[V6] VECT: Add tree_code into "creat_iv" and allow it can handle MINUS_EXPR IV.

Message ID 20230511093852.291864-1-juzhe.zhong@rivai.ai
State Accepted
Headers
Series [V6] VECT: Add tree_code into "creat_iv" and allow it can handle MINUS_EXPR IV. |

Checks

Context Check Description
snail/gcc-patch-check success Github commit url

Commit Message

juzhe.zhong@rivai.ai May 11, 2023, 9:38 a.m. UTC
  From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>

This patch is adding comments:
+/* Creates an induction variable with value BASE (+/-) STEP * iteration in LOOP.
+   If INCR_OP is PLUS_EXPR, the induction variable is BASE + STEP * iteration.
+   If INCR_OP is MINUS_EXPR, the induction variable is BASE - STEP * iteration.
for this V5 patch: https://gcc.gnu.org/pipermail/gcc-patches/2023-May/618110.html
Which has been approved by Richards.

This patch is going to be commited after bootstrap && regression on X86 PASSED.

Thanks Richards.

gcc/ChangeLog:

        * cfgloopmanip.cc (create_empty_loop_on_edge): Add PLUS_EXPR.
        * gimple-loop-interchange.cc (tree_loop_interchange::map_inductions_to_loop): Ditto.
        * tree-ssa-loop-ivcanon.cc (create_canonical_iv): Ditto.
        * tree-ssa-loop-ivopts.cc (create_new_iv): Ditto.
        * tree-ssa-loop-manip.cc (create_iv): Ditto.
        (tree_transform_and_unroll_loop): Ditto.
        (canonicalize_loop_ivs): Ditto.
        * tree-ssa-loop-manip.h (create_iv): Ditto.
        * tree-vect-data-refs.cc (vect_create_data_ref_ptr): Ditto.
        * tree-vect-loop-manip.cc (vect_set_loop_controls_directly): Ditto.
        (vect_set_loop_condition_normal): Ditto.
        * tree-vect-loop.cc (vect_create_epilog_for_reduction): Ditto.
        * tree-vect-stmts.cc (vectorizable_store): Ditto.
        (vectorizable_load): Ditto.
---
 gcc/cfgloopmanip.cc            |  2 +-
 gcc/gimple-loop-interchange.cc |  2 +-
 gcc/tree-ssa-loop-ivcanon.cc   |  2 +-
 gcc/tree-ssa-loop-ivopts.cc    |  2 +-
 gcc/tree-ssa-loop-manip.cc     | 22 ++++++++++++----------
 gcc/tree-ssa-loop-manip.h      |  4 ++--
 gcc/tree-vect-data-refs.cc     |  8 ++++----
 gcc/tree-vect-loop-manip.cc    |  7 ++++---
 gcc/tree-vect-loop.cc          |  2 +-
 gcc/tree-vect-stmts.cc         |  4 ++--
 10 files changed, 29 insertions(+), 26 deletions(-)
  

Comments

Li, Pan2 via Gcc-patches May 11, 2023, 10:48 a.m. UTC | #1
Passed the regression and bootstrap test in X86, will commit v6 as approved.

Pan

-----Original Message-----
From: juzhe.zhong@rivai.ai <juzhe.zhong@rivai.ai> 
Sent: Thursday, May 11, 2023 5:39 PM
To: gcc-patches@gcc.gnu.org
Cc: Li, Pan2 <pan2.li@intel.com>; Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
Subject: [PATCH V6] VECT: Add tree_code into "creat_iv" and allow it can handle MINUS_EXPR IV.

From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>

This patch is adding comments:
+/* Creates an induction variable with value BASE (+/-) STEP * iteration in LOOP.
+   If INCR_OP is PLUS_EXPR, the induction variable is BASE + STEP * iteration.
+   If INCR_OP is MINUS_EXPR, the induction variable is BASE - STEP * iteration.
for this V5 patch: https://gcc.gnu.org/pipermail/gcc-patches/2023-May/618110.html
Which has been approved by Richards.

