Specifically when we are in non-uniform control flow, as we would need
to set the condition for the last instruction. If (for example) a
image atomic load stores directly their value on a NIR register,
last_inst would be a nop, and would fail when set the condition.
Fixes piglit test:
spec/glsl-es-3.10/execution/cs-ssbo-atomic-if-else-2.shader_test
Fixes: 6281f26f06 ("v3d: Add support for shader_image_load_store.")
v2: (Changes suggested by Eric Anholt)
* Cover all sig.ld* signals, not just ldunif and ldtmu, as all of
them have the same restriction.
* Update comment explaining why we add a MOV in that case
* Tweak commit message.
v3:
* Drop extra set of parens (Eric)
* Add missing ld signal to is_ld_signal to fix shader-db regression.
Reviewed-by: Eric Anholt <eric@anholt.net>
b4bc59e37e