nir: Look up the shader when printing a single instruction.

If you've inserted the instruction into a block, then we can get to the
shader.  This improves our instruction output, giving you i/o semantics
and variable names in intrinsics.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6496>

src/compiler/nir/nir_print.c

@@ -1586,6 +1586,11 @@ nir_print_instr(const nir_instr *instr, FILE *fp)
    print_state state = {
       .fp = fp,
    };
+   if (instr->block) {
+      nir_function_impl *impl = nir_cf_node_get_function(&instr->block->cf_node);
+      state.shader = impl->function->shader;
+   }
+
    print_instr(instr, &state, 0);
 
 }