Unconditionally accept symbol sizes from elf

The ELF symbol table always contain the size of the symbols so we
don't have to try to guess them based on the address of the next
symbol (it is needed for mach-o).

The change fixes an issue when a symbol is removed after a 0 size
symbol (e.g. because the second one is not public) what previously
caused the symbol lookup algorithm to end up with showing the 0 size
symbol even for the later addresses (what are not part of any symbol).
That symbol lookup error can confuse the user and also confuses the
current stack unwinder.

Re-commit this CL after fixing the issue with gcc-4.9.2 on i386 Linux.

Differential revision: http://reviews.llvm.org/D16186

llvm-svn: 258113

lldb/include/lldb/Symbol/Symbol.h

@@ -383,6 +383,9 @@ public:
                     bool prefer_file_cache,
                     Stream &strm);
 
+    bool
+    ContainsFileAddress (lldb::addr_t file_addr) const;
+
 protected:
     // This is the internal guts of ResolveReExportedSymbol, it assumes reexport_name is not null, and that module_spec
     // is valid.  We track the modules we've already seen to make sure we don't get caught in a cycle.

lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

@@ -2283,6 +2283,12 @@ ObjectFileELF::ParseSymbols (Symtab *symtab,
                 mangled.SetDemangledName( ConstString((demangled_name + suffix).str()) );
         }
 
+        // In ELF all symbol should have a valid size but it is not true for some code symbols
+        // coming from hand written assembly. As none of the code symbol should have 0 size we try
+        // to calculate the size for these symbols in the symtab with saying that their original
+        // size is not valid.
+        bool symbol_size_valid = symbol.st_size != 0 || symbol_type != eSymbolTypeCode;
+
         Symbol dc_symbol(
             i + start_id,       // ID is the original symbol table index.
             mangled,
@@ -2295,7 +2301,7 @@ ObjectFileELF::ParseSymbols (Symtab *symtab,
                 symbol_section_sp,  // Section in which this symbol is defined or null.
                 symbol_value,       // Offset in section or symbol value.
                 symbol.st_size),    // Size in bytes of this symbol.
-            symbol.st_size != 0,    // Size is valid if it is not 0
+            symbol_size_valid,      // Symbol size is valid
             has_suffix,             // Contains linker annotations?
             flags);                 // Symbol flags.
         symtab->AddSymbol(dc_symbol);
@@ -2304,7 +2310,9 @@ ObjectFileELF::ParseSymbols (Symtab *symtab,
 }
 
 unsigned
-ObjectFileELF::ParseSymbolTable(Symtab *symbol_table, user_id_t start_id, lldb_private::Section *symtab)
+ObjectFileELF::ParseSymbolTable(Symtab *symbol_table,
+                                user_id_t start_id,
+                                lldb_private::Section *symtab)
 {
     if (symtab->GetObjectFile() != this)
     {

lldb/source/Symbol/Symbol.cpp

@@ -737,3 +737,10 @@ Symbol::GetDisassembly (const ExecutionContext &exe_ctx,
     }
     return false;
 }
+
+bool
+Symbol::ContainsFileAddress (lldb::addr_t file_addr) const
+{
+    return m_addr_range.ContainsFileAddress(file_addr);
+}
+

lldb/source/Symbol/Symtab.cpp

@@ -971,12 +971,14 @@ Symtab::InitAddressIndexes()
                     if (end_section_file_addr > symbol_file_addr)
                     {
                         Symbol &symbol = m_symbols[entry.data];
-
+                        if (!symbol.GetByteSizeIsValid())
+                        {
                             symbol.SetByteSize(end_section_file_addr - symbol_file_addr);
                             symbol.SetSizeIsSynthesized(true);
                         }
                     }
                 }
+            }
             // Sort again in case the range size changes the ordering
             m_file_addr_to_index.Sort();
         }
@@ -1039,18 +1041,15 @@ Symtab::FindSymbolContainingFileAddress (addr_t file_addr, const uint32_t* index
             return info.match_symbol;
         }
 
-        const size_t symbol_byte_size = info.match_symbol->GetByteSize();
-        
-        if (symbol_byte_size == 0)
+        if (!info.match_symbol->GetByteSizeIsValid())
         {
-            // We weren't able to find the size of the symbol so lets just go 
-            // with that match we found in our search...
+            // The matched symbol dosn't have a valid byte size so lets just go with that match...
             return info.match_symbol;
         }
 
         // We were able to figure out a symbol size so lets make sure our 
         // offset puts "file_addr" in the symbol's address range.
-        if (info.match_offset < symbol_byte_size)
+        if (info.match_offset < info.match_symbol->GetByteSize())
             return info.match_symbol;
     }
     return nullptr;
@@ -1066,7 +1065,11 @@ Symtab::FindSymbolContainingFileAddress (addr_t file_addr)
 
     const FileRangeToIndexMap::Entry *entry = m_file_addr_to_index.FindEntryThatContains(file_addr);
     if (entry)
-        return SymbolAtIndex(entry->data);
+    {
+        Symbol* symbol = SymbolAtIndex(entry->data);
+        if (symbol->ContainsFileAddress(file_addr))
+            return symbol;
+    }
     return nullptr;
 }