[LLDB] Add bit extraction to DIL (#141422)

kuilpd · web-flow · commit 4236423ee863 · 2025-06-13T16:31:25.000+05:00
diff --git a/lldb/include/lldb/ValueObject/DILAST.h b/lldb/include/lldb/ValueObject/DILAST.h
@@ -19,6 +19,7 @@ namespace lldb_private::dil {
 /// The various types DIL AST nodes (used by the DIL parser).
 enum class NodeKind {
   eArraySubscriptNode,
+  eBitExtractionNode,
   eErrorNode,
   eIdentifierNode,
   eMemberOfNode,
@@ -153,6 +154,30 @@ class ArraySubscriptNode : public ASTNode {
   int64_t m_index;
 };
 
+class BitFieldExtractionNode : public ASTNode {
+public:
+  BitFieldExtractionNode(uint32_t location, ASTNodeUP base, int64_t first_index,
+                         int64_t last_index)
+      : ASTNode(location, NodeKind::eBitExtractionNode),
+        m_base(std::move(base)), m_first_index(first_index),
+        m_last_index(last_index) {}
+
+  llvm::Expected<lldb::ValueObjectSP> Accept(Visitor *v) const override;
+
+  ASTNode *GetBase() const { return m_base.get(); }
+  int64_t GetFirstIndex() const { return m_first_index; }
+  int64_t GetLastIndex() const { return m_last_index; }
+
+  static bool classof(const ASTNode *node) {
+    return node->GetKind() == NodeKind::eBitExtractionNode;
+  }
+
+private:
+  ASTNodeUP m_base;
+  int64_t m_first_index;
+  int64_t m_last_index;
+};
+
 /// This class contains one Visit method for each specialized type of
 /// DIL AST node. The Visit methods are used to dispatch a DIL AST node to
 /// the correct function in the DIL expression evaluator for evaluating that
@@ -168,6 +193,8 @@ class Visitor {
   Visit(const UnaryOpNode *node) = 0;
   virtual llvm::Expected<lldb::ValueObjectSP>
   Visit(const ArraySubscriptNode *node) = 0;
+  virtual llvm::Expected<lldb::ValueObjectSP>
+  Visit(const BitFieldExtractionNode *node) = 0;
 };
 
 } // namespace lldb_private::dil
diff --git a/lldb/include/lldb/ValueObject/DILEval.h b/lldb/include/lldb/ValueObject/DILEval.h
@@ -54,6 +54,8 @@ class Interpreter : Visitor {
   llvm::Expected<lldb::ValueObjectSP> Visit(const UnaryOpNode *node) override;
   llvm::Expected<lldb::ValueObjectSP>
   Visit(const ArraySubscriptNode *node) override;
+  llvm::Expected<lldb::ValueObjectSP>
+  Visit(const BitFieldExtractionNode *node) override;
 
   // Used by the interpreter to create objects, perform casts, etc.
   lldb::TargetSP m_target;
diff --git a/lldb/include/lldb/ValueObject/DILLexer.h b/lldb/include/lldb/ValueObject/DILLexer.h
@@ -31,6 +31,7 @@ class Token {
     identifier,
     l_paren,
     l_square,
+    minus,
     numeric_constant,
     period,
     r_paren,
diff --git a/lldb/source/ValueObject/DILAST.cpp b/lldb/source/ValueObject/DILAST.cpp
@@ -32,4 +32,9 @@ ArraySubscriptNode::Accept(Visitor *v) const {
   return v->Visit(this);
 }
 
+llvm::Expected<lldb::ValueObjectSP>
+BitFieldExtractionNode::Accept(Visitor *v) const {
+  return v->Visit(this);
+}
+
 } // namespace lldb_private::dil
diff --git a/lldb/source/ValueObject/DILEval.cpp b/lldb/source/ValueObject/DILEval.cpp
@@ -430,4 +430,36 @@ Interpreter::Visit(const ArraySubscriptNode *node) {
   return base->GetSyntheticArrayMember(signed_child_idx, true);
 }
 
