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, 28 insertions, 1 deletions

diff --git a/gcc/tree-vectorizer.c b/gcc/tree-vectorizer.c
index 9fbd183..1d55041 100644
--- a/gcc/tree-vectorizer.c
+++ b/gcc/tree-vectorizer.c
@@ -69,6 +69,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "gimple-iterator.h"
 #include "gimple-walk.h"
 #include "tree-ssa-loop-manip.h"
+#include "tree-ssa-loop-niter.h"
 #include "tree-cfg.h"
 #include "cfgloop.h"
 #include "tree-vectorizer.h"
@@ -368,6 +369,20 @@ vect_destroy_datarefs (vec_info *vinfo)
   free_data_refs (vinfo->datarefs);
 }
 
+/* A helper function to free scev and LOOP niter information, as well as
+   clear loop constraint LOOP_C_FINITE.  */
+
+void
+vect_free_loop_info_assumptions (struct loop *loop)
+{
+  scev_reset_htab ();
+  /* We need to explicitly reset upper bound information since they are
+     used even after free_numbers_of_iterations_estimates_loop.  */
+  loop->any_upper_bound = false;
+  loop->any_likely_upper_bound = false;
+  free_numbers_of_iterations_estimates_loop (loop);
+  loop_constraint_clear (loop, LOOP_C_FINITE);
+}
 
 /* Return whether STMT is inside the region we try to vectorize.  */
 
@@ -537,7 +552,14 @@ vectorize_loops (void)
 	loop->aux = loop_vinfo;
 
 	if (!loop_vinfo || !LOOP_VINFO_VECTORIZABLE_P (loop_vinfo))
-	  continue;
+	  {
+	    /* Free existing information if loop is analyzed with some
+	       assumptions.  */
+	    if (loop_constraint_set_p (loop, LOOP_C_FINITE))
+	      vect_free_loop_info_assumptions (loop);
+
+	    continue;
+	  }
 
         if (!dbg_cnt (vect_loop))
 	  {
@@ -545,6 +567,11 @@ vectorize_loops (void)
 	       debug counter.  Set any_ifcvt_loops to visit
 	       them at finalization.  */
 	    any_ifcvt_loops = true;
+	    /* Free existing information if loop is analyzed with some
+	       assumptions.  */
+	    if (loop_constraint_set_p (loop, LOOP_C_FINITE))
+	      vect_free_loop_info_assumptions (loop);
+
 	    break;
 	  }