PR middle-end/71581

	* tree-ssa-uninit.c (warn_uninit): If EXPR and VAR are NULL,
	see if T isn't anonymous SSA_NAME with COMPLEX_EXPR created
	for conversion of scalar user var to complex type and use the
	underlying SSA_NAME_VAR in that case.  If EXPR is still NULL,
	punt.

	* gcc.dg/pr71581.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@237621 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 57 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d4b3aae5d6d..1f47a9d9bef 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,12 @@
 2016-06-20  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/71581
+	* tree-ssa-uninit.c (warn_uninit): If EXPR and VAR are NULL,
+	see if T isn't anonymous SSA_NAME with COMPLEX_EXPR created
+	for conversion of scalar user var to complex type and use the
+	underlying SSA_NAME_VAR in that case.  If EXPR is still NULL,
+	punt.
+
 	PR rtl-optimization/71591
 	* toplev.c (toplev::run_self_tests): If no_backend, complain and
 	don't run any tests.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 4b966e956bc..ce31fb71f5d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2016-06-20  Jakub Jelinek  <jakub@redhat.com>
 
+	PR middle-end/71581
+	* gcc.dg/pr71581.c: New test.
+
 	PR rtl-optimization/71591
 	* gcc.dg/cpp/pr71591.c: New test.
 
diff --git a/gcc/testsuite/gcc.dg/pr71581.c b/gcc/testsuite/gcc.dg/pr71581.c
new file mode 100644
index 00000000000..d82eb1ed5c9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr71581.c
@@ -0,0 +1,24 @@
+/* PR middle-end/71581 */
+/* { dg-do compile } */
+/* { dg-options "-Wuninitialized" } */
+
+_Complex float
+f1 (void)
+{
+  float x;
+  return x;	/* { dg-warning "is used uninitialized in this function" } */
+}
+
+_Complex double
+f2 (void)
+{
+  double x;
+  return x;	/* { dg-warning "is used uninitialized in this function" } */
+}
+
+_Complex int
+f3 (void)
+{
+  int x;
+  return x;	/* { dg-warning "is used uninitialized in this function" } */
+}
diff --git a/gcc/tree-ssa-uninit.c b/gcc/tree-ssa-uninit.c
index 941d575f848..d5f03442c3d 100644
--- a/gcc/tree-ssa-uninit.c
+++ b/gcc/tree-ssa-uninit.c
@@ -131,6 +131,29 @@ warn_uninit (enum opt_code wc, tree t, tree expr, tree var,
   if (!has_undefined_value_p (t))
     return;
 
+  /* Anonymous SSA_NAMEs shouldn't be uninitialized, but ssa_undefined_value_p
+     can return true if the def stmt of anonymous SSA_NAME is COMPLEX_EXPR
+     created for conversion from scalar to complex.  Use the underlying var of
+     the COMPLEX_EXPRs real part in that case.  See PR71581.  */
+  if (expr == NULL_TREE
+      && var == NULL_TREE
+      && SSA_NAME_VAR (t) == NULL_TREE
+      && is_gimple_assign (SSA_NAME_DEF_STMT (t))
+      && gimple_assign_rhs_code (SSA_NAME_DEF_STMT (t)) == COMPLEX_EXPR)
+    {
+      tree v = gimple_assign_rhs1 (SSA_NAME_DEF_STMT (t));
+      if (TREE_CODE (v) == SSA_NAME
+	  && has_undefined_value_p (v)
+	  && zerop (gimple_assign_rhs2 (SSA_NAME_DEF_STMT (t))))
+	{
+	  expr = SSA_NAME_VAR (v);
+	  var = expr;
+	}
+    }
+
+  if (expr == NULL_TREE)
+    return;
+
   /* TREE_NO_WARNING either means we already warned, or the front end
      wishes to suppress the warning.  */
   if ((context