From c838119946c9f75f1e42f4320275355822cc86fc Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacleod@redhat.com>
Date: Mon, 7 Nov 2022 15:07:35 -0500
Subject: Add transitive inferred range processing.

Rewalk statements at the end of a block to see if any inferred ranges
affect earlier calculations and register those as inferred ranges.

	gcc/
	PR tree-optimization/104530
	* gimple-range-cache.cc (ranger_cache::register_inferred_value):
	New.  Split from:
	(ranger_cache::apply_inferred_ranges): Move setting cache to
	separate function.
	* gimple-range-cache.h (register_inferred_value): New prototype.
	* gimple-range-infer.cc (infer_range_manager::has_range_p): New.
	* gimple-range-infer.h (has_range_p): New prototype.
	* gimple-range.cc (register_transitive_inferred_ranges): New.
	* gimple-range.h (register_transitive_inferred_ranges): New proto.
	* tree-vrp.cc (rvrp_folder::fold_stmt): Check for transitive inferred
	ranges at the end of the block before folding final stmt.

	gcc/testsuite/
	* gcc.dg/pr104530.c: New.
---
 gcc/gimple-range.cc | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

(limited to 'gcc/gimple-range.cc')

diff --git a/gcc/gimple-range.cc b/gcc/gimple-range.cc
index 806386918bd..2885d0fa21e 100644
--- a/gcc/gimple-range.cc
+++ b/gcc/gimple-range.cc
@@ -482,6 +482,54 @@ gimple_ranger::register_inferred_ranges (gimple *s)
   m_cache.apply_inferred_ranges (s);
 }
 
+// This function will walk the statements in BB to determine if any
+// discovered inferred ranges in the block have any transitive effects,
+// and if so, register those effects in BB.
+
+void
+gimple_ranger::register_transitive_inferred_ranges (basic_block bb)
+{
+  // Return if there are no inferred ranges in BB.
+  infer_range_manager &infer = m_cache.m_exit;
+  if (!infer.has_range_p (bb))
+    return;
+
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    fprintf (dump_file, "Checking for transitive inferred ranges in BB %d\n",
+	     bb->index);
+
+  for (gimple_stmt_iterator si = gsi_start_bb (bb); !gsi_end_p (si);
+       gsi_next (&si))
+    {
+      gimple *s = gsi_stmt (si);
+      tree lhs = gimple_get_lhs (s);
+      // If the LHS alreayd has an inferred effect, leave it be.
+      if (!gimple_range_ssa_p (lhs) || infer.has_range_p (lhs, bb))
+	continue;
+      // Pick up global value.
+      Value_Range g (TREE_TYPE (lhs));
+      range_of_expr (g, lhs);
+
+      // If either dependency has an inferred range, check if recalculating
+      // the LHS is different than the global value. If so, register it as
+      // an inferred range as well.
+      Value_Range r (TREE_TYPE (lhs));
+      r.set_undefined ();
+      tree name1 = gori ().depend1 (lhs);
+      tree name2 = gori ().depend2 (lhs);
+      if ((name1 && infer.has_range_p (name1, bb))
+	  || (name2 && infer.has_range_p (name2, bb)))
+	{
+	  // Check if folding S produces a different result.
+	  if (fold_range (r, s, this) && g != r)
+	    {
+	      infer.add_range (lhs, bb, r);
+	      m_cache.register_inferred_value (r, lhs, bb);
+	    }
+	}
+    }
+}
+
 // When a statement S has changed since the result was cached, re-evaluate
 // and update the global cache.
 
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