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8b2a1911b2
- On Android, we were already doing it, but using fallible allocations. - On *nix, it probably doesn't make a difference, but can't hurt. For most things in Gecko, operator new/delete are inlined and thus replaced by direct calls to the underlying allocator functions (moz_xmalloc, malloc, etc.). This may have a benefit for some third party libraries that would otherwise go through libstdc++'s to eventually end up back into our allocator via the zone allocator on macOS and via the exported symbols on others. - On Windows, because of how some CRT static libraries are, a non-inlined operator new (thanks to some disabled STL wrapping) would end up linked against the system malloc, causing problems. Overall, this can only be better. This also reduces the number of places where we define those functions. And on Android, this means operator new within mozglue becomes infallible, which is more consistent with everything else. Differential Revision: https://phabricator.services.mozilla.com/D36166 --HG-- extra : moz-landing-system : lando
83 lines
2.6 KiB
C++
83 lines
2.6 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_cxxalloc_h
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#define mozilla_cxxalloc_h
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/*
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* We implement the default operators new/delete as part of
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* libmozalloc, replacing their definitions in libstdc++. The
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* operator new* definitions in libmozalloc will never return a NULL
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* pointer.
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*
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* Each operator new immediately below returns a pointer to memory
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* that can be delete'd by any of
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*
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* (1) the matching infallible operator delete immediately below
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* (2) the matching system |operator delete(void*, std::nothrow)|
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* (3) the matching system |operator delete(void*) noexcept(false)|
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*
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* NB: these are declared |noexcept(false)|, though they will never
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* throw that exception. This declaration is consistent with the rule
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* that |::operator new() noexcept(false)| will never return NULL.
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*
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* NB: mozilla::fallible can be used instead of std::nothrow.
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*/
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#ifndef MOZALLOC_EXPORT_NEW
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# define MOZALLOC_EXPORT_NEW MFBT_API
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#endif
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MOZALLOC_EXPORT_NEW void* operator new(size_t size) noexcept(false) {
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return moz_xmalloc(size);
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}
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MOZALLOC_EXPORT_NEW void* operator new(size_t size,
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const std::nothrow_t&) noexcept(true) {
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return malloc_impl(size);
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}
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MOZALLOC_EXPORT_NEW void* operator new[](size_t size) noexcept(false) {
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return moz_xmalloc(size);
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}
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MOZALLOC_EXPORT_NEW void* operator new[](size_t size,
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const std::nothrow_t&) noexcept(true) {
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return malloc_impl(size);
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}
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MOZALLOC_EXPORT_NEW void operator delete(void* ptr) noexcept(true) {
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return free_impl(ptr);
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}
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MOZALLOC_EXPORT_NEW void operator delete(void* ptr,
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const std::nothrow_t&)noexcept(true) {
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return free_impl(ptr);
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}
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MOZALLOC_EXPORT_NEW void operator delete[](void* ptr) noexcept(true) {
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return free_impl(ptr);
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}
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MOZALLOC_EXPORT_NEW void operator delete[](
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void* ptr, const std::nothrow_t&) noexcept(true) {
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return free_impl(ptr);
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}
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#if defined(XP_WIN)
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// We provide the global sized delete overloads unconditionally because the
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// MSVC runtime headers do, despite compiling with /Zc:sizedDealloc-
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MOZALLOC_EXPORT_NEW void operator delete(void* ptr,
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size_t /*size*/) noexcept(true) {
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return free_impl(ptr);
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}
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MOZALLOC_EXPORT_NEW void operator delete[](void* ptr,
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size_t /*size*/) noexcept(true) {
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return free_impl(ptr);
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}
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#endif
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#endif /* mozilla_cxxalloc_h */
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