This patch is going to be commited after bootstrap && regression on X86 PASSED.

Thanks Richards.

gcc/ChangeLog:

        * cfgloopmanip.cc (create_empty_loop_on_edge): Add PLUS_EXPR.
        * gimple-loop-interchange.cc (tree_loop_interchange::map_inductions_to_loop): Ditto.
        * tree-ssa-loop-ivcanon.cc (create_canonical_iv): Ditto.
        * tree-ssa-loop-ivopts.cc (create_new_iv): Ditto.
        * tree-ssa-loop-manip.cc (create_iv): Ditto.
        (tree_transform_and_unroll_loop): Ditto.
        (canonicalize_loop_ivs): Ditto.
        * tree-ssa-loop-manip.h (create_iv): Ditto.
        * tree-vect-data-refs.cc (vect_create_data_ref_ptr): Ditto.
        * tree-vect-loop-manip.cc (vect_set_loop_controls_directly): Ditto.
        (vect_set_loop_condition_normal): Ditto.
        * tree-vect-loop.cc (vect_create_epilog_for_reduction): Ditto.
        * tree-vect-stmts.cc (vectorizable_store): Ditto.
        (vectorizable_load): Ditto.
---
 gcc/cfgloopmanip.cc            |  2 +-
 gcc/gimple-loop-interchange.cc |  2 +-
 gcc/tree-ssa-loop-ivcanon.cc   |  2 +-
 gcc/tree-ssa-loop-ivopts.cc    |  2 +-
 gcc/tree-ssa-loop-manip.cc     | 22 ++++++++++++----------
 gcc/tree-ssa-loop-manip.h      |  4 ++--
 gcc/tree-vect-data-refs.cc     |  8 ++++----
 gcc/tree-vect-loop-manip.cc    |  7 ++++---
 gcc/tree-vect-loop.cc          |  2 +-
 gcc/tree-vect-stmts.cc         |  4 ++--
 10 files changed, 29 insertions(+), 26 deletions(-)

diff --git a/gcc/cfgloopmanip.cc b/gcc/cfgloopmanip.cc index 0e3ad8ed742..6e09dcbb0b1 100644
--- a/gcc/cfgloopmanip.cc
+++ b/gcc/cfgloopmanip.cc
@@ -826,7 +826,7 @@ create_empty_loop_on_edge (edge entry_edge,
     }
 
   gsi = gsi_last_bb (loop_header);
-  create_iv (initial_value, stride, iv, loop, &gsi, false,
+  create_iv (initial_value, PLUS_EXPR, stride, iv, loop, &gsi, false,
 	     iv_before, iv_after);
 
   /* Insert loop exit condition.  */
diff --git a/gcc/gimple-loop-interchange.cc b/gcc/gimple-loop-interchange.cc index 1b77bfd46b2..e5590374e59 100644
--- a/gcc/gimple-loop-interchange.cc
+++ b/gcc/gimple-loop-interchange.cc
@@ -1185,7 +1185,7 @@ tree_loop_interchange::map_inductions_to_loop (loop_cand &src, loop_cand &tgt)
 	  tree var_before, var_after;
 	  tree base = unshare_expr (iv->init_expr);
 	  tree step = unshare_expr (iv->step);
-	  create_iv (base, step, SSA_NAME_VAR (iv->var),
+	  create_iv (base, PLUS_EXPR, step, SSA_NAME_VAR (iv->var),
 		     tgt.m_loop, &incr_pos, false, &var_before, &var_after);
 	  bitmap_set_bit (m_dce_seeds, SSA_NAME_VERSION (var_before));
 	  bitmap_set_bit (m_dce_seeds, SSA_NAME_VERSION (var_after)); diff --git a/gcc/tree-ssa-loop-ivcanon.cc b/gcc/tree-ssa-loop-ivcanon.cc index f678de41cb0..6a962a9f503 100644
--- a/gcc/tree-ssa-loop-ivcanon.cc
+++ b/gcc/tree-ssa-loop-ivcanon.cc
@@ -113,7 +113,7 @@ create_canonical_iv (class loop *loop, edge exit, tree niter,
 		       niter,
 		       build_int_cst (type, 1));
   incr_at = gsi_last_bb (in->src);
-  create_iv (niter,
+  create_iv (niter, PLUS_EXPR,
 	     build_int_cst (type, -1),
 	     NULL_TREE, loop,
 	     &incr_at, false, var_before, &var); diff --git a/gcc/tree-ssa-loop-ivopts.cc b/gcc/tree-ssa-loop-ivopts.cc index 324703054b5..6fbd2d59318 100644
--- a/gcc/tree-ssa-loop-ivopts.cc
+++ b/gcc/tree-ssa-loop-ivopts.cc
@@ -7267,7 +7267,7 @@ create_new_iv (struct ivopts_data *data, struct iv_cand *cand)
 
