dwarf2out.c (reference_to_unused): Don't emit strings in initializers just…

dwarf2out.c (reference_to_unused): Don't emit strings in initializers just because of debug information.

gcc/ChangeLog:
* dwarf2out.c (reference_to_unused): Don't emit strings in
initializers just because of debug information.
* tree.h (TREE_ASM_WRITTEN): Document use for STRING_CSTs.
gcc/testsuite/ChangeLog:
* gcc.dg/debug/const-3.c: New.

From-SVN: r130959

gcc/ChangeLog

+2007-12-15  Alexandre Oliva  <aoliva@redhat.com>
+
+	* dwarf2out.c (reference_to_unused): Don't emit strings in
+	initializers just because of debug information.
+	* tree.h (TREE_ASM_WRITTEN): Document use for STRING_CSTs.
+
 2007-12-15  Sebastian Pop  <sebastian.pop@amd.com>
 
 	* tree-scalar-evolution.c (number_of_iterations_for_all_loops): Replace

gcc/dwarf2out.c

@@ -10365,6 +10365,8 @@ reference_to_unused (tree * tp, int * walk_subtrees,
       if (!node->output)
 	return *tp;
     }
+  else if (TREE_CODE (*tp) == STRING_CST && !TREE_ASM_WRITTEN (*tp))
+    return *tp;
 
   return NULL_TREE;
 }

gcc/testsuite/ChangeLog

+2007-12-15  Alexandre Oliva  <aoliva@redhat.com>
+
+	* gcc.dg/debug/const-3.c: New.
+
 2007-12-15  John David Anglin  <dave.anglin@nrc-cnrc.gc.ca>
 
 	* g++.dg/other/datasec1.C: Require named section support.

gcc/testsuite/gcc.dg/debug/const-3.c

+/* Make sure we don't emit strings just because of debug information
+   for string initializers.  */
+/* { dg-do compile } */
+/* { dg-options "-O2 -g" } */
+/* { dg-final { scan-assembler-not "dontgenerate" } } */
+static const char *p = "dontgenerate1";
+static const char *q[2] = { 0, "dontgenerate2" };

gcc/tree.h

@@ -546,7 +546,7 @@ struct gimple_stmt GTY(())
 
        TREE_ASM_WRITTEN in
            VAR_DECL, FUNCTION_DECL, RECORD_TYPE, UNION_TYPE, QUAL_UNION_TYPE
-	   BLOCK, SSA_NAME
+	   BLOCK, SSA_NAME, STRING_CST
 
    used_flag:
 
@@ -1300,7 +1300,7 @@ extern void omp_clause_range_check_failed (const_tree, const char *, int,
 /* In integral and pointer types, means an unsigned type.  */
 #define TYPE_UNSIGNED(NODE) (TYPE_CHECK (NODE)->base.unsigned_flag)
 
-/* Nonzero in a VAR_DECL means assembler code has been written.
+/* Nonzero in a VAR_DECL or STRING_CST means assembler code has been written.
    Nonzero in a FUNCTION_DECL means that the function has been compiled.
    This is interesting in an inline function, since it might not need
    to be compiled separately.