DWARF: Add support for type units+split dwarf combo

Summary:
With the last round of refactors, supporting type units in dwo files
becomes almost trivial. This patch contains a couple of small fixes,
which taken as a whole make type units work in the split dwarf scenario
(both DWARF4 and DWARF5):
- DWARFContext: make sure we actually read the debug_types.dwo section
- DWARFUnit: set string offsets base on all units in the dwo file, not
  just the main CU
- ManualDWARFIndex: index all units in the file
- SymbolFileDWARFDwo: Search for the single compile unit in the file, as
  we can no longer assume it will be the first one

The last part makes it obvious that there is still some work to be done
here, namely that we do not support dwo files with multiple compile
units. That is something that should be easier after the DIERef
refactors, but it still requires more work.

Tests are added for the type units+split dwarf + dwarf4/5 scenarios, as
well as a test that checks we behave reasonably in the presence of dwo
files with multiple CUs.

Reviewers: clayborg, JDevlieghere, aprantl

Subscribers: arphaman, lldb-commits

Differential Revision: https://reviews.llvm.org/D63643

llvm-svn: 364274

9 files changed, 117 insertions, 24 deletions

diff --git a/lldb/lit/SymbolFile/DWARF/debug-types-basic.test b/lldb/lit/SymbolFile/DWARF/debug-types-basic.test
index bf2c9c69d1d..24a6a651d5f 100644
--- a/lldb/lit/SymbolFile/DWARF/debug-types-basic.test
+++ b/lldb/lit/SymbolFile/DWARF/debug-types-basic.test
@@ -2,15 +2,27 @@
 
 # Make sure DWARF v4 type units work.
 # RUN: %clangxx -target x86_64-pc-linux %S/Inputs/debug-types-basic.cpp \
-# RUN:   -g -gdwarf-4 -fdebug-types-section -c -o %t.o
-# RUN: ld.lld %t.o -o %t
-# RUN: %lldb %t -s %s -o exit | FileCheck %s
+# RUN:   -g -gdwarf-4 -fdebug-types-section -c -o %t4.o
+# RUN: ld.lld %t4.o -o %t4
+# RUN: %lldb %t4 -s %s -o exit | FileCheck %s
 
 # Now do the same for DWARF v5.
 # RUN: %clangxx -target x86_64-pc-linux %S/Inputs/debug-types-basic.cpp \
-# RUN:   -g -gdwarf-5 -fdebug-types-section -c -o %t.o
-# RUN: ld.lld %t.o -o %t
-# RUN: %lldb %t -s %s -o exit | FileCheck %s
+# RUN:   -g -gdwarf-5 -fdebug-types-section -c -o %t5.o
+# RUN: ld.lld %t5.o -o %t5
+# RUN: %lldb %t5 -s %s -o exit | FileCheck %s
+
+# Test type units in dwo files.
+# RUN: %clangxx -target x86_64-pc-linux %S/Inputs/debug-types-basic.cpp \
+# RUN:   -g -gdwarf-4 -fdebug-types-section -gsplit-dwarf -c -o %t4dwo.o
+# RUN: ld.lld %t4dwo.o -o %t4dwo
+# RUN: %lldb %t4dwo -s %s -o exit | FileCheck %s
+
+# And type units+dwo+dwarf5.
+# RUN: %clangxx -target x86_64-pc-linux %S/Inputs/debug-types-basic.cpp \
+# RUN:   -g -gdwarf-5 -fdebug-types-section -c -o %t5dwo.o
+# RUN: ld.lld %t5dwo.o -o %t5dwo
+# RUN: %lldb %t5dwo -s %s -o exit | FileCheck %s
 
 type lookup A
 # CHECK-LABEL: type lookup A
diff --git a/lldb/lit/SymbolFile/DWARF/debug-types-expressions.test b/lldb/lit/SymbolFile/DWARF/debug-types-expressions.test
index da40269461a..6da06d7b74f 100644
--- a/lldb/lit/SymbolFile/DWARF/debug-types-expressions.test
+++ b/lldb/lit/SymbolFile/DWARF/debug-types-expressions.test
@@ -2,13 +2,23 @@
 
 # Make sure DWARF v4 type units work.
 # RUN: %clangxx %S/Inputs/debug-types-expressions.cpp \
-# RUN:   -g -fdebug-types-section -o %t
-# RUN: %lldb %t -s %s -o exit | FileCheck %s
+# RUN:   -g -gdwarf-4 -fdebug-types-section -o %t4
+# RUN: %lldb %t4 -s %s -o exit | FileCheck %s
 
