[LLDB] Add unary plus and minus to DIL (#155617)

This patch adds unary nodes plus and minus, introduces unary type
conversions, and adds integral promotion to the type system.

Author: kuilpd

lldb/docs/dil-expr-lang.ebnf

@@ -8,7 +8,7 @@ expression = unary_expression ;
 unary_expression = postfix_expression
                  | unary_operator expression ;
 
-unary_operator = "*" | "&" ;
+unary_operator = "*" | "&" | "+" | "-";
 
 postfix_expression = primary_expression
                    | postfix_expression "[" integer_literal "]"

lldb/include/lldb/Symbol/TypeSystem.h

@@ -411,6 +411,18 @@ class TypeSystem : public PluginInterface,
   GetIntegralTemplateArgument(lldb::opaque_compiler_type_t type, size_t idx,
                               bool expand_pack);
 
+  // DIL
+
+  /// Checks if the type is eligible for integral promotion.
+  virtual bool IsPromotableIntegerType(lldb::opaque_compiler_type_t type);
+
+  /// Perform integral promotion on a given type.
+  /// This promotes eligible types (boolean, integers, unscoped enumerations)
+  /// to a larger integer type according to type system rules.
+  /// \returns Promoted type.
+  virtual llvm::Expected<CompilerType>
+  DoIntegralPromotion(CompilerType from, ExecutionContextScope *exe_scope);
+
   // Dumping types
 
 #ifndef NDEBUG

lldb/include/lldb/ValueObject/DILAST.h

@@ -33,6 +33,8 @@ enum class NodeKind {
 enum class UnaryOpKind {
   AddrOf, // "&"
   Deref,  // "*"
+  Minus,  // "-"
+  Plus,   // "+"
 };
 
 /// Forward declaration, for use in DIL AST nodes. Definition is at the very

lldb/include/lldb/ValueObject/DILEval.h

@@ -61,6 +61,10 @@ class Interpreter : Visitor {
   llvm::Expected<lldb::ValueObjectSP>
   Visit(const BooleanLiteralNode *node) override;
 
+  /// Perform usual unary conversions on a value. At the moment this
+  /// includes array-to-pointer and integral promotion for eligible types.
+  llvm::Expected<lldb::ValueObjectSP>
+  UnaryConversion(lldb::ValueObjectSP valobj, uint32_t location);
   llvm::Expected<CompilerType>
   PickIntegerType(lldb::TypeSystemSP type_system,
                   std::shared_ptr<ExecutionContextScope> ctx,

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp

@@ -7346,6 +7346,102 @@ CompilerType TypeSystemClang::GetTypeForFormatters(void *type) {
   return CompilerType();
 }
 
+bool TypeSystemClang::IsPromotableIntegerType(
+    lldb::opaque_compiler_type_t type) {
+  // Unscoped enums are always considered as promotable, even if their
+  // underlying type does not need to be promoted (e.g. "int").
+  bool is_signed = false;
+  bool isUnscopedEnumerationType =
+      IsEnumerationType(type, is_signed) && !IsScopedEnumerationType(type);
+  if (isUnscopedEnumerationType)
+    return true;
+
+  switch (GetBasicTypeEnumeration(type)) {
+  case lldb::eBasicTypeBool:
+  case lldb::eBasicTypeChar:
+  case lldb::eBasicTypeSignedChar:
+  case lldb::eBasicTypeUnsignedChar:
+  case lldb::eBasicTypeShort:
+  case lldb::eBasicTypeUnsignedShort:
+  case lldb::eBasicTypeWChar:
+  case lldb::eBasicTypeSignedWChar:
+  case lldb::eBasicTypeUnsignedWChar:
+  case lldb::eBasicTypeChar16:
+  case lldb::eBasicTypeChar32:
+    return true;
+
+  default:
+    return false;
+  }
+
+  llvm_unreachable("All cases handled above.");
+}
+
+llvm::Expected<CompilerType>
+TypeSystemClang::DoIntegralPromotion(CompilerType from,
+                                     ExecutionContextScope *exe_scope) {
+  if (!from.IsInteger() && !from.IsUnscopedEnumerationType())
+    return from;
+
+  if (!from.IsPromotableIntegerType())
+    return from;
+
+  if (from.IsUnscopedEnumerationType()) {
+    EnumDecl *enum_decl = GetAsEnumDecl(from);
+    CompilerType promotion_type = GetType(enum_decl->getPromotionType());
+    return DoIntegralPromotion(promotion_type, exe_scope);
+  }
+
+  lldb::BasicType builtin_type =
+      from.GetCanonicalType().GetBasicTypeEnumeration();
+  uint64_t from_size = 0;
+  if (builtin_type == lldb::eBasicTypeWChar ||
+      builtin_type == lldb::eBasicTypeSignedWChar ||
+      builtin_type == lldb::eBasicTypeUnsignedWChar ||
+      builtin_type == lldb::eBasicTypeChar16 ||
+      builtin_type == lldb::eBasicTypeChar32) {
+    // Find the type that can hold the entire range of values for our type.
+    bool is_signed = from.IsSigned();
+    llvm::Expected<uint64_t> from_size = from.GetByteSize(exe_scope);
+    if (!from_size)
+      return from_size.takeError();
+    CompilerType promote_types[] = {
+        GetBasicTypeFromAST(lldb::eBasicTypeInt),
+        GetBasicTypeFromAST(lldb::eBasicTypeUnsignedInt),
+        GetBasicTypeFromAST(lldb::eBasicTypeLong),
+        GetBasicTypeFromAST(lldb::eBasicTypeUnsignedLong),
+        GetBasicTypeFromAST(lldb::eBasicTypeLongLong),
+        GetBasicTypeFromAST(lldb::eBasicTypeUnsignedLongLong),
+    };
+    for (CompilerType &type : promote_types) {
+      llvm::Expected<uint64_t> byte_size = type.GetByteSize(exe_scope);
+      if (!byte_size)
+        return byte_size.takeError();
+      if (*from_size < *byte_size ||
+          (*from_size == *byte_size && is_signed == type.IsSigned())) {
+        return type;
+      }
+    }
+    llvm_unreachable("char type should fit into long long");
+  }
+
+  // Here we can promote only to "int" or "unsigned int".
+  CompilerType int_type = GetBasicTypeFromAST(lldb::eBasicTypeInt);
+  llvm::Expected<uint64_t> int_byte_size = int_type.GetByteSize(exe_scope);
+  if (!int_byte_size)
+    return int_byte_size.takeError();
+
+  // Signed integer types can be safely promoted to "int".
+  if (from.IsSigned()) {
+    return int_type;
+  }
+  // Unsigned integer types are promoted to "unsigned int" if "int" cannot hold
+  // their entire value range.
+  return (from_size == *int_byte_size)
+             ? GetBasicTypeFromAST(lldb::eBasicTypeUnsignedInt)
+             : int_type;
+}
+
 clang::EnumDecl *TypeSystemClang::GetAsEnumDecl(const CompilerType &type) {
   const clang::EnumType *enutype =
       llvm::dyn_cast<clang::EnumType>(ClangUtil::GetCanonicalQualType(type));