   base = unshare_expr (cand->iv->base);
 
-  create_iv (base, unshare_expr (cand->iv->step),
+  create_iv (base, PLUS_EXPR, unshare_expr (cand->iv->step),
 	     cand->var_before, data->current_loop,
 	     &incr_pos, after, &cand->var_before, &cand->var_after);  } diff --git a/gcc/tree-ssa-loop-manip.cc b/gcc/tree-ssa-loop-manip.cc index 598e2189f6c..f336d222433 100644
--- a/gcc/tree-ssa-loop-manip.cc
+++ b/gcc/tree-ssa-loop-manip.cc
@@ -47,7 +47,9 @@ along with GCC; see the file COPYING3.  If not see
    so that we can free them all at once.  */  static bitmap_obstack loop_renamer_obstack;
 
-/* Creates an induction variable with value BASE + STEP * iteration in LOOP.
+/* Creates an induction variable with value BASE (+/-) STEP * iteration in LOOP.
+   If INCR_OP is PLUS_EXPR, the induction variable is BASE + STEP * iteration.
+   If INCR_OP is MINUS_EXPR, the induction variable is BASE - STEP * iteration.
    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 @@ -57,16 +59,16 @@ static bitmap_obstack loop_renamer_obstack;
    VAR_AFTER (unless they are NULL).  */
 
 void
-create_iv (tree base, tree step, tree var, class loop *loop,
-	   gimple_stmt_iterator *incr_pos, bool after,
-	   tree *var_before, tree *var_after)
+create_iv (tree base, tree_code incr_op, tree step, tree var, class loop *loop,
+	   gimple_stmt_iterator *incr_pos, bool after, tree *var_before,
+	   tree *var_after)
 {
   gassign *stmt;
   gphi *phi;
   tree initial, step1;
   gimple_seq stmts;
   tree vb, va;
-  enum tree_code incr_op = PLUS_EXPR;
+  gcc_assert (incr_op == PLUS_EXPR || incr_op == MINUS_EXPR);
   edge pe = loop_preheader_edge (loop);
 
