Extend vectorizer to handle nonlinear induction for neg, mul/lshift/rshift with a constant.

For neg, the patch create a vec_init as [ a, -a, a, -a, ...  ] and no
vec_step is needed to update vectorized iv since vf is always multiple
of 2(negative * negative is positive).

For shift, the patch create a vec_init as [ a, a >> c, a >> 2*c, ..]
as vec_step as [ c * nunits, c * nunits, c * nunits, ... ], vectorized iv is
updated as vec_def = vec_init >>/<< vec_step.

For mul, the patch create a vec_init as [ a, a * c, a * pow(c, 2), ..]
as vec_step as [ pow(c,nunits), pow(c,nunits),...] iv is updated as vec_def =
vec_init * vec_step.

The patch handles nonlinear iv for
1. Integer type only, floating point is not handled.
2. No slp_node.
3. iv_loop should be same as vector loop, not nested loop.
4. No UD is created, for mul, use unsigned mult to avoid UD, for
   shift, shift count should be less than type precision.

gcc/ChangeLog:

	PR tree-optimization/103144
	* tree-vect-loop.cc (vect_is_nonlinear_iv_evolution): New function.
	(vect_analyze_scalar_cycles_1): Detect nonlinear iv by upper function.
	(vect_create_nonlinear_iv_init): New function.
	(vect_peel_nonlinear_iv_init): Ditto.
	(vect_create_nonlinear_iv_step): Ditto
	(vect_create_nonlinear_iv_vec_step): Ditto
	(vect_update_nonlinear_iv): Ditto
	(vectorizable_nonlinear_induction): Ditto.
	(vectorizable_induction): Call
	vectorizable_nonlinear_induction when induction_type is not
	vect_step_op_add.
	* tree-vect-loop-manip.cc (vect_update_ivs_after_vectorizer):
	Update nonlinear iv for epilogue loop.
	* tree-vectorizer.h (enum vect_induction_op_type): New enum.
	(STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE): New Macro.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr103144-mul-1.c: New test.
	* gcc.target/i386/pr103144-mul-2.c: New test.
	* gcc.target/i386/pr103144-neg-1.c: New test.
	* gcc.target/i386/pr103144-neg-2.c: New test.
	* gcc.target/i386/pr103144-shift-1.c: New test.
	* gcc.target/i386/pr103144-shift-2.c: New test.

1 files changed, 15 insertions, 0 deletions

diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index a2b0afb..5e75ed1 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -68,6 +68,15 @@ enum vect_def_type {
   vect_unknown_def_type
 };
 
+/* Define operation type of linear/non-linear induction variable.  */
+enum vect_induction_op_type {
+   vect_step_op_add = 0,
+   vect_step_op_neg,
+   vect_step_op_mul,
+   vect_step_op_shl,
+   vect_step_op_shr
+};
+
 /* Define type of reduction.  */
 enum vect_reduction_type {
   TREE_CODE_REDUCTION,
@@ -1190,6 +1199,7 @@ public:
      the version here.  */
   tree loop_phi_evolution_base_unchanged;
   tree loop_phi_evolution_part;
+  enum vect_induction_op_type loop_phi_evolution_type;
 
   /* Used for various bookkeeping purposes, generally holding a pointer to
      some other stmt S that is in some way "related" to this stmt.
@@ -1423,6 +1433,7 @@ struct gather_scatter_info {
   ((S)->dr_aux.dr && DR_GROUP_FIRST_ELEMENT(S))
 #define STMT_VINFO_LOOP_PHI_EVOLUTION_BASE_UNCHANGED(S) (S)->loop_phi_evolution_base_unchanged
 #define STMT_VINFO_LOOP_PHI_EVOLUTION_PART(S) (S)->loop_phi_evolution_part
+#define STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE(S) (S)->loop_phi_evolution_type
 #define STMT_VINFO_MIN_NEG_DIST(S)	(S)->min_neg_dist
 #define STMT_VINFO_REDUC_TYPE(S)	(S)->reduc_type
 #define STMT_VINFO_REDUC_CODE(S)	(S)->reduc_code
@@ -2329,6 +2340,10 @@ extern int vect_get_known_peeling_cost (loop_vec_info, int, int *,
 					stmt_vector_for_cost *);
 extern tree cse_and_gimplify_to_preheader (loop_vec_info, tree);
 
+/* Nonlinear induction.  */
+extern tree vect_peel_nonlinear_iv_init (gimple_seq*, tree, tree,
+					 tree, enum vect_induction_op_type);
+
 /* In tree-vect-slp.cc.  */
 extern void vect_slp_init (void);
 extern void vect_slp_fini (void);