PR82413: Mismatched precisions in build_range_check

build_range_check explicitly allows LOW and HIGH to be a different type
from EXP, so we need to use w::to_widest when comparing a value based on
HIGH with a value based on EXP's type.

2017-10-04  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	PR tree-optimization/82413
	* fold-const.c (build_range_check): Use widest_int when comparing
	the maximum ETYPE value with HIGH.

gcc/testsuite/
	PR tree-optimization/82413
	* g++.dg/pr82413.C: New test.

From-SVN: r253401

gcc/ChangeLog

+2017-10-04  Richard Sandiford  <richard.sandiford@linaro.org>
+
+	PR tree-optimization/82413
+	* fold-const.c (build_range_check): Use widest_int when comparing
+	the maximum ETYPE value with HIGH.
+
 2017-10-04  Wilco Dijkstra  <wdijkstr@arm.com>
 
 	PR rtl-optimization/82396

gcc/fold-const.c

@@ -4851,7 +4851,7 @@ build_range_check (location_t loc, tree type, tree exp, int in_p,
     {
       int prec = TYPE_PRECISION (etype);
 
-      if (wi::mask (prec - 1, false, prec) == high)
+      if (wi::mask <widest_int> (prec - 1, false) == wi::to_widest (high))
 	{
 	  if (TYPE_UNSIGNED (etype))
 	    {

gcc/testsuite/ChangeLog

+2017-10-04  Richard Sandiford  <richard.sandiford@linaro.org>
+
+	PR tree-optimization/82413
+	* g++.dg/pr82413.C: New test.
+
 2017-10-04  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/77296

gcc/testsuite/g++.dg/pr82413.C

+bool a;
+int b;
+void c() { b &&a <= 0; }