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re PR c++/71537 (GCC rejects consetxpr boolean conversions and comparisons on the result of pointer arithmetic.)

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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
This commit is contained in:
Jakub Jelinek 2016-12-06 10:24:36 +01:00 committed by Jakub Jelinek
parent 66972191ee
commit 0f57194bfc
4 changed files with 36 additions and 8 deletions
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5
gcc/ChangeLog
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@ -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,

18
gcc/fold-const.c
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@ -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))

3
gcc/testsuite/ChangeLog
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@ -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.

18
gcc/testsuite/g++.dg/cpp0x/constexpr-71537.C Normal file
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@ -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, "");