[COMMITTED] PR tree-optimization/126814 - fold_using_range should set the current query.

Andrew MacLeod <[email protected]>
Newsgroups gmane.comp.gcc.patches
Message-ID <[email protected]> 
We also ran into this in PR 125854..  so lets fix it permanently.

fold_using_range provides a richer interface where you can choose to 
fold statements using a specified range_query.  If you do not specify 
one, the current_range-query is used.

Ranger's cache counts on being able to call into this interface using 
its own read-only version of the cache, as well as occassional uses 
where the global_range_query is used for safety.    With 
get_range_query(cfun) being used more frequently in simplification, 
folding and other locations, we are starting to trip over it more 
frequently.

In this case, the global_range_query is passed in to be used, but when 
range_of_call is invoked, it checks for gimple_stmt_nonzero_p(), and 
down the call chain eventually tree_expr_nonzero_p() invokes, you 
guessed it, get_range_query ()->range_of_expr.    This escaped the 
read-only range query that was specified, and is causing the 
non-reentrant cache filling to be entered again and trip the assert.

To avoid this i the future, The permanent fix currently  is when 
fold_using_range::fold_stmt is invoked, if the current query doesn't 
match the specified one, replace the current query for the duration of 
the calculations...    then all get_range_query() calls will invoke to 
correct query, and fold_stmt will then replace the current query when 
its done.   All calls from within fold_using_range will then use the 
correct range_query.

This resolves the current PR, and deprecates/replaces the fix for 125854 
as it covers that as well.

Bootstrapped on x86_64-pc-linux-gnu with no regressions.  pushed.

Andrew
0003-fold_using_range-should-set-the-current-query.patch (text/x-patch, 4.7 KB) 
From 196f90d7d53cc8e0354f536a85719498f51adc37 Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <[email protected]>
Date: Wed, 12 Aug 2026 17:03:21 -0400
Subject: [PATCH 3/4] fold_using_range should set the current query.

	PR tree-optimization/126814
	gcc/
	* gimple-range-fold.cc (fold_using_range::fold_stmt): Temporarily
	replace the current range query with the specified one.

	gcc/testsuite/
	* gcc.dg/pr126814.c: New.
---
 gcc/gimple-range-fold.cc        | 59 +++++++++++++++++++--------------
 gcc/testsuite/gcc.dg/pr126814.c | 17 ++++++++++
 2 files changed, 52 insertions(+), 24 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr126814.c

diff --git a/gcc/gimple-range-fold.cc b/gcc/gimple-range-fold.cc
index 5a2736c6ebc..a64529603f8 100644
--- a/gcc/gimple-range-fold.cc
+++ b/gcc/gimple-range-fold.cc
@@ -690,6 +690,14 @@ fold_using_range::fold_stmt (vrange &r, gimple *s, fur_source &src, tree name)
   if (gimple_code (s) == GIMPLE_ASSIGN && range_from_readonly_var (r, s))
     return true;
 
+  // Save the current range query and restore it before returning.
+  // If the specified query is different, make it the current one.
+  // PR 125854 - The fold machinery may make a query call.
+  // PR 126814 - tree_expr_nonnegative_p may make a call.
+  range_query *save = cfun->x_range_query;
+  if (src.query () != get_range_query (cfun))
+    cfun->x_range_query = src.query ();
+
   gimple_range_op_handler handler (s);
   if (gimple_code (s) == GIMPLE_ASSIGN
       && gimple_assign_rhs_code (s) == ADDR_EXPR)
@@ -722,6 +730,8 @@ fold_using_range::fold_stmt (vrange &r, gimple *s, fur_source &src, tree name)
 
   if (!res)
     {
+      // Restore the original query.
+      cfun->x_range_query = save;
       // If no name specified or range is unsupported, bail.
       if (!name || !gimple_range_ssa_p (name))
 	return false;
@@ -731,7 +741,11 @@ fold_using_range::fold_stmt (vrange &r, gimple *s, fur_source &src, tree name)
     }
 
   if (r.undefined_p ())
-    return true;
+    {
+      // Restore the original query.
+      cfun->x_range_query = save;
+      return true;
+    }
 
   // We sometimes get compatible types copied from operands, make sure
   // the correct type is being returned.
@@ -741,35 +755,32 @@ fold_using_range::fold_stmt (vrange &r, gimple *s, fur_source &src, tree name)
       range_cast (r, TREE_TYPE (name));
     }
 
-  // IF this is not a prange, we are done.
-  if (!is_a <prange> (r))
-    return true;
-
-  prange &p = as_a <prange> (r);
-  // Check to see if points_to should be set.
-  if (p.pt_unknown_p () && name && gimple_code (s) == GIMPLE_ASSIGN)
+  if (is_a <prange> (r))
     {
-      tree rhs = gimple_assign_rhs1 (s);
-      tree_code code = gimple_assign_rhs_code (s);
-      // If code is SSA_NAME, any points to would already be copied.
-      if (code != SSA_NAME && get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS
-	  && TREE_CODE (rhs) == ADDR_EXPR)
+      prange &p = as_a <prange> (r);
+      // Check to see if points_to should be set.
+      if (p.pt_unknown_p () && name && gimple_code (s) == GIMPLE_ASSIGN)
 	{
-	  p.set_pt (rhs, true);
-	}
-      // PR 125854 - Do not attempt to invoke the fold machinery unless this
-      // query is the same as the current query (which fold may invoke).
-      else if (src.query () == get_range_query (cfun))
-	{
-	  // If we couldn't find anything, try fold.
-	  x_fold_context = { s, src.query () };
-	  rhs = gimple_fold_stmt_to_constant_1 (s, pta_valueize, pta_valueize);
-	  if (rhs && TREE_CODE (rhs) == ADDR_EXPR)
+	  tree rhs = gimple_assign_rhs1 (s);
+	  tree_code code = gimple_assign_rhs_code (s);
+	  // If code is SSA_NAME, any points to would already be copied.
+	  if (code != SSA_NAME
+	      && get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS
+	      && TREE_CODE (rhs) == ADDR_EXPR)
+	    p.set_pt (rhs, true);
+	  else
 	    {
-	      p.set_pt (rhs, true);
+	      // If we couldn't find anything, try fold.
+	      x_fold_context = { s, src.query () };
+	      rhs = gimple_fold_stmt_to_constant_1 (s, pta_valueize,
+						    pta_valueize);
+	      if (rhs && TREE_CODE (rhs) == ADDR_EXPR)
+		p.set_pt (rhs, true);
 	    }
 	}
     }
+  // Restore the original query.
+  cfun->x_range_query = save;
   return true;
 }
 
diff --git a/gcc/testsuite/gcc.dg/pr126814.c b/gcc/testsuite/gcc.dg/pr126814.c
new file mode 100644
index 00000000000..b7a937d9c98
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr126814.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -funsafe-math-optimizations" } */
+
+float r;
+void use (int);
+
+void
+check (int n)
+{
+  for (int j = 0; j < n; j++)
+    {
+      int y = (int) __builtin_ceilf (j * r);
+      if (y >= n)
+        y = -n;
+      use (y * 4);
+    }
+}
-- 
2.45.0
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