+llvm::Expected<lldb::ValueObjectSP>
+Interpreter::Visit(const BitFieldExtractionNode *node) {
+  auto lhs_or_err = Evaluate(node->GetBase());
+  if (!lhs_or_err)
+    return lhs_or_err;
+  lldb::ValueObjectSP base = *lhs_or_err;
+  int64_t first_index = node->GetFirstIndex();
+  int64_t last_index = node->GetLastIndex();
+
+  // if the format given is [high-low], swap range
+  if (first_index > last_index)
+    std::swap(first_index, last_index);
+
+  Status error;
+  if (base->GetCompilerType().IsReferenceType()) {
+    base = base->Dereference(error);
+    if (error.Fail())
+      return error.ToError();
+  }
+  lldb::ValueObjectSP child_valobj_sp =
+      base->GetSyntheticBitFieldChild(first_index, last_index, true);
+  if (!child_valobj_sp) {
+    std::string message = llvm::formatv(
+        "bitfield range {0}-{1} is not valid for \"({2}) {3}\"", first_index,
+        last_index, base->GetTypeName().AsCString("<invalid type>"),
+        base->GetName().AsCString());
+    return llvm::make_error<DILDiagnosticError>(m_expr, message,
+                                                node->GetLocation());
+  }
+  return child_valobj_sp;
+}
+
 } // namespace lldb_private::dil
diff --git a/lldb/source/ValueObject/DILLexer.cpp b/lldb/source/ValueObject/DILLexer.cpp
@@ -34,6 +34,8 @@ llvm::StringRef Token::GetTokenName(Kind kind) {
     return "l_paren";
   case Kind::l_square:
     return "l_square";
+  case Kind::minus:
+    return "minus";
   case Kind::numeric_constant:
     return "numeric_constant";
   case Kind::period:
@@ -113,8 +115,9 @@ llvm::Expected<Token> DILLexer::Lex(llvm::StringRef expr,
 
   constexpr std::pair<Token::Kind, const char *> operators[] = {
       {Token::amp, "&"},     {Token::arrow, "->"},   {Token::coloncolon, "::"},
-      {Token::l_paren, "("}, {Token::l_square, "["}, {Token::period, "."},
-      {Token::r_paren, ")"}, {Token::r_square, "]"}, {Token::star, "*"},
+      {Token::l_paren, "("}, {Token::l_square, "["}, {Token::minus, "-"},
+      {Token::period, "."},  {Token::r_paren, ")"},  {Token::r_square, "]"},
+      {Token::star, "*"},
   };
   for (auto [kind, str] : operators) {
     if (remainder.consume_front(str))
diff --git a/lldb/source/ValueObject/DILParser.cpp b/lldb/source/ValueObject/DILParser.cpp
@@ -120,6 +120,7 @@ ASTNodeUP DILParser::ParseUnaryExpression() {
 //  postfix_expression:
 //    primary_expression
 //    postfix_expression "[" integer_literal "]"
+//    postfix_expression "[" integer_literal "-" integer_literal "]"
 //    postfix_expression "." id_expression
 //    postfix_expression "->" id_expression
 //
@@ -131,17 +132,30 @@ ASTNodeUP DILParser::ParsePostfixExpression() {
     switch (token.GetKind()) {
     case Token::l_square: {
       m_dil_lexer.Advance();
-      std::optional<int64_t> rhs = ParseIntegerConstant();
-      if (!rhs) {
+      std::optional<int64_t> index = ParseIntegerConstant();
+      if (!index) {
         BailOut(
             llvm::formatv("failed to parse integer constant: {0}", CurToken()),
             CurToken().GetLocation(), CurToken().GetSpelling().length());
         return std::make_unique<ErrorNode>();
       }
+      if (CurToken().GetKind() == Token::minus) {
+        m_dil_lexer.Advance();
+        std::optional<int64_t> last_index = ParseIntegerConstant();
+        if (!last_index) {
+          BailOut(llvm::formatv("failed to parse integer constant: {0}",
+                                CurToken()),
+                  CurToken().GetLocation(), CurToken().GetSpelling().length());
+          return std::make_unique<ErrorNode>();
+        }
+        lhs = std::make_unique<BitFieldExtractionNode>(
+            loc, std::move(lhs), std::move(*index), std::move(*last_index));
+      } else {
+        lhs = std::make_unique<ArraySubscriptNode>(loc, std::move(lhs),
+                                                   std::move(*index));
+      }
       Expect(Token::r_square);
       m_dil_lexer.Advance();
-      lhs = std::make_unique<ArraySubscriptNode>(loc, std::move(lhs),
-                                                 std::move(*rhs));
       break;
     }
     case Token::period:
diff --git a/lldb/test/API/commands/frame/var-dil/basics/ArraySubscript/TestFrameVarDILArraySubscript.py b/lldb/test/API/commands/frame/var-dil/basics/ArraySubscript/TestFrameVarDILArraySubscript.py
@@ -63,7 +63,7 @@ def test_subscript(self):
         self.expect(
             "frame var 'int_arr[-1]'",
             error=True,
-            substrs=["unrecognized token"],
+            substrs=["failed to parse integer constant"],
         )
 
