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28 lines
1.2 KiB
C
28 lines
1.2 KiB
C
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/* 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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#include <mozilla/Assertions.h>
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// This function is used in vtables to point at pure virtual methods.
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// The implementation in the standard library usually aborts, but
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// the function is normally never called (a call would be a bug).
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// Each of these entries in vtables, however, require an unnecessary
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// dynamic relocation. Defining our own function makes the linker
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// point the vtables here instead of the standard library, replacing
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// the dynamic relocations with relative relocations.
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//
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// On Windows, it doesn't really make a difference, but on macOS it
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// can be packed better, saving about 10KB in libxul, and on 64-bits
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// ELF systems, with packed relative relocations, it saves 140KB.
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//
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// Another advantage of having our own is that we can use MOZ_CRASH
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// instead of the system's abort.
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#ifdef _MSC_VER
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int __cdecl _purecall() { MOZ_CRASH("pure virtual call"); }
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#else
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__attribute__((visibility("hidden"))) void __cxa_pure_virtual() {
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MOZ_CRASH("pure virtual call");
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}
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#endif
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