[lldb/DWARF] Fix mixed v4+v5 location lists

Summary:
Our code was expecting that a single (symbol) file contains only one
kind of location lists. This is not correct (on non-apple platforms, at
least) as a file can compile units with different dwarf versions.

This patch moves the deteremination of location list flavour down to the
compile unit level, fixing this problem. I have also tried to rougly
align the code with the llvm DWARFUnit. Fully matching the API is not
possible because of how lldb's DWARFExpression lives separately from the
rest of the DWARF code, but this is at least a step in the right
direction.

Reviewers: JDevlieghere, aprantl, clayborg

Subscribers: dblaikie, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D71751

8 files changed, 30 insertions, 66 deletions

diff --git a/lldb/source/Expression/DWARFExpression.cpp b/lldb/source/Expression/DWARFExpression.cpp
index c67e35b1451..69c84640ef9 100644
--- a/lldb/source/Expression/DWARFExpression.cpp
+++ b/lldb/source/Expression/DWARFExpression.cpp
@@ -54,29 +54,6 @@ ReadAddressFromDebugAddrSection(const DWARFUnit *dwarf_cu,
   return LLDB_INVALID_ADDRESS;
 }
 
-/// Return the location list parser for the given format.
-static std::unique_ptr<llvm::DWARFLocationTable>
-GetLocationTable(DWARFExpression::LocationListFormat format, const DataExtractor &data) {
-  llvm::DWARFDataExtractor llvm_data(
-      toStringRef(data.GetData()),
-      data.GetByteOrder() == lldb::eByteOrderLittle, data.GetAddressByteSize());
-
-  switch (format) {
-  case DWARFExpression::NonLocationList:
-    return nullptr;
-  // DWARF<=4 .debug_loc
-  case DWARFExpression::RegularLocationList:
-    return std::make_unique<llvm::DWARFDebugLoc>(llvm_data);
-  // Non-standard DWARF 4 extension (fission) .debug_loc.dwo
-  case DWARFExpression::SplitDwarfLocationList:
-  // DWARF 5 .debug_loclists(.dwo)
-  case DWARFExpression::LocLists:
-    return std::make_unique<llvm::DWARFDebugLoclists>(
-        llvm_data, format == DWARFExpression::LocLists ? 5 : 4);
-  }
-  llvm_unreachable("Invalid LocationListFormat!");
-}
-
 // DWARFExpression constructor
 DWARFExpression::DWARFExpression()
     : m_module_wp(), m_data(), m_dwarf_cu(nullptr),
@@ -157,10 +134,8 @@ void DWARFExpression::GetDescription(Stream *s, lldb::DescriptionLevel level,
   if (IsLocationList()) {
     // We have a location list
     lldb::offset_t offset = 0;
-    std::unique_ptr<llvm::DWARFLocationTable> loctable_up = GetLocationTable(
-        m_dwarf_cu->GetSymbolFileDWARF().GetLocationListFormat(), m_data);
-    if (!loctable_up)
-      return;
+    std::unique_ptr<llvm::DWARFLocationTable> loctable_up =
+        m_dwarf_cu->GetLocationTable(m_data);
 
     llvm::MCRegisterInfo *MRI = abi ? &abi->GetMCRegisterInfo() : nullptr;
 
@@ -2812,10 +2787,8 @@ DWARFExpression::GetLocationExpression(addr_t load_function_start,
                                        addr_t addr) const {
   Log *log = GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS);
 
