In my application I use single-channel signed integer texture of the format R16I to store data. Attempting to use imageAtomicAdd() on the image the texture is bound to fails, with debug output as:
Compute shader failed to compile with the following errors:
ERROR: 0:23: error(#370) Missing or invalid layout qualifier for image variable
ERROR: error(#273) 1 compilation errors. No code generated
(Apologies, I don't know how to format text as code here).
Changing the format in the layout() to r32i or removing the imageAtomicAdd() use results in a successful compilation.
As far as I can read in the OpenGL specification, there is no restriction on imageAtomicAdd() (or any other image functions) based on format.
Basic test shader:
#version 430 core
layout(binding = 1, r16i) uniform iimage2D sampleTexture; //fail
//layout(binding =1, r32i) uniform iimage2D sampleTexture; //success
ivec2 pix = ivec2(gl_GlobalInvocationID.xy);
imageAtomicAdd(sampleTexture, pix, 1); //if this is commented out/removed, success