups,
+                                const MCSubtargetInfo &STI) const;
+
   // getBranchTargetOpValue - Return binary encoding of the branch
   // target operand. If the machine operand requires relocation,
   // record the relocation and return zero.

lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.cpp

 }
 
 unsigned MipsMCCodeEmitter::
+getUImm5Lsl2Encoding(const MCInst &MI, unsigned OpNo,
+                     SmallVectorImpl<MCFixup> &Fixups,
+                     const MCSubtargetInfo &STI) const {
+
+  const MCOperand &MO = MI.getOperand(OpNo);
+  if (MO.isImm()) {
+    // The immediate is encoded as 'immediate << 2'.
+    unsigned Res = getMachineOpValue(MI, MO, Fixups, STI);
+    assert((Res & 3) == 0);
+    return Res >> 2;
+  }
+
+  assert(MO.isExpr() &&
+         "getUImm5Lsl2Encoding expects only expressions or an immediate");
+
+  return 0;
+}
+
+unsigned MipsMCCodeEmitter::
 getExprOpValue(const MCExpr *Expr,SmallVectorImpl<MCFixup> &Fixups,
                const MCSubtargetInfo &STI) const {
   int64_t Res;

lib/Target/Mips/MicroMipsInstrFormats.td

   let Inst{4-0}   = rd;
 }
 
+class JRADDIUSP_FM_MM16<bits<5> op> {
+  bits<5> rs;
+  bits<5> imm;
+
+  bits<16> Inst;
+
+  let Inst{15-10} = 0x11;
+  let Inst{9-5}   = op;
+  let Inst{4-0}   = imm;
+}
+
 //===----------------------------------------------------------------------===//
 // MicroMIPS 32-bit Instruction Formats
 //===----------------------------------------------------------------------===//

lib/Target/Mips/MicroMipsInstrInfo.td

   let DecoderMethod = "DecodeSimm12";
 }
 
+def uimm5_lsl2 : Operand<OtherVT> {
+  let EncoderMethod = "getUImm5Lsl2Encoding";
+}
+
 def mem_mm_12 : Operand<i32> {
   let PrintMethod = "printMemOperand";
   let MIOperandInfo = (ops GPR32, simm12);

   let Defs = [RA];
 }
 
+// Base class for JRADDIUSP instruction.
+class JumpRAddiuStackMM16 :
+  MicroMipsInst16<(outs), (ins uimm5_lsl2:$imm), "jraddiusp\t$imm",
+           [], IIBranch, FrmR> {
+  let isTerminator = 1;
+  let isBarrier = 1;
+  let hasDelaySlot = 1;
+  let isBranch = 1;
+  let isIndirectBranch = 1;
+}
+
 // MicroMIPS Jump and Link (Call) - Short Delay Slot
 let isCall = 1, hasDelaySlot = 1, Defs = [RA] in {
   class JumpLinkMM<string opstr, DAGOperand opnd> :

 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>;
+def JRADDIUSP : JumpRAddiuStackMM16, JRADDIUSP_FM_MM16<0x18>;
 
 class WaitMM<string opstr> :
   InstSE<(outs), (ins uimm10:$code_), !strconcat(opstr, "\t$code_"), [],

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

 # CHECK-EL: mflo    $9              # encoding: [0x49,0x46]
 # CHECK-EL: move    $25, $1         # encoding: [0x21,0x0f]
 # CHECK-EL: jalr    $9              # encoding: [0xc9,0x45]
+# CHECK-EL: jraddiusp 20            # encoding: [0x05,0x47]
+# CHECK-EL: nop                     # encoding: [0x00,0x00,0x00,0x00]
 #------------------------------------------------------------------------------
 # Big endian
 #------------------------------------------------------------------------------

 # CHECK-EB: mflo    $9              # encoding: [0x46,0x49]
 # CHECK-EB: move    $25, $1         # encoding: [0x0f,0x21]
 # CHECK-EB: jalr    $9              # encoding: [0x45,0xc9]
+# CHECK-EB: jraddiusp 20            # encoding: [0x47,0x05]
+# CHECK-EB: nop                     # encoding: [0x00,0x00,0x00,0x00]
 
     mfhi    $9
     mflo    $9
     move    $25, $1
     jalr    $9
+    jraddiusp 20