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Re: [PATCH] Don't instrument DECL_INITIAL of statics (PR sanitizer/66190)

On Fri, May 29, 2015 at 10:41:34AM +0200, Marek Polacek wrote:
> Ping.
> On Thu, May 21, 2015 at 09:36:59PM +0200, Marek Polacek wrote:
> > In this PR, we find ourselves instrumenting a static initializer and
> > then crashing when expanding an unlowered UBSAN_NULL.  Jakub suggests
> > to not instrument DECL_INITIAL of a static variable.  The following
> > patch is an attempt to do that.  Note that we're still able to sanitize
> > similar cases (they don't have DECL_INITIAL but something else).
> > 
> > Bootstrap/regtest/bootstrap-ubsan passed on x86_64-linux, ok for trunk?
> > 
> > 2015-05-21  Marek Polacek  <>
> > 
> > 	PR sanitizer/66190
> > 	* cp-gimplify.c (struct cp_genericize_data): Add no_sanitize_p.
> > 	(cp_genericize_r): Don't instrument static initializers.
> > 	(cp_genericize_tree): Initialize wtd.no_sanitize_p.

This seems strange.  Normally DECL_INITIAL of vars isn't walked when
processing DECL_EXPRs, so IMHO you shouldn't either.
I think it would be much better to handle this case where the tree.c
code handles it, thus in cp_genericize_r's BIND_EXPR handling.
Just do there something along the lines:
  if (flag_sanitize
      bool no_sanitize_p = wtd->no_sanitize_p;
      wtd->no_sanitize_p = true;
      for (tree decl = BIND_EXPR_VARS (*tp); decl; decl = DECL_CHAIN (decl))
	if (VAR_P (decl)
	    && TREE_STATIC (decl)
	    && DECL_INITIAL (decl))
	  cp_walk_tree (&DECL_INITIAL (decl), cp_genericize_r, data, NULL);
      wtd->no_sanitize_p = no_sanitize_p;
with some appripriate comments.  As cp_genericize_r gives up early for
expressions it has walked already, this should DTRT then.


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