[LLDB][NFC] Added the interface DWARFExpression::Delegate to break dependencies and reduce lldb-server size (#131645)

This patch addresses the issue #129543.
After this patch DWARFExpression does not call DWARFUnit directly and does not depend on
lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp and a lot of clang code.
After this patch the size of lldb-server binary (Linux Aarch64) is reduced from 47MB to 17MB.

Author: slydiman

lldb/include/lldb/Expression/DWARFExpression.h

@@ -11,6 +11,7 @@
 
 #include "lldb/Core/Address.h"
 #include "lldb/Core/Disassembler.h"
+#include "lldb/Core/dwarf.h"
 #include "lldb/Utility/DataExtractor.h"
 #include "lldb/Utility/Scalar.h"
 #include "lldb/Utility/Status.h"
@@ -21,12 +22,6 @@
 
 namespace lldb_private {
 
-namespace plugin {
-namespace dwarf {
-class DWARFUnit;
-} // namespace dwarf
-} // namespace plugin
-
 /// \class DWARFExpression DWARFExpression.h
 /// "lldb/Expression/DWARFExpression.h" Encapsulates a DWARF location
 /// expression and interprets it.
@@ -40,6 +35,30 @@ class DWARFUnit;
 /// location expression or a location list and interprets it.
 class DWARFExpression {
 public:
+  class Delegate {
+  public:
+    Delegate() = default;
+    virtual ~Delegate() = default;
+
+    virtual uint16_t GetVersion() const = 0;
+    virtual dw_addr_t GetBaseAddress() const = 0;
+    virtual uint8_t GetAddressByteSize() const = 0;
+    virtual llvm::Expected<std::pair<uint64_t, bool>>
+    GetDIEBitSizeAndSign(uint64_t relative_die_offset) const = 0;
+    virtual dw_addr_t ReadAddressFromDebugAddrSection(uint32_t index) const = 0;
+    virtual lldb::offset_t
+    GetVendorDWARFOpcodeSize(const DataExtractor &data,
+                             const lldb::offset_t data_offset,
+                             const uint8_t op) const = 0;
+    virtual bool ParseVendorDWARFOpcode(uint8_t op,
+                                        const DataExtractor &opcodes,
+                                        lldb::offset_t &offset,
+                                        std::vector<Value> &stack) const = 0;
+
+    Delegate(const Delegate &) = delete;
+    Delegate &operator=(const Delegate &) = delete;
+  };
+
   DWARFExpression();
 
   /// Constructor
@@ -66,19 +85,17 @@ class DWARFExpression {
   ///     The address specified by the operation, if the operation exists, or
   ///     an llvm::Error otherwise.
   llvm::Expected<lldb::addr_t>
-  GetLocation_DW_OP_addr(const plugin::dwarf::DWARFUnit *dwarf_cu) const;
+  GetLocation_DW_OP_addr(const Delegate *dwarf_cu) const;
 
-  bool Update_DW_OP_addr(const plugin::dwarf::DWARFUnit *dwarf_cu,
-                         lldb::addr_t file_addr);
+  bool Update_DW_OP_addr(const Delegate *dwarf_cu, lldb::addr_t file_addr);
 
   void UpdateValue(uint64_t const_value, lldb::offset_t const_value_byte_size,
                    uint8_t addr_byte_size);
 
-  bool
-  ContainsThreadLocalStorage(const plugin::dwarf::DWARFUnit *dwarf_cu) const;
+  bool ContainsThreadLocalStorage(const Delegate *dwarf_cu) const;
 
   bool LinkThreadLocalStorage(
-      const plugin::dwarf::DWARFUnit *dwarf_cu,
+      const Delegate *dwarf_cu,
       std::function<lldb::addr_t(lldb::addr_t file_addr)> const
           &link_address_callback);
 
@@ -132,13 +149,8 @@ class DWARFExpression {
   static llvm::Expected<Value>
   Evaluate(ExecutionContext *exe_ctx, RegisterContext *reg_ctx,
            lldb::ModuleSP module_sp, const DataExtractor &opcodes,
-           const plugin::dwarf::DWARFUnit *dwarf_cu,
-           const lldb::RegisterKind reg_set, const Value *initial_value_ptr,
-           const Value *object_address_ptr);
-
-  static bool ParseDWARFLocationList(const plugin::dwarf::DWARFUnit *dwarf_cu,
-                                     const DataExtractor &data,
-                                     DWARFExpressionList *loc_list);
+           const Delegate *dwarf_cu, const lldb::RegisterKind reg_set,
+           const Value *initial_value_ptr, const Value *object_address_ptr);
 