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.h

@@ -938,6 +938,14 @@ class TypeSystemClang : public TypeSystem {
 
   CompilerType GetTypeForFormatters(void *type) override;
 
+  // DIL
+
+  bool IsPromotableIntegerType(lldb::opaque_compiler_type_t type) override;
+
+  llvm::Expected<CompilerType>
+  DoIntegralPromotion(CompilerType from,
+                      ExecutionContextScope *exe_scope) override;
+
 #define LLDB_INVALID_DECL_LEVEL UINT32_MAX
   // LLDB_INVALID_DECL_LEVEL is returned by CountDeclLevels if child_decl_ctx
   // could not be found in decl_ctx.

lldb/source/Symbol/CompilerType.cpp

@@ -370,30 +370,10 @@ bool CompilerType::IsScalarOrUnscopedEnumerationType() const {
 }
 
 bool CompilerType::IsPromotableIntegerType() const {
-  // Unscoped enums are always considered as promotable, even if their
-  // underlying type does not need to be promoted (e.g. "int").
-  if (IsUnscopedEnumerationType())
-    return true;
-
-  switch (GetBasicTypeEnumeration()) {
-  case lldb::eBasicTypeBool:
-  case lldb::eBasicTypeChar:
-  case lldb::eBasicTypeSignedChar:
-  case lldb::eBasicTypeUnsignedChar:
-  case lldb::eBasicTypeShort:
-  case lldb::eBasicTypeUnsignedShort:
-  case lldb::eBasicTypeWChar:
-  case lldb::eBasicTypeSignedWChar:
-  case lldb::eBasicTypeUnsignedWChar:
-  case lldb::eBasicTypeChar16:
-  case lldb::eBasicTypeChar32:
-    return true;
-
-  default:
-    return false;
-  }
-
-  llvm_unreachable("All cases handled above.");
+  if (IsValid())
+    if (auto type_system_sp = GetTypeSystem())
+      return type_system_sp->IsPromotableIntegerType(m_type);
+  return false;
 }
 
 bool CompilerType::IsPointerToVoid() const {

lldb/source/Symbol/TypeSystem.cpp

@@ -123,6 +123,17 @@ CompilerType TypeSystem::GetTypeForFormatters(void *type) {
   return CompilerType(weak_from_this(), type);
 }
 
+bool TypeSystem::IsPromotableIntegerType(lldb::opaque_compiler_type_t type) {
+  return false;
+}
+
+llvm::Expected<CompilerType>
+TypeSystem::DoIntegralPromotion(CompilerType from,
+                                ExecutionContextScope *exe_scope) {
+  return llvm::createStringError(
+      "Integral promotion is not implemented for this TypeSystem");
+}
+
 bool TypeSystem::IsTemplateType(lldb::opaque_compiler_type_t type) {
   return false;
 }