riscv64: add compile support

This patch is a basic enablement that supports riscv64 compile.
We are working on adding vector optimizations with riscv64 rvv
extensions, and will push the implementations later.

Makefile

@@ -194,6 +194,25 @@ endif
 OBJCHK += tools/checkasm-aarch64.o
 endif
 
+# RISCV64 RVV optims
+ifeq ($(SYS_ARCH),RISCV64)
+ifneq ($(findstring HAVE_RVV 1, $(CONFIG)),)
+SRCASM_X =
+
+SRCS_X  +=
+
+OBJASM +=
+ifneq ($(findstring HAVE_BITDEPTH8 1, $(CONFIG)),)
+OBJASM += $(SRCASM_X:%.S=%-8.o)
+endif
+ifneq ($(findstring HAVE_BITDEPTH10 1, $(CONFIG)),)
+OBJASM += $(SRCASM_X:%.S=%-10.o)
+endif
+
+OBJCHK +=
+endif
+endif
+
 # MSA optims
 ifeq ($(SYS_ARCH),MIPS)
 ifneq ($(findstring HAVE_MSA 1, $(CONFIG)),)

common/cpu.c

@@ -99,6 +99,8 @@ const x264_cpu_name_t x264_cpu_names[] =
     {"I8MM",            X264_CPU_I8MM},
     {"SVE",             X264_CPU_SVE},
     {"SVE2",            X264_CPU_SVE2},
+#elif ARCH_RISCV64
+    {"RVV",             X264_CPU_RVV},
 #elif ARCH_MIPS
     {"MSA",             X264_CPU_MSA},
 #elif ARCH_LOONGARCH
@@ -459,6 +461,28 @@ uint32_t x264_cpu_detect( void )
     return flags;
 }
 
+#elif HAVE_RISCV64
+
+#define HWCAP_RISCV64_RVV     (1 << ('V' - 'A'))
+
+uint32_t x264_cpu_detect( void )
+{
+    uint32_t flags = 0;
+
+#if HAVE_GETAUXVAL || HAVE_ELF_AUX_INFO
+    unsigned long hwcap = x264_getauxval( AT_HWCAP );
+
+    if ( hwcap & HWCAP_RISCV64_RVV )
+        flags |= X264_CPU_RVV;
+#else
+#if HAVE_RVV
+    flags |= X264_CPU_RVV;
+#endif
+#endif
+
+    return flags;
+}
+
 #elif HAVE_AARCH64
 
 #if defined(__linux__) || HAVE_ELF_AUX_INFO

config.guess

@@ -882,6 +882,9 @@ EOF
 	UNAME_MACHINE=aarch64_be
 	echo ${UNAME_MACHINE}-unknown-linux-gnu
 	exit ;;
+    riscv64:Linux:*:*)
+	echo ${UNAME_MACHINE}-unknown-linux-gnu
+	exit ;;
     alpha:Linux:*:*)
 	case `sed -n '/^cpu model/s/^.*: \(.*\)/\1/p' < /proc/cpuinfo` in
 	  EV5)   UNAME_MACHINE=alphaev5 ;;

config.sub

@@ -255,6 +255,7 @@ case $basic_machine in
 	# Some are omitted here because they have special meanings below.
 	1750a | 580 \
 	| a29k \
+	| riscv64 \
 	| aarch64 | aarch64_be | arm64 \
 	| alpha | alphaev[4-8] | alphaev56 | alphaev6[78] | alphapca5[67] \
 	| alpha64 | alpha64ev[4-8] | alpha64ev56 | alpha64ev6[78] | alpha64pca5[67] \
@@ -370,6 +371,7 @@ case $basic_machine in
 	# Recognize the basic CPU types with company name.
 	580-* \
 	| a29k-* \
+	| riscv64-* \
 	| aarch64-* | aarch64_be-* | arm64*-* \
 	| alpha-* | alphaev[4-8]-* | alphaev56-* | alphaev6[78]-* \
 	| alpha64-* | alpha64ev[4-8]-* | alpha64ev56-* | alpha64ev6[78]-* \

configure

@@ -426,6 +426,7 @@ CONFIG_HAVE="MALLOC_H ALTIVEC ALTIVEC_H MMX ARMV6 ARMV6T2 NEON AARCH64 BEOSTHREA
              MSA LSX MMAP WINRT VSX ARM_INLINE_ASM STRTOK_R CLOCK_GETTIME BITDEPTH8 BITDEPTH10 ELF_AUX_INFO GETAUXVAL \
              SYSCONF SYNC_FETCH_AND_ADD \
              DOTPROD I8MM SVE SVE2 \
+             RISCV64 RVV \
              AS_ARCHEXT_DOTPROD_DIRECTIVE AS_ARCHEXT_I8MM_DIRECTIVE AS_ARCHEXT_SVE_DIRECTIVE AS_ARCHEXT_SVE2_DIRECTIVE"
 
