[PATCH] Two DW_OP_GNU_variable_value fixes / tweaks

[Richard Biener]

While bringing early LTO debug up-to-speed I noticed the following two
issues.  The first patch avoids useless work in 
note_variable_value_in_expr and actually makes use of the DIE we
eventually create in resolve_variable_value_in_expr.

The second avoids generating a DW_OP_GNU_variable_value for a decl
we'll never have a DIE for -- this might be less obvious than the
other patch but I think we'll also never have any other debug info
we can resolve the decl with(?)

Bootstrapped and tested the first patch sofar
on x86_64-unknown-linux-gnu, 2nd is pending.

Ok?

Thanks,
Richard.

2017-05-15  Richard Biener  <rguent...@suse.de>

        * dwarf2out.c (resolve_variable_value_in_expr): Lookup DIE
        just generated.
        (note_variable_value_in_expr): If we resolved the decl ref
        do not push to the stack.

Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c     (revision 248055)
+++ gcc/dwarf2out.c     (working copy)
@@ -30109,8 +30109,9 @@ resolve_variable_value_in_expr (dw_attr_
              break;
            }
          /* Create DW_TAG_variable that we can refer to.  */
-         ref = gen_decl_die (decl, NULL_TREE, NULL,
-                             lookup_decl_die (current_function_decl));
+         gen_decl_die (decl, NULL_TREE, NULL,
+                       lookup_decl_die (current_function_decl));
+         ref = lookup_decl_die (decl);
          if (ref)
            {
              loc->dw_loc_oprnd1.val_class = dw_val_class_die_ref;
@@ -30203,6 +30204,7 @@ note_variable_value_in_expr (dw_die_ref
            loc->dw_loc_oprnd1.val_class = dw_val_class_die_ref;
            loc->dw_loc_oprnd1.v.val_die_ref.die = ref;
            loc->dw_loc_oprnd1.v.val_die_ref.external = 0;
+           continue;
          }
        if (VAR_P (decl)
            && DECL_CONTEXT (decl)


2017-05-15  Richard Biener  <rguent...@suse.de>

        * dwarf2out.c (loc_list_from_tree_1): Do not create
        DW_OP_GNU_variable_value for DECL_IGNORED_P decls.

Index: gcc/dwarf2out.c
===================================================================
--- gcc/dwarf2out.c     (revision 248054)
+++ gcc/dwarf2out.c     (working copy)
@@ -17373,6 +17685,7 @@ loc_list_from_tree_1 (tree loc, int want
                && early_dwarf
                && current_function_decl
                && want_address != 1
+               && ! DECL_IGNORED_P (loc)
                && (INTEGRAL_TYPE_P (TREE_TYPE (loc))
                    || POINTER_TYPE_P (TREE_TYPE (loc)))
                && DECL_CONTEXT (loc) == current_function_decl