re PR tree-optimization/79408 (Missed VRP optimization of integer modulo)

	PR tree-optimization/79408
	* tree-vrp.c (simplify_div_or_mod_using_ranges): Handle also the
	case when on TRUNC_MOD_EXPR op0 is INTEGER_CST.
	(simplify_stmt_using_ranges): Call simplify_div_or_mod_using_ranges
	also if rhs1 is INTEGER_CST.

	* gcc.dg/tree-ssa/pr79408-2.c: New test.

From-SVN: r245420

4 files changed, 73 insertions, 6 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 03c2808..c6adaff 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2017-02-14  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/79408
+	* tree-vrp.c (simplify_div_or_mod_using_ranges): Handle also the
+	case when on TRUNC_MOD_EXPR op0 is INTEGER_CST.
+	(simplify_stmt_using_ranges): Call simplify_div_or_mod_using_ranges
+	also if rhs1 is INTEGER_CST.
+
 2017-02-14  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/79432
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 7881615..105444e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-02-14  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/79408
+	* gcc.dg/tree-ssa/pr79408-2.c: New test.
+
 2017-02-14  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/79432
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr79408-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr79408-2.c
new file mode 100644
index 0000000..696fb582
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr79408-2.c
@@ -0,0 +1,34 @@
+/* PR tree-optimization/79408 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+void link_error (void);
+
+void
+foo (unsigned int y)
+{
+  if (y <= 7312)
+    return;
+  if (7312 % y != 7312)
+    link_error ();
+}
+
+void
+bar (int x, int y)
+{
+  if (y <= 7312)
+    return;
+  if (7312 % y != 7312)
+    link_error ();
+}
+
+void
+baz (int x, int y)
+{
+  if (y <= 7312)
+    return;
+  if (-7312 % y != -7312)
+    link_error ();
+}
+
+/* { dg-final { scan-tree-dump-times "link_error" 0 "optimized"} } */
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index e058d8d..9ffecc9 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -9241,8 +9241,24 @@ simplify_div_or_mod_using_ranges (gimple_stmt_iterator *gsi, gimple *stmt)
   tree val = NULL;
   tree op0 = gimple_assign_rhs1 (stmt);
   tree op1 = gimple_assign_rhs2 (stmt);
+  tree op0min = NULL_TREE, op0max = NULL_TREE;
   tree op1min = op1;
-  value_range *vr = get_value_range (op0);
+  value_range *vr = NULL;
+
+  if (TREE_CODE (op0) == INTEGER_CST)
+    {
+      op0min = op0;
+      op0max = op0;
+    }
+  else
+    {
+      vr = get_value_range (op0);
+      if (range_int_cst_p (vr))
+	{
+	  op0min = vr->min;
+	  op0max = vr->max;
+	}
+    }
 
   if (rhs_code == TRUNC_MOD_EXPR
       && TREE_CODE (op1) == SSA_NAME)
@@ -9254,13 +9270,13 @@ simplify_div_or_mod_using_ranges (gimple_stmt_iterator *gsi, gimple *stmt)
   if (rhs_code == TRUNC_MOD_EXPR
       && TREE_CODE (op1min) == INTEGER_CST
       && tree_int_cst_sgn (op1min) == 1
-      && range_int_cst_p (vr)
-      && tree_int_cst_lt (vr->max, op1min))
+      && op0max
+      && tree_int_cst_lt (op0max, op1min))
     {
       if (TYPE_UNSIGNED (TREE_TYPE (op0))
-	  || tree_int_cst_sgn (vr->min) >= 0
+	  || tree_int_cst_sgn (op0min) >= 0
 	  || tree_int_cst_lt (fold_unary (NEGATE_EXPR, TREE_TYPE (op1min), op1min),
-			      vr->min))
+			      op0min))
 	{
 	  /* If op0 already has the range op0 % op1 has,
 	     then TRUNC_MOD_EXPR won't change anything.  */
@@ -9269,6 +9285,9 @@ simplify_div_or_mod_using_ranges (gimple_stmt_iterator *gsi, gimple *stmt)
 	}
     }
 
+  if (TREE_CODE (op0) != SSA_NAME)
+    return false;
+
   if (!integer_pow2p (op1))
     {
       /* X % -Y can be only optimized into X % Y either if
@@ -10377,7 +10396,8 @@ simplify_stmt_using_ranges (gimple_stmt_iterator *gsi)
 	 range.  */
 	case TRUNC_DIV_EXPR:
 	case TRUNC_MOD_EXPR:
-	  if (TREE_CODE (rhs1) == SSA_NAME
+	  if ((TREE_CODE (rhs1) == SSA_NAME
+	       || TREE_CODE (rhs1) == INTEGER_CST)
 	      && INTEGRAL_TYPE_P (TREE_TYPE (rhs1)))
 	    return simplify_div_or_mod_using_ranges (gsi, stmt);
 	  break;