re PR tree-optimization/57558 (Loop not vectorized if iteration count could be infinite)

	PR tree-optimization/57558
	* tree-vect-loop-manip.c (vect_create_cond_for_niters_checks): New
	function.
	(vect_loop_versioning): Support versioning with niter assumptions.
	* tree-vect-loop.c (tree-ssa-loop.h): Include header file.
	(vect_get_loop_niters): New parameter.  Reimplement to support
	assumptions in loop niter info.
	(vect_analyze_loop_form_1, vect_analyze_loop_form): Ditto.
	(new_loop_vec_info): Init LOOP_VINFO_NITERS_ASSUMPTIONS.
	(vect_estimate_min_profitable_iters): Use LOOP_REQUIRES_VERSIONING.
	Support loop versioning for niters.
	* tree-vectorizer.c (tree-ssa-loop-niter.h): Include header file.
	(vect_free_loop_info_assumptions): New function.
	(vectorize_loops): Free loop niter info for loops with flag
	LOOP_F_ASSUMPTIONS set if vectorization failed.
	* tree-vectorizer.h (struct _loop_vec_info): New field
	num_iters_assumptions.
	(LOOP_VINFO_NITERS_ASSUMPTIONS): New macro.
	(LOOP_REQUIRES_VERSIONING_FOR_NITERS): New macro.
	(LOOP_REQUIRES_VERSIONING): New macro.
	(vect_free_loop_info_assumptions): New decl.

	gcc/testsuite
	PR tree-optimization/57558
	* gcc.dg/vect/pr57558-1.c: New test.
	* gcc.dg/vect/pr57558-2.c: New test.

From-SVN: r238877

1 files changed, 57 insertions, 11 deletions

diff --git a/gcc/tree-vect-loop-manip.c b/gcc/tree-vect-loop-manip.c
index 819abcd..c1381b3 100644
--- a/gcc/tree-vect-loop-manip.c
+++ b/gcc/tree-vect-loop-manip.c
@@ -2082,6 +2082,37 @@ vect_do_peeling_for_alignment (loop_vec_info loop_vinfo, tree ni_name,
   free_original_copy_tables ();
 }
 
+/* Function vect_create_cond_for_niters_checks.
+
+   Create a conditional expression that represents the run-time checks for
+   loop's niter.  The loop is guaranteed to to terminate if the run-time
+   checks hold.
+
+   Input:
+   COND_EXPR  - input conditional expression.  New conditions will be chained
+		with logical AND operation.  If it is NULL, then the function
+		is used to return the number of alias checks.
+   LOOP_VINFO - field LOOP_VINFO_MAY_ALIAS_STMTS contains the list of ddrs
+		to be checked.
+
+   Output:
+   COND_EXPR - conditional expression.
+
+   The returned COND_EXPR is the conditional expression to be used in the
+   if statement that controls which version of the loop gets executed at
+   runtime.  */
+
+static void
+vect_create_cond_for_niters_checks (loop_vec_info loop_vinfo, tree *cond_expr)
+{
+  tree part_cond_expr = LOOP_VINFO_NITERS_ASSUMPTIONS (loop_vinfo);
+
+  if (*cond_expr)
+    *cond_expr = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
+			      *cond_expr, part_cond_expr);
+  else
+    *cond_expr = part_cond_expr;
+}
 
 /* Function vect_create_cond_for_align_checks.
 
@@ -2330,7 +2361,7 @@ void
 vect_loop_versioning (loop_vec_info loop_vinfo,
 		      unsigned int th, bool check_profitability)
 {
-  struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
+  struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo), *nloop;
   struct loop *scalar_loop = LOOP_VINFO_SCALAR_LOOP (loop_vinfo);
   basic_block condition_bb;
   gphi_iterator gsi;
@@ -2347,14 +2378,19 @@ vect_loop_versioning (loop_vec_info loop_vinfo,
   tree scalar_loop_iters = LOOP_VINFO_NITERS (loop_vinfo);
   bool version_align = LOOP_REQUIRES_VERSIONING_FOR_ALIGNMENT (loop_vinfo);
   bool version_alias = LOOP_REQUIRES_VERSIONING_FOR_ALIAS (loop_vinfo);
+  bool version_niter = LOOP_REQUIRES_VERSIONING_FOR_NITERS (loop_vinfo);
 
   if (check_profitability)
-    {
-      cond_expr = fold_build2 (GT_EXPR, boolean_type_node, scalar_loop_iters,
-			       build_int_cst (TREE_TYPE (scalar_loop_iters), th));
-      cond_expr = force_gimple_operand_1 (cond_expr, &cond_expr_stmt_list,
-					  is_gimple_condexpr, NULL_TREE);
-    }
+    cond_expr = fold_build2 (GT_EXPR, boolean_type_node, scalar_loop_iters,
+			     build_int_cst (TREE_TYPE (scalar_loop_iters),
+						       th));
+
+  if (version_niter)
+    vect_create_cond_for_niters_checks (loop_vinfo, &cond_expr);
+
+  if (cond_expr)
+    cond_expr = force_gimple_operand_1 (cond_expr, &cond_expr_stmt_list,
+					is_gimple_condexpr, NULL_TREE);
 
   if (version_align)
     vect_create_cond_for_align_checks (loop_vinfo, &cond_expr,
@@ -2375,8 +2411,8 @@ vect_loop_versioning (loop_vec_info loop_vinfo,
 
       /* We don't want to scale SCALAR_LOOP's frequencies, we need to
 	 scale LOOP's frequencies instead.  */
-      loop_version (scalar_loop, cond_expr, &condition_bb,
-		    prob, REG_BR_PROB_BASE, REG_BR_PROB_BASE - prob, true);
+      nloop = loop_version (scalar_loop, cond_expr, &condition_bb, prob,
+			    REG_BR_PROB_BASE, REG_BR_PROB_BASE - prob, true);
       scale_loop_frequencies (loop, prob, REG_BR_PROB_BASE);
       /* CONDITION_BB was created above SCALAR_LOOP's preheader,
 	 while we need to move it above LOOP's preheader.  */
@@ -2403,8 +2439,18 @@ vect_loop_versioning (loop_vec_info loop_vinfo,
 			       condition_bb);
     }
   else
-    loop_version (loop, cond_expr, &condition_bb,
-		  prob, prob, REG_BR_PROB_BASE - prob, true);
+    nloop = loop_version (loop, cond_expr, &condition_bb,
+			  prob, prob, REG_BR_PROB_BASE - prob, true);
+
+  if (version_niter)
+    {
+      /* The versioned loop could be infinite, we need to clear existing
+	 niter information which is copied from the original loop.  */
+      gcc_assert (loop_constraint_set_p (loop, LOOP_C_FINITE));
+      vect_free_loop_info_assumptions (nloop);
+      /* And set constraint LOOP_C_INFINITE for niter analyzer.  */
+      loop_constraint_set (loop, LOOP_C_INFINITE);
+    }
 
   if (LOCATION_LOCUS (vect_location) != UNKNOWN_LOCATION
       && dump_enabled_p ())