   if (var != NULL_TREE)
@@ -93,7 +95,7 @@ create_iv (tree base, tree step, tree var, class loop *loop,
 	  step1 = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
 	  if (tree_int_cst_lt (step1, step))
 	    {
-	      incr_op = MINUS_EXPR;
+	      incr_op = (incr_op == PLUS_EXPR ? MINUS_EXPR : PLUS_EXPR);
 	      step = step1;
 	    }
 	}
@@ -104,7 +106,7 @@ create_iv (tree base, tree step, tree var, class loop *loop,
 	  if (!tree_expr_nonnegative_warnv_p (step, &ovf)
 	      && may_negate_without_overflow_p (step))
 	    {
-	      incr_op = MINUS_EXPR;
+	      incr_op = (incr_op == PLUS_EXPR ? MINUS_EXPR : PLUS_EXPR);
 	      step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
 	    }
 	}
@@ -1365,7 +1367,7 @@ tree_transform_and_unroll_loop (class loop *loop, unsigned factor,
       tree ctr_before, ctr_after;
       gimple_stmt_iterator bsi = gsi_last_nondebug_bb (new_exit->src);
       exit_if = as_a <gcond *> (gsi_stmt (bsi));
-      create_iv (exit_base, exit_step, NULL_TREE, loop,
+      create_iv (exit_base, PLUS_EXPR, exit_step, NULL_TREE, loop,
 		 &bsi, false, &ctr_before, &ctr_after);
       gimple_cond_set_code (exit_if, exit_cmp);
       gimple_cond_set_lhs (exit_if, ctr_after); @@ -1580,8 +1582,8 @@ canonicalize_loop_ivs (class loop *loop, tree *nit, bool bump_in_latch)
     gsi = gsi_last_bb (loop->latch);
   else
     gsi = gsi_last_nondebug_bb (loop->header);
-  create_iv (build_int_cst_type (type, 0), build_int_cst (type, 1), NULL_TREE,
-	     loop, &gsi, bump_in_latch, &var_before, NULL);
+  create_iv (build_int_cst_type (type, 0), PLUS_EXPR, build_int_cst (type, 1),
+	     NULL_TREE, loop, &gsi, bump_in_latch, &var_before, NULL);
 
   rewrite_all_phi_nodes_with_iv (loop, var_before);
 
diff --git a/gcc/tree-ssa-loop-manip.h b/gcc/tree-ssa-loop-manip.h index d49273a3987..bda09f51d56 100644
--- a/gcc/tree-ssa-loop-manip.h
+++ b/gcc/tree-ssa-loop-manip.h
@@ -22,8 +22,8 @@ along with GCC; see the file COPYING3.  If not see
 
 typedef void (*transform_callback)(class loop *, void *);
 
-extern void create_iv (tree, tree, tree, class loop *, gimple_stmt_iterator *,
-		       bool, tree *, tree *);
+extern void create_iv (tree, tree_code, tree, tree, class loop *,
+		       gimple_stmt_iterator *, bool, tree *, tree *);
 extern void rewrite_into_loop_closed_ssa (bitmap, unsigned);  extern void verify_loop_closed_ssa (bool, class loop * = NULL);
 
diff --git a/gcc/tree-vect-data-refs.cc b/gcc/tree-vect-data-refs.cc index 6721ab6efc4..5c9103b16e5 100644
--- a/gcc/tree-vect-data-refs.cc
+++ b/gcc/tree-vect-data-refs.cc
@@ -5099,7 +5099,7 @@ vect_create_data_ref_ptr (vec_info *vinfo, stmt_vec_info stmt_info,
 
       standard_iv_increment_position (loop, &incr_gsi, &insert_after);
 
-      create_iv (aggr_ptr_init,
+      create_iv (aggr_ptr_init, PLUS_EXPR,
 		 fold_convert (aggr_ptr_type, iv_step),
 		 aggr_ptr, loop, &incr_gsi, insert_after,
 		 &indx_before_incr, &indx_after_incr); @@ -5129,9 +5129,9 @@ vect_create_data_ref_ptr (vec_info *vinfo, stmt_vec_info stmt_info,
     {
       standard_iv_increment_position (containing_loop, &incr_gsi,
 				      &insert_after);
-      create_iv (aptr, fold_convert (aggr_ptr_type, DR_STEP (dr)), aggr_ptr,
-		 containing_loop, &incr_gsi, insert_after, &indx_before_incr,
-		 &indx_after_incr);
+      create_iv (aptr, PLUS_EXPR, fold_convert (aggr_ptr_type, DR_STEP (dr)),
+		 aggr_ptr, containing_loop, &incr_gsi, insert_after,
+		 &indx_before_incr, &indx_after_incr);
       incr = gsi_stmt (incr_gsi);
 
