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

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b9b36de..fe18079 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,10 @@
 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.

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index e1f87b3..6e0afb0 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 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.
 

diff --git a/gcc/testsuite/gcc.target/i386/pr70593.c b/gcc/testsuite/gcc.target/i386/pr70593.c
new file mode 100644 (file)
index 0000000..c013683
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr70593.c
@@ -0,0 +1,19 @@
+/* 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;
+}

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