PR middle-end/31490

	* output.h (SECTION_RELRO): Define.
	(SECTION_MACH_DEP): Adjust.
	(get_variable_section): New prototype.
	* varpool.c (varpool_finalize_named_section_flags): New function.
	(varpool_assemble_pending_decls): Call it.
	* cgraph.h (varpool_finalize_named_section_flags): New prototype.
	* cgraphunit.c (cgraph_output_in_order): Call
	varpool_finalize_named_section_flags.
	* varasm.c (get_section): Allow section flags conflicts between
	relro and read-only sections if the section hasn't been declared yet.
	Set SECTION_OVERRIDE after diagnosing section type conflict.
	(get_variable_section): No longer static.
	(default_section_type_flags): Use SECTION_WRITE | SECTION_RELRO for
	readonly sections that need relocations.
	(decl_readonly_section_1): New function.
	(decl_readonly_section): Use it.

	Revert:
	2010-11-17  Dinar Temirbulatov <dtemirbulatov@gmail.com>
		    Steve Ellcey  <sje@cup.hp.com>

	PR middle-end/31490
	* varasm.c (categorize_decl_for_section): Ignore reloc_rw_mask
	if section attribute used.

	* gcc.dg/pr31490-2.c: New test.
	* gcc.dg/pr31490-3.c: New test.
	* gcc.dg/pr31490-4.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@169804 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 46 insertions, 15 deletions

diff --git a/gcc/varasm.c b/gcc/varasm.c
index a1cddac16c1..3a9fbae5901 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -119,6 +119,7 @@ static void output_addressed_constants (tree);
 static unsigned HOST_WIDE_INT array_size_for_constructor (tree);
 static unsigned min_align (unsigned, unsigned);
 static void globalize_decl (tree);
+static bool decl_readonly_section_1 (enum section_category);
 #ifdef BSS_SECTION_ASM_OP
 #ifdef ASM_OUTPUT_BSS
 static void asm_output_bss (FILE *, tree, const char *,
@@ -294,11 +295,31 @@ get_section (const char *name, unsigned int flags, tree decl)
       if ((sect->common.flags & ~SECTION_DECLARED) != flags
 	  && ((sect->common.flags | flags) & SECTION_OVERRIDE) == 0)
 	{
+	  /* It is fine if one of the section flags is
+	     SECTION_WRITE | SECTION_RELRO and the other has none of these
+	     flags (i.e. read-only) in named sections and either the
+	     section hasn't been declared yet or has been declared as writable.
+	     In that case just make sure the resulting flags are
+	     SECTION_WRITE | SECTION_RELRO, ie. writable only because of
+	     relocations.  */
+	  if (((sect->common.flags ^ flags) & (SECTION_WRITE | SECTION_RELRO))
+	      == (SECTION_WRITE | SECTION_RELRO)
+	      && (sect->common.flags
+		  & ~(SECTION_DECLARED | SECTION_WRITE | SECTION_RELRO))
+		 == (flags & ~(SECTION_WRITE | SECTION_RELRO))
+	      && ((sect->common.flags & SECTION_DECLARED) == 0
+		  || (sect->common.flags & SECTION_WRITE)))
+	    {
+	      sect->common.flags |= (SECTION_WRITE | SECTION_RELRO);
+	      return sect;
+	    }
 	  /* Sanity check user variables for flag changes.  */
 	  if (decl == 0)
 	    decl = sect->named.decl;
 	  gcc_assert (decl);
 	  error ("%+D causes a section type conflict", decl);
+	  /* Make sure we don't error about one section multiple times.  */
+	  sect->common.flags |= SECTION_OVERRIDE;
 	}
     }
   return sect;
@@ -985,7 +1006,7 @@ align_variable (tree decl, bool dont_output_data)
    should be placed.  PREFER_NOSWITCH_P is true if a noswitch
    section should be used wherever possible.  */
 
-static section *
+section *
 get_variable_section (tree decl, bool prefer_noswitch_p)
 {
   addr_space_t as = ADDR_SPACE_GENERIC;
@@ -6026,8 +6047,18 @@ default_section_type_flags (tree decl, const char *name, int reloc)
 
   if (decl && TREE_CODE (decl) == FUNCTION_DECL)
     flags = SECTION_CODE;
-  else if (decl && decl_readonly_section (decl, reloc))
-    flags = 0;
+  else if (decl)
+    {
+      enum section_category category
+	= categorize_decl_for_section (decl, reloc);
+      if (decl_readonly_section_1 (category))
+	flags = 0;
+      else if (category == SECCAT_DATA_REL_RO
+	       || category == SECCAT_DATA_REL_RO_LOCAL)
+	flags = SECTION_WRITE | SECTION_RELRO;
+      else
+	flags = SECTION_WRITE;
+    }
   else
     flags = SECTION_WRITE;
 
@@ -6250,17 +6281,13 @@ categorize_decl_for_section (const_tree decl, int reloc)
 	  /* Here the reloc_rw_mask is not testing whether the section should
 	     be read-only or not, but whether the dynamic link will have to
 	     do something.  If so, we wish to segregate the data in order to
-	     minimize cache misses inside the dynamic linker.  If the data
-	     has a section attribute, ignore reloc_rw_mask() so that all data
-             in a given named section is catagorized in the same way.  */
-	  if (reloc & targetm.asm_out.reloc_rw_mask ()
-	      && !lookup_attribute ("section", DECL_ATTRIBUTES (decl)))
+	     minimize cache misses inside the dynamic linker.  */
+	  if (reloc & targetm.asm_out.reloc_rw_mask ())
 	    ret = reloc == 1 ? SECCAT_DATA_REL_LOCAL : SECCAT_DATA_REL;
 	  else
 	    ret = SECCAT_DATA;
 	}
-      else if (reloc & targetm.asm_out.reloc_rw_mask ()
-	       && !lookup_attribute ("section", DECL_ATTRIBUTES (decl)))
+      else if (reloc & targetm.asm_out.reloc_rw_mask ())
 	ret = reloc == 1 ? SECCAT_DATA_REL_RO_LOCAL : SECCAT_DATA_REL_RO;
       else if (reloc || flag_merge_constants < 2)
 	/* C and C++ don't allow different variables to share the same
@@ -6311,10 +6338,10 @@ categorize_decl_for_section (const_tree decl, int reloc)
   return ret;
 }
 
-bool
-decl_readonly_section (const_tree decl, int reloc)
+static bool
+decl_readonly_section_1 (enum section_category category)
 {
-  switch (categorize_decl_for_section (decl, reloc))
+  switch (category)
     {
     case SECCAT_RODATA:
     case SECCAT_RODATA_MERGE_STR:
@@ -6322,13 +6349,17 @@ decl_readonly_section (const_tree decl, int reloc)
     case SECCAT_RODATA_MERGE_CONST:
     case SECCAT_SRODATA:
       return true;
-      break;
     default:
       return false;
-      break;
     }
 }
 
+bool
+decl_readonly_section (const_tree decl, int reloc)
+{
+  return decl_readonly_section_1 (categorize_decl_for_section (decl, reloc));
+}
+
 /* Select a section based on the above categorization.  */
 
 section *