ARM64: Detect some arm features and let LLVM know if they are or aren't present via attributes

- On x86, LLVM has robust detection for the CPU name. If a CPU like skylake has AVX disabled, it will fall back to something without AVX (nehalem)
- On ARM, detection is not as robust. For instance, on my snapdragon 8 gen 2, it assumes that we have SVE support, as the cortex-x3 supports SVE.
- If an ARM cpu is paired with other cpus from another generation which doesn't support the same instructions as the cortex-x3, or if the cortex-x3 just has SVE disabled for no apparant reason (in the case of the snapdragon 8 gen 2)
- We need to actually detect that ourselves.
- Beyond SVE also detect support for some instructions that might be useful SPU LLVM when optimized with intrinsics.

Utilities/JITLLVM.cpp

@@ -688,6 +688,30 @@ jit_compiler::jit_compiler(const std::unordered_map<std::string, u64>& _link, co
 		mem = std::make_unique<MemoryManager1>(std::move(symbols_cement));
 	}
 
+	std::vector<std::string> attributes;
+
+#if defined(ARCH_ARM64)
+	if (utils::has_sha3())
+		attributes.push_back("+sha3");
+	else
+		attributes.push_back("-sha3");
+
+	if (utils::has_dotprod())
+		attributes.push_back("+dotprod");
+	else
+		attributes.push_back("-dotprod");
+
+	if (utils::has_sve())
+		attributes.push_back("+sve");
+	else
+		attributes.push_back("-sve");
+
+	if (utils::has_sve2())
+		attributes.push_back("+sve2");
+	else
+		attributes.push_back("-sve2");
+#endif
+
 	{
 		m_engine.reset(llvm::EngineBuilder(std::move(null_mod))
 			.setErrorStr(&result)
@@ -699,6 +723,7 @@ jit_compiler::jit_compiler(const std::unordered_map<std::string, u64>& _link, co
 			//.setCodeModel(llvm::CodeModel::Large)
 #endif
 			.setRelocationModel(llvm::Reloc::Model::PIC_)
+			.setMAttrs(attributes)
 			.setMCPU(m_cpu)
 			.create());
 	}

rpcs3/util/sysinfo.cpp

@@ -16,9 +16,15 @@
 #else
 #include <unistd.h>
 #include <sys/resource.h>
-#ifndef __APPLE__
+#ifdef __APPLE__
+#include <sys/sysctl.h>
+#else
 #include <sys/utsname.h>
 #include <errno.h>
+#if defined(ARCH_ARM64) && defined(__linux__)
+#include <sys/auxv.h>
+#include <asm/hwcap.h>
+#endif
 #endif
 #endif
 
@@ -444,6 +450,100 @@ u32 utils::get_rep_movsb_threshold()
 	return g_value;
 }
 
+#ifdef ARCH_ARM64
+
+bool utils::has_neon()
+{
+	static const bool g_value = []() -> bool
+	{
+#if defined(__linux__)
+		return (getauxval(AT_HWCAP) & HWCAP_ASIMD) != 0;
+#elif defined(__APPLE__)
+		int val = 0;
+		size_t len = sizeof(val);
+		sysctlbyname("hw.optional.AdvSIMD", &val, &len, nullptr, 0);
+		return val != 0;
+#elif defined(_WIN32)
+		return IsProcessorFeaturePresent(PF_ARM_VFP_32_REGISTERS_AVAILABLE) != 0;
+#endif
+	}();
+	return g_value;
+}
+
+bool utils::has_sha3()
+{
+	static const bool g_value = []() -> bool
+	{
+#if defined(__linux__)
+		return (getauxval(AT_HWCAP) & HWCAP_SHA3) != 0;
+#elif defined(__APPLE__)
+		int val = 0;
+		size_t len = sizeof(val);
+		sysctlbyname("hw.optional.arm.FEAT_SHA3", &val, &len, nullptr, 0);
+		return val != 0;
+#elif defined(_WIN32)
+		return IsProcessorFeaturePresent(PF_ARM_SHA3_INSTRUCTIONS_AVAILABLE) != 0;
+#endif
+	}();
+	return g_value;
+}
+
+bool utils::has_dotprod()
+{
+	static const bool g_value = []() -> bool
+	{
+#if defined(__linux__)
+		return (getauxval(AT_HWCAP) & HWCAP_ASIMDDP) != 0;
+#elif defined(__APPLE__)
+		int val = 0;
+		size_t len = sizeof(val);
+		sysctlbyname("hw.optional.arm.FEAT_DotProd", &val, &len, nullptr, 0);
+		return val != 0;
+#elif defined(_WIN32)
+		return IsProcessorFeaturePresent(PF_ARM_V82_DP_INSTRUCTIONS_AVAILABLE) != 0;
+#endif
+	}();
+	return g_value;
+}
+
+bool utils::has_sve()
+{
+	static const bool g_value = []() -> bool
+	{
+#if defined(__linux__)
+		return (getauxval(AT_HWCAP) & HWCAP_SVE) != 0;
+#elif defined(__APPLE__)
+		int val = 0;
+		size_t len = sizeof(val);
+		sysctlbyname("hw.optional.arm.FEAT_SVE", &val, &len, nullptr, 0);
+		return val != 0;
+#elif defined(_WIN32)
+		return IsProcessorFeaturePresent(PF_ARM_SVE_INSTRUCTIONS_AVAILABLE) != 0;
+#endif
+	}();
+	return g_value;
+}
+
+bool utils::has_sve2()
+{
+	static const bool g_value = []() -> bool
+	{
+#if defined(__linux__)
+		return (getauxval(AT_HWCAP2) & HWCAP2_SVE2) != 0;
+#elif defined(__APPLE__)
+		int val = 0;
+		size_t len = sizeof(val);
+		sysctlbyname("hw.optional.arm.FEAT_SVE2", &val, &len, nullptr, 0);
+		return val != 0;
+#elif defined(_WIN32)
+		return IsProcessorFeaturePresent(PF_ARM_SVE2_INSTRUCTIONS_AVAILABLE) != 0;
+#endif
+	}();
+	return g_value;
+}
+
+#endif
+
 std::string utils::get_cpu_brand()
 {
 #if defined(ARCH_X64)
@@ -496,6 +596,17 @@ std::string utils::get_system_info()
 	{
 		fmt::append(result, " | TSC: Disabled");
 	}
+#ifdef ARCH_ARM64
+
+	if (has_neon())
+	{
+		result += " | Neon";
+	}
+	else
+	{
+		fmt::throw_exception("Neon support not present");
+	}
+#else
 
 	if (has_avx())
 	{
@@ -562,6 +673,7 @@ std::string utils::get_system_info()
 	{
 		result += " | TSX disabled via microcode";
 	}
+#endif
 
 	return result;
 }

rpcs3/util/sysinfo.hpp

@@ -54,7 +54,17 @@ namespace utils
 	bool has_appropriate_um_wait();
 
 	bool has_um_wait();
+#ifdef ARCH_ARM64
+	bool has_neon();
 
+	bool has_sha3();
+
+	bool has_dotprod();
+
+	bool has_sve();
+
+	bool has_sve2();
+#endif
 	std::string get_cpu_brand();
 
 	std::string get_system_info();