re PR tree-optimization/70128 (Linux kernel div patching optimized away)

2016-03-10  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/70128
	* tree-ssa-structalias.c (set_uids_in_ptset): Set
	vars_contains_nonlocal for any FUNCTION_DECL or LABEL_DECL.

	* gcc.dg/tree-ssa/alias-34.c: New testcase.
	* gcc.dg/tree-ssa/alias-35.c: Likewise.

From-SVN: r234099

gcc/ChangeLog

+2016-03-10  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/70128
+	* tree-ssa-structalias.c (set_uids_in_ptset): Set
+	vars_contains_nonlocal for any FUNCTION_DECL or LABEL_DECL.
+
 2016-03-09  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/70152

gcc/testsuite/ChangeLog

+2016-03-10  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/70128
+	* gcc.dg/tree-ssa/alias-34.c: New testcase.
+	* gcc.dg/tree-ssa/alias-35.c: Likewise.
+
 2016-03-09  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/70152

gcc/testsuite/gcc.dg/tree-ssa/alias-34.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-strict-aliasing -fdump-tree-optimized" } */
+
+void foo (int b)
+{
+  void *p;
+lab:
+  if (b)
+    p = &&lab;
+  else
+    {
+lab2:
+      p = &&lab2;
+    }
+  *(char *)p = 1;
+}
+
+/* We should keep the store to the label locations.  */
+/* { dg-final { scan-tree-dump " = 1;" "optimized" } } */

gcc/testsuite/gcc.dg/tree-ssa/alias-35.c

+/* PR70128 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-strict-aliasing -fdump-tree-optimized" } */
+
+void foo (int b)
+{
+  extern void bar (void);
+  extern void baz (void);
+  void *p;
+  if (b)
+    p = bar;
+  else
+    p = baz;
+  *(char *)p = 1;
+}
+
+/* We should keep the store to the function locations.  */
+/* { dg-final { scan-tree-dump " = 1;" "optimized" } } */

gcc/tree-ssa-structalias.c

@@ -6280,6 +6280,16 @@ set_uids_in_ptset (bitmap into, bitmap from, struct pt_solution *pt,
 		  && ! auto_var_in_fn_p (vi->decl, fndecl)))
 	    pt->vars_contains_nonlocal = true;
 	}
+
+      else if (TREE_CODE (vi->decl) == FUNCTION_DECL
+	       || TREE_CODE (vi->decl) == LABEL_DECL)
+	{
+	  /* Nothing should read/write from/to code so we can
+	     save bits by not including them in the points-to bitmaps.
+	     Still mark the points-to set as containing global memory
+	     to make code-patching possible - see PR70128.  */
+	  pt->vars_contains_nonlocal = true;
+	}
     }
 }