Shader.DebugInfo.100 DebugGlobalVariable using DebugExpression

[spencer-lunarg]

In the DebugGlobalVariable spec it says

Variable can hold two kinds of values. First it can hold the of the source global variable or constant that is described by this instruction. If the variable is optimized out, this operand can be the of a DebugExpression instruction that contains the constant value of the variable that was optimized out. Otherwise this operand must be DebugInfoNone.

I was trying to find an example of it using DebugExpression, but looking at spirv-val it doesn't even allow DebugExpression, it only allows

• OpVariable result ID
• DebugInfoNone
• OpConstant (and variants)

So not sure if the spec is wrong or spirv-val

cc @dnovillo as you are probably knee deep in this stuff

[spencer-lunarg]

ok, figured it out, in OpenCL.DebugInfo.100.html#DebugGlobalVariable it was

Variable is the of the source global variable or constant that is described by this instruction. If the variable is optimized out, this operand must be DebugInfoNone.

so this means spirv-val is wrong here, it should not allow an OpConstant if using Shader.DebugInfo and force a DebugExpression

[dnovillo]

ok, figured it out, in OpenCL.DebugInfo.100.html#DebugGlobalVariable it was

Variable is the of the source global variable or constant that is described by this instruction. If the variable is optimized out, this operand must be DebugInfoNone.

so this means spirv-val is wrong here, it should not allow an OpConstant if using Shader.DebugInfo and force a DebugExpression

Yes. I think spirv-val should allow a DebugExpression here for NSDI. I am not actually sure if the traditional DebugInfo spec has DebugExpressions. I'm mostly familiar with NSDI.