re PR middle-end/84237 (xen build faiulre only zero initializers are allowed in…

re PR middle-end/84237 (xen build faiulre only zero initializers are allowed in section '.bss.page_aligned.const')

	PR middle-end/84237
	* output.h (bss_initializer_p): Add NAMED argument, defaulted to false.
	* varasm.c (bss_initializer_p): Add NAMED argument, if true, ignore
	TREE_READONLY bit.
	(get_variable_section): For decls in named .bss* sections pass true as
	second argument to bss_initializer_p.

	* gcc.dg/pr84237.c: New test.

From-SVN: r257513

gcc/ChangeLog

+2018-02-09  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/84237
+	* output.h (bss_initializer_p): Add NAMED argument, defaulted to false.
+	* varasm.c (bss_initializer_p): Add NAMED argument, if true, ignore
+	TREE_READONLY bit.
+	(get_variable_section): For decls in named .bss* sections pass true as
+	second argument to bss_initializer_p.
+
 2018-02-09  Marek Polacek  <polacek@redhat.com>
 	    Jakub Jelinek  <jakub@redhat.com>
 

gcc/output.h

@@ -552,7 +552,7 @@ extern void output_file_directive (FILE *, const char *);
 extern unsigned int default_section_type_flags (tree, const char *, int);
 
 extern bool have_global_bss_p (void);
-extern bool bss_initializer_p (const_tree);
+extern bool bss_initializer_p (const_tree, bool = false);
 
 extern void default_no_named_section (const char *, unsigned int, tree);
 extern void default_elf_asm_named_section (const char *, unsigned int, tree);

gcc/testsuite/ChangeLog

+2018-02-09  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/84237
+	* gcc.dg/pr84237.c: New test.
+
 2018-02-09  Marek Polacek  <polacek@redhat.com>
 	    Jakub Jelinek  <jakub@redhat.com>
 

gcc/testsuite/gcc.dg/pr84237.c

+/* PR middle-end/84237 */
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "" } */
+
+const char __attribute__((__section__(".bss.page_aligned.const"), __aligned__(4096))) zero_page[4096];

gcc/varasm.c

@@ -983,11 +983,11 @@ decode_reg_name (const char *name)
 /* Return true if DECL's initializer is suitable for a BSS section.  */
 
 bool
-bss_initializer_p (const_tree decl)
+bss_initializer_p (const_tree decl, bool named)
 {
   /* Do not put non-common constants into the .bss section, they belong in
-     a readonly section.  */
-  return ((!TREE_READONLY (decl) || DECL_COMMON (decl))
+     a readonly section, except when NAMED is true.  */
+  return ((!TREE_READONLY (decl) || DECL_COMMON (decl) || named)
 	  && (DECL_INITIAL (decl) == NULL
 	      /* In LTO we have no errors in program; error_mark_node is used
 	         to mark offlined constructors.  */
@@ -1165,7 +1165,8 @@ get_variable_section (tree decl, bool prefer_noswitch_p)
     {
       section *sect = get_named_section (decl, NULL, reloc);
 
-      if ((sect->common.flags & SECTION_BSS) && !bss_initializer_p (decl))
+      if ((sect->common.flags & SECTION_BSS)
+	  && !bss_initializer_p (decl, true))
 	{
 	  error_at (DECL_SOURCE_LOCATION (decl),
 		    "only zero initializers are allowed in section %qs",