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Re: [debug-early] C++: emit early debug info for all globals, not just statics

On 10/02/14 08:46, Jason Merrill wrote:
On 10/01/2014 05:31 PM, Aldy Hernandez wrote:
+  for (tree t = level->names; t; t = TREE_CHAIN(t))
+    if (TREE_CODE (t) != TYPE_DECL
+    && TREE_CODE (t) != PARM_DECL
+    && !DECL_IS_BUILTIN (t))
+      debug_hooks->early_global_decl (t);

What does this do for templates?  I think we don't want to send a
template off to early_global_decl, but rather walk through its
specializations and emit them.

Hmm, I'll look into this.

Why do you need to check for PARM_DECL?  There shouldn't be any
PARM_DECL at namespace scope.

Why do you want to skip TYPE_DECL?  I think we should leave the decision
about whether to emit a typedef to the debugging back end.

Actually, I think we/I need to rethink this whole globals thing. Currently we're early dumping global *_DECLs, and hoping dwarf2out recursion will also pick up types and any derivatives from the *_DECLs, but taking a closer look I've noticed a lot of things are not being dumped early.

For instance:

	  typedef int ITYPE;
	  ITYPE var = 5;

For the above code, var's DIE gets outputted _after_ the compilation proper has been run here:

  if (! declaration && outer_scope && TREE_CODE (outer_scope) != ERROR_MARK
      && (!DECL_STRUCT_FUNCTION (decl)
	  || DECL_STRUCT_FUNCTION (decl)->gimple_df))
	decls_for_scope (outer_scope, subr_die, 0);

I think we should be outputting DIEs for locals at the end of parsing, so my patch going through level->names IMO is wrong. We should be dumping all *_DECLs created by the FE, not just globally scoped ones.

This means that we'll need to clean up unreachable/unused DIEs after the flow graph has been built.

Another example currently not being dumped early is...

	  class Local {
	    void loc_foo (void) { }
	  Local l;
	  l.loc_foo ();

...since loc_foo() is not in level->names. Again, this seems like an argument for early dumping all *_DECLs directly from rest_of_decl_compilation() (as you've hinted) and then cleaning up unused DIEs after we have flow information.

Does this seem reasonable?


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