[lldb] Add support for sorting by size to target module dump symtab

This patch adds support to sort the symbol table by size. The command
already supports sorting and it already reports sizes. Sorting by size
helps diagnosing size issues.

rdar://123788375

Author: JDevlieghere

lldb/include/lldb/Interpreter/CommandOptionArgumentTable.h

@@ -50,6 +50,11 @@ static constexpr OptionEnumValueElement g_sort_option_enumeration[] = {
         "name",
         "Sort output by symbol name.",
     },
+    {
+        eSortOrderBySize,
+        "size",
+        "Sort output by symbol byte size.",
+    },
 };
 
 // Note that the negation in the argument name causes a slightly confusing

lldb/include/lldb/lldb-private-enumerations.h

@@ -108,7 +108,12 @@ enum ArgumentRepetitionType {
                               // optional
 };
 
-enum SortOrder { eSortOrderNone, eSortOrderByAddress, eSortOrderByName };
+enum SortOrder {
+  eSortOrderNone,
+  eSortOrderByAddress,
+  eSortOrderByName,
+  eSortOrderBySize
+};
 
 // LazyBool is for boolean values that need to be calculated lazily. Values
 // start off set to eLazyBoolCalculate, and then they can be calculated once

lldb/source/Symbol/Symtab.cpp

@@ -124,12 +124,8 @@ void Symtab::Dump(Stream *s, Target *target, SortOrder sort_order,
       DumpSymbolHeader(s);
 
       std::multimap<llvm::StringRef, const Symbol *> name_map;
-      for (const_iterator pos = m_symbols.begin(), end = m_symbols.end();
-           pos != end; ++pos) {
-        const char *name = pos->GetName().AsCString();
-        if (name && name[0])
-          name_map.insert(std::make_pair(name, &(*pos)));
-      }
+      for (const Symbol &symbol : m_symbols)
+        name_map.emplace(llvm::StringRef(symbol.GetName()), &symbol);
 
       for (const auto &name_to_symbol : name_map) {
         const Symbol *symbol = name_to_symbol.second;
@@ -138,6 +134,21 @@ void Symtab::Dump(Stream *s, Target *target, SortOrder sort_order,
       }
     } break;
 
+    case eSortOrderBySize: {
+      s->PutCString(" (sorted by size):\n");
+      DumpSymbolHeader(s);
+
+      std::multimap<size_t, const Symbol *, std::greater<size_t>> size_map;
+      for (const Symbol &symbol : m_symbols)
+        size_map.emplace(symbol.GetByteSize(), &symbol);
+
+      for (const auto &size_to_symbol : size_map) {
+        const Symbol *symbol = size_to_symbol.second;
+        s->Indent();
+        symbol->Dump(s, target, symbol - &m_symbols[0], name_preference);
+      }
+    } break;
+
     case eSortOrderByAddress:
       s->PutCString(" (sorted by address):\n");
       DumpSymbolHeader(s);

lldb/test/Shell/SymbolFile/Breakpad/symtab-sorted-by-size.test

@@ -0,0 +1,11 @@
+# RUN: yaml2obj %S/Inputs/basic-elf.yaml -o %T/symtab.out
+# RUN: %lldb %T/symtab.out -o "target symbols add -s symtab.out %S/Inputs/symtab.syms" \
+# RUN:   -s %s | FileCheck %s
+
+# CHECK: num_symbols = 4 (sorted by size):
+# CHECK: [    0]      0  SX Code            0x0000000000400000                    0x00000000000000b0 0x00000000 ___lldb_unnamed_symbol0
+# CHECK: [    3]      0   X Code            0x00000000004000d0                    0x0000000000000022 0x00000000 _start
+# CHECK: [    1]      0   X Code            0x00000000004000b0                    0x0000000000000010 0x00000000 f1
+# CHECK: [    2]      0   X Code            0x00000000004000c0                    0x0000000000000010 0x00000000 f2
+
+image dump symtab -s size symtab.out