Fix disassembly of Thumb2 LDRSH with a #-0 offset.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139943 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index 685b921..2818e77 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -2731,7 +2731,10 @@
 static DecodeStatus DecodeT2Imm8(llvm::MCInst &Inst, unsigned Val,
                          uint64_t Address, const void *Decoder) {
   int imm = Val & 0xFF;
-  if (!(Val & 0x100)) imm *= -1;
+  if (Val == 0)
+    imm = INT32_MIN;
+  else if (!(Val & 0x100))
+    imm *= -1;
   Inst.addOperand(MCOperand::CreateImm(imm));
 
   return MCDisassembler::Success;