ARM: Create configure option --enable-arm-simd to govern assembly opt…

…imizations --- configure.in | 60 +++++++++++++++++++-------------------- include/SDL_config.h.in | 1 + include/SDL_cpuinfo.h | 3 ++ src/cpuinfo/SDL_cpuinfo.c | 53 ++++++++++++++++++++++++++++++++++ 4 files changed, 87 insertions(+), 30 deletions(-)
libsdl-org · Oct 31, 2019 · 36c7b0c · 36c7b0c
1 parent 9c7648d
commit 36c7b0c
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Showing 4 changed files with 94 additions and 0 deletions.
diff --git a/configure.in b/configure.in
@@ -893,6 +893,42 @@ AC_HELP_STRING([--enable-altivec], [use altivec assembly blitters on PPC [[defau
     fi
 }
 
+dnl Check for ARM instruction support using gas syntax
+CheckARM()
+{
+    AC_ARG_ENABLE(arm-simd,
+AC_HELP_STRING([--enable-arm-simd], [use SIMD assembly blitters on ARM [[default=yes]]]),
+                  enable_arm_simd=$enableval, enable_arm_simd=yes)
+    if test x$enable_video = xyes -a x$enable_assembly = xyes -a x$enable_arm_simd = xyes; then
+        save_CFLAGS="$CFLAGS"
+        have_arm_simd=no
+        CFLAGS="-x assembler-with-cpp $CFLAGS"
+
+        AC_MSG_CHECKING(for ARM SIMD)
+        AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+        .text
+        .arch armv6
+        .object_arch armv4
+        .arm
+        .altmacro
+        #ifndef __ARM_EABI__
+        #error EABI is required (to be sure that calling conventions are compatible)
+        #endif
+        pld [r0]
+        uqadd8 r0, r0, r0
+        ]])], have_arm_simd=yes)
+        AC_MSG_RESULT($have_arm_simd)
+
+        CFLAGS="$save_CFLAGS"
+
+        if test x$have_arm_simd = xyes; then
+            AC_DEFINE(SDL_ARM_SIMD_BLITTERS)
+dnl            SOURCES="$SOURCES $srcdir/src/video/arm/pixman-arm-simd*.c"
+            SOURCES="$SOURCES $srcdir/src/video/arm/pixman-arm-simd*.S"
+        fi
+    fi
+}
+
 dnl See if GCC's -fvisibility=hidden is supported (gcc4 and later, usually).
 dnl  Details of this flag are here: http://gcc.gnu.org/wiki/Visibility
 CheckVisibilityHidden()
@@ -2436,6 +2472,7 @@ case "$host" in
         CheckDLOPEN
         CheckNASM
         CheckAltivec
+        CheckARM
         CheckOSS
         CheckDMEDIA
         CheckMME

diff --git a/include/SDL_config.h.in b/include/SDL_config.h.in
@@ -312,5 +312,6 @@
 #undef SDL_ASSEMBLY_ROUTINES
 #undef SDL_HERMES_BLITTERS
 #undef SDL_ALTIVEC_BLITTERS
+#undef SDL_ARM_SIMD_BLITTERS
 
 #endif /* _SDL_config_h */
diff --git a/include/SDL_cpuinfo.h b/include/SDL_cpuinfo.h
@@ -60,6 +60,9 @@ extern DECLSPEC SDL_bool SDLCALL SDL_HasSSE2(void);
 /** This function returns true if the CPU has AltiVec features */
 extern DECLSPEC SDL_bool SDLCALL SDL_HasAltiVec(void);
 
+/** This function returns true if the CPU has ARM SIMD (ARMv6) features */
+extern DECLSPEC SDL_bool SDLCALL SDL_HasARMSIMD(void);
+
 /* Ends C function definitions when using C++ */
 #ifdef __cplusplus
 }

diff --git a/src/cpuinfo/SDL_cpuinfo.c b/src/cpuinfo/SDL_cpuinfo.c
@@ -45,6 +45,7 @@
 #define CPU_HAS_SSE	0x00000040
 #define CPU_HAS_SSE2	0x00000080
 #define CPU_HAS_ALTIVEC	0x00000100
+#define CPU_HAS_ARM_SIMD 0x00000200
 
 #if SDL_ALTIVEC_BLITTERS && HAVE_SETJMP && !__MACOSX__ && !__OpenBSD__
 /* This is the brute force way of detecting instruction sets...
@@ -390,6 +391,46 @@ static __inline__ int CPU_haveAltiVec(void)
 	return altivec; 
 }
 
+#ifdef __linux__
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <elf.h>
+
+static __inline__ int CPU_haveARMSIMD(void)
+{
+	int arm_simd = 0;
+	int fd;
+
+	fd = open("/proc/self/auxv", O_RDONLY);
+	if (fd >= 0)
+	{
+		Elf32_auxv_t aux;
+		while (read(fd, &aux, sizeof aux) == sizeof aux)
+		{
+			if (aux.a_type == AT_PLATFORM)
+			{
+				const char *plat = (const char *) aux.a_un.a_val;
+				arm_simd = strncmp(plat, "v6l", 3) == 0 ||
+				           strncmp(plat, "v7l", 3) == 0;
+			}
+		}
+		close(fd);
+	}
+	return arm_simd;
+}
+
+#else
+
+static __inline__ int CPU_haveARMSIMD(void)
+{
+	return 0;
+}
+
+#endif
+
 static Uint32 SDL_CPUFeatures = 0xFFFFFFFF;
 
 static Uint32 SDL_GetCPUFeatures(void)
@@ -420,6 +461,9 @@ static Uint32 SDL_GetCPUFeatures(void)
 		if ( CPU_haveAltiVec() ) {
 			SDL_CPUFeatures |= CPU_HAS_ALTIVEC;
 		}
+		if ( CPU_haveARMSIMD() ) {
+			SDL_CPUFeatures |= CPU_HAS_ARM_SIMD;
+		}
 	}
 	return SDL_CPUFeatures;
 }
@@ -488,6 +532,14 @@ SDL_bool SDL_HasAltiVec(void)
 	return SDL_FALSE;
 }
 
+SDL_bool SDL_HasARMSIMD(void)
+{
+	if ( SDL_GetCPUFeatures() & CPU_HAS_ARM_SIMD ) {
+		return SDL_TRUE;
+	}
+	return SDL_FALSE;
+}
+
 #ifdef TEST_MAIN
 
 #include <stdio.h>
@@ -502,6 +554,7 @@ int main()
 	printf("SSE: %d\n", SDL_HasSSE());
 	printf("SSE2: %d\n", SDL_HasSSE2());
 	printf("AltiVec: %d\n", SDL_HasAltiVec());
+	printf("ARM SIMD: %d\n", SDL_HasARMSIMD());
 	return 0;
 }