[llvm] [LLVM][TableGen][DecoderEmitter] Add wrapper class for `bit_value_t` (PR #146248)

[Craig Topper via llvm-commits]

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@@ -252,84 +246,97 @@ class DecoderEmitter {
   StringRef PredicateNamespace;
 };
 
-} // end anonymous namespace
-
 // The set (BIT_TRUE, BIT_FALSE, BIT_UNSET) represents a ternary logic system
 // for a bit value.
 //
 // BIT_UNFILTERED is used as the init value for a filter position.  It is used
 // only for filter processings.
-typedef enum : uint8_t {
-  BIT_FALSE,     // '0'
-  BIT_TRUE,      // '1'
-  BIT_UNSET,     // '?'
-  BIT_UNFILTERED // unfiltered
-} bit_value_t;
-
-static bool ValueSet(bit_value_t V) {
-  return (V == BIT_TRUE || V == BIT_FALSE);
-}
-
-static bool ValueNotSet(bit_value_t V) { return (V == BIT_UNSET); }
-
-static int Value(bit_value_t V) {
-  return ValueNotSet(V) ? -1 : (V == BIT_FALSE ? 0 : 1);
-}
+struct BitValue {
+  enum bit_value_t : uint8_t {
+    BIT_FALSE,     // '0'
+    BIT_TRUE,      // '1'
+    BIT_UNSET,     // '?', printed as '_'
+    BIT_UNFILTERED // unfiltered, printed as '.'
+  };
 
-static bit_value_t bitFromBits(const BitsInit &bits, unsigned index) {
-  if (const BitInit *bit = dyn_cast<BitInit>(bits.getBit(index)))
-    return bit->getValue() ? BIT_TRUE : BIT_FALSE;
+  BitValue(bit_value_t V) : V(V) {}
+  explicit BitValue(const Init *Init) {
+    if (const auto *Bit = dyn_cast<BitInit>(Init))
+      V = Bit->getValue() ? BIT_TRUE : BIT_FALSE;
+    else
+      V = BIT_UNSET;
+  }
+  BitValue(const BitsInit &Bits, unsigned Idx) : BitValue(Bits.getBit(Idx)) {}
 
-  // The bit is uninitialized.
-  return BIT_UNSET;
-}
+  bool isSet() const { return V == BIT_TRUE || V == BIT_FALSE; }
+  bool isUnset() const { return V == BIT_UNSET; }
+  std::optional<uint64_t> getValue() const {
+    if (isSet())
+      return static_cast<uint64_t>(V);
+    return std::nullopt;
+  }
+  bit_value_t getRawValue() const { return V; }
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topperc wrote:

Remove getRawValue

https://github.com/llvm/llvm-project/pull/146248