   bool GetExpressionData(DataExtractor &data) const {
     data = m_data;

lldb/source/Expression/DWARFExpression.cpp

@@ -15,7 +15,6 @@
 
 #include "lldb/Core/Module.h"
 #include "lldb/Core/Value.h"
-#include "lldb/Core/dwarf.h"
 #include "lldb/Utility/DataEncoder.h"
 #include "lldb/Utility/LLDBLog.h"
 #include "lldb/Utility/Log.h"
@@ -37,11 +36,8 @@
 #include "lldb/Target/StackID.h"
 #include "lldb/Target/Target.h"
 #include "lldb/Target/Thread.h"
-#include "llvm/DebugInfo/DWARF/DWARFDebugLoc.h"
 #include "llvm/DebugInfo/DWARF/DWARFExpression.h"
 
-#include "Plugins/SymbolFile/DWARF/DWARFUnit.h"
-
 using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_private::dwarf;
@@ -130,10 +126,10 @@ static llvm::Error ReadRegisterValueAsScalar(RegisterContext *reg_ctx,
 
 /// Return the length in bytes of the set of operands for \p op. No guarantees
 /// are made on the state of \p data after this call.
-static lldb::offset_t GetOpcodeDataSize(const DataExtractor &data,
-                                        const lldb::offset_t data_offset,
-                                        const LocationAtom op,
-                                        const DWARFUnit *dwarf_cu) {
+static lldb::offset_t
+GetOpcodeDataSize(const DataExtractor &data, const lldb::offset_t data_offset,
+                  const LocationAtom op,
+                  const DWARFExpression::Delegate *dwarf_cu) {
   lldb::offset_t offset = data_offset;
   switch (op) {
   // Only used in LLVM metadata.
@@ -362,7 +358,8 @@ static lldb::offset_t GetOpcodeDataSize(const DataExtractor &data,
                                // + LEB128
   {
     data.Skip_LEB128(&offset);
-    return DWARFUnit::GetAddressByteSize(dwarf_cu) + offset - data_offset;
+    return (dwarf_cu ? dwarf_cu->GetAddressByteSize() : 4) + offset -
+           data_offset;
   }
 
   case DW_OP_GNU_entry_value:
@@ -387,14 +384,23 @@ static lldb::offset_t GetOpcodeDataSize(const DataExtractor &data,
   }
 
   if (dwarf_cu)
-    return dwarf_cu->GetSymbolFileDWARF().GetVendorDWARFOpcodeSize(
-        data, data_offset, op);
+    return dwarf_cu->GetVendorDWARFOpcodeSize(data, data_offset, op);
 
   return LLDB_INVALID_OFFSET;
 }
 
-llvm::Expected<lldb::addr_t>
-DWARFExpression::GetLocation_DW_OP_addr(const DWARFUnit *dwarf_cu) const {
+static const char *DW_OP_value_to_name(uint32_t val) {
+  static char invalid[100];
+  llvm::StringRef llvmstr = llvm::dwarf::OperationEncodingString(val);
+  if (llvmstr.empty()) {
+    snprintf(invalid, sizeof(invalid), "Unknown DW_OP constant: 0x%x", val);
+    return invalid;
+  }
+  return llvmstr.data();
+}
+
+llvm::Expected<lldb::addr_t> DWARFExpression::GetLocation_DW_OP_addr(
+    const DWARFExpression::Delegate *dwarf_cu) const {
   lldb::offset_t offset = 0;
   while (m_data.ValidOffset(offset)) {
     const LocationAtom op = static_cast<LocationAtom>(m_data.GetU8(&offset));
@@ -422,8 +428,8 @@ DWARFExpression::GetLocation_DW_OP_addr(const DWARFUnit *dwarf_cu) const {
   return LLDB_INVALID_ADDRESS;
 }
 