       /* Copy the points-to information if it exists. */ diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc index 44bd5f2c805..ff6159e08d5 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -468,8 +468,9 @@ vect_set_loop_controls_directly (class loop *loop, loop_vec_info loop_vinfo,
   gimple_stmt_iterator incr_gsi;
   bool insert_after;
   standard_iv_increment_position (loop, &incr_gsi, &insert_after);
-  create_iv (build_int_cst (iv_type, 0), nitems_step, NULL_TREE, loop,
-	     &incr_gsi, insert_after, &index_before_incr, &index_after_incr);
+  create_iv (build_int_cst (iv_type, 0), PLUS_EXPR, nitems_step, NULL_TREE,
+	     loop, &incr_gsi, insert_after, &index_before_incr,
+	     &index_after_incr);
 
   tree zero_index = build_int_cst (compare_type, 0);
   tree test_index, test_limit, first_limit; @@ -893,7 +894,7 @@ vect_set_loop_condition_normal (class loop *loop, tree niters, tree step,
     }
 
   standard_iv_increment_position (loop, &incr_gsi, &insert_after);
-  create_iv (init, step, NULL_TREE, loop,
+  create_iv (init, PLUS_EXPR, step, NULL_TREE, loop,
              &incr_gsi, insert_after, &indx_before_incr, &indx_after_incr);
   indx_after_incr = force_gimple_operand_gsi (&loop_cond_gsi, indx_after_incr,
 					      true, NULL_TREE, true,
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc index 6ea0f21fd13..ed0166fedab 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -5567,7 +5567,7 @@ vect_create_epilog_for_reduction (loop_vec_info loop_vinfo,
       gimple_stmt_iterator incr_gsi;
       bool insert_after;
       standard_iv_increment_position (loop, &incr_gsi, &insert_after);
-      create_iv (series_vect, vec_step, NULL_TREE, loop, &incr_gsi,
+      create_iv (series_vect, PLUS_EXPR, vec_step, NULL_TREE, loop, 
+ &incr_gsi,
 		 insert_after, &indx_before_incr, &indx_after_incr);
 
       /* Next create a new phi node vector (NEW_PHI_TREE) which starts diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc index 61a2da4ecee..7313191b0db 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -8286,7 +8286,7 @@ vectorizable_store (vec_info *vinfo,
 
       stride_base = cse_and_gimplify_to_preheader (loop_vinfo, stride_base);
       ivstep = cse_and_gimplify_to_preheader (loop_vinfo, ivstep);
-      create_iv (stride_base, ivstep, NULL,
+      create_iv (stride_base, PLUS_EXPR, ivstep, NULL,
 		 loop, &incr_gsi, insert_after,
 		 &offvar, NULL);
       incr = gsi_stmt (incr_gsi);
@@ -9457,7 +9457,7 @@ vectorizable_load (vec_info *vinfo,
 
       stride_base = cse_and_gimplify_to_preheader (loop_vinfo, stride_base);
       ivstep = cse_and_gimplify_to_preheader (loop_vinfo, ivstep);
-      create_iv (stride_base, ivstep, NULL,
+      create_iv (stride_base, PLUS_EXPR, ivstep, NULL,
 		 loop, &incr_gsi, insert_after,
 		 &offvar, NULL);
 
--
2.36.1
  

Patch

diff --git a/gcc/cfgloopmanip.cc b/gcc/cfgloopmanip.cc
index 0e3ad8ed742..6e09dcbb0b1 100644
--- a/gcc/cfgloopmanip.cc
+++ b/gcc/cfgloopmanip.cc
@@ -826,7 +826,7 @@  create_empty_loop_on_edge (edge entry_edge,
     }
 
   gsi = gsi_last_bb (loop_header);
-  create_iv (initial_value, stride, iv, loop, &gsi, false,
+  create_iv (initial_value, PLUS_EXPR, stride, iv, loop, &gsi, false,
 	     iv_before, iv_after);
 
   /* Insert loop exit condition.  */
diff --git a/gcc/gimple-loop-interchange.cc b/gcc/gimple-loop-interchange.cc
index 1b77bfd46b2..e5590374e59 100644
--- a/gcc/gimple-loop-interchange.cc
+++ b/gcc/gimple-loop-interchange.cc
@@ -1185,7 +1185,7 @@  tree_loop_interchange::map_inductions_to_loop (loop_cand &src, loop_cand &tgt)
 	  tree var_before, var_after;
 	  tree base = unshare_expr (iv->init_expr);
 	  tree step = unshare_expr (iv->step);
-	  create_iv (base, step, SSA_NAME_VAR (iv->var),
+	  create_iv (base, PLUS_EXPR, step, SSA_NAME_VAR (iv->var),
 		     tgt.m_loop, &incr_pos, false, &var_before, &var_after);
 	  bitmap_set_bit (m_dce_seeds, SSA_NAME_VERSION (var_before));
 	  bitmap_set_bit (m_dce_seeds, SSA_NAME_VERSION (var_after));
diff --git a/gcc/tree-ssa-loop-ivcanon.cc b/gcc/tree-ssa-loop-ivcanon.cc
index f678de41cb0..6a962a9f503 100644
--- a/gcc/tree-ssa-loop-ivcanon.cc
+++ b/gcc/tree-ssa-loop-ivcanon.cc
@@ -113,7 +113,7 @@  create_canonical_iv (class loop *loop, edge exit, tree niter,
 		       niter,
 		       build_int_cst (type, 1));
   incr_at = gsi_last_bb (in->src);
-  create_iv (niter,
+  create_iv (niter, PLUS_EXPR,
 	     build_int_cst (type, -1),
 	     NULL_TREE, loop,
 	     &incr_at, false, var_before, &var);
diff --git a/gcc/tree-ssa-loop-ivopts.cc b/gcc/tree-ssa-loop-ivopts.cc
index 324703054b5..6fbd2d59318 100644
--- a/gcc/tree-ssa-loop-ivopts.cc
+++ b/gcc/tree-ssa-loop-ivopts.cc
@@ -7267,7 +7267,7 @@  create_new_iv (struct ivopts_data *data, struct iv_cand *cand)
 
   base = unshare_expr (cand->iv->base);
 
-  create_iv (base, unshare_expr (cand->iv->step),
+  create_iv (base, PLUS_EXPR, unshare_expr (cand->iv->step),
 	     cand->var_before, data->current_loop,
 	     &incr_pos, after, &cand->var_before, &cand->var_after);
 }
diff --git a/gcc/tree-ssa-loop-manip.cc b/gcc/tree-ssa-loop-manip.cc
index 598e2189f6c..f336d222433 100644
--- a/gcc/tree-ssa-loop-manip.cc
+++ b/gcc/tree-ssa-loop-manip.cc
@@ -47,7 +47,9 @@  along with GCC; see the file COPYING3.  If not see
    so that we can free them all at once.  */
 static bitmap_obstack loop_renamer_obstack;
 
-/* Creates an induction variable with value BASE + STEP * iteration in LOOP.
+/* Creates an induction variable with value BASE (+/-) STEP * iteration in LOOP.
+   If INCR_OP is PLUS_EXPR, the induction variable is BASE + STEP * iteration.
+   If INCR_OP is MINUS_EXPR, the induction variable is BASE - STEP * iteration.
    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
@@ -57,16 +59,16 @@  static bitmap_obstack loop_renamer_obstack;
    VAR_AFTER (unless they are NULL).  */
 
 void
-create_iv (tree base, tree step, tree var, class loop *loop,
-	   gimple_stmt_iterator *incr_pos, bool after,
-	   tree *var_before, tree *var_after)
+create_iv (tree base, tree_code incr_op, tree step, tree var, class loop *loop,
+	   gimple_stmt_iterator *incr_pos, bool after, tree *var_before,
+	   tree *var_after)
 {
   gassign *stmt;
   gphi *phi;
   tree initial, step1;
   gimple_seq stmts;
   tree vb, va;
-  enum tree_code incr_op = PLUS_EXPR;
+  gcc_assert (incr_op == PLUS_EXPR || incr_op == MINUS_EXPR);
   edge pe = loop_preheader_edge (loop);
 
