Windows ARM I8MM detection

[edgchen1]

On my Windows ARM device, cpuinfo_has_arm_i8mm() returns false but the value of ID_AA64ISAR1_EL1 indicates that I8MM is supported.

From a look at the code, I did not see where cpuinfo_isa.i8mm gets set in the Windows ARM code path.

cpuinfo/src/arm/windows/init.c

Lines 189 to 219 in b73ae6c

	static void set_cpuinfo_isa_fields(void) {
	cpuinfo_isa.atomics = IsProcessorFeaturePresent(PF_ARM_V81_ATOMIC_INSTRUCTIONS_AVAILABLE) != 0;
	const bool dotprod = IsProcessorFeaturePresent(PF_ARM_V82_DP_INSTRUCTIONS_AVAILABLE) != 0;
	cpuinfo_isa.dot = dotprod;
	SYSTEM_INFO system_info;
	GetSystemInfo(&system_info);
	switch (system_info.wProcessorLevel) {
	case 0x803: // Kryo 385 Silver (Snapdragon 850)
	cpuinfo_isa.fp16arith = dotprod;
	cpuinfo_isa.rdm = dotprod;
	break;
	default:
	// Assume that Dot Product support implies FP16
	// arithmetics and RDM support. ARM manuals don't
	// guarantee that, but it holds in practice.
	cpuinfo_isa.fp16arith = dotprod;
	cpuinfo_isa.rdm = dotprod;
	break;
	}
	/* Windows API reports all or nothing for cryptographic instructions. */
	const bool crypto = IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE) != 0;
	cpuinfo_isa.aes = crypto;
	cpuinfo_isa.sha1 = crypto;
	cpuinfo_isa.sha2 = crypto;
	cpuinfo_isa.pmull = crypto;
	cpuinfo_isa.crc32 = IsProcessorFeaturePresent(PF_ARM_V8_CRC32_INSTRUCTIONS_AVAILABLE) != 0;
	}

Is I8MM detection implemented for Windows ARM?

[digantdesai]

You are right, it doesn't look like it. Do you want to create a PR?