-fstrict-aliasing fixes 1/5: propagate -fno-strict-aliasing in the inliner

[Jan Hubicka]

Hi,
this is first patch in the broken up series.  It adds the logic into
ipa-inline-transform to drop the flag when inlining.  I do it always until
we find a way to make early optimizations safe WRT this transform.

The testcase triggers with GCC 5.0/4.9 too, older compilers passes if
-fstrict-aliasing is used at linktime and fails otherwise.

Bootstrapped/regtested x86_64-linux, will commit it after re-testing on
Firefox.

Honza

	* ipa-inline-transform.c (inline_call): Drop -fstrict-aliasing when
	inlining -fno-strict-aliasing into -fstrict-aliasing body.
	* gcc.dg/lto/alias-1_0.c: New testcase.
	* gcc.dg/lto/alias-1_1.c: New testcase.
Index: ipa-inline-transform.c
===================================================================
--- ipa-inline-transform.c	(revision 231081)
+++ ipa-inline-transform.c	(working copy)
@@ -322,6 +322,21 @@ inline_call (struct cgraph_edge *e, bool
   if (DECL_FUNCTION_PERSONALITY (callee->decl))
     DECL_FUNCTION_PERSONALITY (to->decl)
       = DECL_FUNCTION_PERSONALITY (callee->decl);
+  if (!opt_for_fn (callee->decl, flag_strict_aliasing)
+      && opt_for_fn (to->decl, flag_strict_aliasing))
+    {
+      struct gcc_options opts = global_options;
+
+      cl_optimization_restore (&opts,
+	 TREE_OPTIMIZATION (DECL_FUNCTION_SPECIFIC_OPTIMIZATION (to->decl)));
+      opts.x_flag_strict_aliasing = false;
+      if (dump_file)
+	fprintf (dump_file, "Dropping flag_strict_aliasing on %s:%i\n",
+		 to->name (), to->order);
+      build_optimization_node (&opts);
+      DECL_FUNCTION_SPECIFIC_OPTIMIZATION (to->decl)
+	 = build_optimization_node (&opts);
+    }
 
   /* If aliases are involved, redirect edge to the actual destination and
      possibly remove the aliases.  */
Index: testsuite/gcc.dg/lto/alias-1_0.c
===================================================================
--- testsuite/gcc.dg/lto/alias-1_0.c	(revision 0)
+++ testsuite/gcc.dg/lto/alias-1_0.c	(revision 0)
@@ -0,0 +1,23 @@
+/* { dg-lto-do run } */
+/* { dg-lto-options { { -O2 -flto } } } */
+int val;
+
+__attribute__ ((used))
+int *ptr = &val;
+__attribute__ ((used))
+float *ptr2 = (void *)&val;
+
+extern void typefun(float val);
+
+void link_error (void);
+
+int
+main()
+{ 
+  *ptr=1;
+  typefun (0);
+  if (*ptr)
+    __builtin_abort ();
+  return 0;
+}
+
Index: testsuite/gcc.dg/lto/alias-1_1.c
===================================================================
--- testsuite/gcc.dg/lto/alias-1_1.c	(revision 0)
+++ testsuite/gcc.dg/lto/alias-1_1.c	(revision 0)
@@ -0,0 +1,7 @@
+/* { dg-options "-fno-strict-aliasing" } */
+extern float *ptr2;
+void
+typefun (float val)
+{ 
+  *ptr2=val;
+}