From: Jakub Jelinek <jakub@redhat.com>
Date: Fri, 8 Apr 2016 17:28:20 +0000 (+0200)
Subject: re PR middle-end/70593 (Miscompilation of xen starting with r226901)
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=abc0647a4d9f9a7acf0fdf39e9abc2fe39c5948d;p=gcc.git

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 b9b36de74a5..fe18079b600 100644
--- 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 e1f87b396f1..6e0afb0e832 100644
--- 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
index 00000000000..c013683688b
--- /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 93e1e2eafe9..4b0134d082c 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);