[lldb] Add support for sorting by size to target module dump symtab (llvm#83527)

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