 # Now do the same for DWARF v5.
 # RUN: %clangxx %S/Inputs/debug-types-expressions.cpp \
-# RUN:   -g -gdwarf-5 -fdebug-types-section -o %t
-# RUN: %lldb %t -s %s -o exit | FileCheck %s
+# RUN:   -g -gdwarf-5 -fdebug-types-section -o %t5
+# RUN: %lldb %t5 -s %s -o exit | FileCheck %s
+
+# Test type units in dwo files.
+# RUN: %clangxx %S/Inputs/debug-types-expressions.cpp \
+# RUN:   -g -gdwarf-4 -fdebug-types-section -o %t4dwo
+# RUN: %lldb %t4dwo -s %s -o exit | FileCheck %s
+
+# And type units+dwo+dwarf5.
+# RUN: %clangxx %S/Inputs/debug-types-expressions.cpp \
+# RUN:   -g -gdwarf-5 -fdebug-types-section -o %t5dwo
+# RUN: %lldb %t5dwo -s %s -o exit | FileCheck %s
 
 breakpoint set -n foo
 process launch
diff --git a/lldb/lit/SymbolFile/DWARF/split-dwarf-multiple-cu.ll b/lldb/lit/SymbolFile/DWARF/split-dwarf-multiple-cu.ll
new file mode 100644
index 00000000000..9c2348750cf
--- /dev/null
+++ b/lldb/lit/SymbolFile/DWARF/split-dwarf-multiple-cu.ll
@@ -0,0 +1,40 @@
+; Check handling of dwo files with multiple compile units. Right now this is not
+; supported, but it should not cause us to crash or misbehave either...
+
+; RUN: llc %s -filetype=obj -o %t.o --split-dwarf-file=%t.o
+; RUN: %lldb %t.o -o "image lookup -s x1 -v" -o "image lookup -s x2 -v" -b | FileCheck %s
+
+; CHECK: image lookup -s x1
+; CHECK: 1 symbols match 'x1'
+; CHECK-NOT: CompileUnit:
+; CHECK-NOT: Variable:
+
+; CHECK: image lookup -s x2
+; CHECK: 1 symbols match 'x2'
+; CHECK-NOT: CompileUnit:
+; CHECK-NOT: Variable:
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@x1 = dso_local global i32 42, align 4, !dbg !10
+@x2 = dso_local global i32 47, align 4, !dbg !20
+
+!llvm.dbg.cu = !{!12, !22}
+!llvm.module.flags = !{!8, !9, !1}
+
+!10 = !DIGlobalVariableExpression(var: !11, expr: !DIExpression())
+!11 = distinct !DIGlobalVariable(name: "x1", scope: !12, type: !7)
+!12 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, emissionKind: FullDebug, globals: !15)
+!15 = !{!10}
+
+!20 = !DIGlobalVariableExpression(var: !21, expr: !DIExpression())
+!21 = distinct !DIGlobalVariable(name: "x2", scope: !22, type: !7)
+!22 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, emissionKind: FullDebug, globals: !25)
+!25 = !{!20}
+
+!3 = !DIFile(filename: "-", directory: "/tmp")
+!7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!8 = !{i32 2, !"Dwarf Version", i32 4}
+!9 = !{i32 2, !"Debug Info Version", i32 3}
+!1 = !{i32 1, !"wchar_size", i32 4}
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFContext.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFContext.cpp
index 96d193cbf82..9fd4ec616e2 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFContext.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFContext.cpp
@@ -97,6 +97,6 @@ const DWARFDataExtractor &DWARFContext::getOrLoadStrOffsetsData() {
 }
 
 const DWARFDataExtractor &DWARFContext::getOrLoadDebugTypesData() {
-  return LoadOrGetSection(eSectionTypeDWARFDebugTypes, llvm::None,
-                          m_data_debug_types);
+  return LoadOrGetSection(eSectionTypeDWARFDebugTypes,
+                          eSectionTypeDWARFDebugTypesDwo, m_data_debug_types);
 }
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
index 06e9bed3190..917fbf916c5 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
@@ -19,13 +19,14 @@
 #include "lldb/Symbol/ObjectFile.h"
 #include "lldb/Utility/Stream.h"
 
-#include "DWARFUnit.h"
+#include "DWARFCompileUnit.h"
 #include "DWARFDebugAbbrev.h"
 #include "DWARFDebugAranges.h"
 #include "DWARFDebugInfo.h"
 #include "DWARFDebugRanges.h"
 #include "DWARFDeclContext.h"
 #include "DWARFFormValue.h"
+#include "DWARFUnit.h"
 #include "SymbolFileDWARF.h"
 #include "SymbolFileDWARFDwo.h"
 
@@ -657,7 +658,7 @@ dw_offset_t DWARFDebugInfoEntry::GetAttributeValue(
   if (!dwo_symbol_file)
     return 0;
 
-  DWARFUnit *dwo_cu = dwo_symbol_file->GetCompileUnit();
+  DWARFCompileUnit *dwo_cu = dwo_symbol_file->GetCompileUnit();
   if (!dwo_cu)
     return 0;
 
