tree-optimization/97897 - complex lowering on abnormal edges

This fixes complex lowering to not put constants into abnormal
edge PHI values by making sure abnormally used SSA names are
VARYING in its propagation lattice.

2020-11-19  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/97897
	* tree-complex.c (complex_propagate::visit_stmt): Make sure
	abnormally used SSA names are VARYING.
	(complex_propagate::visit_phi): Likewise.

	* gcc.dg/pr97897.c: New testcase.

diff --git a/gcc/testsuite/gcc.dg/pr97897.c b/gcc/testsuite/gcc.dg/pr97897.c
new file mode 100644 (file)
index 0000000..084c1cd
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr97897.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+void h ();
+void f () __attribute__ ((returns_twice));
+void g (_Complex int a)
+{
+  f ();
+  if (a != 0)
+  {
+    a = 0;
+    h ();
+  }
+}

diff --git a/gcc/tree-complex.c b/gcc/tree-complex.c
index aa7288b008ba1c3e63b4703acc108fe96e4c247a..6a7b31d00198dd583d523bb6f5993f771246a464 100644 (file)
--- a/gcc/tree-complex.c
+++ b/gcc/tree-complex.c
@@ -318,7 +318,7 @@ complex_propagate::visit_stmt (gimple *stmt, edge *taken_edge_p ATTRIBUTE_UNUSED
 
   lhs = gimple_get_lhs (stmt);
   /* Skip anything but GIMPLE_ASSIGN and GIMPLE_CALL with a lhs.  */
-  if (!lhs)
+  if (!lhs || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
     return SSA_PROP_VARYING;
 
   /* These conditions should be satisfied due to the initial filter
@@ -417,6 +417,9 @@ complex_propagate::visit_phi (gphi *phi)
      set up in init_dont_simulate_again.  */
   gcc_assert (TREE_CODE (TREE_TYPE (lhs)) == COMPLEX_TYPE);
 
+  if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
+    return SSA_PROP_VARYING;
+
   /* We've set up the lattice values such that IOR neatly models PHI meet.  */
   new_l = UNINITIALIZED;
   for (i = gimple_phi_num_args (phi) - 1; i >= 0; --i)