Re: [PATCH] Fix PR81090, properly free niter estimates

[Richard Biener <rguenther@suse.de>]

On Wed, 14 Jun 2017, Richard Biener wrote:

> 
> niter estimates are not kept up-to-date (they reference gimple stmts
> and trees) in the keep-loop-stuff infrastructure so similar to the
> SCEV cache we rely on people freeing it after passes.
> 
> The following brings us a step closer to that by freeing them whenever
> SCEV is invalidated (we only compute them when SCEV is active) plus
> removing the odd record-bounds pass that just computes them, leaving
> scavenging to following passes.
> 
> Bootstrap and regtest running on x86_64-unknown-linux-gnu.

Some awkward interactions with peeling means I'm installing the
following less aggressive variant.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2017-06-16  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/81090
	* passes.def (pass_record_bounds): Remove.
	* tree-pass.h (make_pass_record_bounds): Likewise.
	* tree-ssa-loop.c (pass_data_record_bounds, pass_record_bounds,
	make_pass_record_bounds): Likewise.
	* tree-ssa-loop-ivcanon.c (canonicalize_induction_variables): Do
	not free niter estimates at the beginning but at the end.
	* tree-scalar-evolution.c (scev_finalize): Free niter estimates.

	* gcc.dg/graphite/pr81090.c: New testcase.

Index: gcc/passes.def
===================================================================
--- gcc/passes.def	(revision 249246)
+++ gcc/passes.def	(working copy)
@@ -276,7 +276,6 @@ along with GCC; see the file COPYING3.
 	  /* All unswitching, final value replacement and splitting can expose
 	     empty loops.  Remove them now.  */
 	  NEXT_PASS (pass_cd_dce);
-	  NEXT_PASS (pass_record_bounds);
 	  NEXT_PASS (pass_iv_canon);
 	  NEXT_PASS (pass_loop_distribution);
 	  NEXT_PASS (pass_copy_prop);
Index: gcc/testsuite/gcc.dg/graphite/pr81090.c
===================================================================
--- gcc/testsuite/gcc.dg/graphite/pr81090.c	(nonexistent)
+++ gcc/testsuite/gcc.dg/graphite/pr81090.c	(working copy)
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -floop-nest-optimize" } */
+
+int x3, za;
+int hg[1];
+
+void
+yw (int dq)
+{
+  const int r7 = 2;
+
+  while (dq < 1)
+    {
+      for (x3 = 0; x3 < r7; ++x3)
+	for (za = 0; za < r7; ++za)
+	  hg[1] = 0;
+      ++dq;
+    }
+
+  x3 = 0;
+  while (x3 < r7)
+    {
+      ++x3;
+      if (x3 == 0)
+	break;
+    }
+}
Index: gcc/tree-pass.h
===================================================================
--- gcc/tree-pass.h	(revision 249246)
+++ gcc/tree-pass.h	(working copy)
@@ -373,7 +373,6 @@ extern gimple_opt_pass *make_pass_predco
 extern gimple_opt_pass *make_pass_iv_canon (gcc::context *ctxt);
 extern gimple_opt_pass *make_pass_scev_cprop (gcc::context *ctxt);
 extern gimple_opt_pass *make_pass_empty_loop (gcc::context *ctxt);
-extern gimple_opt_pass *make_pass_record_bounds (gcc::context *ctxt);
 extern gimple_opt_pass *make_pass_graphite (gcc::context *ctxt);
 extern gimple_opt_pass *make_pass_graphite_transforms (gcc::context *ctxt);
 extern gimple_opt_pass *make_pass_if_conversion (gcc::context *ctxt);
Index: gcc/tree-scalar-evolution.c
===================================================================
--- gcc/tree-scalar-evolution.c	(revision 249246)
+++ gcc/tree-scalar-evolution.c	(working copy)
@@ -3636,6 +3636,7 @@ scev_finalize (void)
     return;
   scalar_evolution_info->empty ();
   scalar_evolution_info = NULL;
+  free_numbers_of_iterations_estimates (cfun);
 }
 
 /* Returns true if the expression EXPR is considered to be too expensive
Index: gcc/tree-ssa-loop-ivcanon.c
===================================================================
--- gcc/tree-ssa-loop-ivcanon.c	(revision 249246)
+++ gcc/tree-ssa-loop-ivcanon.c	(working copy)
@@ -1212,7 +1212,6 @@ canonicalize_induction_variables (void)
   bool irred_invalidated = false;
   bitmap loop_closed_ssa_invalidated = BITMAP_ALLOC (NULL);
 
-  free_numbers_of_iterations_estimates (cfun);
   estimate_numbers_of_iterations ();
 
   FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
@@ -1230,6 +1229,7 @@ canonicalize_induction_variables (void)
 
   /* Clean up the information about numbers of iterations, since brute force
      evaluation could reveal new information.  */
+  free_numbers_of_iterations_estimates (cfun);
   scev_reset ();
 
   if (!bitmap_empty_p (loop_closed_ssa_invalidated))
Index: gcc/tree-ssa-loop.c
===================================================================
--- gcc/tree-ssa-loop.c	(revision 249246)
+++ gcc/tree-ssa-loop.c	(working copy)
@@ -459,54 +459,6 @@ make_pass_scev_cprop (gcc::context *ctxt
   return new pass_scev_cprop (ctxt);
 }
 
-/* Record bounds on numbers of iterations of loops.  */
-
-namespace {
-
-const pass_data pass_data_record_bounds =
-{
-  GIMPLE_PASS, /* type */
-  "*record_bounds", /* name */
-  OPTGROUP_NONE, /* optinfo_flags */
-  TV_TREE_LOOP_BOUNDS, /* tv_id */
-  ( PROP_cfg | PROP_ssa ), /* properties_required */
-  0, /* properties_provided */
-  0, /* properties_destroyed */
-  0, /* todo_flags_start */
-  0, /* todo_flags_finish */
-};
-
-class pass_record_bounds : public gimple_opt_pass
-{
-public:
-  pass_record_bounds (gcc::context *ctxt)
-    : gimple_opt_pass (pass_data_record_bounds, ctxt)
-  {}
-
-  /* opt_pass methods: */
-  virtual unsigned int execute (function *);
-
-}; // class pass_record_bounds
-
-unsigned int
-pass_record_bounds::execute (function *fun)
-{
-  if (number_of_loops (fun) <= 1)
-    return 0;
-
-  estimate_numbers_of_iterations ();
-  scev_reset ();
-  return 0;
-}
-
-} // anon namespace
-
-gimple_opt_pass *
-make_pass_record_bounds (gcc::context *ctxt)
-{
-  return new pass_record_bounds (ctxt);
-}
-
 /* Induction variable optimizations.  */
 
 namespace {