-bool DWARFExpression::Update_DW_OP_addr(const DWARFUnit *dwarf_cu,
-                                        lldb::addr_t file_addr) {
+bool DWARFExpression::Update_DW_OP_addr(
+    const DWARFExpression::Delegate *dwarf_cu, lldb::addr_t file_addr) {
   lldb::offset_t offset = 0;
   while (m_data.ValidOffset(offset)) {
     const LocationAtom op = static_cast<LocationAtom>(m_data.GetU8(&offset));
@@ -481,7 +487,7 @@ bool DWARFExpression::Update_DW_OP_addr(const DWARFUnit *dwarf_cu,
 }
 
 bool DWARFExpression::ContainsThreadLocalStorage(
-    const DWARFUnit *dwarf_cu) const {
+    const DWARFExpression::Delegate *dwarf_cu) const {
   lldb::offset_t offset = 0;
   while (m_data.ValidOffset(offset)) {
     const LocationAtom op = static_cast<LocationAtom>(m_data.GetU8(&offset));
@@ -497,7 +503,7 @@ bool DWARFExpression::ContainsThreadLocalStorage(
   return false;
 }
 bool DWARFExpression::LinkThreadLocalStorage(
-    const DWARFUnit *dwarf_cu,
+    const DWARFExpression::Delegate *dwarf_cu,
     std::function<lldb::addr_t(lldb::addr_t file_addr)> const
         &link_address_callback) {
   const uint32_t addr_byte_size = m_data.GetAddressByteSize();
@@ -783,9 +789,9 @@ enum LocationDescriptionKind {
   /* Composite*/
 };
 /// Adjust value's ValueType according to the kind of location description.
-void UpdateValueTypeFromLocationDescription(Log *log, const DWARFUnit *dwarf_cu,
-                                            LocationDescriptionKind kind,
-                                            Value *value = nullptr) {
+void UpdateValueTypeFromLocationDescription(
+    Log *log, const DWARFExpression::Delegate *dwarf_cu,
+    LocationDescriptionKind kind, Value *value = nullptr) {
   // Note that this function is conflating DWARF expressions with
   // DWARF location descriptions. Perhaps it would be better to define
   // a wrapper for DWARFExpression::Eval() that deals with DWARF
@@ -875,8 +881,9 @@ static Scalar DerefSizeExtractDataHelper(uint8_t *addr_bytes,
 llvm::Expected<Value> DWARFExpression::Evaluate(
     ExecutionContext *exe_ctx, RegisterContext *reg_ctx,
     lldb::ModuleSP module_sp, const DataExtractor &opcodes,
-    const DWARFUnit *dwarf_cu, const lldb::RegisterKind reg_kind,
-    const Value *initial_value_ptr, const Value *object_address_ptr) {
+    const DWARFExpression::Delegate *dwarf_cu,
+    const lldb::RegisterKind reg_kind, const Value *initial_value_ptr,
+    const Value *object_address_ptr) {
 
   if (opcodes.GetByteSize() == 0)
     return llvm::createStringError(
@@ -2150,10 +2157,10 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
     // DESCRIPTION: Pop the top stack element, convert it to a
     // different type, and push the result.
     case DW_OP_convert: {
-      const uint64_t die_offset = opcodes.GetULEB128(&offset);
+      const uint64_t relative_die_offset = opcodes.GetULEB128(&offset);
       uint64_t bit_size;
       bool sign;
-      if (die_offset == 0) {
+      if (relative_die_offset == 0) {
         // The generic type has the size of an address on the target
         // machine and an unspecified signedness. Scalar has no
         // "unspecified signedness", so we use unsigned types.
@@ -2164,35 +2171,12 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
         if (!bit_size)
           return llvm::createStringError("unspecified architecture");
       } else {
-        // Retrieve the type DIE that the value is being converted to. This
-        // offset is compile unit relative so we need to fix it up.
-        const uint64_t abs_die_offset = die_offset +  dwarf_cu->GetOffset();
-        // FIXME: the constness has annoying ripple effects.
-        DWARFDIE die = const_cast<DWARFUnit *>(dwarf_cu)->GetDIE(abs_die_offset);
-        if (!die)
-          return llvm::createStringError(
-              "cannot resolve DW_OP_convert type DIE");
-        uint64_t encoding =
-            die.GetAttributeValueAsUnsigned(DW_AT_encoding, DW_ATE_hi_user);
-        bit_size = die.GetAttributeValueAsUnsigned(DW_AT_byte_size, 0) * 8;
-        if (!bit_size)
-          bit_size = die.GetAttributeValueAsUnsigned(DW_AT_bit_size, 0);
-        if (!bit_size)
-          return llvm::createStringError(
-              "unsupported type size in DW_OP_convert");
-        switch (encoding) {
-        case DW_ATE_signed:
-        case DW_ATE_signed_char:
-          sign = true;
-          break;
-        case DW_ATE_unsigned:
-        case DW_ATE_unsigned_char:
-          sign = false;
-          break;
-        default:
-          return llvm::createStringError(
-              "unsupported encoding in DW_OP_convert");
-        }
+        auto bit_size_sign_or_err =
+            dwarf_cu->GetDIEBitSizeAndSign(relative_die_offset);
+        if (!bit_size_sign_or_err)
+          return bit_size_sign_or_err.takeError();
+        bit_size = bit_size_sign_or_err->first;
+        sign = bit_size_sign_or_err->second;
       }
       Scalar &top = stack.back().ResolveValue(exe_ctx);
       top.TruncOrExtendTo(bit_size, sign);
@@ -2316,8 +2300,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
 