         # Test for floating point index
diff --git a/lldb/test/API/commands/frame/var-dil/basics/BitFieldExtraction/Makefile b/lldb/test/API/commands/frame/var-dil/basics/BitFieldExtraction/Makefile
@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+
+include Makefile.rules
diff --git a/lldb/test/API/commands/frame/var-dil/basics/BitFieldExtraction/TestFrameVarDILBitFieldExtraction.py b/lldb/test/API/commands/frame/var-dil/basics/BitFieldExtraction/TestFrameVarDILBitFieldExtraction.py
@@ -0,0 +1,56 @@
+"""
+Test DIL BifField extraction.
+"""
+
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+from lldbsuite.test import lldbutil
+
+
+class TestFrameVarDILBitFieldExtraction(TestBase):
+    NO_DEBUG_INFO_TESTCASE = True
+
+    def expect_var_path(self, expr, compare_to_framevar=False, value=None, type=None):
+        value_dil = super().expect_var_path(expr, value=value, type=type)
+        if compare_to_framevar:
+            self.runCmd("settings set target.experimental.use-DIL false")
+            value_frv = super().expect_var_path(expr, value=value, type=type)
+            self.runCmd("settings set target.experimental.use-DIL true")
+            self.assertEqual(value_dil.GetValue(), value_frv.GetValue())
+
+    def test_bitfield_extraction(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, "Set a breakpoint here", lldb.SBFileSpec("main.cpp")
+        )
+
+        self.runCmd("settings set target.experimental.use-DIL true")
+
+        # Test ranges and type
+        self.expect_var_path("value[0-1]", True, value="3", type="int:2")
+        self.expect_var_path("value[4-7]", True, value="7", type="int:4")
+        self.expect_var_path("value[7-0]", True, value="115", type="int:8")
+
+        # Test reference and dereferenced pointer
+        self.expect_var_path("value_ref[0-1]", value="3", type="int:2")
+        self.expect_var_path("(*value_ptr)[0-1]", value="3", type="int:2")
+
+        # Test array and pointer
+        self.expect(
+            "frame var 'int_arr[0-2]'",
+            error=True,
+            substrs=["bitfield range 0-2 is not valid"],
+        )
+        self.expect(
+            "frame var 'value_ptr[0-1]'",
+            error=True,
+            substrs=["bitfield range 0-1 is not valid"],
+        )
+
+        # Test invalid input
+        self.expect(
+            "frame var 'value[1-]'",
+            error=True,
+            substrs=["failed to parse integer constant"],
+        )
diff --git a/lldb/test/API/commands/frame/var-dil/basics/BitFieldExtraction/main.cpp b/lldb/test/API/commands/frame/var-dil/basics/BitFieldExtraction/main.cpp
@@ -0,0 +1,9 @@
+int main(int argc, char **argv) {
+  int value = 0b01110011;
+  int &value_ref = value;
+  int *value_ptr = &value;
+
+  int int_arr[] = {7, 3, 1};
+
+  return 0; // Set a breakpoint here
+}

Original file line number	Diff line number	Diff line change
`@@ -32,4 +32,9 @@ ArraySubscriptNode::Accept(Visitor *v) const {`
`32`	`32`	`return v->Visit(this);`
`33`	`33`	`}`
`34`	`34`
	`35`	`+llvm::Expected<lldb::ValueObjectSP>`
	`36`	`+BitFieldExtractionNode::Accept(Visitor *v) const {`
	`37`	`+ return v->Visit(this);`
	`38`	`+}`
	`39`	`+`
`35`	`40`	`} // namespace lldb_private::dil`
Original file line number	Diff line number	Diff line change
`@@ -63,7 +63,7 @@ def test_subscript(self):`
`63`	`63`	`self.expect(`
`64`	`64`	`"frame var 'int_arr[-1]'",`
`65`	`65`	`error=True,`
`66`		`- substrs=["unrecognized token"],`
	`66`	`+ substrs=["failed to parse integer constant"],`
`67`	`67`	`)`
`68`	`68`
`69`	`69`	`# Test for floating point index`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+CXX_SOURCES := main.cpp`
	`2`	`+`
	`3`	`+include Makefile.rules`