Fixed bug 4557 - SDL_SIMDAlloc and *Free should be in the public interface

Martin Gerhardy

These functions are really useful and should get exposed imo.

include/SDL_cpuinfo.h

@@ -196,6 +196,69 @@ extern DECLSPEC SDL_bool SDLCALL SDL_HasNEON(void);
  */
 extern DECLSPEC int SDLCALL SDL_GetSystemRAM(void);
 
+/**
+ * \brief Report the alignment this system needs for SIMD allocations.
+ *
+ * This will return the minimum number of bytes to which a pointer must be
+ *  aligned to be compatible with SIMD instructions on the current machine.
+ *  For example, if the machine supports SSE only, it will return 16, but if
+ *  it supports AVX-512F, it'll return 64 (etc). This only reports values for
+ *  instruction sets SDL knows about, so if your SDL build doesn't have
+ *  SDL_HasAVX512F(), then it might return 16 for the SSE support it sees and
+ *  not 64 for the AVX-512 instructions that exist but SDL doesn't know about.
+ *  Plan accordingly.
+ */
+extern DECLSPEC size_t SDLCALL SDL_SIMDGetAlignment(void);
+
+/**
+ * \brief Allocate memory in a SIMD-friendly way.
+ *
+ * This will allocate a block of memory that is suitable for use with SIMD
+ *  instructions. Specifically, it will be properly aligned and padded for
+ *  the system's supported vector instructions.
+ *
+ * The memory returned will be padded such that it is safe to read or write
+ *  an incomplete vector at the end of the memory block. This can be useful
+ *  so you don't have to drop back to a scalar fallback at the end of your
+ *  SIMD processing loop to deal with the final elements without overflowing
+ *  the allocated buffer.
+ *
+ * You must free this memory with SDL_FreeSIMD(), not free() or SDL_free()
+ *  or delete[], etc.
+ *
+ * Note that SDL will only deal with SIMD instruction sets it is aware of;
+ *  for example, SDL 2.0.8 knows that SSE wants 16-byte vectors
+ *  (SDL_HasSSE()), and AVX2 wants 32 bytes (SDL_HasAVX2()), but doesn't
+ *  know that AVX-512 wants 64. To be clear: if you can't decide to use an
+ *  instruction set with an SDL_Has*() function, don't use that instruction
+ *  set with memory allocated through here.
+ *
+ * SDL_AllocSIMD(0) will return a non-NULL pointer, assuming the system isn't
+ *  out of memory.
+ *
+ *  \param len The length, in bytes, of the block to allocated. The actual
+ *             allocated block might be larger due to padding, etc.
+ * \return Pointer to newly-allocated block, NULL if out of memory.
+ *
+ * \sa SDL_SIMDAlignment
+ * \sa SDL_SIMDFree
+ */
+extern DECLSPEC void * SDLCALL SDL_SIMDAlloc(const size_t len);
+
+/**
+ * \brief Deallocate memory obtained from SDL_SIMDAlloc
+ *
+ * It is not valid to use this function on a pointer from anything but
+ *  SDL_SIMDAlloc(). It can't be used on pointers from malloc, realloc,
+ *  SDL_malloc, memalign, new[], etc.
+ *
+ * However, SDL_SIMDFree(NULL) is a legal no-op.
+ *
+ * \sa SDL_SIMDAlloc
+ */
+extern DECLSPEC void SDLCALL SDL_SIMDFree(void *ptr);
+
+/* vi: set ts=4 sw=4 expandtab: */
 /* Ends C function definitions when using C++ */
 #ifdef __cplusplus
 }

src/cpuinfo/SDL_cpuinfo.c

@@ -22,7 +22,6 @@
 #include "SDL_config.h"
 #else
 #include "../SDL_internal.h"
-#include "SDL_simd.h"
 #endif
 
 #if defined(__WIN32__) || defined(__WINRT__)