     default:
       if (dwarf_cu) {
-        if (dwarf_cu->GetSymbolFileDWARF().ParseVendorDWARFOpcode(
-                op, opcodes, offset, stack)) {
+        if (dwarf_cu->ParseVendorDWARFOpcode(op, opcodes, offset, stack)) {
           break;
         }
       }
@@ -2352,43 +2335,6 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
   return stack.back();
 }
 
-bool DWARFExpression::ParseDWARFLocationList(
-    const DWARFUnit *dwarf_cu, const DataExtractor &data,
-    DWARFExpressionList *location_list) {
-  location_list->Clear();
-  std::unique_ptr<llvm::DWARFLocationTable> loctable_up =
-      dwarf_cu->GetLocationTable(data);
-  Log *log = GetLog(LLDBLog::Expressions);
-  auto lookup_addr =
-      [&](uint32_t index) -> std::optional<llvm::object::SectionedAddress> {
-    addr_t address = dwarf_cu->ReadAddressFromDebugAddrSection(index);
-    if (address == LLDB_INVALID_ADDRESS)
-      return std::nullopt;
-    return llvm::object::SectionedAddress{address};
-  };
-  auto process_list = [&](llvm::Expected<llvm::DWARFLocationExpression> loc) {
-    if (!loc) {
-      LLDB_LOG_ERROR(log, loc.takeError(), "{0}");
-      return true;
-    }
-    auto buffer_sp =
-        std::make_shared<DataBufferHeap>(loc->Expr.data(), loc->Expr.size());
-    DWARFExpression expr = DWARFExpression(DataExtractor(
-        buffer_sp, data.GetByteOrder(), data.GetAddressByteSize()));
-    location_list->AddExpression(loc->Range->LowPC, loc->Range->HighPC, expr);
-    return true;
-  };
-  llvm::Error error = loctable_up->visitAbsoluteLocationList(
-      0, llvm::object::SectionedAddress{dwarf_cu->GetBaseAddress()},
-      lookup_addr, process_list);
-  location_list->Sort();
-  if (error) {
-    LLDB_LOG_ERROR(log, std::move(error), "{0}");
-    return false;
-  }
-  return true;
-}
-
 bool DWARFExpression::MatchesOperand(
     StackFrame &frame, const Instruction::Operand &operand) const {
   using namespace OperandMatchers;

lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp

@@ -240,7 +240,7 @@ bool DWARFDebugInfoEntry::GetDIENamesAndRanges(
                 data = DataExtractor(data, offset, data.GetByteSize() - offset);
                 if (lo_pc != LLDB_INVALID_ADDRESS) {
                   assert(lo_pc >= cu->GetBaseAddress());
-                  DWARFExpression::ParseDWARFLocationList(cu, data, frame_base);
+                  cu->ParseDWARFLocationList(data, *frame_base);
                   frame_base->SetFuncFileAddress(lo_pc);
                 } else
                   set_frame_base_loclist_addr = true;

lldb/source/Plugins/SymbolFile/DWARF/DWARFDefines.cpp

@@ -23,15 +23,5 @@ llvm::StringRef DW_TAG_value_to_name(dw_tag_t tag) {
   return s_unknown_tag_name;
 }
 
-const char *DW_OP_value_to_name(uint32_t val) {
-  static char invalid[100];
-  llvm::StringRef llvmstr = llvm::dwarf::OperationEncodingString(val);
-  if (llvmstr.empty()) {
-    snprintf(invalid, sizeof(invalid), "Unknown DW_OP constant: 0x%x", val);
-    return invalid;
-  }
-  return llvmstr.data();
-}
-
 } // namespace dwarf
 } // namespace lldb_private::plugin

lldb/source/Plugins/SymbolFile/DWARF/DWARFDefines.h

@@ -17,8 +17,6 @@ namespace dwarf {
 
 llvm::StringRef DW_TAG_value_to_name(dw_tag_t tag);
 
-const char *DW_OP_value_to_name(uint32_t val);
-
 } // namespace dwarf
 } // namespace lldb_private::plugin