I've almost gotten atomics work in spv-in, but then stumbled upon the fact that generating new types ruins the guarantee that IR has that a dependent type always shows up before the parent... So I'm going to drop spv-in from this PR and leave it for a follow-up.
For future reference, here is GLSL example for spv parsing:

#version 310 es

layout(local_size_x = 64) in;

// Persistent LIFO structure with a count of elements
layout(std430, binding = 0) restrict buffer SMyBuffer
{
    int count;
    float data[];
} MyBuffer;

void main()
{
    for (uint i = gl_GlobalInvocationID.x; i < 20U; i += gl_WorkGroupSize.x)
    {
            int dataIndex = atomicAdd(MyBuffer.count, 1);
            MyBuffer.data[dataIndex] = float(i);
    }
}

I think this review is amazing, thank you!
I addressed everything that I felt needed to be addressed.