-  std::unique_ptr<llvm::DWARFLocationTable> loctable_up = GetLocationTable(
-      m_dwarf_cu->GetSymbolFileDWARF().GetLocationListFormat(), m_data);
-  if (!loctable_up)
-    return llvm::None;
+  std::unique_ptr<llvm::DWARFLocationTable> loctable_up =
+      m_dwarf_cu->GetLocationTable(m_data);
   llvm::Optional<DataExtractor> result;
   uint64_t offset = 0;
   auto lookup_addr =
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
index 5612c59059b..5b95912909e 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
@@ -344,7 +344,7 @@ bool DWARFDebugInfoEntry::GetDIENamesAndRanges(
               *frame_base = DWARFExpression(
                   module, DataExtractor(data, block_offset, block_length), cu);
             } else {
-              DataExtractor data = dwarf.DebugLocData();
+              DataExtractor data = cu->GetLocationData();
               const dw_offset_t offset = form_value.Unsigned();
               if (data.ValidOffset(offset)) {
                 data = DataExtractor(data, offset, data.GetByteSize() - offset);
@@ -478,8 +478,6 @@ void DWARFDebugInfoEntry::DumpAttribute(
 
   s.PutCString("( ");
 
-  SymbolFileDWARF &dwarf = cu->GetSymbolFileDWARF();
-
   // Check to see if we have any special attribute formatters
   switch (attr) {
   case DW_AT_stmt_list:
@@ -509,7 +507,7 @@ void DWARFDebugInfoEntry::DumpAttribute(
       // We have a location list offset as the value that is the offset into
       // the .debug_loc section that describes the value over it's lifetime
       uint64_t debug_loc_offset = form_value.Unsigned();
-      DWARFExpression::PrintDWARFLocationList(s, cu, dwarf.DebugLocData(),
+      DWARFExpression::PrintDWARFLocationList(s, cu, cu->GetLocationData(),
                                               debug_loc_offset);
     }
   } break;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
index 32f0f89c042..dcb38da3c43 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
@@ -462,6 +462,22 @@ void DWARFUnit::SetLoclistsBase(dw_addr_t loclists_base) {
   }
 }
 
+std::unique_ptr<llvm::DWARFLocationTable>
+DWARFUnit::GetLocationTable(const DataExtractor &data) const {
+  llvm::DWARFDataExtractor llvm_data(
+      toStringRef(data.GetData()),
+      data.GetByteOrder() == lldb::eByteOrderLittle, data.GetAddressByteSize());
+
+  if (m_is_dwo || GetVersion() >= 5)
+    return std::make_unique<llvm::DWARFDebugLoclists>(llvm_data, GetVersion());
+  return std::make_unique<llvm::DWARFDebugLoc>(llvm_data);
+}
+
+const DWARFDataExtractor &DWARFUnit::GetLocationData() const {
+  return GetVersion() >= 5 ? GetSymbolFileDWARF().get_debug_loclists_data()
+                           : GetSymbolFileDWARF().get_debug_loc_data();
+}
+
 void DWARFUnit::SetRangesBase(dw_addr_t ranges_base) {
   m_ranges_base = ranges_base;
 
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
index 5e94dc106ce..6bee4ab8be8 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
@@ -243,6 +243,13 @@ public:
     return *Offset + m_loclists_base;
   }
 
+  /// Return the location table for parsing the given location list data. The
+  /// format is chosen according to the unit type. Never returns null.
+  std::unique_ptr<llvm::DWARFLocationTable>
+  GetLocationTable(const lldb_private::DataExtractor &data) const;
+
+  const lldb_private::DWARFDataExtractor &GetLocationData() const;
+
 protected:
   DWARFUnit(SymbolFileDWARF &dwarf, lldb::user_id_t uid,
             const DWARFUnitHeader &header,
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index 53339ea31e7..0792260e36f 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -597,13 +597,6 @@ void SymbolFileDWARF::LoadSectionData(lldb::SectionType sect_type,
   m_objfile_sp->ReadSectionData(section_sp.get(), data);
 }
 