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
index 7eea51fbfd3..33e83d1fe57 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
@@ -363,7 +363,10 @@ void DWARFUnit::AddUnitDIE(const DWARFDebugInfoEntry &cu_die) {
   else if (gnu_ranges_base)
     dwo_cu->SetRangesBase(*gnu_ranges_base);
 
-  SetDwoStrOffsetsBase(dwo_cu);
+  for (size_t i = 0; i < m_dwo_symbol_file->DebugInfo()->GetNumUnits(); ++i) {
+    DWARFUnit *unit = m_dwo_symbol_file->DebugInfo()->GetUnitAtIndex(i);
+    SetDwoStrOffsetsBase(unit);
+  }
 }
 
 DWARFDIE DWARFUnit::LookupAddress(const dw_addr_t address) {
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp b/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
index 00f2dbfa037..aff8b5d8c15 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
@@ -104,9 +104,10 @@ void ManualDWARFIndex::IndexUnit(DWARFUnit &unit, IndexSet &set) {
 
   IndexUnitImpl(unit, cu_language, set);
 
-  SymbolFileDWARFDwo *dwo_symbol_file = unit.GetDwoSymbolFile();
-  if (dwo_symbol_file && dwo_symbol_file->GetCompileUnit()) {
-    IndexUnitImpl(*dwo_symbol_file->GetCompileUnit(), cu_language, set);
+  if (SymbolFileDWARFDwo *dwo_symbol_file = unit.GetDwoSymbolFile()) {
+    DWARFDebugInfo &dwo_info = *dwo_symbol_file->DebugInfo();
+    for (size_t i = 0; i < dwo_info.GetNumUnits(); ++i)
+      IndexUnitImpl(*dwo_info.GetUnitAtIndex(i), cu_language, set);
   }
 }
 
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp
index c6911449c73..c5b54b65ea2 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp
@@ -12,6 +12,7 @@
 #include "lldb/Expression/DWARFExpression.h"
 #include "lldb/Symbol/ObjectFile.h"
 #include "lldb/Utility/LLDBAssert.h"
+#include "llvm/Support/Casting.h"
 
 #include "DWARFCompileUnit.h"
 #include "DWARFDebugInfo.h"
@@ -54,12 +55,34 @@ SymbolFileDWARFDwo::ParseCompileUnit(DWARFCompileUnit &dwarf_cu) {
   return GetBaseSymbolFile().ParseCompileUnit(m_base_dwarf_cu);
 }
 
-DWARFUnit *SymbolFileDWARFDwo::GetCompileUnit() {
-  // Only dwo files with 1 compile unit is supported
-  if (GetNumCompileUnits() == 1)
-    return DebugInfo()->GetUnitAtIndex(0);
-  else
+DWARFCompileUnit *SymbolFileDWARFDwo::GetCompileUnit() {
+  if (!m_cu)
+    m_cu = ComputeCompileUnit();
+  return m_cu;
+}
+
+DWARFCompileUnit *SymbolFileDWARFDwo::ComputeCompileUnit() {
+  DWARFDebugInfo *debug_info = DebugInfo();
+  if (!debug_info)
     return nullptr;
+
+  // Right now we only support dwo files with one compile unit. If we don't have
+  // type units, we can just check for the unit count.
+  if (!debug_info->ContainsTypeUnits() && debug_info->GetNumUnits() == 1)
+    return llvm::cast<DWARFCompileUnit>(debug_info->GetUnitAtIndex(0));
+
+  // Otherwise, we have to run through all units, and find the compile unit that
+  // way.
+  DWARFCompileUnit *cu = nullptr;
+  for (size_t i = 0; i < debug_info->GetNumUnits(); ++i) {
+    if (auto *candidate =
+            llvm::dyn_cast<DWARFCompileUnit>(debug_info->GetUnitAtIndex(i))) {
+      if (cu)
+        return nullptr; // More that one CU found.
+      cu = candidate;
+    }
+  }
+  return cu;
 }
 
 DWARFUnit *
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
index 663f2d40054..9b2f3bb84c4 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
@@ -19,7 +19,7 @@ public:
 
   lldb::CompUnitSP ParseCompileUnit(DWARFCompileUnit &dwarf_cu) override;
 
-  DWARFUnit *GetCompileUnit();
+  DWARFCompileUnit *GetCompileUnit();
 
   DWARFUnit *
   GetDWARFCompileUnit(lldb_private::CompileUnit *comp_unit) override;
@@ -69,8 +69,11 @@ protected:
 
   SymbolFileDWARF &GetBaseSymbolFile();
 
+  DWARFCompileUnit *ComputeCompileUnit();
+
   lldb::ObjectFileSP m_obj_file_sp;
   DWARFCompileUnit &m_base_dwarf_cu;
+  DWARFCompileUnit *m_cu = nullptr;
 };
 
 #endif // SymbolFileDWARFDwo_SymbolFileDWARFDwo_h_