Re: C PATCH to fix ASAN ICE with a compound literal (PR sanitizer/80659)

[Marek Polacek <polacek@redhat.com>]

On Wed, May 17, 2017 at 09:42:08AM +0200, Richard Biener wrote:
> On Tue, 16 May 2017, Marek Polacek wrote:
> 
> > Martin L. asked me to have a look at this ICE with ASAN.  This is an ICE with a
> > compound literal in a switch.  A hash map gimplify_ctxp->live_switch_vars is
> > filled when processing DECL_EXPRs with their DECL_EXPR_DECLs.  Such decls should
> > then be removed from the hash map when gimplifying a BIND_EXPR.
> > 
> > In C, non-static compound literals aren't pushed into any scope, so they were
> > never found by gimplify_bind_expr, so they stayed in the hash map resulting in
> > a crash on
> >  2299       if (gimplify_ctxp->live_switch_vars)
> >  2300         {
> >  2301           gcc_assert (gimplify_ctxp->live_switch_vars->elements () == 0);
> >  2302           delete gimplify_ctxp->live_switch_vars;
> >  2303         }
> > 
> > We don't add artificial decls to the hash map:
> >  1647           if (!DECL_ARTIFICIAL (decl) && gimplify_ctxp->live_switch_vars)
> >  1648             gimplify_ctxp->live_switch_vars->add (decl);
> > 
> > build_compound_literal only marks a decl of a compound literal as artificial
> > when the compound literal is static.  I think there's no harm in marking
> > decls of non-static compound literals as artificial, too (provided it's fine to
> > skip asan instrumentation of compound literals).
> 
> But probably DECL_IGNORED_P as well at the same time?

Good point.

> > Bootstrapped/regtested on x86_64-linux, ok for trunk?
> 
> Ok with moving that as well (and re-testing).

Thus applying:

Bootstrapped/regtested on x86_64-linux.

2017-05-17  Marek Polacek  <polacek@redhat.com>

	PR sanitizer/80659
	* c-decl.c (build_compound_literal): Set DECL_ARTIFICIAL and
	DECL_IGNORED_P even for non-static compound literals.

	* gcc.dg/asan/pr80659.c: New test.

diff --git gcc/c/c-decl.c gcc/c/c-decl.c
index b779d37..74186da 100644
--- gcc/c/c-decl.c
+++ gcc/c/c-decl.c
@@ -5261,6 +5261,8 @@ build_compound_literal (location_t loc, tree type, tree init, bool non_const)
   DECL_CONTEXT (decl) = current_function_decl;
   TREE_USED (decl) = 1;
   DECL_READ_P (decl) = 1;
+  DECL_ARTIFICIAL (decl) = 1;
+  DECL_IGNORED_P (decl) = 1;
   TREE_TYPE (decl) = type;
   TREE_READONLY (decl) = (TYPE_READONLY (type)
 			  || (TREE_CODE (type) == ARRAY_TYPE
@@ -5297,8 +5299,6 @@ build_compound_literal (location_t loc, tree type, tree init, bool non_const)
       set_compound_literal_name (decl);
       DECL_DEFER_OUTPUT (decl) = 1;
       DECL_COMDAT (decl) = 1;
-      DECL_ARTIFICIAL (decl) = 1;
-      DECL_IGNORED_P (decl) = 1;
       pushdecl (decl);
       rest_of_decl_compilation (decl, 1, 0);
     }
diff --git gcc/testsuite/gcc.dg/asan/pr80659.c gcc/testsuite/gcc.dg/asan/pr80659.c
index e69de29..0cbf2e4 100644
--- gcc/testsuite/gcc.dg/asan/pr80659.c
+++ gcc/testsuite/gcc.dg/asan/pr80659.c
@@ -0,0 +1,13 @@
+/* PR sanitizer/80659 */
+/* { dg-do compile } */
+
+void
+foo (int a)
+{
+  switch (a)
+    {
+    case 0:
+      (int[3]) { };
+      int h;
+    }
+}

	Marek