[committed] PR82413: Mismatched precisions in build_range_check

[Richard Sandiford]

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.

Tested on powerpc64le-linux-gnu and installed as obvious.

Richard


2017-10-04  Richard Sandiford  <richard.sandif...@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.

Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c    2017-10-04 11:43:11.653350269 +0100
+++ gcc/fold-const.c    2017-10-04 11:43:49.030813918 +0100
@@ -4851,7 +4851,7 @@ build_range_check (location_t loc, tree
     {
       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))
            {
Index: gcc/testsuite/g++.dg/pr82413.C
===================================================================
--- /dev/null   2017-10-04 10:21:58.939451407 +0100
+++ gcc/testsuite/g++.dg/pr82413.C      2017-10-04 11:43:49.030813918 +0100
@@ -0,0 +1,3 @@
+bool a;
+int b;
+void c() { b &&a <= 0; }