libLTO has a bug in that it will keep every symbol if none is needed. We used

to hack around this in the gold plugin by deleting a module if no symbol was
needed. Unfortunately, the hack is wrong in the case of o module having no
visible symbols but still having side effects via static constructors.

The bug will have to be fixed in libLTO itself.

llvm-svn: 166745

diff --git a/llvm/tools/gold/gold-plugin.cpp b/llvm/tools/gold/gold-plugin.cpp
index 9c17da6..b0a0dd2 100644 (file)
--- a/llvm/tools/gold/gold-plugin.cpp
+++ b/llvm/tools/gold/gold-plugin.cpp
@@ -378,9 +378,6 @@ static ld_plugin_status all_symbols_read_hook(void) {
     }
   }
 
-  // If we don't preserve any symbols, libLTO will assume that all symbols are
-  // needed. Keep all symbols unless we're producing a final executable.
-  bool anySymbolsPreserved = false;
   for (std::list<claimed_file>::iterator I = Modules.begin(),
          E = Modules.end(); I != E; ++I) {
     if (I->syms.empty())
@@ -389,7 +386,6 @@ static ld_plugin_status all_symbols_read_hook(void) {
     for (unsigned i = 0, e = I->syms.size(); i != e; i++) {
       if (I->syms[i].resolution == LDPR_PREVAILING_DEF) {
         lto_codegen_add_must_preserve_symbol(code_gen, I->syms[i].name);
-        anySymbolsPreserved = true;
 
         if (options::generate_api_file)
           api_file << I->syms[i].name << "\n";
@@ -400,12 +396,6 @@ static ld_plugin_status all_symbols_read_hook(void) {
   if (options::generate_api_file)
     api_file.close();
 
-  if (!anySymbolsPreserved) {
-    // All of the IL is unnecessary!
-    lto_codegen_dispose(code_gen);
-    return LDPS_OK;
-  }
-
   lto_codegen_set_pic_model(code_gen, output_type);
   lto_codegen_set_debug_model(code_gen, LTO_DEBUG_MODEL_DWARF);
   if (!options::mcpu.empty())