1 files changed, 71 insertions, 0 deletions
diff --git a/gcc/tree-ssa-loop-manip.c b/gcc/tree-ssa-loop-manip.c
index 19b0ca2..e096d26 100644
--- a/gcc/tree-ssa-loop-manip.c
+++ b/gcc/tree-ssa-loop-manip.c
@@ -37,6 +37,77 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #include "cfglayout.h"
 #include "tree-scalar-evolution.h"
 
+/* Creates an induction variable with value BASE + STEP * iteration in LOOP.
+   It is expected that neither BASE nor STEP are shared with other expressions
+   (unless the sharing rules allow this).  Use VAR as a base var_decl for it
+   (if NULL, a new temporary will be created).  The increment will occur at
+   INCR_POS (after it if AFTER is true, before it otherwise).  The ssa versions
+   of the variable before and after increment will be stored in VAR_BEFORE and
+   VAR_AFTER (unless they are NULL).  */
+
+void
+create_iv (tree base, tree step, tree var, struct loop *loop,
+	   block_stmt_iterator *incr_pos, bool after,
+	   tree *var_before, tree *var_after)
+{
+  tree stmt, initial, step1;
+  tree vb, va;
+  enum tree_code incr_op = PLUS_EXPR;
+
+  if (!var)
+    {
+      var = create_tmp_var (TREE_TYPE (base), "ivtmp");
+      add_referenced_tmp_var (var);
+    }
+
+  vb = make_ssa_name (var, NULL_TREE);
+  if (var_before)
+    *var_before = vb;
+  va = make_ssa_name (var, NULL_TREE);
+  if (var_after)
+    *var_after = va;
+
+  /* For easier readability of the created code, produce MINUS_EXPRs
+     when suitable.  */
+  if (TREE_CODE (step) == INTEGER_CST)
+    {
+      if (TYPE_UNSIGNED (TREE_TYPE (step)))
+	{
+	  step1 = fold (build1 (NEGATE_EXPR, TREE_TYPE (step), step));
+	  if (tree_int_cst_lt (step1, step))
+	    {
+	      incr_op = MINUS_EXPR;
+	      step = step1;
+	    }
+	}
+      else
+	{
+	  if (!tree_expr_nonnegative_p (step)
+	      && may_negate_without_overflow_p (step))
+	    {
+	      incr_op = MINUS_EXPR;
+	      step = fold (build1 (NEGATE_EXPR, TREE_TYPE (step), step));
+	    }
+	}
+    }
+
+  stmt = build2 (MODIFY_EXPR, void_type_node, va,
+		 build2 (incr_op, TREE_TYPE (base),
+			 vb, step));
+  SSA_NAME_DEF_STMT (va) = stmt;
+  if (after)
+    bsi_insert_after (incr_pos, stmt, BSI_NEW_STMT);
+  else
+    bsi_insert_before (incr_pos, stmt, BSI_NEW_STMT);
+
+  initial = base;
+
+  stmt = create_phi_node (vb, loop->header);
+  SSA_NAME_DEF_STMT (vb) = stmt;
+  add_phi_arg (&stmt, initial, loop_preheader_edge (loop));
+  add_phi_arg (&stmt, va, loop_latch_edge (loop));
+}
+
 /* Add exit phis for the USE on EXIT.  */
 
 static void