tree-optimization/104960 - unsplit edges after late sinking

Something went wrong when testing the earlier patch to move the
late sinking to before the late phiopt for PR102008.  The following
makes sure to unsplit edges after the late sinking since the split
edges confuse the following phiopt leading to missed optimizations.

I've went for a new pass parameter for this to avoid changing the
CFG after the early sinking pass at this point.

2022-03-17  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/104960
	* passes.def: Add pass parameter to pass_sink_code, mark
	last one to unsplit edges.
	* tree-ssa-sink.cc (pass_sink_code::set_pass_param): New.
	(pass_sink_code::execute): Always execute TODO_cleanup_cfg
	when we need to unsplit edges.

	* gcc.dg/gimplefe-37.c: Adjust to allow either the true
	or false edge to have a forwarder.

diff --git a/gcc/passes.def b/gcc/passes.def
index c8903b4ec16ba13b5ebc1be91ccdff0db011a879..3e44797b10f5855d6337d174236399d0f1ceb670 100644 (file)
--- a/gcc/passes.def
+++ b/gcc/passes.def
@@ -259,7 +259,7 @@ along with GCC; see the file COPYING3.  If not see
       NEXT_PASS (pass_lim);
       NEXT_PASS (pass_walloca, false);
       NEXT_PASS (pass_pre);
-      NEXT_PASS (pass_sink_code);
+      NEXT_PASS (pass_sink_code, false /* unsplit edges */);
       NEXT_PASS (pass_sancov);
       NEXT_PASS (pass_asan);
       NEXT_PASS (pass_tsan);
@@ -349,7 +349,7 @@ along with GCC; see the file COPYING3.  If not see
       /* After late CD DCE we rewrite no longer addressed locals into SSA
         form if possible.  */
       NEXT_PASS (pass_forwprop);
-      NEXT_PASS (pass_sink_code);
+      NEXT_PASS (pass_sink_code, true /* unsplit edges */);
       NEXT_PASS (pass_phiopt, false /* early_p */);
       NEXT_PASS (pass_fold_builtins);
       NEXT_PASS (pass_optimize_widening_mul);

diff --git a/gcc/testsuite/gcc.dg/gimplefe-37.c b/gcc/testsuite/gcc.dg/gimplefe-37.c
index d3ea186d7f955ae16eab6b7c8c9848f17a33e7c9..12f6f64fc2c3b7d26daa68b51712d7ea110666bd 100644 (file)
--- a/gcc/testsuite/gcc.dg/gimplefe-37.c
+++ b/gcc/testsuite/gcc.dg/gimplefe-37.c
@@ -22,6 +22,6 @@ main (int argc)
 
 
 /* { dg-final { scan-tree-dump-times "<bb \[0-9\]> \\\[count: 3" 2 "optimized" } } */
-/* { dg-final { scan-tree-dump-times "<bb \[0-9\]> \\\[count: 2" 1 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "<bb \[0-9\]> \\\[count: \[12\]" 1 "optimized" } } */
 /* { dg-final { scan-tree-dump-times "goto <bb \[0-9\]>; \\\[33\\\.33%\\\]" 1 "optimized" } } */
 /* { dg-final { scan-tree-dump-times "goto <bb \[0-9\]>; \\\[66\\\.67%\\\]" 1 "optimized" } } */

diff --git a/gcc/tree-ssa-sink.cc b/gcc/tree-ssa-sink.cc
index 66d7ae89e9034c2c575f5a6392454d9c99d32d53..1c226406febd0eb177948840bc5b25a7420a42d4 100644 (file)
--- a/gcc/tree-ssa-sink.cc
+++ b/gcc/tree-ssa-sink.cc
@@ -822,14 +822,21 @@ class pass_sink_code : public gimple_opt_pass
 {
 public:
   pass_sink_code (gcc::context *ctxt)
-    : gimple_opt_pass (pass_data_sink_code, ctxt)
+    : gimple_opt_pass (pass_data_sink_code, ctxt), unsplit_edges (false)
   {}
 
   /* opt_pass methods: */
   virtual bool gate (function *) { return flag_tree_sink != 0; }
   virtual unsigned int execute (function *);
   opt_pass *clone (void) { return new pass_sink_code (m_ctxt); }
+  void set_pass_param (unsigned n, bool param)
+    {
+      gcc_assert (n == 0);
+      unsplit_edges = param;
+    }
 
+private:
+  bool unsplit_edges;
 }; // class pass_sink_code
 
 unsigned int
@@ -837,11 +844,13 @@ pass_sink_code::execute (function *fun)
 {
   loop_optimizer_init (LOOPS_NORMAL);
   split_edges_for_insertion ();
+  /* Arrange for the critical edge splitting to be undone if requested.  */
+  unsigned todo = unsplit_edges ? TODO_cleanup_cfg : 0;
   connect_infinite_loops_to_exit ();
   memset (&sink_stats, 0, sizeof (sink_stats));
   calculate_dominance_info (CDI_DOMINATORS);
   calculate_dominance_info (CDI_POST_DOMINATORS);
-  unsigned todo = sink_code_in_bb (EXIT_BLOCK_PTR_FOR_FN (fun));
+  todo |= sink_code_in_bb (EXIT_BLOCK_PTR_FOR_FN (fun));
   statistics_counter_event (fun, "Sunk statements", sink_stats.sunk);
   statistics_counter_event (fun, "Commoned stores", sink_stats.commoned);
   free_dominance_info (CDI_POST_DOMINATORS);