[PATCH] Don't ICE on symbolic ranges in VRP (PR tree-optimization/68455)

[Marek Polacek <polacek@redhat.com>]

We blow up on the following testcase because we find ourselves passing
[_13 + 1, INT_MAX] as a vr1 to extract_range_from_multiplicative_op_1;
that's bad because this function immediately calls vrp_int_const_binop
which just doesn't work for symbolic ranges, it only wants int_csts.

This started with Richards S.'s changes in r228614 -- we're now since
able to recurse into SSA names, thus get better info about ranges.
That means that range_includes_zero_p in extract_range_from_binary_expr_1
for the *_DIV_EXPR cases was able to determine that the range doesn't
include zero, so we went through a different code path and ended up
calling extract_range_from_multiplicative_op_1 even with symbolic ranges.

I couldn't come up with anything better than checking that we're dealing
with nonsymbolic ranges for such a case.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2015-11-23  Marek Polacek  <polacek@redhat.com>

	PR tree-optimization/68455
	* tree-vrp.c (extract_range_from_binary_expr_1): Don't call
	extract_range_from_multiplicative_op_1 on symbolic ranges.

	* gcc.dg/tree-ssa/pr68455.c: New test.

diff --git gcc/testsuite/gcc.dg/tree-ssa/pr68455.c gcc/testsuite/gcc.dg/tree-ssa/pr68455.c
index e69de29..6b46b30 100644
--- gcc/testsuite/gcc.dg/tree-ssa/pr68455.c
+++ gcc/testsuite/gcc.dg/tree-ssa/pr68455.c
@@ -0,0 +1,19 @@
+/* PR tree-optimization/68455 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+int r;
+int n;
+
+void
+fn1 (void)
+{
+  int i;
+
+  for (i = 0; i < 1; ++i)
+    {
+      unsigned short int u;
+      if (u < n)
+	r = 1 / n;
+    }
+}
diff --git gcc/tree-vrp.c gcc/tree-vrp.c
index 7001190..acbb70b 100644
--- gcc/tree-vrp.c
+++ gcc/tree-vrp.c
@@ -3015,7 +3015,7 @@ extract_range_from_binary_expr_1 (value_range *vr,
 	      return;
 	    }
 	}
-      else
+      else if (!symbolic_range_p (&vr0) && !symbolic_range_p (&vr1))
 	{
 	  extract_range_from_multiplicative_op_1 (vr, code, &vr0, &vr1);
 	  return;

	Marek