[PATCH] Fix up assembly thunks with -gstabs+ (PR debug/54499)

[Jakub Jelinek]

Hi!

Cary added recently a debug_hooks->source_line call for asm thunks,
but that breaks e.g. for -gstabs+, which emits a relocation relative to
whatever label is emitted in the begin_prologue debug hook, so obviously
doesn't work well if called before the begin_prologue debug hook.

Fixed by reverting that change and instead setting up proper
prologue_location, so that final_start_function called by output_mi_thunk
when calling the debug_hooks->begin_prologue hook passes the right
line/file.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2012-11-08  Jakub Jelinek  <ja...@redhat.com>

        PR debug/54499
        * cgraphunit.c (assemble_thunk): Don't call source_line debug hook
        here, instead call insn_locations_{init,finalize} and initialize
        prologue_location.

        * g++.dg/debug/pr54499.C: New test.

--- gcc/cgraphunit.c.jj 2012-11-06 09:03:53.000000000 +0100
+++ gcc/cgraphunit.c    2012-11-08 13:16:48.010938659 +0100
@@ -1413,16 +1413,16 @@ assemble_thunk (struct cgraph_node *node
       DECL_INITIAL (thunk_fndecl) = fn_block;
       init_function_start (thunk_fndecl);
       cfun->is_thunk = 1;
+      insn_locations_init ();
+      set_curr_insn_location (DECL_SOURCE_LOCATION (thunk_fndecl));
+      prologue_location = curr_insn_location ();
       assemble_start_function (thunk_fndecl, fnname);
-      (*debug_hooks->source_line) (DECL_SOURCE_LINE (thunk_fndecl),
-                                  DECL_SOURCE_FILE (thunk_fndecl),
-                                  /* discriminator */ 0,
-                                  /* is_stmt */ 1);
 
       targetm.asm_out.output_mi_thunk (asm_out_file, thunk_fndecl,
                                       fixed_offset, virtual_value, alias);
 
       assemble_end_function (thunk_fndecl, fnname);
+      insn_locations_finalize ();
       init_insn_lengths ();
       free_after_compilation (cfun);
       set_cfun (NULL);
--- gcc/testsuite/g++.dg/debug/pr54499.C.jj     2012-11-08 13:23:19.906740003 
+0100
+++ gcc/testsuite/g++.dg/debug/pr54499.C        2012-11-08 13:23:55.189531409 
+0100
@@ -0,0 +1,22 @@
+// PR debug/54499
+// { dg-do assemble }
+
+struct S1
+{
+  virtual void f () = 0;
+};
+
+struct S2
+{
+  virtual ~S2 () { }
+};
+
+struct S3 : public S1, public S2
+{
+  void f ();
+};
+
+void
+S3::f ()
+{
+}

        Jakub