[clang] [Clang][AArch64]Refactor typespec handling in SveEmitter.cpp (PR #117717)

[via cfe-commits]

================
@@ -423,131 +434,143 @@ const std::array<SVEEmitter::ReinterpretTypeInfo, 12> SVEEmitter::Reinterprets =
 // Type implementation
 //===----------------------------------------------------------------------===//
 
-std::string SVEType::builtin_str() const {
-  std::string S;
-  if (isVoid())
+std::string SVEType::builtinBaseType() const {
+  switch (Kind) {
+  case TypeKind::Void:
     return "v";
-
-  if (isScalarPredicate())
-    return "b";
-
-  if (isSvcount())
+  case TypeKind::Svcount:
     return "Qa";
-
-  if (isVoidPointer())
-    S += "v";
-  else if (!isFloatingPoint())
+  case TypeKind::BFloat16:
+    assert(ElementBitwidth == 16 && "Invalid BFloat16!");
+    return "y";
+  case TypeKind::MFloat8:
+    assert(ElementBitwidth == 8 && "Invalid MFloat8!");
+    return "c";
+  case TypeKind::Float:
     switch (ElementBitwidth) {
-    case 1: S += "b"; break;
-    case 8: S += "c"; break;
-    case 16: S += "s"; break;
-    case 32: S += "i"; break;
-    case 64: S += "Wi"; break;
-    case 128: S += "LLLi"; break;
-    default: llvm_unreachable("Unhandled case!");
+    case 16:
+      return "h";
+    case 32:
+      return "f";
+    case 64:
+      return "d";
+    default:
+      llvm_unreachable("Unhandled float width!");
     }
-  else if (isFloat())
+  case TypeKind::Predicate:
+    if (isScalar())
+      return "b";
+    [[fallthrough]];
+  // SInt/UInt, PredicatePattern, PrefetchOp.
+  default:
     switch (ElementBitwidth) {
-    case 16: S += "h"; break;
-    case 32: S += "f"; break;
-    case 64: S += "d"; break;
-    default: llvm_unreachable("Unhandled case!");
+    case 1:
+      return "b";
+    case 8:
+      return "c";
+    case 16:
+      return "s";
+    case 32:
+      return "i";
+    case 64:
+      return "Wi";
+    case 128:
+      return "LLLi";
+    default:
+      llvm_unreachable("Unhandled bitwidth!");
     }
-  else if (isBFloat()) {
-    assert(ElementBitwidth == 16 && "Not a valid BFloat.");
-    S += "y";
-  } else if (isMFloat()) {
-    assert(ElementBitwidth == 8 && "Not a valid MFloat.");
-    S += "m";
   }
+}
 
-  if (!isFloatingPoint()) {
-    if ((isChar() || isPointer()) && !isVoidPointer()) {
-      // Make chars and typed pointers explicitly signed.
-      if (Signed)
-        S = "S" + S;
-      else if (!Signed)
-        S = "U" + S;
-    } else if (!isVoidPointer() && !Signed) {
-      S = "U" + S;
-    }
-  }
+std::string SVEType::builtin_str() const {
 
-  // Constant indices are "int", but have the "constant expression" modifier.
-  if (isImmediate()) {
-    assert(!isFloat() && "fp immediates are not supported");
-    S = "I" + S;
-  }
+  std::string Prefix;
 
-  if (isScalar()) {
-    if (Constant) S += "C";
-    if (Pointer) S += "*";
-    return S;
+  if (isScalableVector())
+    Prefix = "q" + llvm::utostr(getNumElements() * NumVectors);
+  else if (isFixedLengthVector())
+    Prefix = "V" + llvm::utostr(getNumElements() * NumVectors);
+  else if (isImmediate()) {
+    assert(!isFloatingPoint() && "fp immediates are not supported");
+    Prefix = "I";
   }
 
-  if (isFixedLengthVector())
-    return "V" + utostr(getNumElements() * NumVectors) + S;
-  return "q" + utostr(getNumElements() * NumVectors) + S;
+  // Make chars and integer pointers explicitly signed.
+  if ((ElementBitwidth == 8 || isPointer()) && isSignedInteger())
----------------
SpencerAbson wrote:

Before this patch, the code that performed `// Make chars explicitly typed` deduced that a type was a `char` from `!isFloatingPoint()` and `ElementBitWidth == 8`. One effect of this is that the builtin string for a the type `Pc` would be `q16Sc` (vector of signed chars). The change that I have made here will ignore sign information for predicates. @sdesmalen-arm do you know if this was the intent of the original code?

https://github.com/llvm/llvm-project/pull/117717