tree-ssa-dse.c (compute_trims): Handle case where the reference's type does not…

tree-ssa-dse.c (compute_trims): Handle case where the reference's type does not have a TYPE_SIZE_UNIT.

	* tree-ssa-dse.c (compute_trims): Handle case where the reference's
	type does not have a TYPE_SIZE_UNIT.

	* gcc.c-torture/compile/dse.c: New test.

From-SVN: r263896

gcc/ChangeLog

+2018-08-27  Jeff Law  <law@redhat.com>
+
+	* tree-ssa-dse.c (compute_trims): Handle case where the reference's
+	type does not have a TYPE_SIZE_UNIT.
+
 2018-08-27  Steve Ellcey  <sellcey@cavium.com>
 
 	* config/aarch64/aarch64-speculation.cc: Replace include of cfg.h

gcc/testsuite/ChangeLog

+2018-08-27  Jeff Law  <law@redhat.com>
+
+	* gcc.c-torture/compile/dse.c: New test.
+
 2018-08-27  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/86993

gcc/testsuite/gcc.c-torture/compile/dse.c

+typedef unsigned long microblaze_reg_t;
+struct pt_regs
+{
+  microblaze_reg_t msr;
+  int pt_mode;
+};
+struct task_struct
+{
+  void *stack;
+};
+int
+copy_thread (struct task_struct *p)
+{
+  struct pt_regs *childregs =
+    (((struct pt_regs *) ((1 << 13) + ((void *) (p)->stack))) - 1);
+  memset (childregs, 0, sizeof (struct pt_regs));
+  childregs->pt_mode = 1;
+}
+

gcc/tree-ssa-dse.c

@@ -252,6 +252,7 @@ compute_trims (ao_ref *ref, sbitmap live, int *trim_head, int *trim_tail,
       /* But don't trim away out of bounds accesses, as this defeats
 	 proper warnings.  */
       if (*trim_tail
+	  && TYPE_SIZE_UNIT (TREE_TYPE (ref->base))
 	  && compare_tree_int (TYPE_SIZE_UNIT (TREE_TYPE (ref->base)),
 			       last_orig) <= 0)
 	*trim_tail = 0;