[llvm] [GlobalISel][LLT] Introduce FPInfo for LLT (Enable bfloat, ppc128float and others in GlobalISel) (PR #155107)

[Serge Pavlov via llvm-commits]

================
@@ -39,68 +42,156 @@ class raw_ostream;
 
 class LLT {
 public:
+  using FpSemantics = APFloat::Semantics;
+
+  enum class Kind : uint8_t {
+    INVALID,
+    ANY_SCALAR,
+    INTEGER,
+    FLOAT,
+    POINTER,
+    VECTOR_ANY,
+    VECTOR_INTEGER,
+    VECTOR_FLOAT,
+    VECTOR_POINTER,
+  };
+
+  constexpr static Kind toVector(Kind Ty) {
+    if (Ty == Kind::POINTER)
+      return Kind::VECTOR_POINTER;
+
+    if (Ty == Kind::INTEGER)
+      return Kind::VECTOR_INTEGER;
+
+    if (Ty == Kind::FLOAT)
+      return Kind::VECTOR_FLOAT;
+
+    return Kind::VECTOR_ANY;
+  }
+
+  constexpr static Kind toScalar(Kind Ty) {
+    if (Ty == Kind::VECTOR_POINTER)
+      return Kind::POINTER;
+
+    if (Ty == Kind::VECTOR_INTEGER)
+      return Kind::INTEGER;
+
+    if (Ty == Kind::VECTOR_FLOAT)
+      return Kind::FLOAT;
+
+    return Kind::ANY_SCALAR;
+  }
+
   /// Get a low-level scalar or aggregate "bag of bits".
   static constexpr LLT scalar(unsigned SizeInBits) {
-    return LLT{/*isPointer=*/false, /*isVector=*/false, /*isScalar=*/true,
-               ElementCount::getFixed(0), SizeInBits,
-               /*AddressSpace=*/0};
+    return LLT{Kind::ANY_SCALAR, ElementCount::getFixed(0), SizeInBits,
+               /*AddressSpace=*/0, static_cast<FpSemantics>(0)};
----------------
spavloff wrote:

`static_cast<FpSemantics>(0)` is `S_IEEEhalf`, which looks strange. Instead of passing bogus values, could we have several constructors for various layouts?



https://github.com/llvm/llvm-project/pull/155107