[lldb][nfc] Refactor methods with out parameter

Currently, the method `GetAttributeAddressRanges` takes a DWARFRangeList as a
parameter, just to immediately clear it. The method also returns the size of
this list. Such an API was obfuscating the intent of the call sites (it's not
clear from the method name what it returns) and it was obfuscating redundant
checks on the size of the list.

This commit refactors the method to return the list and to also make the call
sites use the more explicit `IsEmpty` method.

Differential Revision: https://reviews.llvm.org/D151451

5 files changed, 27 insertions, 34 deletions

diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.cpp
index dbe86c6..f839a59 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFCompileUnit.cpp
@@ -40,18 +40,14 @@ void DWARFCompileUnit::BuildAddressRangeTable(
 
   const dw_offset_t cu_offset = GetOffset();
   if (die) {
-    DWARFRangeList ranges;
-    const size_t num_ranges =
-        die->GetAttributeAddressRanges(this, ranges, /*check_hi_lo_pc=*/true);
-    if (num_ranges > 0) {
-      for (size_t i = 0; i < num_ranges; ++i) {
-        const DWARFRangeList::Entry &range = ranges.GetEntryRef(i);
-        debug_aranges->AppendRange(cu_offset, range.GetRangeBase(),
-                                   range.GetRangeEnd());
-      }
+    DWARFRangeList ranges =
+        die->GetAttributeAddressRanges(this, /*check_hi_lo_pc=*/true);
+    for (const DWARFRangeList::Entry &range : ranges)
+      debug_aranges->AppendRange(cu_offset, range.GetRangeBase(),
+                                 range.GetRangeEnd());
 
+    if (!ranges.IsEmpty())
       return;
-    }
   }
 
   if (debug_aranges->GetNumRanges() == num_debug_aranges) {
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDIE.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDIE.cpp
index 65fab50..b31c5dc 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDIE.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDIE.cpp
@@ -168,10 +168,9 @@ DWARFDIE::LookupDeepestBlock(lldb::addr_t address) const {
   }
 
   if (match_addr_range) {
-    DWARFRangeList ranges;
-    if (m_die->GetAttributeAddressRanges(m_cu, ranges,
-                                         /*check_hi_lo_pc=*/true) &&
-        ranges.FindEntryThatContains(address)) {
+    DWARFRangeList ranges =
+        m_die->GetAttributeAddressRanges(m_cu, /*check_hi_lo_pc=*/true);
+    if (ranges.FindEntryThatContains(address)) {
       check_children = true;
       switch (Tag()) {
       default:
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
index a929046..f26fb2f 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
@@ -636,15 +636,16 @@ bool DWARFDebugInfoEntry::GetAttributeAddressRange(
   return false;
 }
 
-size_t DWARFDebugInfoEntry::GetAttributeAddressRanges(
-    DWARFUnit *cu, DWARFRangeList &ranges, bool check_hi_lo_pc,
+DWARFRangeList DWARFDebugInfoEntry::GetAttributeAddressRanges(
+    DWARFUnit *cu, bool check_hi_lo_pc,
     bool check_specification_or_abstract_origin) const {
-  ranges.Clear();
 
   DWARFFormValue form_value;
-  if (GetAttributeValue(cu, DW_AT_ranges, form_value)) {
-    ranges = GetRangesOrReportError(*cu, *this, form_value);
-  } else if (check_hi_lo_pc) {
+  if (GetAttributeValue(cu, DW_AT_ranges, form_value))
+    return GetRangesOrReportError(*cu, *this, form_value);
+
+  DWARFRangeList ranges;
+  if (check_hi_lo_pc) {
     dw_addr_t lo_pc = LLDB_INVALID_ADDRESS;
     dw_addr_t hi_pc = LLDB_INVALID_ADDRESS;
     if (GetAttributeAddressRange(cu, lo_pc, hi_pc, LLDB_INVALID_ADDRESS,
@@ -653,7 +654,7 @@ size_t DWARFDebugInfoEntry::GetAttributeAddressRanges(
         ranges.Append(DWARFRangeList::Entry(lo_pc, hi_pc - lo_pc));
     }
   }
-  return ranges.GetSize();
+  return ranges;
 }
 
 // GetName
@@ -716,9 +717,8 @@ void DWARFDebugInfoEntry::BuildFunctionAddressRangeTable(
     DWARFUnit *cu, DWARFDebugAranges *debug_aranges) const {
   if (m_tag) {
     if (m_tag == DW_TAG_subprogram) {
-      DWARFRangeList ranges;
-      GetAttributeAddressRanges(cu, ranges,
-                                /*check_hi_lo_pc=*/true);
+      DWARFRangeList ranges =
+          GetAttributeAddressRanges(cu, /*check_hi_lo_pc=*/true);
       for (const auto &r : ranges) {
         debug_aranges->AppendRange(GetOffset(), r.GetRangeBase(),
                                    r.GetRangeEnd());
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.h b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.h
index a674db8..c2ea400 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.h
@@ -94,8 +94,8 @@ public:
       uint64_t fail_value,
       bool check_specification_or_abstract_origin = false) const;
 
-  size_t GetAttributeAddressRanges(
-      DWARFUnit *cu, DWARFRangeList &ranges, bool check_hi_lo_pc,
+  DWARFRangeList GetAttributeAddressRanges(
+      DWARFUnit *cu, bool check_hi_lo_pc,
       bool check_specification_or_abstract_origin = false) const;
 
   const char *GetName(const DWARFUnit *cu) const;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index a71849b..f5edcd7 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -840,9 +840,9 @@ Function *SymbolFileDWARF::ParseFunction(CompileUnit &comp_unit,
   if (!dwarf_ast)
     return nullptr;
 
-  DWARFRangeList ranges;
-  if (die.GetDIE()->GetAttributeAddressRanges(die.GetCU(), ranges,
-                                              /*check_hi_lo_pc=*/true) == 0)
+  DWARFRangeList ranges = die.GetDIE()->GetAttributeAddressRanges(
+      die.GetCU(), /*check_hi_lo_pc=*/true);
+  if (ranges.IsEmpty())
     return nullptr;
 
   // Union of all ranges in the function DIE (if the function is
@@ -3208,10 +3208,9 @@ size_t SymbolFileDWARF::ParseVariablesForContext(const SymbolContext &sc) {
       DWARFDIE function_die = GetDIE(sc.function->GetID());
 
       dw_addr_t func_lo_pc = LLDB_INVALID_ADDRESS;
-      DWARFRangeList ranges;
-      if (function_die.GetDIE()->GetAttributeAddressRanges(
-              function_die.GetCU(), ranges,
-              /*check_hi_lo_pc=*/true))
+      DWARFRangeList ranges = function_die.GetDIE()->GetAttributeAddressRanges(
+          function_die.GetCU(), /*check_hi_lo_pc=*/true);
+      if (!ranges.IsEmpty())
         func_lo_pc = ranges.GetMinRangeBase(0);
       if (func_lo_pc != LLDB_INVALID_ADDRESS) {
         const size_t num_variables =
@@ -4282,4 +4281,3 @@ void SymbolFileDWARF::GetCompileOptions(
     args.insert({comp_unit, Args(flags)});
   }
 }
-