PR ld/10515
[binutils-gdb.git] / gold / reloc.cc
index f6bef1d973a6bb347b9a9341a2872d2ecc8cf286..0842a73ca83a78d7725a1fbf0ea9343bae6777dc 100644 (file)
@@ -1,6 +1,6 @@
 // reloc.cc -- relocate input files for gold.
 
-// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
+// Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
 // Written by Ian Lance Taylor <iant@google.com>.
 
 // This file is part of gold.
@@ -62,11 +62,28 @@ Read_relocs::run(Workqueue* workqueue)
 {
   Read_relocs_data *rd = new Read_relocs_data;
   this->object_->read_relocs(rd);
+  this->object_->set_relocs_data(rd);
   this->object_->release();
 
-  workqueue->queue_next(new Scan_relocs(this->options_, this->symtab_,
-                                       this->layout_, this->object_, rd,
-                                       this->symtab_lock_, this->blocker_));
+  // If garbage collection or identical comdat folding is desired, we  
+  // process the relocs first before scanning them.  Scanning of relocs is
+  // done only after garbage or identical sections is identified.
+  if (parameters->options().gc_sections() || parameters->options().icf())
+    {
+      workqueue->queue_next(new Gc_process_relocs(this->options_,
+                                                  this->symtab_,
+                                                  this->layout_, 
+                                                  this->object_, rd,
+                                                  this->symtab_lock_, 
+                                                  this->blocker_));
+    }
+  else
+    {
+      workqueue->queue_next(new Scan_relocs(this->options_, this->symtab_,
+                                            this->layout_, this->object_, rd,
+                                            this->symtab_lock_, 
+                                            this->blocker_));
+    }
 }
 
 // Return a debugging name for the task.
@@ -77,6 +94,43 @@ Read_relocs::get_name() const
   return "Read_relocs " + this->object_->name();
 }
 
+// Gc_process_relocs methods.
+
+// These tasks process the relocations read by Read_relocs and 
+// determine which sections are referenced and which are garbage.
+// This task is done only when --gc-sections is used.
+
+Task_token*
+Gc_process_relocs::is_runnable()
+{
+  if (this->object_->is_locked())
+    return this->object_->token();
+  return NULL;
+}
+
+void
+Gc_process_relocs::locks(Task_locker* tl)
+{
+  tl->add(this, this->object_->token());
+  tl->add(this, this->blocker_);
+}
+
+void
+Gc_process_relocs::run(Workqueue*)
+{
+  this->object_->gc_process_relocs(this->options_, this->symtab_, this->layout_,
+                    this->rd_);
+  this->object_->release();
+}
+
+// Return a debugging name for the task.
+
+std::string
+Gc_process_relocs::get_name() const
+{
+  return "Gc_process_relocs " + this->object_->name();
+}
+
 // Scan_relocs methods.
 
 // These tasks scan the relocations read by Read_relocs and mark up
@@ -225,7 +279,9 @@ Sized_relobj<size, big_endian>::do_read_relocs(Read_relocs_data* rd)
       // PLT sections.  Relocations for sections which are not
       // allocated (typically debugging sections) should not add new
       // GOT and PLT entries.  So we skip them unless this is a
-      // relocatable link or we need to emit relocations.
+      // relocatable link or we need to emit relocations.  FIXME: What
+      // should we do if a linker script maps a section with SHF_ALLOC
+      // clear to a section with SHF_ALLOC set?
       typename This::Shdr secshdr(pshdrs + shndx * This::shdr_size);
       bool is_section_allocated = ((secshdr.get_sh_flags() & elfcpp::SHF_ALLOC)
                                   != 0);
@@ -296,6 +352,47 @@ Sized_relobj<size, big_endian>::do_read_relocs(Read_relocs_data* rd)
     }
 }
 
