Most SPIR-V validation can be divided into two groups, Standalone and Runtime.
Standalone are things caught in spirv-val because it's invalid SPIR-V. For example, trying to use a OpTypeFloat in your OpUDiv integer divide.
Runtime are things that need API information. For example, using an instruction without the required Vulkan feature.
There is a 3rd group that, while small, doesn't quite fall into neither. A simple example is dividing an integer by zero. The spirv-v spec says
Behavior is undefined if Operand 2 is 0.
spirv-val won't validate this, even if using a constant, because SPIR-V is valid and might not be ran. It doesn't make sense to mark this as Runtime in the sense it has nothing to do with the Vulkan API.
For these, we use the term Sanitizer!
The idea of Shader Sanitization is a way to group these types of checks that need to be done in VVL. They all have 2 parts:
- In core validation we will check cases where using
OpConstant, we can detect potential issues and raise a warning. - In GPU-AV we will inject a check and report an error if, and only if, the invalid code is actually executed.