Add Arm SVE build flags and run-time CPU feature detection

Add 'sve' arch options to the configure, build and unit test files -
adding appropriate conditional options where necessary. Arm SIMD
extensions are treated as supersets in libvpx, so disable SVE if
either Neon DotProd or I8MM are unavailable.

Change-Id: I39dd24f2b209251084d1e28d7ac68099460309bb

build/make/Makefile

@@ -148,6 +148,8 @@ $(BUILD_PFX)%_neon_dotprod.c.d: CFLAGS += -march=armv8.2-a+dotprod
 $(BUILD_PFX)%_neon_dotprod.c.o: CFLAGS += -march=armv8.2-a+dotprod
 $(BUILD_PFX)%_neon_i8mm.c.d: CFLAGS += -march=armv8.2-a+dotprod+i8mm
 $(BUILD_PFX)%_neon_i8mm.c.o: CFLAGS += -march=armv8.2-a+dotprod+i8mm
+$(BUILD_PFX)%_sve.c.d: CFLAGS += -march=armv8.2-a+dotprod+i8mm+sve
+$(BUILD_PFX)%_sve.c.o: CFLAGS += -march=armv8.2-a+dotprod+i8mm+sve
 
 # POWER
 $(BUILD_PFX)%_vsx.c.d: CFLAGS += -maltivec -mvsx

build/make/rtcd.pl

@@ -487,7 +487,7 @@ ()
   @ALL_ARCHS = filter(qw/neon_asm neon/);
   arm;
 } elsif ($opts{arch} eq 'armv8' || $opts{arch} eq 'arm64' ) {
-  @ALL_ARCHS = filter(qw/neon neon_dotprod neon_i8mm/);
+  @ALL_ARCHS = filter(qw/neon neon_dotprod neon_i8mm sve/);
   @REQUIRES = filter(qw/neon/);
   &require(@REQUIRES);
   arm;

configure

@@ -257,6 +257,7 @@ ARCH_EXT_LIST_AARCH64="
     neon
     neon_dotprod
     neon_i8mm
+    sve
 "
 
 ARCH_EXT_LIST_X86="

test/init_vpx_test.cc

@@ -54,6 +54,9 @@ void init_vpx_test() {
   if (!(caps & HAS_NEON_I8MM)) {
     append_negative_gtest_filter(":NEON_I8MM.*:NEON_I8MM/*");
   }
+  if (!(caps & HAS_SVE)) {
+    append_negative_gtest_filter(":SVE.*:SVE/*");
+  }
 #elif VPX_ARCH_ARM
   const int caps = arm_cpu_caps();
   if (!(caps & HAS_NEON)) append_negative_gtest_filter(":NEON.*:NEON/*");

vpx_ports/aarch64_cpudetect.c

@@ -77,7 +77,7 @@ static int arm_get_cpu_caps(void) {
   }
 #endif  // defined(PF_ARM_V82_DP_INSTRUCTIONS_AVAILABLE)
 #endif  // HAVE_NEON_DOTPROD
-  // No I8MM feature detection available on Windows at time of writing.
+  // No I8MM or SVE feature detection available on Windows at time of writing.
   return flags;
 }
 
@@ -98,6 +98,7 @@ static int arm_get_cpu_caps(void) {
 // Define hwcap values ourselves: building with an old auxv header where these
 // hwcap values are not defined should not prevent features from being enabled.
 #define VPX_AARCH64_HWCAP_ASIMDDP (1 << 20)
+#define VPX_AARCH64_HWCAP_SVE (1 << 22)
 #define VPX_AARCH64_HWCAP2_I8MM (1 << 13)
 
 static int arm_get_cpu_caps(void) {
@@ -117,6 +118,11 @@ static int arm_get_cpu_caps(void) {
     flags |= HAS_NEON_I8MM;
   }
 #endif  // HAVE_NEON_I8MM
+#if HAVE_SVE
+  if (hwcap & VPX_AARCH64_HWCAP_SVE) {
+    flags |= HAS_SVE;
+  }
+#endif  // HAVE_SVE
   return flags;
 }
 
@@ -129,6 +135,10 @@ static int arm_get_cpu_caps(void) {
 #ifndef ZX_ARM64_FEATURE_ISA_I8MM
 #define ZX_ARM64_FEATURE_ISA_I8MM ((uint32_t)(1u << 19))
 #endif
+// Added in https://fuchsia-review.googlesource.com/c/fuchsia/+/895083.
+#ifndef ZX_ARM64_FEATURE_ISA_SVE
+#define ZX_ARM64_FEATURE_ISA_SVE ((uint32_t)(1u << 20))
+#endif
 
 static int arm_get_cpu_caps(void) {
   int flags = 0;
@@ -150,6 +160,11 @@ static int arm_get_cpu_caps(void) {
     flags |= HAS_NEON_I8MM;
   }
 #endif  // HAVE_NEON_I8MM
+#if HAVE_SVE
+  if (features & ZX_ARM64_FEATURE_ISA_SVE) {
+    flags |= HAS_SVE;
+  }
+#endif  // HAVE_SVE
   return flags;
 }
 
@@ -170,5 +185,13 @@ int arm_cpu_caps(void) {
     flags &= ~HAS_NEON_I8MM;
   }
 
+  // Restrict flags: FEAT_SVE assumes that FEAT_{DotProd,I8MM} are available.
+  if (!(flags & HAS_NEON_DOTPROD)) {
+    flags &= ~HAS_SVE;
+  }
+  if (!(flags & HAS_NEON_I8MM)) {
+    flags &= ~HAS_SVE;
+  }
+
   return flags;
 }

vpx_ports/arm.h

@@ -23,6 +23,8 @@ extern "C" {
 #define HAS_NEON_DOTPROD (1 << 1)
 // Armv8.2-A optional Neon i8mm instructions, mandatory from Armv8.6-A.
 #define HAS_NEON_I8MM (1 << 2)
+// Armv8.2-A optional SVE instructions, mandatory from Armv9.0-A.
+#define HAS_SVE (1 << 3)
 
 int arm_cpu_caps(void);