+// Process the relocs to generate mappings from source sections to referenced
+// sections.  This is used during garbage colletion to determine garbage 
+// sections.
+
+template<int size, bool big_endian>
+void
+Sized_relobj<size, big_endian>::do_gc_process_relocs(const General_options& options,
+                                              Symbol_table* symtab,
+                                              Layout* layout,
+                                              Read_relocs_data* rd)
+{  
+  Sized_target<size, big_endian>* target = this->sized_target();
+
+  const unsigned char* local_symbols;
+  if (rd->local_symbols == NULL)
+    local_symbols = NULL;
+  else
+    local_symbols = rd->local_symbols->data();
+
+  for (Read_relocs_data::Relocs_list::iterator p = rd->relocs.begin();
+       p != rd->relocs.end();
+       ++p)
+    {
+      if (!parameters->options().relocatable())
+         {
+           // As noted above, when not generating an object file, we
+           // only scan allocated sections.  We may see a non-allocated
+           // section here if we are emitting relocs.
+           if (p->is_data_section_allocated)
+              target->gc_process_relocs(options, symtab, layout, this, 
+                                        p->data_shndx, p->sh_type, 
+                                        p->contents->data(), p->reloc_count, 
+                                        p->output_section,
+                                        p->needs_special_offset_handling,
+                                        this->local_symbol_count_, 
+                                        local_symbols);
+        }
+    }
+}
+
+
 // Scan the relocs and adjust the symbol table.  This looks for
 // relocations which require GOT/PLT/COPY relocations.
 
@@ -318,6 +415,14 @@ Sized_relobj<size, big_endian>::do_scan_relocs(const General_options& options,
        p != rd->relocs.end();
        ++p)
     {
+      // When garbage collection is on, unreferenced sections are not included
+      // in the link that would have been included normally. This is known only
+      // after Read_relocs hence this check has to be done again.
+      if (parameters->options().gc_sections() || parameters->options().icf())
+        {
+          if (p->output_section == NULL)
+            continue;
+        }
       if (!parameters->options().relocatable())
        {
          // As noted above, when not generating an object file, we
@@ -717,6 +822,10 @@ Sized_relobj<size, big_endian>::relocate_sections(
       if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
        continue;
 
+      off_t sh_size = shdr.get_sh_size();
+      if (sh_size == 0)
+       continue;
+
       unsigned int index = this->adjust_shndx(shdr.get_sh_info());
       if (index >= this->shnum())
        {
@@ -746,7 +855,6 @@ Sized_relobj<size, big_endian>::relocate_sections(
          continue;
        }
 
-      off_t sh_size = shdr.get_sh_size();
       const unsigned char* prelocs = this->get_view(shdr.get_sh_offset(),
                                                    sh_size, true, false);
 
@@ -1077,6 +1185,42 @@ void
 Sized_relobj<64, true>::do_read_relocs(Read_relocs_data* rd);
 #endif
 
+#ifdef HAVE_TARGET_32_LITTLE
+template
+void
+Sized_relobj<32, false>::do_gc_process_relocs(const General_options& options,
+                                       Symbol_table* symtab,
+                                       Layout* layout,
+                                       Read_relocs_data* rd);
+#endif
+
+#ifdef HAVE_TARGET_32_BIG
+template
+void
+Sized_relobj<32, true>::do_gc_process_relocs(const General_options& options,
+                                      Symbol_table* symtab,
+                                      Layout* layout,
+                                      Read_relocs_data* rd);
+#endif
+
+#ifdef HAVE_TARGET_64_LITTLE
+template
+void
+Sized_relobj<64, false>::do_gc_process_relocs(const General_options& options,
+                                       Symbol_table* symtab,
+                                       Layout* layout,
+                                       Read_relocs_data* rd);
+#endif
+
+#ifdef HAVE_TARGET_64_BIG
+template
+void
+Sized_relobj<64, true>::do_gc_process_relocs(const General_options& options,
+                                      Symbol_table* symtab,
+                                      Layout* layout,
+                                      Read_relocs_data* rd);
+#endif
+
 #ifdef HAVE_TARGET_32_LITTLE
 template
 void