   if (var != NULL_TREE)
@@ -93,7 +95,7 @@  create_iv (tree base, tree step, tree var, class loop *loop,
 	  step1 = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
 	  if (tree_int_cst_lt (step1, step))
 	    {
-	      incr_op = MINUS_EXPR;
+	      incr_op = (incr_op == PLUS_EXPR ? MINUS_EXPR : PLUS_EXPR);
 	      step = step1;
 	    }
 	}
@@ -104,7 +106,7 @@  create_iv (tree base, tree step, tree var, class loop *loop,
 	  if (!tree_expr_nonnegative_warnv_p (step, &ovf)
 	      && may_negate_without_overflow_p (step))
 	    {
-	      incr_op = MINUS_EXPR;
+	      incr_op = (incr_op == PLUS_EXPR ? MINUS_EXPR : PLUS_EXPR);
 	      step = fold_build1 (NEGATE_EXPR, TREE_TYPE (step), step);
 	    }
 	}
@@ -1365,7 +1367,7 @@  tree_transform_and_unroll_loop (class loop *loop, unsigned factor,
       tree ctr_before, ctr_after;
       gimple_stmt_iterator bsi = gsi_last_nondebug_bb (new_exit->src);
       exit_if = as_a <gcond *> (gsi_stmt (bsi));
-      create_iv (exit_base, exit_step, NULL_TREE, loop,
+      create_iv (exit_base, PLUS_EXPR, exit_step, NULL_TREE, loop,
 		 &bsi, false, &ctr_before, &ctr_after);
       gimple_cond_set_code (exit_if, exit_cmp);
       gimple_cond_set_lhs (exit_if, ctr_after);
@@ -1580,8 +1582,8 @@  canonicalize_loop_ivs (class loop *loop, tree *nit, bool bump_in_latch)
     gsi = gsi_last_bb (loop->latch);
   else
     gsi = gsi_last_nondebug_bb (loop->header);
-  create_iv (build_int_cst_type (type, 0), build_int_cst (type, 1), NULL_TREE,
-	     loop, &gsi, bump_in_latch, &var_before, NULL);
+  create_iv (build_int_cst_type (type, 0), PLUS_EXPR, build_int_cst (type, 1),
+	     NULL_TREE, loop, &gsi, bump_in_latch, &var_before, NULL);
 
   rewrite_all_phi_nodes_with_iv (loop, var_before);
 
diff --git a/gcc/tree-ssa-loop-manip.h b/gcc/tree-ssa-loop-manip.h
index d49273a3987..bda09f51d56 100644
--- a/gcc/tree-ssa-loop-manip.h
+++ b/gcc/tree-ssa-loop-manip.h
@@ -22,8 +22,8 @@  along with GCC; see the file COPYING3.  If not see
 
 typedef void (*transform_callback)(class loop *, void *);
 
-extern void create_iv (tree, tree, tree, class loop *, gimple_stmt_iterator *,
-		       bool, tree *, tree *);
+extern void create_iv (tree, tree_code, tree, tree, class loop *,
+		       gimple_stmt_iterator *, bool, tree *, tree *);
 extern void rewrite_into_loop_closed_ssa (bitmap, unsigned);
 extern void verify_loop_closed_ssa (bool, class loop * = NULL);
 
diff --git a/gcc/tree-vect-data-refs.cc b/gcc/tree-vect-data-refs.cc
index 6721ab6efc4..5c9103b16e5 100644
--- a/gcc/tree-vect-data-refs.cc
+++ b/gcc/tree-vect-data-refs.cc
@@ -5099,7 +5099,7 @@  vect_create_data_ref_ptr (vec_info *vinfo, stmt_vec_info stmt_info,
 
       standard_iv_increment_position (loop, &incr_gsi, &insert_after);
 
