Merge GetCompileUnitAtOffset + GetCompileUnitContainingDIEOffset

These two methods are very similar and various refactorizations need to modify
both similar ways.

One could also just remove GetCompileUnitAtOffset and make
GetCompileUnitContainingDIEOffset to also accept offset of the CU itself
(currently it accepts only DIE offsets after the CU header).
But that would be less safe regarding some internal sanity checking.

Further code refactorization has been suggested by Pavel Labath.

Differential Revision: https://reviews.llvm.org/D61498

llvm-svn: 360038

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

@@ -123,37 +123,30 @@ bool DWARFDebugInfo::OffsetLessThanCompileUnitOffset(
   return offset < cu_sp->GetOffset();
 }
 
+uint32_t DWARFDebugInfo::FindCompileUnitIndex(dw_offset_t offset) {
+  ParseCompileUnitHeadersIfNeeded();
+
+  // llvm::lower_bound is not used as for DIE offsets it would still return
+  // index +1 and GetOffset() returning index itself would be a special case.
+  auto pos = llvm::upper_bound(m_compile_units, offset,
+                               OffsetLessThanCompileUnitOffset);
+  uint32_t idx = std::distance(m_compile_units.begin(), pos);
+  if (idx == 0)
+    return DW_INVALID_OFFSET;
+  return idx - 1;
+}
+
 DWARFUnit *DWARFDebugInfo::GetCompileUnitAtOffset(dw_offset_t cu_offset,
                                                   uint32_t *idx_ptr) {
-  DWARFUnitSP cu_sp;
-  uint32_t cu_idx = DW_INVALID_INDEX;
-  if (cu_offset != DW_INVALID_OFFSET) {
-    ParseCompileUnitHeadersIfNeeded();
-
-    // Watch out for single compile unit executable as they are pretty common
-    const size_t num_cus = m_compile_units.size();
-    if (num_cus == 1) {
-      if (m_compile_units[0]->GetOffset() == cu_offset) {
-        cu_sp = m_compile_units[0];
-        cu_idx = 0;
-      }
-    } else if (num_cus) {
-      CompileUnitColl::const_iterator end_pos = m_compile_units.end();
-      CompileUnitColl::const_iterator begin_pos = m_compile_units.begin();
-      CompileUnitColl::const_iterator pos = std::upper_bound(
-          begin_pos, end_pos, cu_offset, OffsetLessThanCompileUnitOffset);
-      if (pos != begin_pos) {
-        --pos;
-        if ((*pos)->GetOffset() == cu_offset) {
-          cu_sp = *pos;
-          cu_idx = std::distance(begin_pos, pos);
-        }
-      }
-    }
+  uint32_t idx = FindCompileUnitIndex(cu_offset);
+  DWARFUnit *result = GetCompileUnitAtIndex(idx);
+  if (result && result->GetOffset() != cu_offset) {
+    result = nullptr;
+    idx = DW_INVALID_INDEX;
   }
   if (idx_ptr)
-    *idx_ptr = cu_idx;
-  return cu_sp.get();
+    *idx_ptr = idx;
+  return result;
 }
 
 DWARFUnit *DWARFDebugInfo::GetCompileUnit(const DIERef &die_ref) {
@@ -165,28 +158,11 @@ DWARFUnit *DWARFDebugInfo::GetCompileUnit(const DIERef &die_ref) {
 
 DWARFUnit *
 DWARFDebugInfo::GetCompileUnitContainingDIEOffset(dw_offset_t die_offset) {
-  ParseCompileUnitHeadersIfNeeded();
-
-  DWARFUnitSP cu_sp;
-
-  // Watch out for single compile unit executable as they are pretty common
-  const size_t num_cus = m_compile_units.size();
-  if (num_cus == 1) {
-    if (m_compile_units[0]->ContainsDIEOffset(die_offset))
-      return m_compile_units[0].get();
-  } else if (num_cus) {
-    CompileUnitColl::const_iterator end_pos = m_compile_units.end();
-    CompileUnitColl::const_iterator begin_pos = m_compile_units.begin();
-    CompileUnitColl::const_iterator pos = std::upper_bound(
-        begin_pos, end_pos, die_offset, OffsetLessThanCompileUnitOffset);
-    if (pos != begin_pos) {
-      --pos;
-      if ((*pos)->ContainsDIEOffset(die_offset))
-        return (*pos).get();
-    }
-  }
-
-  return nullptr;
+  uint32_t idx = FindCompileUnitIndex(die_offset);
+  DWARFUnit *result = GetCompileUnitAtIndex(idx);
+  if (result && !result->ContainsDIEOffset(die_offset))
+    return nullptr;
+  return result;
 }
 
 DWARFDIE

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

@@ -75,6 +75,8 @@ class DWARFDebugInfo {
   // accessors are called.
   void ParseCompileUnitHeadersIfNeeded();
 
+  uint32_t FindCompileUnitIndex(dw_offset_t offset);
+
   DISALLOW_COPY_AND_ASSIGN(DWARFDebugInfo);
 };