[PATCH] PR libstdc++/70940 make pmr::resource_adaptor return aligned memory

[Jonathan Wakely]

On 22/06/18 13:42 +0100, Jonathan Wakely wrote:
>On 22/06/18 14:34 +0200, Rainer Orth wrote:
>>Hi Jonathan,
>>
>>>	PR libstdc++/70940
>>>	* include/experimental/memory_resource (__resource_adaptor_common):
>>>	New base class.
>>>	(__resource_adaptor_common::_AlignMgr): Helper for obtaining aligned
>>>	pointer from unaligned, and vice versa.
>>>	(__resource_adaptor_imp::do_allocate): Use _AlignMgr to adjust
>>>	allocated pointer to meet alignment request.
>>>	(__resource_adaptor_imp::do_deallocate): Use _AlignMgr to retrieve
>>>	original pointer for deallocation.
>>>	(__resource_adaptor_imp::do_is_equal): Reformat.
>>>	(__resource_adaptor_imp::_S_aligned_size): Remove.
>>>	(__resource_adaptor_imp::_S_supported): Remove.
>>>	(new_delete_resource): Use __gnu_cxx::new_allocator.
>>>	* testsuite/experimental/memory_resource/resource_adaptor.cc: Test
>>>	extended alignments and use debug_allocator to check for matching
>>>	allocate/deallocate pairs.
>>>
>>>Tested x86_64-linux, committed to trunk. This is more experimental TS
>>>material, so I'll probably backport it.
>>
>>this patch has cause a couple of FAILures on 32-bit targets/multilibs.
>>I'm seeing it on i386-pc-solaris2.11 and sparc-sun-solaris2.11, with
>>gcc-testresults postings to the same effect for
>>i586-unknown-freebsd10.4, i686-pc-linux-gnu, s390x-ibm-linux-gnu,
>>x86_64-pc-linux-gnu:
>>
>>+FAIL: experimental/memory_resource/1.cc (test for excess errors)
>>+FAIL: experimental/memory_resource/70966.cc (test for excess errors)
>>+FAIL: experimental/memory_resource/null_memory_resource.cc (test for excess errors)
>>+FAIL: experimental/memory_resource/resource_adaptor.cc (test for excess errors)
>>+XPASS: experimental/memory_resource/resource_adaptor.cc execution test
>>+FAIL: experimental/type_erased_allocator/2.cc (test for excess errors)
>>
>>FAIL: experimental/type_erased_allocator/2.cc (test for excess errors)
>>Excess errors:
>>/var/gcc/regression/trunk/11.4-gcc/build/i386-pc-solaris2.11/libstdc++-v3/include/experimental/memory_resource:329: warning: left shift count >= width of type [-Wshift-count-overflow]
>
>David just created https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86280
>
>This should fix it. I'll commit it later, or if you want to test and
>commit it please go ahead.
>
>--- a/libstdc++-v3/include/experimental/memory_resource
>+++ b/libstdc++-v3/include/experimental/memory_resource
>@@ -326,7 +326,7 @@ namespace pmr {
>         return 1;
>       if (_M_align <= (1ul << (sizeof(short) * __CHAR_BIT__)))
>         return sizeof(short);
>-       if (_M_align <= (1ul << (sizeof(int) * __CHAR_BIT__)))
>+       if (_M_align <= (1ull << (sizeof(int) * __CHAR_BIT__)))
>         return sizeof(int);
>       return sizeof(char*);
>      }
>

Committed to trunk.