Re: [patch][gold] Don't put rodata and text in the same segment.

[Rafael Espindola <espindola at google dot com>]

> Please commit the patch which always moves to a new page. ÂI suspect
> that that is more likely to do the right thing in practice.

Done. And the patch with only the rosegment option is attached.

2010-09-01  Rafael Espindola  <espindola@google.com>

	* layout.cc (Layout::attach_allocated_section_to_segment): Don't put
	sections with different PF_X flags in the same segment.
	(Layout::find_first_load_seg): Search all segments to find the first
	one.
	* options.h (rosegment): New.

> Ian
>

Cheers,
-- 
Rafael Ãvila de EspÃndola

diff --git a/gold/layout.cc b/gold/layout.cc
index f0a431e..b5490d6 100644
--- a/gold/layout.cc
+++ b/gold/layout.cc
@@ -1171,10 +1171,11 @@ Layout::attach_allocated_section_to_segment(Output_section* os)
   bool is_address_set = parameters->options().section_start(os->name(), &addr);
 
   // In general the only thing we really care about for PT_LOAD
-  // segments is whether or not they are writable, so that is how we
-  // search for them.  Large data sections also go into their own
-  // PT_LOAD segment.  People who need segments sorted on some other
-  // basis will have to use a linker script.
+  // segments is whether or not they are writable or executable,
+  // so that is how we search for them.
+  // Large data sections also go into their own PT_LOAD segment.
+  // People who need segments sorted on some other basis will
+  // have to use a linker script.
 
   Segment_list::const_iterator p;
   for (p = this->segment_list_.begin();
@@ -1186,6 +1187,9 @@ Layout::attach_allocated_section_to_segment(Output_section* os)
       if (!parameters->options().omagic()
 	  && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W))
 	continue;
+      if (parameters->options().rosegment()
+          && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X))
+        continue;
       // If -Tbss was specified, we need to separate the data and BSS
       // segments.
       if (parameters->options().user_set_Tbss())
@@ -1454,6 +1458,7 @@ Layout::define_group_signatures(Symbol_table* symtab)
 Output_segment*
 Layout::find_first_load_seg()
 {
+  Output_segment* best = NULL;
   for (Segment_list::const_iterator p = this->segment_list_.begin();
        p != this->segment_list_.end();
        ++p)
@@ -1462,8 +1467,13 @@ Layout::find_first_load_seg()
 	  && ((*p)->flags() & elfcpp::PF_R) != 0
 	  && (parameters->options().omagic()
 	      || ((*p)->flags() & elfcpp::PF_W) == 0))
-	return *p;
+        {
+          if (best == NULL || this->segment_precedes(*p, best))
+            best = *p;
+        }
     }
+  if (best != NULL)
+    return best;
 
   gold_assert(!this->script_options_->saw_phdrs_clause());
 
diff --git a/gold/options.h b/gold/options.h
index c5e24cc..c990961 100644
--- a/gold/options.h
+++ b/gold/options.h
@@ -808,6 +808,10 @@ class General_options
               N_(" Only search directories specified on the command line."),
               NULL);
 
+  DEFINE_bool(rosegment, options::TWO_DASHES, '\0', false,
+              N_(" Put read-only non-executable sections in their own segment"),
+              NULL);
+
   DEFINE_string(m, options::EXACTLY_ONE_DASH, 'm', "",
                 N_("Ignored for compatibility"), N_("EMULATION"));