re PR c++/71537 (GCC rejects consetxpr boolean conversions and comparisons on the...

	PR c++/71537
	* fold-const.c (fold_comparison): Assume CONSTANT_CLASS_P (base0)
	plus offset is non-zero.  For maybe_nonzero_address decl base0,
	require indirect_base0.

	* g++.dg/cpp0x/constexpr-71537.C: New test.

From-SVN: r243286

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9ed8f5f829507c019d6b1e75850e767ab3460b51..aef86e3566ccffaa97b2d4ee12dad2041f84adb8 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,10 @@
 2016-12-06  Jakub Jelinek  <jakub@redhat.com>
 
+       PR c++/71537
+       * fold-const.c (fold_comparison): Assume CONSTANT_CLASS_P (base0)
+       plus offset is non-zero.  For maybe_nonzero_address decl base0,
+       require indirect_base0.
+
        PR c++/71537
        * fold-const-call.c (fold_const_call_1): Remove memchr handling here.
        (fold_const_call) <case CFN_BUILT_IN_STRNCMP,

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 6517188c4c6026205731e044a5e0fde3c1011c0d..c649e547ead5997504b5b3addd22471532878e6f 100644 (file)
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -8419,14 +8419,16 @@ fold_comparison (location_t loc, enum tree_code code, tree type,
         below follow the C++ rules with the additional property that
         every object pointer compares greater than a null pointer.
       */
-      else if (DECL_P (base0)
-              && maybe_nonzero_address (base0) > 0
-              /* Avoid folding references to struct members at offset 0 to
-                 prevent tests like '&ptr->firstmember == 0' from getting
-                 eliminated.  When ptr is null, although the -> expression
-                 is strictly speaking invalid, GCC retains it as a matter
-                 of QoI.  See PR c/44555. */
-              && (offset0 == NULL_TREE && bitpos0 != 0)
+      else if (((DECL_P (base0)
+                && maybe_nonzero_address (base0) > 0
+                /* Avoid folding references to struct members at offset 0 to
+                   prevent tests like '&ptr->firstmember == 0' from getting
+                   eliminated.  When ptr is null, although the -> expression
+                   is strictly speaking invalid, GCC retains it as a matter
+                   of QoI.  See PR c/44555. */
+                && (offset0 == NULL_TREE && bitpos0 != 0))
+               || CONSTANT_CLASS_P (base0))
+              && indirect_base0
               /* The caller guarantees that when one of the arguments is
                  constant (i.e., null in this case) it is second.  */
               && integer_zerop (arg1))

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b44993b956b927360a25a1651d29b809439ad2ab..7aa429fca28505ce86b4d65af671fa2cb712ed93 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2016-12-06  Jakub Jelinek  <jakub@redhat.com>
 
+       PR c++/71537
+       * g++.dg/cpp0x/constexpr-71537.C: New test.
+
        PR c++/71537
        * g++.dg/cpp0x/constexpr-memchr.C: New test.
 

diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-71537.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-71537.C
new file mode 100644 (file)
index 0000000..3d5ac34
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-71537.C
@@ -0,0 +1,18 @@
+// PR c++/71537
+// { dg-do compile { target c++11 } }
+
+constexpr int n[42] = {1};
+constexpr int x1 = n ? 1 : 0;
+constexpr int x2 = n + 1 ? 1 : 0;
+constexpr int x3 = "abc" ? 1 : 0;
+constexpr int x4 = "abc" + 1 ? 1 : 0;
+constexpr bool x5 = "abc" + 1;
+constexpr bool x6 = "abc" + 4;
+constexpr bool x7 = n + 42;
+static_assert (x1 == 1, "");
+static_assert (x2 == 1, "");
+static_assert (x3 == 1, "");
+static_assert (x4 == 1, "");
+static_assert (x5, "");
+static_assert (x6, "");
+static_assert (x7, "");