Vulkan F16 shader calculations support on G76/G78 GPUs

Hi! Half a year later, I'm back with the same question, albeit regarding Vulkan :)

We're developing for G76/G78 devices, such as Note 8 Pro or Samsung S20FE, and we're unable to see any effect of F16 support on any of our Mali GPUs. By effects, I mean even intentional half overflows in shader calculations don't show any artifacts on Mali GPUs, while they do show up on Adreno and desktop hardware. There's no effect on performance, with or without F16 extensions.

Here's how we create the VkDevice:

	VkPhysicalDeviceFeatures deviceFeatures = {};
	deviceFeatures.imageCubeArray = true;
	deviceFeatures.independentBlend = true;
	
    devCreateInfo.pEnabledFeatures = &deviceFeatures;
    devCreateInfo.enabledLayerCount = 0;
    devCreateInfo.ppEnabledExtensionNames = deviceExtensions.data();
    devCreateInfo.enabledExtensionCount = (uint32_t)deviceExtensions.size();

	VkPhysicalDeviceFloat16Int8FeaturesKHR float16Features = { VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_FLOAT16_INT8_FEATURES_KHR };
	float16Features.shaderFloat16 = true;

	devCreateInfo.pNext = &float16Features;

	VK_CALL( vkCreateDevice( physDevice, &devCreateInfo, nullptr, &m_device.device ) );

We also include VK_KHR_shader_float16_int8 into ppEnabledExtensionNames.

What's strange, while the GLES extensions app reports support for VK_KHR_shader_float16_int8 extension, when we capture and replay RenderDoc captures on Mali hardware, RenderDoc fails on replay, stating that VK_KHR_shader_float16_int8 is not supported. We've also tried forcing the compiler to use RelaxedPrecision decorations, but this didn't produce any visual results.

Can you please clarify:

• Are F16 calculations supported on G76/G78 hardware?
• If they are, what is the correct way to enable F16 support for Mali?
• If there's a way; for SPIR-V, what does driver look for, float16_t types or RelaxedPrecision decorations?
• Should F16 overflows be even visible on Mali GPUs or there's some internal handling of such situations e.g clamping, which could be why we can't see overflow artefacts on Mali GPUs?
• I don't know if this is a secret information, but generally, do vendors receive drivers as part of some kind of hardware support packages, and as such, we can expect identical feature sets for different vendors on same hardware (e.g, Xiaomi and Samsung releasing phones on same SoC) ? Or from time to time vendors can (and did) choose to block specific features, such as F16?