re PR rtl-optimization/84878 (ICE: Segmentation fault (in add_cross_iteration_register_deps))

gcc/
	PR rtl-optimization/84878
	* ddg.c (add_cross_iteration_register_deps): Use DF_REF_BB to determine
	the basic block.  Assert the use reference is not artificial and that
	it has an associated insn.

gcc/testsuite/
	PR rtl-optimization/84878
	* gcc.target/powerpc/pr84878.c: New test.

From-SVN: r259085

gcc/ChangeLog

+2018-04-04  Peter Bergner  <bergner@vnet.ibm.com>
+
+	PR rtl-optimization/84878
+	* ddg.c (add_cross_iteration_register_deps): Use DF_REF_BB to determine
+	the basic block.  Assert the use reference is not artificial and that
+	it has an associated insn.
+
 2018-04-04  Michael Matz  <matz@suse.de>
 
 	* builtins.c (compute_objsize): Pass correct operand

gcc/ddg.c

@@ -295,11 +295,14 @@ add_cross_iteration_register_deps (ddg_ptr g, df_ref last_def)
   /* Create inter-loop true dependences and anti dependences.  */
   for (r_use = DF_REF_CHAIN (last_def); r_use != NULL; r_use = r_use->next)
     {
-      rtx_insn *use_insn = DF_REF_INSN (r_use->ref);
-
-      if (BLOCK_FOR_INSN (use_insn) != g->bb)
+      if (DF_REF_BB (r_use->ref) != g->bb)
 	continue;
 
+      gcc_assert (!DF_REF_IS_ARTIFICIAL (r_use->ref)
+		  && DF_REF_INSN_INFO (r_use->ref) != NULL);
+
+      rtx_insn *use_insn = DF_REF_INSN (r_use->ref);
+
       /* ??? Do not handle uses with DF_REF_IN_NOTE notes.  */
       use_node = get_node_of_insn (g, use_insn);
       gcc_assert (use_node);

gcc/testsuite/ChangeLog

+2018-04-04  Peter Bergner  <bergner@vnet.ibm.com>
+
+	PR rtl-optimization/84878
+	* gcc.target/powerpc/pr84878.c: New test.
+
 2018-04-04  Michael Matz  <matz@suse.de>
 
 	* gcc.dg/Wstringop-overflow-4.c: New test.

gcc/testsuite/gcc.target/powerpc/pr84878.c

+/* PR rtl-optimization/84878 */
+/* { dg-do compile { target { powerpc*-*-* } } } */
+/* { dg-require-effective-target powerpc_altivec_ok } */
+/* { dg-options "-O2 -maltivec -mno-vsx -fmodulo-sched -ftree-vectorize -funroll-loops -fassociative-math -fno-signed-zeros -fno-trapping-math" } */
+
+int ek;
+float zu;
+
+int
+k5 (int ks)
+{
+  while (ek < 1)
+    {
+      ks += (int)(0x1000000 + zu + !ek);
+      ++ek;
+    }
+  return ks;
+}