-const DWARFDataExtractor &SymbolFileDWARF::DebugLocData() {
-  const DWARFDataExtractor &debugLocData = get_debug_loc_data();
-  if (debugLocData.GetByteSize() > 0)
-    return debugLocData;
-  return get_debug_loclists_data();
-}
-
 const DWARFDataExtractor &SymbolFileDWARF::get_debug_loc_data() {
   return GetCachedSectionData(eSectionTypeDWARFDebugLoc, m_data_debug_loc);
 }
@@ -3361,7 +3354,7 @@ VariableSP SymbolFileDWARF::ParseVariableDIE(const SymbolContext &sc,
                   module, DataExtractor(data, block_offset, block_length),
                   die.GetCU());
             } else {
-              DataExtractor data = DebugLocData();
+              DataExtractor data = die.GetCU()->GetLocationData();
               dw_offset_t offset = form_value.Unsigned();
               if (form_value.Form() == DW_FORM_loclistx)
                 offset = die.GetCU()->GetLoclistOffset(offset).getValueOr(-1);
@@ -3978,13 +3971,6 @@ SymbolFileDWARFDebugMap *SymbolFileDWARF::GetDebugMapSymfile() {
   return m_debug_map_symfile;
 }
 
-DWARFExpression::LocationListFormat
-SymbolFileDWARF::GetLocationListFormat() const {
-  if (m_data_debug_loclists.m_data.GetByteSize() > 0)
-    return DWARFExpression::LocLists;
-  return DWARFExpression::RegularLocationList;
-}
-
 SymbolFileDWARFDwp *SymbolFileDWARF::GetDwpSymbolFile() {
   llvm::call_once(m_dwp_symfile_once_flag, [this]() {
     ModuleSpec module_spec;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
index bf9a6e5b237..f816dd77800 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
@@ -21,7 +21,6 @@
 
 #include "lldb/Core/UniqueCStringMap.h"
 #include "lldb/Core/dwarf.h"
-#include "lldb/Expression/DWARFExpression.h"
 #include "lldb/Symbol/DebugMacros.h"
 #include "lldb/Symbol/SymbolContext.h"
 #include "lldb/Symbol/SymbolFile.h"
@@ -236,8 +235,6 @@ public:
 
   DWARFDebugRanges *GetDebugRanges();
 
-  const lldb_private::DWARFDataExtractor &DebugLocData();
-
   static bool SupportedVersion(uint16_t version);
 
   DWARFDIE
@@ -260,9 +257,6 @@ public:
 
   virtual lldb::CompUnitSP ParseCompileUnit(DWARFCompileUnit &dwarf_cu);
 
-  virtual lldb_private::DWARFExpression::LocationListFormat
-  GetLocationListFormat() const;
-
   lldb::ModuleSP GetExternalModule(lldb_private::ConstString name);
 
   typedef std::map<lldb_private::ConstString, lldb::ModuleSP>
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp
index 331417fe5cd..f75f06f31e2 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp
@@ -137,13 +137,6 @@ SymbolFileDWARF &SymbolFileDWARFDwo::GetBaseSymbolFile() {
   return m_base_dwarf_cu.GetSymbolFileDWARF();
 }
 
-DWARFExpression::LocationListFormat
-SymbolFileDWARFDwo::GetLocationListFormat() const {
-  return m_base_dwarf_cu.GetVersion() >= 5
-             ? DWARFExpression::LocLists
-             : DWARFExpression::SplitDwarfLocationList;
-}
-
 llvm::Expected<TypeSystem &>
 SymbolFileDWARFDwo::GetTypeSystemForLanguage(LanguageType language) {
   return GetBaseSymbolFile().GetTypeSystemForLanguage(language);
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
index 641fd1f2ce3..0855dba044e 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
@@ -35,9 +35,6 @@ public:
   DWARFUnit *
   GetDWARFCompileUnit(lldb_private::CompileUnit *comp_unit) override;
 
-  lldb_private::DWARFExpression::LocationListFormat
-  GetLocationListFormat() const override;
-
   size_t GetObjCMethodDIEOffsets(lldb_private::ConstString class_name,
                                  DIEArray &method_die_offsets) override;