 # parse options
@@ -885,6 +886,12 @@ case $host_cpu in
             AS="${AS-${CC}}"
         fi
         ;;
+    riscv64)
+        ARCH="RISCV64"
+        stack_alignment=16
+
+        AS="${AS-${CC}}"
+        ;;
     s390|s390x)
         ARCH="S390"
         ;;
@@ -1076,6 +1083,15 @@ if [ $asm = auto -a $ARCH = MIPS ] ; then
     fi
 fi
 
+if [ $asm = auto -a $ARCH = RISCV64 ] ; then
+    define HAVE_RISCV64
+    if cc_check '' '' '__asm__(".option arch, +v\n" "vsetvli t0, a0, e32, m1, ta, ma");' ; then
+        define HAVE_RVV
+    fi
+
+    ASFLAGS="$ASFLAGS -c"
+fi
+
 if [ $asm = auto -a $ARCH = LOONGARCH ] ; then
     if cc_check '' '' '__asm__("xvadd.b $xr0, $xr1, $xr2");' ; then
         # Use HAVE_LSX as the base flag, compiler support LA SIMD(LSX and LASX)
@@ -1750,7 +1766,7 @@ cat conftest.log >> config.log
 cat conftest.log
 
 [ "$SRCPATH" != "." ] && ln -sf ${SRCPATH}/Makefile ./Makefile
-mkdir -p common/{aarch64,arm,mips,ppc,x86,loongarch} encoder extras filters/video input output tools
+mkdir -p common/{aarch64,arm,mips,ppc,x86,loongarch,riscv64} encoder extras filters/video input output tools
 
 echo
 echo "You can run 'make' or 'make fprofiled' now."

tools/checkasm.c

@@ -115,6 +115,8 @@ static inline uint32_t read_time(void)
     uint64_t b = 0;
     asm volatile( "mrs %0, pmccntr_el0" : "=r"(b) :: "memory" );
     a = b;
+#elif ARCH_RISCV64
+    asm volatile( "rdtime %0" : "=r"(a) :: "memory" );
 #elif ARCH_MIPS
     asm volatile( "rdhwr %0, $2" : "=r"(a) :: "memory" );
 #elif ARCH_LOONGARCH
@@ -220,6 +222,8 @@ static void print_bench(void)
                     b->cpu&X264_CPU_DOTPROD ? "dotprod" :
                     b->cpu&X264_CPU_NEON ? "neon" :
                     b->cpu&X264_CPU_ARMV8 ? "armv8" :
+#elif ARCH_RISCV64
+                    b->cpu&X264_CPU_RVV ? "rvv" :
 #elif ARCH_MIPS
                     b->cpu&X264_CPU_MSA ? "msa" :
 #elif ARCH_LOONGARCH
@@ -276,6 +280,10 @@ intptr_t x264_checkasm_call_noneon( intptr_t (*func)(), int *ok, ... );
 intptr_t (*x264_checkasm_call)( intptr_t (*func)(), int *ok, ... ) = x264_checkasm_call_noneon;
 #endif
 
+#if ARCH_RISCV64
+intptr_t x264_checkasm_call( intptr_t (*func)(), int *ok, ... );
+#endif
+
 #if ARCH_LOONGARCH
 intptr_t x264_checkasm_call( intptr_t (*func)(), int *ok, ... );
 #endif
@@ -3014,6 +3022,9 @@ static int check_all_flags( void )
         ret |= add_flags( &cpu0, &cpu1, X264_CPU_SVE2, buf );
     }
 #endif
+#elif ARCH_RISCV64
+    if( cpu_detect & X264_CPU_RVV )
+        ret |= add_flags( &cpu0, &cpu1, X264_CPU_RVV, "RVV" );
 #elif ARCH_MIPS
     if( cpu_detect & X264_CPU_MSA )
         ret |= add_flags( &cpu0, &cpu1, X264_CPU_MSA, "MSA" );
@@ -3035,7 +3046,7 @@ REALIGN_STACK int main( int argc, char **argv )
 
     if( argc > 1 && !strncmp( argv[1], "--bench", 7 ) )
     {
-#if !ARCH_X86 && !ARCH_X86_64 && !ARCH_PPC && !ARCH_ARM && !ARCH_AARCH64 && !ARCH_MIPS && !ARCH_LOONGARCH
+#if !ARCH_X86 && !ARCH_X86_64 && !ARCH_PPC && !ARCH_ARM && !ARCH_AARCH64 && !ARCH_MIPS && !ARCH_LOONGARCH && !ARCH_RISCV64
         fprintf( stderr, "no --bench for your cpu until you port rdtsc\n" );
         return 1;
 #endif

x264.h

@@ -182,6 +182,9 @@ typedef struct x264_nal_t
 #define X264_CPU_DOTPROD         0x0000040U  /* AArch64 DotProd */
 #define X264_CPU_I8MM            0x0000080U  /* AArch64 I8MM */
 
+/* RISCV64 */
+#define X264_CPU_RVV             0x0000001U  /* RISCV64 RVV */
+
 /* MIPS */
 #define X264_CPU_MSA             0x0000001U  /* MIPS MSA */