nir: Return progress from nir_move_vec_src_uses_to_dest().

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/compiler/nir/nir.h

@@ -2397,7 +2397,7 @@ bool nir_remove_dead_variables(nir_shader *shader, nir_variable_mode modes);
 bool nir_lower_constant_initializers(nir_shader *shader,
                                      nir_variable_mode modes);
 
-void nir_move_vec_src_uses_to_dest(nir_shader *shader);
+bool nir_move_vec_src_uses_to_dest(nir_shader *shader);
 bool nir_lower_vec_to_movs(nir_shader *shader);
 bool nir_lower_alu_to_scalar(nir_shader *shader);
 bool nir_lower_load_const_to_scalar(nir_shader *shader);

src/compiler/nir/nir_move_vec_src_uses_to_dest.c

@@ -64,6 +64,8 @@ ssa_def_dominates_instr(nir_ssa_def *def, nir_instr *instr)
 static bool
 move_vec_src_uses_to_dest_block(nir_block *block)
 {
+   bool progress = false;
+
    nir_foreach_instr(instr, block) {
       if (instr->type != nir_instr_type_alu)
          continue;
@@ -167,34 +169,44 @@ move_vec_src_uses_to_dest_block(nir_block *block)
                   continue;
 
                use_alu_src->swizzle[j] = swizzle[use_alu_src->swizzle[j]];
+               progress = true;
             }
          }
       }
    }
 
-   return true;
+   return progress;
 }
 
-static void
+static bool
 nir_move_vec_src_uses_to_dest_impl(nir_shader *shader, nir_function_impl *impl)
 {
+   bool progress = false;
+
    nir_metadata_require(impl, nir_metadata_dominance);
 
    nir_index_instrs(impl);
 
    nir_foreach_block(block, impl) {
-      move_vec_src_uses_to_dest_block(block);
+      progress |= move_vec_src_uses_to_dest_block(block);
    }
 
    nir_metadata_preserve(impl, nir_metadata_block_index |
                                nir_metadata_dominance);
+
+   return progress;
 }
 
-void
+bool
 nir_move_vec_src_uses_to_dest(nir_shader *shader)
 {
+   bool progress = false;
+
    nir_foreach_function(function, shader) {
       if (function->impl)
-         nir_move_vec_src_uses_to_dest_impl(shader, function->impl);
+         progress |= nir_move_vec_src_uses_to_dest_impl(shader,
+                                                        function->impl);
    }
+
+   return progress;
 }