binutils: Add ICF alignment fix.

third_party/binutils/icf-align.patch

+commit ac423761af22f7858a1413cda5df3e1d5e88d4e4
+Author: Gergely Nagy <ngg@tresorit.com>
+Date:   Fri Oct 21 11:08:20 2016 -0700
+
+    Fix PR 17704.
+    
+    This fix keeps the section with the highest alignment when folding sections with ICF.
+    
+            PR gold/17704
+            * icf.cc (match_sections): Add new parameter section_addraligns.
+            Check section alignment and keep the section with the strictest
+            alignment.
+            (find_identical_sections): New local variable section_addraligns.
+            Store each section's alignment.
+            * testsuite/pr17704a_test.s: New file.
+            * testsuite/Makefile.am (pr17704a_test): New test.
+            * testsuite/Makefile.in: Regenerate.
+
+diff --git a/gold/icf.cc b/gold/icf.cc
+index dce0b8b3e2..c09c746ae1 100644
+--- a/gold/icf.cc
++++ b/gold/icf.cc
+@@ -590,6 +590,7 @@ match_sections(unsigned int iteration_num,
+                std::vector<unsigned int>* num_tracked_relocs,
+                std::vector<unsigned int>* kept_section_id,
+                const std::vector<Section_id>& id_section,
++              const std::vector<uint64_t>& section_addraligns,
+                std::vector<bool>* is_secn_or_group_unique,
+                std::vector<std::string>* section_contents)
+ {
+@@ -630,13 +631,7 @@ match_sections(unsigned int iteration_num,
+         {
+           if ((*kept_section_id)[i] != i)
+             {
+-              // This section is already folded into something.  See
+-              // if it should point to a different kept section.
+-              unsigned int kept_section = (*kept_section_id)[i];
+-              if (kept_section != (*kept_section_id)[kept_section])
+-                {
+-                  (*kept_section_id)[i] = (*kept_section_id)[kept_section];
+-                }
++              // This section is already folded into something.
+               continue;
+             }
+           this_secn_contents = get_section_contents(false, secn, i, NULL,
+@@ -671,7 +666,25 @@ match_sections(unsigned int iteration_num,
+                          this_secn_contents.c_str(),
+                          this_secn_contents.length()) != 0)
+                   continue;
+-              (*kept_section_id)[i] = kept_section;
++
++             // Check section alignment here.
++             // The section with the larger alignment requirement
++             // should be kept.  We assume alignment can only be 
++             // zero or postive integral powers of two.
++             uint64_t align_i = section_addraligns[i];
++             uint64_t align_kept = section_addraligns[kept_section];
++             if (align_i <= align_kept)
++               {
++                 (*kept_section_id)[i] = kept_section;
++               }
++             else
++               {
++                 (*kept_section_id)[kept_section] = i;
++                 it->second = i;
++                 full_section_contents[kept_section].swap(
++                     full_section_contents[i]);
++               }
++
+               converged = false;
+               break;
+             }
+@@ -688,6 +701,26 @@ match_sections(unsigned int iteration_num,
+         (*is_secn_or_group_unique)[i] = true;
+     }
+ 
++  // If a section was folded into another section that was later folded
++  // again then the former has to be updated.
++  for (unsigned int i = 0; i < id_section.size(); i++)
++    {
++      // Find the end of the folding chain
++      unsigned int kept = i;
++      while ((*kept_section_id)[kept] != kept)
++        {
++          kept = (*kept_section_id)[kept];
++        }
++      // Update every element of the chain
++      unsigned int current = i;
++      while ((*kept_section_id)[current] != kept)
++        {
++          unsigned int next = (*kept_section_id)[current];
++          (*kept_section_id)[current] = kept;
++          current = next;
++        }
++    }
++
+   return converged;
+ }
+ 
+@@ -719,6 +752,7 @@ Icf::find_identical_sections(const Input_objects* input_objects,
+ {
+   unsigned int section_num = 0;
+   std::vector<unsigned int> num_tracked_relocs;
++  std::vector<uint64_t> section_addraligns;
+   std::vector<bool> is_secn_or_group_unique;
+   std::vector<std::string> section_contents;
+   const Target& target = parameters->target();
+@@ -759,6 +793,7 @@ Icf::find_identical_sections(const Input_objects* input_objects,
+           this->section_id_[Section_id(*p, i)] = section_num;
+           this->kept_section_id_.push_back(section_num);
+           num_tracked_relocs.push_back(0);
++         section_addraligns.push_back((*p)->section_addralign(i));
+           is_secn_or_group_unique.push_back(false);
+           section_contents.push_back("");
+           section_num++;
+@@ -779,8 +814,8 @@ Icf::find_identical_sections(const Input_objects* input_objects,
+       num_iterations++;
+       converged = match_sections(num_iterations, symtab,
+                                  &num_tracked_relocs, &this->kept_section_id_,
+-                                 this->id_section_, &is_secn_or_group_unique,
+-                                 &section_contents);
++                                 this->id_section_, section_addraligns,
++                                 &is_secn_or_group_unique, &section_contents);
+     }
+ 
+   if (parameters->options().print_icf_sections())