re PR middle-end/70593 (Miscompilation of xen starting with r226901)

	PR middle-end/70593
	* tree-ssa-coalesce.c (build_ssa_conflict_graph): For stmt
	with multiple SSA_NAME defs, force the outputs other than first
	to be live before calling live_track_process_def on each output.

	* gcc.target/i386/pr70593.c: New test.

From-SVN: r234834

gcc/ChangeLog

 2016-04-08  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/70593
+	* tree-ssa-coalesce.c (build_ssa_conflict_graph): For stmt
+	with multiple SSA_NAME defs, force the outputs other than first
+	to be live before calling live_track_process_def on each output.
+
 	PR rtl-optimization/70574
 	* fwprop.c (forward_propagate_and_simplify): Don't add
 	REG_EQUAL note if DF_REF_REG (use) is a paradoxical subreg.

gcc/testsuite/ChangeLog

 2016-04-08  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/70593
+	* gcc.target/i386/pr70593.c: New test.
+
 	PR rtl-optimization/70574
 	* gcc.target/i386/avx2-pr70574.c: New test.
 

gcc/testsuite/gcc.target/i386/pr70593.c

+/* PR middle-end/70593 */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+__attribute__((noinline, noclone)) unsigned long
+foo (unsigned x)
+{
+  unsigned long a, c = x;
+  asm volatile ("xorl\t%k1, %k1\n\tmovl\t$7, %k0" : "=c" (c), "=a" (a) : "0" (c), "1" (c) : "memory");
+  return c;
+}
+
+int
+main ()
+{
+  if (foo (3) != 7)
+    __builtin_abort ();
+  return 0;
+}

gcc/tree-ssa-coalesce.c

@@ -906,6 +906,23 @@ build_ssa_conflict_graph (tree_live_info_p liveinfo)
 	  else if (is_gimple_debug (stmt))
 	    continue;
 
+	  /* For stmts with more than one SSA_NAME definition pretend all the
+	     SSA_NAME outputs but the first one are live at this point, so
+	     that conflicts are added in between all those even when they are
+	     actually not really live after the asm, because expansion might
+	     copy those into pseudos after the asm and if multiple outputs
+	     share the same partition, it might overwrite those that should
+	     be live.  E.g.
+	     asm volatile (".." : "=r" (a) : "=r" (b) : "0" (a), "1" (a));
+	     return a;
+	     See PR70593.  */
+	  bool first = true;
+	  FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_DEF)
+	    if (first)
+	      first = false;
+	    else
+	      live_track_process_use (live, var);
+
 	  FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_DEF)
 	    live_track_process_def (live, var, graph);