From b925e935d7fd17814304bb29b52e8ed4a25ed3be Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Fri, 16 Sep 2011 23:04:48 +0000
Subject: [PATCH] Fix bitfield decoding based on Eli's feedback.

llvm-svn: 139969
---
 llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index d1eb5b3004bf..4e9c3e58a5f3 100644
--- a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -1004,10 +1004,9 @@ static DecodeStatus DecodeBitfieldMaskOperand(llvm::MCInst &Inst, unsigned Val,
   unsigned msb = fieldFromInstruction32(Val, 5, 5);
   unsigned lsb = fieldFromInstruction32(Val, 0, 5);
 
-  uint32_t msb_mask = (1 << (msb+1)) - 1;
-  if (msb == 31) msb_mask = 0xFFFFFFFF;
-  uint32_t lsb_mask = (1 << lsb) - 1;
-  if (lsb == 31) lsb_mask = 0xFFFFFFFF;
+  uint32_t msb_mask = 0xFFFFFFFF;
+  if (msb != 31) msb_mask = (1U << (msb+1)) - 1;
+  uint32_t lsb_mask = (1U << lsb) - 1;
 
   Inst.addOperand(MCOperand::CreateImm(~(msb_mask ^ lsb_mask)));
   return MCDisassembler::Success;