[mips] Add new format for dmtc2/dmfc2 for Octeon CPUs.

Octeon CPUs use dmtc2 rt,imm16 and dmfcp2 rt,imm16 for the crypto coprocessor.
E.g. dmtc2 rt,0x4057 starts calculation of sha-1.

I had to introduce a new deconding namespace to avoid a decoding conflict.

Reviewed By: dsanders

Differential Revision: http://reviews.llvm.org/D10083


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238439 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/Mips/Disassembler/MipsDisassembler.cpp

@@ -47,6 +47,8 @@ public:
 
   bool isGP64() const { return STI.getFeatureBits()[Mips::FeatureGP64Bit]; }
 
+  bool hasCnMips() const { return STI.getFeatureBits()[Mips::FeatureCnMips]; }
+
   bool hasCOP3() const {
     // Only present in MIPS-I and MIPS-II
     return !hasMips32() && !hasMips3();
@@ -889,6 +891,16 @@ DecodeStatus MipsDisassembler::getInstruction(MCInst &Instr, uint64_t &Size,
     }
   }
 
+  if (hasCnMips()) {
+    DEBUG(dbgs() << "Trying CnMips table (32-bit opcodes):\n");
+    Result = decodeInstruction(DecoderTableCnMips32, Instr, Insn,
+                               Address, this, STI);
+    if (Result != MCDisassembler::Fail) {
+      Size = 4;
+      return Result;
+    }
+  }
+
   if (isGP64()) {
     DEBUG(dbgs() << "Trying Mips64 (GPR64) table (32-bit opcodes):\n");
     Result = decodeInstruction(DecoderTableMips6432, Instr, Insn,