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ae7446a959
This is done such that we can disable LTO for these 2 functions when building with MSVC. This is due to a limitation of Link Time Code Generation (LTCG). Code generation might generate a new reference to memset after linking has started. The LTCG must make assumptions about where memset is defined which is normally the C runtime.
80 lines
2.5 KiB
C
80 lines
2.5 KiB
C
/*
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Simple DirectMedia Layer
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Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#include "../SDL_internal.h"
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/* This file contains a portable memcpy manipulation function for SDL */
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void *
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SDL_memcpy(SDL_OUT_BYTECAP(len) void *dst, SDL_IN_BYTECAP(len) const void *src, size_t len)
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{
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#ifdef __GNUC__
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/* Presumably this is well tuned for speed.
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On my machine this is twice as fast as the C code below.
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*/
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return __builtin_memcpy(dst, src, len);
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#elif defined(HAVE_MEMCPY)
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return memcpy(dst, src, len);
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#elif defined(HAVE_BCOPY)
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bcopy(src, dst, len);
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return dst;
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#else
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/* GCC 4.9.0 with -O3 will generate movaps instructions with the loop
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using Uint32* pointers, so we need to make sure the pointers are
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aligned before we loop using them.
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*/
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if (((uintptr_t)src & 0x3) || ((uintptr_t)dst & 0x3)) {
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/* Do an unaligned byte copy */
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Uint8 *srcp1 = (Uint8 *)src;
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Uint8 *dstp1 = (Uint8 *)dst;
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while (len--) {
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*dstp1++ = *srcp1++;
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}
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} else {
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size_t left = (len % 4);
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Uint32 *srcp4, *dstp4;
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Uint8 *srcp1, *dstp1;
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srcp4 = (Uint32 *) src;
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dstp4 = (Uint32 *) dst;
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len /= 4;
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while (len--) {
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*dstp4++ = *srcp4++;
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}
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srcp1 = (Uint8 *) srcp4;
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dstp1 = (Uint8 *) dstp4;
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switch (left) {
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case 3:
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*dstp1++ = *srcp1++;
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case 2:
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*dstp1++ = *srcp1++;
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case 1:
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*dstp1++ = *srcp1++;
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}
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}
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return dst;
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#endif /* __GNUC__ */
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}
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/* vi: set ts=4 sw=4 expandtab: */
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