Retain existing range knowledge when prefilling statements.

When range_of_stmt was adjusted to avoid large recursion depth, we need to
intersect the calculated range whth the any known range to avoid losing
info.  Range_of_stmt does this, but the new prefill code missed it.

	PR tree-optimization/105276
	gcc/
	* gimple-range.cc (gimple_ranger::prefill_stmt_dependencies): Include
	existing global range with calculated value.

	gcc/testsuite/
	* g++.dg/pr105276.C: New.

diff --git a/gcc/gimple-range.cc b/gcc/gimple-range.cc
index 04075a9..f0caefc 100644 (file)
--- a/gcc/gimple-range.cc
+++ b/gcc/gimple-range.cc
@@ -394,6 +394,10 @@ gimple_ranger::prefill_stmt_dependencies (tree ssa)
              // Fold and save the value for NAME.
              stmt = SSA_NAME_DEF_STMT (name);
              fold_range_internal (r, stmt, name);
+             // Make sure we don't lose any current global info.
+             int_range_max tmp;
+             m_cache.get_global_range (tmp, name);
+             r.intersect (tmp);
              m_cache.set_global_range (name, r);
            }
          continue;

diff --git a/gcc/testsuite/g++.dg/pr105276.C b/gcc/testsuite/g++.dg/pr105276.C
new file mode 100644 (file)
index 0000000..ad0e9dd
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr105276.C
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+bool
+foo(unsigned i)
+{
+  bool result = true;
+  while (i)
+    {
+      i = i % 3;
+      i = i - (i == 2 ? 2 : i ? 1 : 0);
+      result = !result;
+    }
+  return result;
+}
+
+/* We should be able to eliminate the i - operation.  */
+/* { dg-final { scan-tree-dump-not "i_.* - " "optimized" } } */