[Mips] Fix for decoding DINS instruction - disassembler

This patch fixes decoding of size and position for DINSM
and DINSU instructions.

Differential Revision: https://reviews.llvm.org/D31072

llvm-svn: 298593

Author: Strahinja Petrovic

llvm/lib/Target/Mips/Disassembler/MipsDisassembler.cpp

@@ -2264,7 +2264,14 @@ static DecodeStatus DecodeInsSize(MCInst &Inst,
                                   const void *Decoder) {
   // First we need to grab the pos(lsb) from MCInst.
   int Pos = Inst.getOperand(2).getImm();
-  int Size = (int) Insn - Pos + 1;
+  if (Inst.getOpcode() == Mips::DINSU)
+    Pos += 32;
+  int Size;
+  if (Inst.getOpcode() == Mips::DINSM ||
+      Inst.getOpcode() == Mips::DINSU)
+    Size = (int) Insn - Pos + 33;
+  else
+    Size = (int) Insn - Pos + 1;
   Inst.addOperand(MCOperand::createImm(SignExtend32<16>(Size)));
   return MCDisassembler::Success;
 }

llvm/test/MC/Mips/mips64extins.s

@@ -5,5 +5,5 @@
         dextu $2, $4, 34, 6  # CHECK: dextu ${{[0-9]+}}, ${{[0-9]+}}, 34, 6
         dextm $2, $4, 5, 34  # CHECK: dextm ${{[0-9]+}}, ${{[0-9]+}}, 5, 34
         dins $4, $5, 8, 10   # CHECK: dins ${{[0-9]+}}, ${{[0-9]+}}, 8, 10
-        dinsm $4, $5, 10, 1  # CHECK: dinsm ${{[0-9]+}}, ${{[0-9]+}}, 10, 1
+        dinsm $4, $5, 30, 6  # CHECK: dinsm ${{[0-9]+}}, ${{[0-9]+}}, 30, 6
         dinsu $4, $5, 40, 13 # CHECK: dinsu ${{[0-9]+}}, ${{[0-9]+}}, 40, 13