This provides a definition of aligned_alloc for targets which have
none of aligned_alloc, posix_memalign, memalign or _aligned_alloc.
The code is based on gcc/config/i386/gmm_malloc.h but modified to only
use sizeof(void*) not 2*sizeof(void*), because I don't understand why
that's used in gmm_malloc.h, or what the comment means.
libstdc++-v3:
PR libstdc++/79190
* libsupc++/del_opa.cc (operator delete(void*, std::align_val_t))
[!_GLIBCXX_HAVE_ALIGNED_ALLOC && !_GLIBCXX_HAVE_POSIX_MEMALIGN
&& !_GLIBCXX_HAVE_MEMALIGN && !_GLIBCXX_HAVE__ALIGNED_MALLOC]:
Retrieve original pointer value allocated by malloc.
* libsupc++/new_opa.cc [!_GLIBCXX_HAVE_ALIGNED_ALLOC
&& !_GLIBCXX_HAVE_POSIX_MEMALIGN && !_GLIBCXX_HAVE_MEMALIGN
&& !_GLIBCXX_HAVE__ALIGNED_MALLOC] (aligned_alloc(size_t, size_t)):
Define, adjusting pointer value allocated by malloc and storing for
retrieval by operator delete.
gcc/testsuite:
PR libstdc++/79190
* g++.dg/cpp1z/aligned-new3.C: Replace operator new so behaviour
matches replaced operator delete.
Tested powerpc64le-linux, and also tested after tweaking the
preprocessor checks so the new code was used.
If this works for HPUX I plan to commit it to trunk.
commit 2f17c7769b6917b6ab6884c87c4496e32d4cc057
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Tue Jan 24 16:17:15 2017 +0000
PR libstdc++/79190 add fallback aligned_alloc implementation
libstdc++-v3:
PR libstdc++/79190
* libsupc++/del_opa.cc (operator delete(void*, std::align_val_t))
[!_GLIBCXX_HAVE_ALIGNED_ALLOC && !_GLIBCXX_HAVE_POSIX_MEMALIGN
&& !_GLIBCXX_HAVE_MEMALIGN && !_GLIBCXX_HAVE__ALIGNED_MALLOC]:
Retrieve original pointer value allocated by malloc.
* libsupc++/new_opa.cc [!_GLIBCXX_HAVE_ALIGNED_ALLOC
&& !_GLIBCXX_HAVE_POSIX_MEMALIGN && !_GLIBCXX_HAVE_MEMALIGN
&& !_GLIBCXX_HAVE__ALIGNED_MALLOC] (aligned_alloc(size_t, size_t)):
Define, adjusting pointer value allocated by malloc and storing for
retrieval by operator delete.
gcc/testsuite:
PR libstdc++/79190
* g++.dg/cpp1z/aligned-new3.C: Replace operator new so behaviour
matches replaced operator delete.
diff --git a/gcc/testsuite/g++.dg/cpp1z/aligned-new3.C
b/gcc/testsuite/g++.dg/cpp1z/aligned-new3.C
index 73e3343..e50e62c 100644
--- a/gcc/testsuite/g++.dg/cpp1z/aligned-new3.C
+++ b/gcc/testsuite/g++.dg/cpp1z/aligned-new3.C
@@ -7,6 +7,11 @@ struct alignas(64) A {
int i;
};
+void* operator new (std::size_t n, std::align_val_t)
+{
+ return operator new (n);
+}
+
bool deleted = false;
void operator delete (void *p, std::size_t, std::align_val_t)
{
diff --git a/libstdc++-v3/libsupc++/del_opa.cc
b/libstdc++-v3/libsupc++/del_opa.cc
index c9afb46..f7bf7a4 100644
--- a/libstdc++-v3/libsupc++/del_opa.cc
+++ b/libstdc++-v3/libsupc++/del_opa.cc
@@ -46,9 +46,13 @@ _GLIBCXX_END_NAMESPACE_VERSION
_GLIBCXX_WEAK_DEFINITION void
operator delete(void* ptr, std::align_val_t) _GLIBCXX_USE_NOEXCEPT
{
-#if !_GLIBCXX_HAVE_ALIGNED_ALLOC && _GLIBCXX_HAVE__ALIGNED_MALLOC
+#if _GLIBCXX_HAVE_ALIGNED_ALLOC || _GLIBCXX_HAVE_POSIX_MEMALIGN \
+ || _GLIBCXX_HAVE_MEMALIGN
+ std::free (ptr);
+#elif _GLIBCXX_HAVE__ALIGNED_MALLOC
_aligned_free (ptr);
#else
- std::free(ptr);
+ if (ptr)
+ std::free (((void **) ptr)[-1]); // See aligned_alloc in new_opa.cc
#endif
}
diff --git a/libstdc++-v3/libsupc++/new_opa.cc
b/libstdc++-v3/libsupc++/new_opa.cc
index 0bc2b5f..5d6c185 100644
--- a/libstdc++-v3/libsupc++/new_opa.cc
+++ b/libstdc++-v3/libsupc++/new_opa.cc
@@ -55,9 +55,30 @@ extern "C" void *memalign(std::size_t boundary, std::size_t
size);
#endif
#define aligned_alloc memalign
#else
-// The C library doesn't provide any aligned allocation functions, declare
-// aligned_alloc and get a link failure if aligned new is used.
-extern "C" void *aligned_alloc(std::size_t, std::size_t);
+// This is a modified version of code from gcc/config/i386/gmm_malloc.h
+static inline void*
+aligned_alloc (std::size_t al, std::size_t sz)
+{
+ // Alignment must be a power of two.
+ if (al & (al - 1))
+ return nullptr;
+ else if (!sz)
+ return nullptr;
+
+ // We need extra bytes to store the original value returned by malloc.
+ if (al < sizeof(void*))
+ al = sizeof(void*);
+ void* const malloc_ptr = malloc(sz + al);
+ if (!malloc_ptr)
+ return nullptr;
+ // Align to the requested value, leaving room for the original malloc value.
+ void* const aligned_ptr = (void *) (((size_t) malloc_ptr + al) & -al);
+
+ // Store the original malloc value where it can be found by operator delete.
+ ((void **) aligned_ptr)[-1] = malloc_ptr;
+
+ return aligned_ptr;
+}
#endif
#endif
