Fix DWARF reader to use correct size for DW_FORM_ref_addr.

2017-11-19  Ian Lance Taylor  <iant@google.com>
	    Cary Coutant  <ccoutant@gmail.com>

gold/
	* gold/dwarf_reader.h (class Dwarf_info_reader): Add ref_addr_size
	method.
	* gold/dwarf_reader.cc (Dwarf_die::read_attributes): Use ref_addr_size
	for DW_FORM_ref_addr_size.
	(Dwarf_die::skip_attributes): Likewise.

diff --git a/gold/dwarf_reader.cc b/gold/dwarf_reader.cc
index 8c0d593752..4da9c1e2be 100644
--- a/gold/dwarf_reader.cc
+++ b/gold/dwarf_reader.cc
@@ -737,7 +737,6 @@ Dwarf_die::read_attributes()
 	      break;
 	    }
 	  case elfcpp::DW_FORM_addr:
-	  case elfcpp::DW_FORM_ref_addr:
 	    {
 	      off_t sec_off;
 	      if (this->dwinfo_->address_size() == 4)
@@ -751,6 +750,20 @@ Dwarf_die::read_attributes()
 	      ref_form = true;
 	      break;
 	    }
+	  case elfcpp::DW_FORM_ref_addr:
+	    {
+	      off_t sec_off;
+	      if (this->dwinfo_->ref_addr_size() == 4)
+		sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
+	      else
+		sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
+	      unsigned int shndx =
+		  this->dwinfo_->lookup_reloc(attr_off, &sec_off);
+	      attr_value.aux.shndx = shndx;
+	      attr_value.val.refval = sec_off;
+	      ref_form = true;
+	      break;
+	    }
 	  case elfcpp::DW_FORM_block1:
 	    attr_value.aux.blocklen = *pattr++;
 	    attr_value.val.blockval = pattr;
@@ -947,9 +960,11 @@ Dwarf_die::skip_attributes()
 	    pattr += this->dwinfo_->offset_size();
 	    break;
 	  case elfcpp::DW_FORM_addr:
-	  case elfcpp::DW_FORM_ref_addr:
 	    pattr += this->dwinfo_->address_size();
 	    break;
+	  case elfcpp::DW_FORM_ref_addr:
+	    pattr += this->dwinfo_->ref_addr_size();
+	    break;
 	  case elfcpp::DW_FORM_block1:
 	    pattr += 1 + *pattr;
 	    break;
diff --git a/gold/dwarf_reader.h b/gold/dwarf_reader.h
index b41e057621..31e76ce347 100644
--- a/gold/dwarf_reader.h
+++ b/gold/dwarf_reader.h
@@ -764,6 +764,13 @@ class Dwarf_info_reader
   address_size() const
   { return this->address_size_; }
 
+  // Return the size of a DW_FORM_ref_addr.
+  // In DWARF v2, this was the size of an address; in DWARF v3 and later,
+  // it is the size of an DWARF offset.
+  unsigned int
+  ref_addr_size() const
+  { return this->cu_version_ > 2 ? this->offset_size_ : this->address_size_; }
+
   // Set the section index of the .debug_abbrev section.
   // We use this if there are no relocations for the .debug_info section.
   // If not set, the code parse() routine will search for the section by name.