-      create_iv (aggr_ptr_init,
+      create_iv (aggr_ptr_init, PLUS_EXPR,
 		 fold_convert (aggr_ptr_type, iv_step),
 		 aggr_ptr, loop, &incr_gsi, insert_after,
 		 &indx_before_incr, &indx_after_incr);
@@ -5129,9 +5129,9 @@  vect_create_data_ref_ptr (vec_info *vinfo, stmt_vec_info stmt_info,
     {
       standard_iv_increment_position (containing_loop, &incr_gsi,
 				      &insert_after);
-      create_iv (aptr, fold_convert (aggr_ptr_type, DR_STEP (dr)), aggr_ptr,
-		 containing_loop, &incr_gsi, insert_after, &indx_before_incr,
-		 &indx_after_incr);
+      create_iv (aptr, PLUS_EXPR, fold_convert (aggr_ptr_type, DR_STEP (dr)),
+		 aggr_ptr, containing_loop, &incr_gsi, insert_after,
+		 &indx_before_incr, &indx_after_incr);
       incr = gsi_stmt (incr_gsi);
 
       /* Copy the points-to information if it exists. */
diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
index 44bd5f2c805..ff6159e08d5 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -468,8 +468,9 @@  vect_set_loop_controls_directly (class loop *loop, loop_vec_info loop_vinfo,
   gimple_stmt_iterator incr_gsi;
   bool insert_after;
   standard_iv_increment_position (loop, &incr_gsi, &insert_after);
-  create_iv (build_int_cst (iv_type, 0), nitems_step, NULL_TREE, loop,
-	     &incr_gsi, insert_after, &index_before_incr, &index_after_incr);
+  create_iv (build_int_cst (iv_type, 0), PLUS_EXPR, nitems_step, NULL_TREE,
+	     loop, &incr_gsi, insert_after, &index_before_incr,
+	     &index_after_incr);
 
   tree zero_index = build_int_cst (compare_type, 0);
   tree test_index, test_limit, first_limit;
@@ -893,7 +894,7 @@  vect_set_loop_condition_normal (class loop *loop, tree niters, tree step,
     }
 
   standard_iv_increment_position (loop, &incr_gsi, &insert_after);
-  create_iv (init, step, NULL_TREE, loop,
+  create_iv (init, PLUS_EXPR, step, NULL_TREE, loop,
              &incr_gsi, insert_after, &indx_before_incr, &indx_after_incr);
   indx_after_incr = force_gimple_operand_gsi (&loop_cond_gsi, indx_after_incr,
 					      true, NULL_TREE, true,
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 6ea0f21fd13..ed0166fedab 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -5567,7 +5567,7 @@  vect_create_epilog_for_reduction (loop_vec_info loop_vinfo,
       gimple_stmt_iterator incr_gsi;
       bool insert_after;
       standard_iv_increment_position (loop, &incr_gsi, &insert_after);
-      create_iv (series_vect, vec_step, NULL_TREE, loop, &incr_gsi,
+      create_iv (series_vect, PLUS_EXPR, vec_step, NULL_TREE, loop, &incr_gsi,
 		 insert_after, &indx_before_incr, &indx_after_incr);
 
       /* Next create a new phi node vector (NEW_PHI_TREE) which starts
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 61a2da4ecee..7313191b0db 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -8286,7 +8286,7 @@  vectorizable_store (vec_info *vinfo,
 
       stride_base = cse_and_gimplify_to_preheader (loop_vinfo, stride_base);
       ivstep = cse_and_gimplify_to_preheader (loop_vinfo, ivstep);
-      create_iv (stride_base, ivstep, NULL,
+      create_iv (stride_base, PLUS_EXPR, ivstep, NULL,
 		 loop, &incr_gsi, insert_after,
 		 &offvar, NULL);
       incr = gsi_stmt (incr_gsi);
@@ -9457,7 +9457,7 @@  vectorizable_load (vec_info *vinfo,
 
       stride_base = cse_and_gimplify_to_preheader (loop_vinfo, stride_base);
       ivstep = cse_and_gimplify_to_preheader (loop_vinfo, ivstep);
-      create_iv (stride_base, ivstep, NULL,
+      create_iv (stride_base, PLUS_EXPR, ivstep, NULL,
 		 loop, &incr_gsi, insert_after,
 		 &offvar, NULL);