[LTO] Fix various compile.exp tests

[LTO] Fix various compile.exp tests

[Diego Novillo]

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I added -flto to compile.exp and got quite a few ICEs.  This patch
fixes most of them.  I changed the handling of static variables to use
DECL_CONTEXT instead of just checking for "globalness".  The thing is
that static variables may be declared locally to a function and have
initializers that reference variables in the function.  So I modified
the handler so that they're handled as a regular local variable
instead of the global handler.

Another ICE was related to PR 31899.  There already is a fix on
mainline, so I just backported it.

The only ones I still haven't worked on are:

gcc.c-torture/compile/20020109-2.c
   We ICE in dwarf2out.c:output_die but I haven't really looked why or how.

gcc.c-torture/compile/init-1.c
   We do not write out compund literals yet.  Just need to add the
code to handle them.

The rest of compile.exp seems to work with -O2 -flto.  Next, I will
see about adding dejagnu support to exercise the whole loop (-flto and
then call lto1 on the generated object).  I find this useful to go
through the most obvious problems.

With this patch I get 12 failures on compile.exp.  Committed to the branch.

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2007-10-05  Diego Novillo  <dnovillo@google.com>

	* lto-function-out.c (output_constructor): Handle constructor elts
	with NULL indices.
	(output_expr_operand): Check whether the variable is in the
	global scope.
	(lto_output): Only handle statics that are in the global
	scope.
	* tree-nested.c (get_trampoline_type): Set DECL_CONTEXT for
	the new field.

	Backport

	2007-07-26  Doug Kwan  <dougkwan@google.com>

	* dwarf2out.c: (may_reference_to_unsued) : Renamed from
	reference_to_unsued as it is now more conservative than
	before. Replace unreachable assert into a return that tells
	caller that tree may reference an unused DECL.
	(rtl_for_decl_init): Rename callee to may_reference_to_usused.

testsuite/ChangeLog.lto:

	* lib/gcc-dg.exp: Enable -flto at -O2.

Index: lto-function-out.c
===================================================================
--- lto-function-out.c	(revision 129034)
+++ lto-function-out.c	(working copy)
@@ -1118,7 +1118,7 @@ output_constructor (struct output_block 
 
   FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), idx, purpose, value)
     {
-      if (TREE_CODE (purpose) == RANGE_EXPR)
+      if (purpose && TREE_CODE (purpose) == RANGE_EXPR)
 	{
 	  output_record_start (ob, NULL, NULL, LTO_constructor_range);
 	  /* Need the types here to reconstruct the ranges.  */
@@ -1278,7 +1278,7 @@ output_expr_operand (struct output_block
       break;
 
     case VAR_DECL:
-      if (TREE_STATIC (expr) || DECL_EXTERNAL (expr))
+      if (DECL_CONTEXT (expr) == NULL_TREE)
 	{
 	  bool new;
 	  output_record_start (ob, NULL, NULL, LTO_var_decl1);
@@ -2191,10 +2191,11 @@ lto_output (void)
     if (node->analyzed && cgraph_is_master_clone (node, false))
       output_function (node->decl);
 
-  /* Process the static vars that have initializers or
+  /* Process the global static vars that have initializers or
      constructors.  */
   FOR_EACH_STATIC_INITIALIZER (vnode)
-    output_constructor_or_init (vnode->decl);
+    if (DECL_CONTEXT (vnode->decl) == NULL_TREE)
+      output_constructor_or_init (vnode->decl);
 
   /* Put back the assembly section that was there before we started
      writing lto info.  */
Index: testsuite/lib/gcc-dg.exp
===================================================================
--- testsuite/lib/gcc-dg.exp	(revision 129034)
+++ testsuite/lib/gcc-dg.exp	(working copy)
@@ -42,7 +42,7 @@ if ![info exists TORTURE_OPTIONS] {
     set TORTURE_OPTIONS [list \
 	{ -O0 } \
 	{ -O1 } \
-	{ -O2 } \
+	{ -O2 -flto } \
 	{ -O3 -fomit-frame-pointer } \
 	{ -O3 -fomit-frame-pointer -funroll-loops } \
 	{ -O3 -fomit-frame-pointer -funroll-all-loops -finline-functions } \
Index: dwarf2out.c
===================================================================
--- dwarf2out.c	(revision 129034)
+++ dwarf2out.c	(working copy)
@@ -10374,9 +10374,10 @@ add_const_value_attribute (dw_die_ref di
 /* Determine whether the evaluation of EXPR references any variables
    or functions which aren't otherwise used (and therefore may not be
    output).  */
+
 static tree
-reference_to_unused (tree * tp, int * walk_subtrees,
-		     void * data ATTRIBUTE_UNUSED)
+may_reference_to_unused (tree * tp, int * walk_subtrees,
+			 void * data ATTRIBUTE_UNUSED)
 {
   if (! EXPR_P (*tp) && ! GIMPLE_STMT_P (*tp) && ! CONSTANT_CLASS_P (*tp))
     *walk_subtrees = 0;
@@ -10388,7 +10389,12 @@ reference_to_unused (tree * tp, int * wa
     return NULL_TREE;
   else if (!cgraph_global_info_ready
 	   && (TREE_CODE (*tp) == VAR_DECL || TREE_CODE (*tp) == FUNCTION_DECL))
-    gcc_unreachable ();
+    {
+      /* We don't know if a DECL is really unsued until we have seen
+ 	 the complete call graph.  With no reliable information, we need to
+	 be conservative.  */
+      return *tp;
+    }
   else if (DECL_P (*tp) && TREE_CODE (*tp) == VAR_DECL)
     {
       struct varpool_node *node = varpool_node (*tp);
@@ -10444,7 +10450,7 @@ rtl_for_decl_init (tree init, tree type)
      immediate RTL constant, expand it now.  We must be careful not to
      reference variables which won't be output.  */
   else if (initializer_constant_valid_p (init, type)
-	   && ! walk_tree (&init, reference_to_unused, NULL, NULL))
+	   && ! walk_tree (&init, may_reference_to_unused, NULL, NULL))
     {
       /* Convert vector CONSTRUCTOR initializers to VECTOR_CST if
 	 possible.  */
Index: tree-nested.c
===================================================================
--- tree-nested.c	(revision 129034)
+++ tree-nested.c	(working copy)
@@ -429,6 +429,7 @@ get_trampoline_type (void)
   TYPE_NAME (record) = get_identifier ("__builtin_trampoline");
   TYPE_FIELDS (record) = t;
   layout_type (record);
+  DECL_CONTEXT (t) = record;
 
   return record;
 }