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stlib: Extract SDL_memcpy and SDL_memset to its own file respectively

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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.
This commit is contained in:
Anonymous Maarten 2022-06-15 20:48:54 +02:00 • committed by Sam Lantinga
parent a5d338bd2d
commit ae7446a959
8 changed files with 165 additions and 104 deletions
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75
src/stdlib/SDL_memset.c Normal file
View file

@ -0,0 +1,75 @@
/*
Simple DirectMedia Layer
Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
#include "../SDL_internal.h"
/* This file contains a portable memset manipulation function for SDL */
void *
SDL_memset(SDL_OUT_BYTECAP(len) void *dst, int c, size_t len)
{
#if defined(HAVE_MEMSET)
return memset(dst, c, len);
#else
size_t left;
Uint32 *dstp4;
Uint8 *dstp1 = (Uint8 *) dst;
Uint8 value1;
Uint32 value4;
/* The value used in memset() is a byte, passed as an int */
c &= 0xff;
/* The destination pointer needs to be aligned on a 4-byte boundary to
* execute a 32-bit set. Set first bytes manually if needed until it is
* aligned. */
value1 = (Uint8)c;
while ((uintptr_t)dstp1 & 0x3) {
if (len--) {
*dstp1++ = value1;
} else {
return dst;
}
}
value4 = ((Uint32)c | ((Uint32)c << 8) | ((Uint32)c << 16) | ((Uint32)c << 24));
dstp4 = (Uint32 *) dstp1;
left = (len % 4);
len /= 4;
while (len--) {
*dstp4++ = value4;
}
dstp1 = (Uint8 *) dstp4;
switch (left) {
case 3:
*dstp1++ = value1;
case 2:
*dstp1++ = value1;
case 1:
*dstp1++ = value1;
}
return dst;
#endif /* HAVE_MEMSET */
}
/* vi: set ts=4 sw=4 expandtab: */