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

1 files changed, 17 insertions, 0 deletions

diff --git a/gcc/tree-ssa-coalesce.c b/gcc/tree-ssa-coalesce.c
index 93e1e2e..4b0134d 100644
--- a/gcc/tree-ssa-coalesce.c
+++ b/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);