[gcc r12-4866] Provide some context to folding via ranger.

[gcc r12-4866] Provide some context to folding via ranger.

[Andrew Macleod]

https://gcc.gnu.org/g:fc4076752067fb400b43adbd629081df658da246

commit r12-4866-gfc4076752067fb400b43adbd629081df658da246
Author: Andrew MacLeod <amacleod@redhat.com>
Date:   Mon Nov 1 13:32:11 2021 -0400

    Provide some context to folding via ranger.
    
    Provide an internal mechanism to supply context to range_of_expr for calls
    to ::fold_stmt.
    
            * gimple-range.cc (gimple_ranger::gimple_ranger): Initialize current_bb.
            (gimple_ranger::range_of_expr): Pick up range_on_entry when there is
            no explcit context and current_bb is set.
            (gimple_ranger::fold_stmt): New.
            * gimple-range.h (current_bb, fold_stmt): New.
            * tree-vrp.c (rvrp_folder::fold_stmt): Call ranger's fold_stmt.

Diff:
---
 gcc/gimple-range.cc | 28 +++++++++++++++++++++++++++-
 gcc/gimple-range.h  |  2 ++
 gcc/tree-vrp.c      |  2 +-
 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/gcc/gimple-range.cc b/gcc/gimple-range.cc
index 2c9715a6f2c..e1177b1c5e8 100644
--- a/gcc/gimple-range.cc
+++ b/gcc/gimple-range.cc
@@ -34,11 +34,13 @@ along with GCC; see the file COPYING3.  If not see
 #include "cfgloop.h"
 #include "tree-scalar-evolution.h"
 #include "gimple-range.h"
+#include "gimple-fold.h"
 
 gimple_ranger::gimple_ranger () :
 	non_executable_edge_flag (cfun),
 	m_cache (non_executable_edge_flag),
-	tracer ("")
+	tracer (""),
+	current_bb (NULL)
 {
   // If the cache has a relation oracle, use it.
   m_oracle = m_cache.oracle ();
@@ -82,8 +84,19 @@ gimple_ranger::range_of_expr (irange &r, tree expr, gimple *stmt)
   // If there is no statement, just get the global value.
   if (!stmt)
     {
+      int_range_max tmp;
       if (!m_cache.get_global_range (r, expr))
         r = gimple_range_global (expr);
+      // Pick up implied context information from the on-entry cache
+      // if current_bb is set.
+      if (current_bb && m_cache.block_range (tmp, current_bb, expr))
+	{
+	  r.intersect (tmp);
+	  char str[80];
+	  sprintf (str, "picked up range from bb %d\n",current_bb->index);
+	  if (idx)
+	    tracer.print (idx, str);
+	}
     }
   // For a debug stmt, pick the best value currently available, do not
   // trigger new value calculations.  PR 100781.
@@ -295,6 +308,19 @@ gimple_ranger::range_of_stmt (irange &r, gimple *s, tree name)
   return res;
 }
 
+// This routine will invoke the gimple fold_stmt routine, providing context to
+// range_of_expr calls via an private interal API.
+
+bool
+gimple_ranger::fold_stmt (gimple_stmt_iterator *gsi, tree (*valueize) (tree))
+{
+  gimple *stmt = gsi_stmt (*gsi);
+  current_bb = gimple_bb (stmt);
+  bool ret = ::fold_stmt (gsi, valueize);
+  current_bb = NULL;
+  return ret;
+}
+
 // This routine will export whatever global ranges are known to GCC
 // SSA_RANGE_NAME_INFO and SSA_NAME_PTR_INFO fields.
 
diff --git a/gcc/gimple-range.h b/gcc/gimple-range.h
index 0713af40fcd..615496ec9b8 100644
--- a/gcc/gimple-range.h
+++ b/gcc/gimple-range.h
@@ -58,10 +58,12 @@ public:
   void debug ();
   void dump_bb (FILE *f, basic_block bb);
   auto_edge_flag non_executable_edge_flag;
+  bool fold_stmt (gimple_stmt_iterator *gsi, tree (*) (tree));
 protected:
   bool fold_range_internal (irange &r, gimple *s, tree name);
   ranger_cache m_cache;
   range_tracer tracer;
+  basic_block current_bb;
 };
 
 /* Create a new ranger instance and associate it with a function.
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index dc3e250537a..5380508a9ec 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -4323,7 +4323,7 @@ public:
   {
     if (m_simplifier.simplify (gsi))
       return true;
-    return ::fold_stmt (gsi, follow_single_use_edges);
+    return m_ranger->fold_stmt (gsi, follow_single_use_edges);
   }
 
 private: