[TableGen] Declare loop induction variables in the loop header (NFC)

Author: s-barannikov

llvm/utils/TableGen/DecoderEmitter.cpp

@@ -1579,8 +1579,6 @@ bool FilterChooser::filterProcessor(bool AllowMixed, bool Greedy) {
  }
  }
 
- unsigned BitIndex;
-
  // We maintain BIT_WIDTH copies of the bitAttrs automaton.
  // The automaton consumes the corresponding bit from each
  // instruction.
@@ -1602,14 +1600,14 @@ bool FilterChooser::filterProcessor(bool AllowMixed, bool Greedy) {
 
  // FILTERED bit positions provide no entropy and are not worthy of pursuing.
  // Filter::recurse() set either BIT_TRUE or BIT_FALSE for each position.
- for (BitIndex = 0; BitIndex < BitWidth; ++BitIndex)
+ for (unsigned BitIndex = 0; BitIndex < BitWidth; ++BitIndex)
  if (FilterBitValues[BitIndex].isSet())
  bitAttrs[BitIndex] = ATTR_FILTERED;
 
  for (const auto &OpcPair : Opcodes) {
  insn_t insn = insnWithID(OpcPair.EncodingID);
 
- for (BitIndex = 0; BitIndex < BitWidth; ++BitIndex) {
+ for (unsigned BitIndex = 0; BitIndex < BitWidth; ++BitIndex) {
  switch (bitAttrs[BitIndex]) {
  case ATTR_NONE:
  if (insn[BitIndex] == BitValue::BIT_UNSET)
@@ -1655,7 +1653,7 @@ bool FilterChooser::filterProcessor(bool AllowMixed, bool Greedy) {
  bitAttr_t RA = ATTR_NONE;
  unsigned StartBit = 0;
 
- for (BitIndex = 0; BitIndex < BitWidth; ++BitIndex) {
+ for (unsigned BitIndex = 0; BitIndex < BitWidth; ++BitIndex) {
  bitAttr_t bitAttr = bitAttrs[BitIndex];
 
  assert(bitAttr != ATTR_NONE && "Bit without attributes");
@@ -1736,12 +1734,12 @@ bool FilterChooser::filterProcessor(bool AllowMixed, bool Greedy) {
  case ATTR_FILTERED:
  break;
  case ATTR_ALL_SET:
- reportRegion(RA, StartBit, BitIndex, AllowMixed);
+ reportRegion(RA, StartBit, BitWidth, AllowMixed);
  break;
  case ATTR_ALL_UNSET:
  break;
  case ATTR_MIXED:
- reportRegion(RA, StartBit, BitIndex, AllowMixed);
+ reportRegion(RA, StartBit, BitWidth, AllowMixed);
  break;
  }