src/cpuinfo/SDL_simd.h

@@ -1,88 +0,0 @@
-/*
-  Simple DirectMedia Layer
-  Copyright (C) 1997-2019 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.h"
-#include "../SDL_internal.h"
-
-/**
- * \brief Report the alignment this system needs for SIMD allocations.
- *
- * This will return the minimum number of bytes to which a pointer must be
- *  aligned to be compatible with SIMD instructions on the current machine.
- *  For example, if the machine supports SSE only, it will return 16, but if
- *  it supports AVX-512F, it'll return 64 (etc). This only reports values for
- *  instruction sets SDL knows about, so if your SDL build doesn't have
- *  SDL_HasAVX512F(), then it might return 16 for the SSE support it sees and
- *  not 64 for the AVX-512 instructions that exist but SDL doesn't know about.
- *  Plan accordingly.
- */
-extern size_t SDL_SIMDGetAlignment(void);
-
-/**
- * \brief Allocate memory in a SIMD-friendly way.
- *
- * This will allocate a block of memory that is suitable for use with SIMD
- *  instructions. Specifically, it will be properly aligned and padded for
- *  the system's supported vector instructions.
- *
- * The memory returned will be padded such that it is safe to read or write
- *  an incomplete vector at the end of the memory block. This can be useful
- *  so you don't have to drop back to a scalar fallback at the end of your
- *  SIMD processing loop to deal with the final elements without overflowing
- *  the allocated buffer.
- *
- * You must free this memory with SDL_FreeSIMD(), not free() or SDL_free()
- *  or delete[], etc.
- *
- * Note that SDL will only deal with SIMD instruction sets it is aware of;
- *  for example, SDL 2.0.8 knows that SSE wants 16-byte vectors
- *  (SDL_HasSSE()), and AVX2 wants 32 bytes (SDL_HasAVX2()), but doesn't
- *  know that AVX-512 wants 64. To be clear: if you can't decide to use an
- *  instruction set with an SDL_Has*() function, don't use that instruction
- *  set with memory allocated through here.
- *
- * SDL_AllocSIMD(0) will return a non-NULL pointer, assuming the system isn't
- *  out of memory.
- *
- *  \param len The length, in bytes, of the block to allocated. The actual
- *             allocated block might be larger due to padding, etc.
- * \return Pointer to newly-allocated block, NULL if out of memory.
- *
- * \sa SDL_SIMDAlignment
- * \sa SDL_SIMDFree
- */
-extern void * SDL_SIMDAlloc(const size_t len);
-
-/**
- * \brief Deallocate memory obtained from SDL_SIMDAlloc
- *
- * It is not valid to use this function on a pointer from anything but
- *  SDL_SIMDAlloc(). It can't be used on pointers from malloc, realloc,
- *  SDL_malloc, memalign, new[], etc.
- *
- * However, SDL_SIMDFree(NULL) is a legal no-op.
- *
- * \sa SDL_SIMDAlloc
- */
-extern void SDL_SIMDFree(void *ptr);
-
-/* vi: set ts=4 sw=4 expandtab: */
-

src/dynapi/SDL_dynapi_overrides.h

@@ -714,3 +714,6 @@
 #define SDL_RenderCopyExF SDL_RenderCopyExF_REAL
 #define SDL_GetTouchDeviceType SDL_GetTouchDeviceType_REAL
 #define SDL_UIKitRunApp SDL_UIKitRunApp_REAL
+#define SDL_SIMDGetAlignment SDL_SIMDGetAlignment_REAL
+#define SDL_SIMDAlloc SDL_SIMDAlloc_REAL
+#define SDL_SIMDFree SDL_SIMDFree_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -770,3 +770,6 @@ SDL_DYNAPI_PROC(SDL_TouchDeviceType,SDL_GetTouchDeviceType,(SDL_TouchID a),(a),r
 #ifdef __IPHONEOS__
 SDL_DYNAPI_PROC(int,SDL_UIKitRunApp,(int a, char *b, SDL_main_func c),(a,b,c),return)
 #endif
+SDL_DYNAPI_PROC(size_t,SDL_SIMDGetAlignment,(void),(),return)
+SDL_DYNAPI_PROC(void*,SDL_SIMDAlloc,(const size_t a),(a),return)
+SDL_DYNAPI_PROC(void,SDL_SIMDFree,(void *a),(a),)

src/video/SDL_RLEaccel.c

@@ -89,7 +89,6 @@
 #include "SDL_sysvideo.h"
 #include "SDL_blit.h"
 #include "SDL_RLEaccel_c.h"
-#include "../cpuinfo/SDL_simd.h"
 
 #ifndef MIN
 #define MIN(a, b) ((a) < (b) ? (a) : (b))

src/video/SDL_surface.c

@@ -26,7 +26,6 @@
 #include "SDL_RLEaccel_c.h"
 #include "SDL_pixels_c.h"
 #include "SDL_yuv_c.h"
-#include "../cpuinfo/SDL_simd.h"
 
 
 /* Check to make sure we can safely check multiplication of surface w and pitch and it won't overflow size_t */