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.
	* tree-ssa.c (verify_phi_args): Verify PHI arguments on abnormal
	edges are SSA names.

	* 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..775f34c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr97897.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+
+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 f132e0f41c76d19d4c02f811bb048e831d6ee90a..1cfb3e8d743f8eafc188fd08d08d5a548bc23b8a 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)

diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index c47b963bbb2ff4fbcbb37a18ac5170bd4edba173..b44361f824426f131d195b8d4de41741e64384dc 100644 (file)
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -987,6 +987,12 @@ verify_phi_args (gphi *phi, basic_block bb, basic_block *definition_block)
          err = true;
        }
 
+      if ((e->flags & EDGE_ABNORMAL) && TREE_CODE (op) != SSA_NAME)
+       {
+         error ("PHI argument on abnormal edge is not SSA_NAME");
+         err = true;
+       }
+
       if (TREE_CODE (op) == SSA_NAME)
        {
          err = verify_ssa_name (op, virtual_operand_p (gimple_phi_result (phi)));