ARM Binary encoding information for BFC/BFI instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117072 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMMCCodeEmitter.cpp b/lib/Target/ARM/ARMMCCodeEmitter.cpp
index ea7789c..f0680e8 100644
--- a/lib/Target/ARM/ARMMCCodeEmitter.cpp
+++ b/lib/Target/ARM/ARMMCCodeEmitter.cpp
@@ -88,6 +88,8 @@
     return MI.getOperand(Op).getImm() - 1;
   }
 
+  unsigned getBitfieldInvertedMaskOpValue(const MCInst &MI, unsigned Op) const;
+
   unsigned getNumFixupKinds() const {
     assert(0 && "ARMMCCodeEmitter::getNumFixupKinds() not yet implemented.");
     return 0;
@@ -238,6 +240,18 @@
   return Binary | ARM_AM::getSORegOffset(MO2.getImm()) << 7;
 }
 
+unsigned ARMMCCodeEmitter::getBitfieldInvertedMaskOpValue(const MCInst &MI,
+                                                          unsigned Op) const {
+  // 10 bits. lower 5 bits are are the lsb of the mask, high five bits are the
+  // msb of the mask.
+  const MCOperand &MO = MI.getOperand(Op);
+  uint32_t v = ~MO.getImm();
+  uint32_t lsb = CountTrailingZeros_32(v);
+  uint32_t msb = (32 - CountLeadingZeros_32 (v)) - 1;
+  assert (v != 0 && lsb < 32 && msb < 32 && "Illegal bitfield mask!");
+  return lsb | (msb << 5);
+}
+
 void ARMMCCodeEmitter::
 EncodeInstruction(const MCInst &MI, raw_ostream &OS,
                   SmallVectorImpl<MCFixup> &Fixups) const {